Reducing Potential Impact of Invasive Marine Species in the
Northwestern Hawaiian Islands Marine National Monument
Scott Godwin, Ku‘ulei S. Rodgers and Paul L. Jokiel
Hawai‘i Coral Reef Assessment and Monitoring Program (CRAMP)
Hawai‘i Institute of Marine Biology
P.O. Box 1346
Kane‘ohe, HI 96744
Phone: 808-236-7440
e-mail: lgodwin@hawaii.edu
Report to:
Northwest Hawaiian Islands Marine National Monument Administration
6600 Kalaniana‘ole Hwy. Suite 300
Honolulu, Hawai‘i 96825
This report available from the National Technical Information Service (NTIS)
(http://www.fedworld.gov/onow/) and from the Hawaii Coral Reef Assessment and
Monitoring Program (CRAMP) at http://cramp.wcc.hawaii.edu/
This research conducted under DOI, NOAA, National Ocean Service MOA 2005-008/6882
Amendment No. 001, “Research in Support of the NWHI Coral Reef Ecosystem Reserve, HIMB,
SOEST, UH Manoa” (Dr. Jo-Ann Leong, PI)
1
TABLE OF CONTENTS
List of Figures and Tables ...............................................................................................4
0.0 Conclusions and Recommendations ...................................................................... 5-8
0.1 Conclusions ...........................................................................................................5
0.2 Recommendations .................................................................................................5
0.2.1 Transport Mechanisms.................................................................................... 5-7
0.2.2 Information Collection and Dissemination..................................................... 7-8
1.0 Introduction.......................................................................................................... 8-14
1.1 A Primer for Marine Non-indigenous Species Introductions ..............................8
1.1.1 Species Invasions – Natural and Anthropogenic ........................................9
1.1.2 Dynamics of Non- indigenous Species Introductions ........................... 9-12
1.1.3 Marine Non- indigenous Species Invasions ........................................ 12-14
2.0 Pathways and Mechanisms of Dispersal............................................................ 14-19
2.1 Natural ...............................................................................................................15
2.1.1 Larval Competence and Dispersal Range ........................................... 15-16
2.1.2 Natural Dispersal by Rafting ....................................................................16
2.1.3 Migration of Adults ..................................................................................16
2.1.3.1 Fishes...................................................................................... 16-17
2.1.3.2 Algae ............................................................................................17
2.1.3.3 Monk Seals ...................................................................................18
2.1.3.4 Green Sea Turtles................................................................... 18-19
2.2 Anthropogenic ............................................................................................. 19-27
2.2.1 Ship Movement.........................................................................................21
2.2.1.1 Ballast water .................................................................................21
2.2.1.2 Sediments .....................................................................................22
2.2.1.3 Hull Fouling ................................................................................23
2.2.2 Marine Debris Transport...........................................................................24
2.2.2.1 Bio fouling on Marine Debris ..........................................................24
2.2.2.2 Rafting of Organisms with Debris ..................................................25
2.2.3 Fisheries Activities and Other Pathways ............................................ 25-26
3.0 Marine Non- indigenous Species in the Hawaiian Archipelago ......................... 26-30
3.1 Marine Non- indigenous Species and the NWHI ......................................... 26-27
3.2 Fish ....................................................................................................................28
3.2.1 Introduction...............................................................................................28
3.2.2 Lutjanus kasmira ............................................................................... 28-29
3.2.3 Cephalopholis argus .......................................................................... 29-30
3.3 Invertebrates ................................................................................................ 30-34
3.3.1 Introduction................................................................................................30
3.3.2 Carijoa riisei ...................................................................................... 31-32
3.3.2 Chthamalus proteus ............................................................................ 32-34
3.4 Algae ............................................................................................................ 35-51
3.4.1 Introduction.......................................................................................... 35-36
3.4.2 Algal invasion patterns ........................................................................ 36-37
3.4.3 Growth rates...............................................................................................37
2
3.4.4 Means of dispersal............................................................................... 37-38
3.4.5 Spread .................................................................................................. 38-40
3.4.6 Ecological consequences ...........................................................................40
3.4.7 Hypnea musciformis ............................................................................41.43
3.4.7 Avrainvillea amadelpha ...................................................................... 43-45
3.4.8 Kappaphycus and Eucheuma spp ....................................................... 45-49
3.4.9 Acanthophora spicifera ...................................................................... 49-51
4.0 Management Options ........................................................................................ 51-58
4.1 Prevention...........................................................................................................51
4.1.1 Ballast Water ....................................................................................... 51-52
4.1.2 Sediments...................................................................................................52
4.1.3 Hull Fouling ......................................................................................... 52-54
4.1.4 Other Sources....................................................................................... 54-55
4.2 Legislation and Administrative Rules ........................................................ 55-56
4.3 Limitations and Information Needs ............................................................. 56-57
4.4 Eradication................................................................................................... 57-58
5.0 Literature Cited ................................................................................................. 58-66
3
LIST OF FIGURES AND TABLES
Figures
2.1.3.1-1. Biomass (%) and number of individual fishes (%) by endemic status ..............17
2.1.3.3-1. Female Hawaiian monk seal Monachus schauinslandi nursing pup at
Kalaupapa, Moloka‘i..........................................................................................................18
2.1.3.4-1. The green sea turtle Chelonia midas migrates extensively throughout
the archipelago ...............................................................................................................19
3.2.2-1. Blue-lined snapper (also known as Ta‘ape or Lutjanus kasmira) ........................28
3.2.3-1. The Peacock Grouper, Cephalopholis argus, introduced into Hawai‘i in
the 1950’s .....................................................................................................................29
3.3.1-1. The anemone Diadumene lineata ........................................................................31
3.3.2-1. The octocoral Carijoa riisei ................................................................................32
3.3.3-1. The barnacle Chthamalus proteus .......................................................................33
3.4.7-1. Hypnea musciformis ............................................................................................41
3.4.7-2. Current Distribution-Hypnea musciformis ..........................................................42
3.4.7-3. Mokumanamana (Necker Island), Northwestern Hawaiian Islands ....................43
3.4.8-1. Avrainvillea amadelpha .......................................................................................43
3.4.8-2. Current Distribution-Avrainvillea amadelpha .....................................................44
3.4.9-1. Kappaphycus .......................................................................................................45
3.4.9-2. Current Distribution-Kappaphycus ......................................................................46
3.4.10-1. Acanthophera spicifera ......................................................................................49
3.4.10-2. Current Distribution-Acanthophera spicifera ....................................................50
Tables
1.1.2-1. Scenarios for when Non-Indigenous Species invasions may occur .....................11
1.1.2-2. Theories for biological resistance to species invasions ........................................12
1.1.3-1. Examples of marine Non-Indigenous Species introductions worldwide..............13
2.2-1. Hawai‘ i Non-Indigenous Species introduction mechanisms for
marine invertebrates ................................................................................................20
3.1-1. Marine Non- indigenous Species in the NWHI ........................................................27
3.4.1-1. Partial list of macroalgae intentionally introduced to O‘ahu since 1950 .............36
4
0.0 Conclusions and Recommendations
0.1 Conclusions
• Populations of non- indigenous marine species that have already colonized areas
of the main Hawaiian Islands (MHI) represent the most likely source of invasive
species in the Northwest Hawaiian Islands (NWHI) based on the proximity and
pattern of ship movements associated with the MHI.
•
The non- indigenous marine macroalgae, invertebrates and fish that are currently
known from the MHI can be found from littoral zones to deep water coral beds.
The few alien species known from the NWHI are restricted to the anthropogenic
habitats of Midway Atoll and French Frigate Shoals. Only the marine hydroid
Pennaria disticha and the snapper Lutjanus kasmira are found throughout the
NWHI archipelago.
•
Formal and developing regulations on the national level, such as National Aquatic
Invasive Species Act 2005, provide guidelines for preventative measures for
ballast water but other mechanisms of non- indigenous species transport associated
with maritime activities, such as hull fouling, also exist and need attention.
•
Marine debris has been shown to have the ability to transport non- indigenous
species to the NWHI. Modes of transport suc h as derelict fish nets are problematic
to manage but the impact of other anthropogenic debris, such as Fish Attraction
Devices (FAD) deployed by the State of Hawai‘i, can be minimized.
0.2 Recommendations
0.2.1 Transport Mechanisms
•
•
Establish formal administrative rules and codes of conduct to minimize exposure
from the variety of potent ial transport mechanisms for non- invasive species
transport to the Northwestern Hawaiian Islands Marine National Monument.
Examples of these are as follows:
Ø Marine Debris (e.g. derelict fishing gear, derelict Fishing Aggregation
Devices or FAD’s)
Ø Maritime Vessels
§ Research Platforms (public sector, academic, private sector)
§
Personal Craft
§
Commercial Platforms (cargo, fisheries, cruise/ecotour ism)
§
Military (U.S. Navy, U. S. Coast Guard)
Ø Research and Conservation Activities
5
§
§
§
§
§
No release of any orga nism collected on another island
Proper storage and disposal of marine debris
No sand or soil transport
Inspection and cleaning of marine construction material
Inspection and sanitation of dive boats, SCUBA gear, and
instrument arrays prior to entry into the Northwestern Hawaiian
Islands Marine National Monument
Ø Fisheries Activities
§ No aquaculture or small scale rearing of algae, invertebrates or fish
§ No intentional introduc tions for any purpose
§ No disposal of bait or seafood
§ Sanitation of live wells and fishing gear prior to entry
•
Establish management strategy for transport mechanisms based on:
Ø Pro-active Measures
§
§
Monitoring: Strict monitoring of vessel traffic entering and
operating in the Northwestern Hawaiian Islands Marine National
Monument
Vectors:
Ballast Water and Sediments: Preventative measures to minimize transport
of non- invasive species by ballast water and sediments from source ports
to the Northwestern Hawaiian Islands Marine National Monument are as
follows:
1. Ballast water exchange in water deeper than 2000 m to flush out any
surviving organisms taken in at ports, if pre- intake measures are not in
place.
2. Pre-intake measures such as filtration, ultraviolet treatment, sonic
treatment, or other measures that exist.
3. Do not take in water from global hotspots where organisms that may
be a threat to the environment exist, such as from areas that are
experiencing toxic algal blooms or waterborne disease outbreaks.
4. Do not take in ballast water at night since a more diverse assemblage
of organisms may be present.
5. Avoid areas with high sedimentation or shallow waters, poor water
quality, or regions near sewage discharge.
6. Post-intake extermination of organisms with biodegradable chemicals,
heat, or electrical treatment.
7. Clean ballast tanks regularly and dispose of sediments properly.
8. Inspect deck surfaces and enclosed voids for sediment accumulations
and remove and dispose of properly.
6
Hull Fouling: In order to prevent trans fer of introduced species by vessel hull
fouling, the inspection of all vessels planning to enter the Northwestern
Hawaiian Islands Marine National Monument is imperative and should
include all surfaces at and below the waterline. Preventative measures for
vessels operating regularly in the Northwestern Hawaiian Islands Marine
National Monument should include:
1.
2.
3.
4.
Frequent underwater visual or video inspections
Proper maintenance
Regular cleanings at shipyards
Sea chest and piping time-released biocides
Ø Reactive Measures
§
Rapid Response: Form partnerships with other agencies to create a
core rapid response team that has the capacity to investigate a
variety of disturbances, to include non- indigenous species
introductions.
Ø Post Event Measures
§
Eradication: Altho ugh eradication in the marine environment is
problematic, devise scheme for attempts to eliminate a nonindigenous species introduction that has been discovered in its
early stages.
0.2.2 Information Collection and Dissemination
•
In order to preserve the integrity of the Northwestern Hawaiian Islands Marine
National Monument from the standpoint of marine non-indigenous species, there
are preventative and defensive measures that can be implemented to reduce the
risk of large-scale invasions. Many of these have been proven effective in other
regions.
1. Detect and eradicate introductions early before they have the
opportunity to spread
2. Prevention of accidental and deliberate introductions
3. Better understanding of current patterns and oceanographic conditions
that can favor or reduce dispersal and spread
4. Monitoring to assess changing conditions
5. Understanding dispersal patterns
6. Continue activities pertaining to species richness and diversity as part
of establishing baseline information, and pursue research pertaining to
biogeography focused on connectivity and larval transport
7. Include the issue of marine non- indigenous species in education and
outreach activities
7
8. Integrate the concepts of marine non- indigenous species and invasive
behavior into the mindset of monitoring and assessment activities
occurring in the NWHI.
§
§
§
Develop reference materials of potential species from baseline
MHI inventories
Provide reference materials of species established in NWHI
Recognize species (native and non- indigenous species) exhibiting
invasive behavior
1. INTRODUCTION
Marine habitats can be considered robust when dealing with gradual disturbances such as
climate change measured on a scale of thousands of years. When disturbances occur over
shorter time scales, marine communities can be severely disrupted. Such short time
frames and intense disturbances that are relevant to human society and the anthropogenic
effects induced on marine habitats. The introduction of non-native marine organisms is
one form of anthropogenic change that can cause irreversible alterations to marine
communities that has become of great concern. This document reviews and synthesizes
available information on the situation in the Northwestern Hawaiian Islands (NWHI) as
related to the Main Hawaiian Islands (MHI). The document is arranged into four
sections: First is a discussion of theories behind invasion ecology. The second covers
mechanisms of introduction of marine non-indigenous species. The third section is a
review of the present status of marine non- indigenous species in the Hawaiian
Archipelago and the fourth section covers management options.
1.1 A Primer for Marine Non-indigenous Species Invasions
The native species of the marine and terrestrial environments of Hawai‘i arrived as
natural biological events over a period of millions of years, and through evolution and
adaptation evolved into the present communities uniquely associated with the
archipelago. The islands of Hawai‘i are one of the most isolated areas in the world and all
native plants and animals are derived to the pioneering species that settled here through
natural mechanisms of dispersal. The advent of modern human technology has created a
means for biological introductions that readily overcome the vast geographical barriers
that formerly prevented invasions. Human activity has greatly accelerated the process of
biologic al change and in many cases new introductions have led to the depletion or
extinction of naturally occurring populations.
Presently, the world is experiencing great ecological change in the coastal marine
environments in every region. These areas that provide fisheries, recreation and aesthetic
value are being altered by biological invasions facilitated by anthropogenic mechanisms.
These invasions are decreasing biodiversity through the homogenization of distinctly
separate biological communities that have evolved over millions of years. To truly
understand the importance of these invasions by non-indigenous species, the species
invasion process must be understood.
8
1.1.1 Species Invasions – Natural and Anthropogenic
Over an evolutionary time scale ecosystems experience a variety of disturbances, such as
arrival of new species and climate change. Natural species invasions (i.e., range
expansions) and the resulting competition between species have established the
composition of distinct communities that exist at various locations across the globe.
Natural disturbances, such as storms, help maintain the diversity in ecosystems such as
coral reefs (Connell, 1978). Natural species introductions to new regions are rare on time
scales measured from the human perspective because of the immense geographic barriers
that must be overcome. In Hawai‘i’s marine environment, examples of these natural
barriers are the wide expanses of deep ocean, direction of currents and the distance from
continental land masses and other island groups. It is theorized that marine species that
colonized Hawai‘i before the presence of the first Polynesians arrived on flotsam such as
logs (Hedgepeth, 1993) and pumice stones (Jokiel, 1984 and 1990). However, these
natural species invasion events are very infrequent- on the order of thousands or millions
of years.
Invasions of non-indigenous species have occurred in terrestrial, freshwater and
marine habitats worldwide due to the deliberate or unintentional transport of organisms
throughout the world by humans. Anthropogenic introductions are much more prevalent
than natural events and have caused major changes in ecosystems over short spans of
time. Anthropogenic dispersal breaches the natural barriers that control the rate of
invasion in the natural world. A species can become invasive in a new region when it
escapes its normal predators competitors and diseases. In these situations the invasive
species can cause the reduction or local extinction of native species
1.1.2 Dynamics of non-indigenous species introductions
How important is the introduction of a new species to a region such as the NWHI? In the
realm of ecological research there is evidence that a single species can influence the
structure of entire communities. In the aquatic environment, research by Paine (1966)
helped to develop the theory of “keystone species” that showed the importance of a single
species in structuring a shoreline community. Another example by Estes and Palmisano
(1974) showed that the decline of sea otters in the Aleutian Islands led to population
explosions of sea urchins; a favored food of the otters; which in turn consumed and
reduced the kelp that forms the distinctive community in the region. Further experimental
evidence by Barkai and McQuaid (1988) in South Africa shows that two identical coastal
island communities differing only by the density of one particular species can be very
different. These are examples that show that the absence or lower occurrence of a single
species can completely change the balance of a natural community. A single species in a
naturally occurring community has great importance.
When the subject turns to a non-indigenous species introduction to a new region, a
single species can make a difference by altering the biotic and abiotic factors that control
a community. The extent and cumulative impacts of non- indigenous species introductions
around the world have been documented (Elton, 1958; Mooney and Drake, 1986;
Carlton, 1989) and could prove to be enormous. The effect of a single introduced species
is demonstrated well with freshwater shrimp that were stocked into Flathead Lake in
9
Glacier National Park, Montana, which reduced the salmon population through food
resource competition, in turn, reducing a major nutritional source for bald eagles
(Spencer et al., 1991). This is a case of an introduced species not represented at all in the
receiver environment. A terrestrial example is the tree Melaleuca that has invaded the
Florida Everglades (Ewel, 1986), which has the ability to change wetlands to forest. In
the Pacific, the Brown Tree Snake has invaded Guam, which has no native snakes, and it
has caused the extinction of native bird species (Savidge, 1987). These examples are
extreme cases of non-indigenous species that are not represented by identical or similar
species in the regions that they have invaded and have caused obvious ecosystem
changes.
Ecologists that study the process of biolo gical invasion still debate as to why some
species are successful invaders, while similar species are not. Natural communities are
made up of a number of coexisting species that utilize a common pool of resources. The
natural community theoretically utilizes its resources to their full extent. If a disturbance
such as a biological invasion occurs, the community could react in different ways. One
way would be the successful invasion of a species by its addition to the community and
its allocation of resources without denying other community members. Another outcome
would be the addition of a species and allocation of resources used by other community
members (i.e. out competing) causing local extinction of one, (or more) individuals. A
third outcome would be the failure of the biological invasion due to factors such as
unsuitability of resources and/or environment, and competition. These points only
describe, in theory, the outcomes of a natural or non- indigenous species invasion to a
natural community and do not allow prediction of success or failure in biological
invasions.
Many efforts have been made historically to introduce organisms for aesthetic or
economic reasons and these provide examples of the unpredictability of invasion success.
Of six species of serranid fishes (groupers and their relatives) purposely introduced to
Hawaiian waters for economic reasons in the 1950’s only one (Cephalopholis argus) was
successful, despite the fact that the serranid fauna in the area are not well represented (i.e.
no competition with similar species). The same case exists with four Lutjanidae (snapper)
species introduced during the same period, of which only two survived (Lutjanus kasmira
and Lutjanus fulvus) in a region where this group is poorly represented (Randall and
Kanayama 1972; Maciolek 1984). Another example is the house sparrow (Passer
domescticus), which occupied the entire United States only 50 years after it was
deliberately introduced for aesthetic reasons. The closely related tree sparrow (Passer
montanus) was also intentionally introduced but has not spread too far outside the
original area of introduction after over 100 years (Ehrlich, 1986).
Invasions (natural and non- indigenous species) occur for many reasons, but mainly
it can be attributed to the ease by which a species can colonize a new habitat. There has
been research into the topics of invasion success (Pimm, 1989; Carlton, 1996;
Williamson and Fitter, 1996) and resistance to invasion by a community (Case, 1991;
Baltz and Moyle, 1993; Trowbridge, 1995). Carlton (1996) proposed six scenarios
(Table. 1.1.2-1) to provide a framework for understanding when invasions will occur.
The scenarios assume that the successful establishment of a species is rarely related to
any one environmental parameter (Crawley, 1989). A successful non- indigenous species
10
invasion is a result of the compatibility of the needs of the invading organism and the
characteristics of the invaded habitat. Accurate prediction of successful non- indigenous
species invasion events has not been accomplished due to the fact that the factors
governing the process are complex, and not always obvious. Factors ranging from subtle
shifts in physical parameters such as temperature, salinity, and time of day combined
with unlimited unique variables of the donor and receiver regions make it difficult to
predict the outcome of non- indigenous species invasions. This being the case, organisms
capable of adapting to a variety of environmental parameters and possessing a high
reproductive rate would tend to have greater chance of invasion success.
Table 1.1.2-1. Scenarios for when non-indigenous species invasions may occur (Based on Carlton, 1996)
Phenomenon
Changes in donor region
New donor regions
Changes in recipient region
Invasion windows
Stochastic inoculation events
Dispersal vector changes
Process involved
Environmental changes in donor region lead to:
•
Population increases of resident species (pre-exist with
donor region) making more individuals available for
transport.
•
Range expansion of local species into previously
uninhabitable areas of donor region making these species
available for transport.
New introductions of non-indigenous species occur within donor
region:
•
New species available for transport
New donor regions become available
•
New species available for transport
•
New genomes with different adaptive regimes than
previously transported populations of the same species
from other donor regions become available for transport.
Any environmental changes in recipient region that lead to altered
ecological, biological, chemical, or physical states, thus changing
the susceptibility of the recipient region to invasion.
For example, altered water quality conditions lead to:
•
Increased ability of pollution-intolerant species to invade.
•
Increased ability of pollution-tolerant species to invade.
Invasions occur when the proper combination of colonizing
conditions occur followed by the proper combination of conditions
that permit the long term establishment of reproducing
populations. May or may not be dependent on changes in the
recipient region.
The release of a very large number of inoculants into the recipient
region, increasing potential reproductive success.
Vector size, speed, and quality increase lead to:
•
Increase in inoculant species diversity
•
Increase in abundance of inoculated species
•
Increase in number of post-transport 'fit' individuals
New vector emerges from same donor region
Organisms with more rigid requirements have also proven to be good invaders. An
organism could be adapted to specific predators and habitats and be introduced to an area
that is devoid of similar predators, has a lower degree of competitors, and available
habitat. So the deciding factor for invasion success would be the receiving habitat instead
of flexibility in the invader. The ideal example of this scenario is Spartina alterniflora,
11
Atlantic smooth cordgrass, which is the basis of the extensive saltmarsh habitats of the
North American Atlantic Coast. These saltmarsh habitats support a unique ecosystem that
is typically associated with this region, which can be contrasted with the mudflat habitats
of the Pacific Coast of North America. There are subtle similarities between these
systems but overall they are unique. Spartina has been introduced to the state of
Washington and has become a pest species that could potentially cause great harm as it
blankets the mudflats (Washington Sea Grant, 1998).
These points cover theories as to why a non- indigenous species introduction might
be successful but there are also theories regarding the failure of biological invasions.
Failure of a non- indigenous species to establish, despite seemingly suitable
environmental conditions, can theoretically be attributed to the biological resistance of
the receiving habitat. Table 1.1.2-2 shows the three common theories that support
biological resistance as a factor in preventing establishment of non- indigenous species.
Table 2. Theories for biological resistance to species invasions
§
Species-rich communities may be more resistant to invasions by introduced species than speciespoor communities (Elton, 1958; Diamond and Case, 1986; Case 1991)
§
Invading species from “sophisticated” biotas (with highly competitive and defensive abilities)
become established more frequently than species from “unsophisticated” biotas (Vermeij, 1991).
§
The presence of indigenous species ecologically and/or taxonomically similar to the invading
species may contribute to biotic or community resistance (Moulton and Pimm, 1984; Diamond
and Case, 1986; Baltz and Moyle, 1993).
The first theory has been repeatedly observed in stream fishes (Ross, 1991).
Continental species tend to invade island communities more successfully than the reverse
situation, which is an example of the second proposed theory. Diamond and Case (1986)
refer to communities that are “naïve” in relation to the third theory. This means that a
community has had no experience with similar species and is therefore easier to invade
by this “novel” species. These are theories to explain biotic resistance, although the
underlying mechanisms are not understood.
1.1.3 Marine Non-indigenous Species Invasions
In the terrestrial environment the issue of non- indigenous species invasion and control
has been dealt with as a management issue for some time. The concept of marine nonindigenous species is a relatively new issue, in comparison. In the Unites States,
awareness of marine non-indigenous species in the federal government and the scientific
community has increased more since the late 1980’s than in the past 30 years (Carlton,
1993). This can be attributed to the invasion of the Eurasian Zebra Mussel Dreissena
polymorpha, which was first collected in the Great Lakes in 1988 (Nalepa and
Schloesser, 1993). The Zebra Mussel has overwhelmed the benthic communities of the
Great Lakes but the economic impacts and not the ecological ramifications are what
brought it to the attention of public officials. The Zebra Mussel is a prolific fouling
12
organism in its new environment - the Great Lakes - and one of the consequences is the
clogging of cooling intakes of power plants.
Marine non- indigenous species invasions are a worldwide problem with economic
and ecological consequences. Table 1.1.3-1 gives a few examples of marine nonindigenous species invasions worldwide and includes potential and proven impacts.
These marine non-indigenous species demonstrate the variety of organisms that have
invaded coastal habitats due to anthropogenic facilitation. Maritime shipping activity is
blamed for the introduction of all the species listed, with the exception of the alga,
Caulerpa taxifola, which was accidentally released from the Monaco Aquarium.
Incidentally, Rapana venosa, which was discovered in the southern Chesapeake Bay in
1998 (Harding and Mann, 1999), was likely introduced from the Black Sea, where it is an
alien species introduced from Japan. Carcinus maenus and Asterias amurensis both are
likely to cause ecological changes, as epibenthic predators, in the areas in which they
have been introduced. Potamocorbula amurensis has become the most numerous benthic
invertebrate in its new habitat in San Francisco Bay and could cause drastic changes due
to its ability to filter out large quantities of plankton from the water column, thus
changing the base of the food chain in this habitat (Cohen and Carlton, 1995).
Table 1.1.3-1. Examples of marine non-indigenous species introductions worldwide.
Species
Area(s) and Date of
Introduction
Native Range
Impacts
Asterias amurensis
(sea star)
Australia(1980’s)
Japan, Korea
Negative impacts on the
shellfish industry and
local coastal ecology.
Carcinus maenus
(crab)
North America (late
1800’s-Atlantic coast,
1990’s-Pacific coast),
South Africa(1990’s),
Japan(1980’s),
Australia(early 20th
century)
Western Europe,
British Isles
Negative impacts on
shellfish industry and
local coastal ecology.
Caulerpa taxifola
(macroalgae)
Mediterranean(1980’s)
West Indies
San Francisco
Bay(1980’s)
Asia
North America-Atlantic
coast(1990’s)
Japan
Potamocorbula amurensis
(clam)
Rapana venosa
(snail)
Overgrowth of local
species and habitats with
impacts on local ecology.
Drastic change in local
ecosystem with unknown
long term effects.
Potential impacts to
shellfish industry with
unknown long term
ecosystem impacts.
Whether natural or anthropogenically facilitated, marine non- indigenous species
invasions are a complex issue. Presently, the world is experiencing great ecological
change in the coastal marine environments in every region. These areas are being altered
by biological invasions facilitated by anthropogenic mechanisms. The health of these
environments is crucial to the services and resources that provide a form of security to the
13
global community. There are many issues that effect the health of marine environments,
non- indigenous species invasions is one that has not historically been dealt with before.
Communication of the issue of marine non- indigenous species to individuals responsible
for decisions that affect the marine environment is the only way to prevent and control
further impacts from this disturbance.
2. PATHWAYS AND MECHANISMS OF DISPERSAL.
Lack of adaptive radiation in Hawaiian corals, fish and invertebrates and high rates of
endemism in marine fauna demonstrate isolation of the Hawaiian Archipelago from other
Pacific island groups. In Hawai‘i, genera containing multiple endemic species of marine
invertebrates (Kay and Palumbi, 1987) corals (Jokiel, 1987) and fishes (Hourigan and
Reese, 1987) seem to be derived from separate Indo-west Pacific species rather than
radiating from a common ancestor. Thus, on an evolutionary time scale the geographic
barriers between the different islands of the Hawaiian archipelago are insufficient to
isolate marine populations long enough to allow speciation. The Archipelago is severely
isolated from other islands of the Pacific so fish and invertebrates diverge into true
Hawaiian endemic species. Overall about 30% of invertebrates other than corals, 20% of
corals and 32% of nearshore fishes are endemic (Kay and Palumbi, 1987; Jokiel, 1987;
Hourigan and Reese, 1987). These observations are important because they suggest once
a species has gained a foothold in the Hawaiian Archipelago, it is only a matter of time
before natural means of dispersal will allow it to colonize suitable habitat in all of the
islands. Of course, the rate of spread can be accelerated by human activity.
Invasive species can be either intentionally or accidentally introduced through
many different pathways. The majority of intentional introductions are associated with
aquaculture or commercial fishing operations. Here in Hawai‘i, a number of species of
seaweed were introduced to assess their feasibility as an aquaculture product. Several
species of fishes were also intentionally introduced to enhance recreational fishing. A
sub-component of these intentional introductions is the epibiont and parasitic fauna
associated with the individual species or their shipment medium. Unintentional
introduction is the major mode that invasive species use to gain entry in most cases.
These accidental introductions can occur through attachment to ship hulls, in ballast
water, on anchors, seaplanes, or any floating object such as nets, buoys, or pumice. They
have also been associated with fishing and SCUBA gear. Introductions can even come in
with live seafood or its packing material that is improperly disposed of, or arrive as
hitchhikers in live bait wells. Historically, the hulls of wooden sailing ships facilitated the
transfer of wood-boring organisms, and sessile and mobile fauna were transported by dry
ballast. (Carlton and Hodder, 1995). The single largest ship related source of
introduction is through ballast water that is used by modern commercial vessels (Carlton,
1985). While over half of all North American invasions are associated with the shipping
industry (Ruiz et al. 2000), in Florida, the release of fresh and saltwater aquarium species
has been documented as the single most important means of introduction (Padilla and
Williams 2004).
The probability of success of an introduction is very low and most introductions
fail to establish and spread. It has been suggested by Williamson and Fritter’s “rule of
14
ten” (1996) that only one out of every ten introductions survive, only one tenth of these
become established and spread, and only a tenth of these become invasive.
There are several challenges facing introduced species once they have survived
the transport. They now must endure predators, hostile oceanic conditions, competition
for resources, and disease that may not have been present at their origin. Some predators
actually prefer introduced species. For some species that reproduce sexually, multiple
introductions are necessary to avoid low genetic variability.
Once an introduction becomes established, it may take some time before it
becomes invasive. This may be due to physiological adjustment to a different
environment, time needed for growth and expansion, the availability of resources, or
changes in environmental conditions. The ultimate success of an introduction depends
strongly on its reproductive strategy, its capability of adapting to new environments, and
its ability to compete for food and space.
2.1 Natural
Due to Hawai‘i’s extreme geographic isolation, few species arrived naturally. In the
terrestrial environment, only about 1,000 species of plants and animals formed the basis
for radiation of the Hawaiian endemic species. The rate of colonization was slow, only
one species per 70,000 years. Yet this same isolation and habitat diversity made Hawai‘i
the ideal place for speciation to occur. This is not the case in the marine environment
where there are fewer species (1-2 species in a genus) and a lower number of endemics
(approximately 20%) in contrast to the terrestrial environment (>90%). The distances
between island is not sufficient to isolate populations so that speciation can occur. Larval
dispersal and migration of organisms can bridge the gap between islands of the
archipelago. Niches in the inshore marine environment were filled by constant
immigration rather than by speciation.
The endemic biota of the Hawaiian Islands were severely isolated before the first
intentionally introduced alien arrived. This is believed to have been an oyster, which was
transplanted in Honolulu in 1866 and a species of salmon a decade later. Although
neither one survived, many more successful introductions were to follow. Yet although
aliens have become established worldwide and have been documented to compete with
native species, there are only two marine species that have become extinct in modern
times. Globally, the Caribbean monk seal and the North Atlantic limpet are the only
reported species to have vanished but this may be due to the lack of broad taxonomic
data.
2.1.1 Larval Competence and Dispersal Range
Larval dispersal is mainly dependant on transport by currents. When
development is short, the larvae are retained locally. Variability in currents account for
wide ranges for some species. The average larval life of Hawaiian fishes is 35 days.
With average current velocities of approximately 15 cm/sec., it would take 50 days to
travel from Johnston Atoll and 187 days from Wake Island, which are in the closest
geographic proximity to Hawai‘i
On a local scale, most of the corals of Hawai‘i are widely distributed, not habitat
specific. The supply of larvae reaching a destination depends on production, transport
15
and mortality. Coral larvae vary in competency time. Pocillopora damicornis can
survive over 100 days without settling. The larval stage of Montipora capitata was
determined to be over 200 days but the long-term survival rates were extremely low once
they settled (Kolinski, 2004). A life-strategy for many organisms is to try to increase in
size as quickly as possible to lessen the effects of predation. By traveling on floating
material (rafting), a coral is in the position to reproduce immediately upon arrival,
increasing its chance of survival. This strategy reduces predatory activity due to the
larger size of the coral colony. Montipora capitata can lie dormant at the one-polyp stage
for over a year. At 5 years they are often less than 1cm2 . This extends the time for
predation, competition and disturbances to remove such a small organism.
2.1.2 Natural Dispersal by Rafting
An extensive body of information on the rafting of marine organisms has been
documented. Corals larvae will attach and settle on floating objects along with algae,
barnacles, various crustaceans, tunicates, and other benthic reef creatures (Jokiel 1989,
1990a). Various natural “rafts” that provide the means for such long-range dispersal
include drift logs, wood, seeds, pumice, charcoal, and coconuts. Reef fish commonly are
associated with floating drift logs and are encountered far out at sea. Such natural events
provide a mechanism for brining non- indigenous species to the NWHI. Jokiel and Cox
(2003) were able to establish a relationship between currents, drift material and species
diversity of corals in Hawai‘i and Christmas Island. Jokiel (1990b) showed the potential
genetic importance of rafted corals carried into the Great Barrier Reef.
2.1.3 Migration of Adults
2.1.3.1 Fishes
Sharks and other large fish are known to move freely throughout the archipelago and do
not observe the artificial boundary created by humans (Holland and Meyer, personal
communication). For example, one tiger shark (#005) tagged in the NWHI at East Island,
French Frigate Shoals in July 2000 was detected by an array of acoustic receivers off the
Kona coast of the island of Hawai‘i (approx. 1190 km straight line distance) from
January through March 2003. Another tiger shark (#008) tagged at East Island, in July
2000 was detected by our array of acoustic receivers off Midway (approx. 1280 km
straight line distance) from September through December 2002 (Lowe et al., in press).
Movement of other species has not yet been studied, but it is most likely that some of
these can bridge gaps between the islands as adults. In some cases they may drift under
cover of floating logs or other debris (Jokiel, 1990a).
Most tropical marine species originated near Indonesia and the Philippines where
species diversity is highest, decreasing with distance from this region. From this center
of dispersal, animals spread by island hopping, moving along continental shores, or by
crossing oceanic gaps. Large pelagic species of fishes can easily cross vast expanses
while shallow water reef fishes are not all capable of traversing the gap. Ocean currents
can assist fish larvae as they drift to new destinations but distance is a prime factor in
determining which species will prevail. This natural filter has excluded fishes with short
larval stages such as anemone fish (Family Pomacentridae), while selecting for those
with long larval lives such as the surgeonfishes (Family Acanthuridae). Another limiting
16
factor in the dispersal of fishes to Hawaiian waters is the cooler temperatures as
compared to many tropical Pacific reefs. Geographic distance, temperature, and other
factors limit the number of fish species found in Hawai‘i (680) (Hoover, 2003).
Although species richness is low, endemics are often the most dominant species since
they are well adapted to local conditions. This can be seen with the success of the Saddle
Wrasse, Thalassoma duperrey and the Milletseed Butterflyfish, Chaetodon miliaris. The
Saddle Wrasse, hinalea, is the most prevalent endemic species found in the MHI,
according to the most comprehensive study to date (Rodgers, 2005), more commonly
observed than any other species (frequency of occurrence=87%). Indigenous fish
species, which are native but not unique to the Hawaiian Islands marine environment,
comprise the vast majority of the abundance of fishes. Only a few percent of the total
can be attributed to non-native species (Figure 2.1.3.1-1). The alien species recorded in
the study include two introduced snappers, the Bluestripe Snapper, Lutjanus kasmira,
(ta’ape) and the Blacktail Snapper, L. fulvus (to‘au) and a grouper, the Peacock Grouper,
Cephalopholis argus (roi) (Rodgers 2005).
80
Total biomass (%)
Total numbers of individuals (%)
70
60
50
40
30
20
10
0
Endemic
Indigenous
Non-native
Figure 2.1.3.1-1. Biomass (%) and number of individual fishes (%) by endemic status (Rodgers, 2005).
2.1.3.2 Algae
The currents that brought algal propagules to the Hawaiian Islands are variable.
The northeast tradewinds drive the North Pacific Current in a circular motion across the
Pacific. Near the Hawaiian chain, eddies and current reversals can bring algae from other
places. Local currents are also wind driven and highly variable between sites. Surface
currents are seasonal with the majority coming from the East-northeast, turning northerly
17
in the winter, and south in the summer as winds begin to slacken. Once propagules
arrive, they must locate a suitable substrate. The depth at which an alga settles is
dependant on light, temperature, and water motion. Its rapid horizontal expansion and
invasion of new territories is a reflection of asexual means of reproduction, particularly
fragmentation. Some algae such as the invasive, Hypnea musciformis, has tiny hooks to
attach to other algal species. Others, such as Gracilaria salicornia can form large mats
that will detach and float to other suitable destinations. Morphological plasticity allows
algae to thrive in a variety of conditions.
Figure 2.1.3.3-1. Female Hawaiian monk seal Monachus schauislandi nursing newborn pup at Kalaupapa, Molokai. Photo by
Bill Eichenlaub.
2.1.3.3 Monk Seals-Monachus schauislandi
Of the three species of monk seals worldwide, the Caribbean monk seal is extinct; the
Mediterranean monk seal is endangered with as few as 500 individuals remaining, and
the Hawaiian monk seal has approximately 1,200 remaining individuals. The majority of
the endangered Hawaiian monk seals forage and pup in the NWHI (95%) although more
individuals have recently been establishing populations in the MHI. At least 50
individuals have been observed in the MHI in recent years. (Baker and Johanos, 2005).
These adults must have migrated as much as 15,000 miles to reach the MHI.
2.1.3.4 Green Sea Turtles-Chelonia mydas
Chelonia mydas, the green sea turtle can be found throughout the world. The Hawaiian
population is genetically isolated from other populations found throughout the Pacific.
This is a result of geographic isolation where these turtles tend to remain within the
Hawaiian Archipelago throughout their entire lives. Although the adults use the MHI as
foraging grounds, feeding on nearshore algae, the vast majority (90%) migrate to the
18
NWHI to mate and nest. Unlike the herbivorous adults, omnivorous juveniles also feed
on floating plankton, fish eggs, and jellyfish. It is not known where turtles hatched in the
NWHI live during their first 3-7 years. Subsequent to these “lost years” they remain in
the MHI until they reach sexual maturity. This usually occurs at an age of approximately
25 years but can be as long as 50 years. This migration from the MHI foraging grounds
to the NWHI nesting grounds occurs annually for males and every 2-4 years for females.
The green sea turtle will return to nest at the location of their hatching. The majority
migrate to French Frigate Shoals, a distance of about 800 miles. This continues
throughout their lifetime, which can last 80 years or longer.
Figure 2.1.3.4-1.The green sea turtle Chelonia mydas migrates extensively throughout the archipelago. Photo Credit: F. Ferrell
2.2 Anthropogenic
The Hawaiian Islands are the most isolated archipelago in the world. Located 1,600 km
from the nearest islands and 4,000 km away from the closest continent, this geographic
isolation has resulted in unique, endemic biota. With the advent of human habitation
both accidental and intentional introductions have occurred. With the increase in
population in recent times, an increase in shipping activity has accelerated the
introduction of marine species into Hawai‘i at an alarming rate. Although most of these
newcomers don’t survive, a few persistent species have become a source of serious
ecological and economic impacts to the state.
Some of the non- indigenous species that have become established in the MHI have
dispersed more rapidly to other islands because of anthropogenic interisland transport.
The potential of these species to threaten the NWHI through anthropogenic mechanisms
of transport also exists. The global transfer of alien species by human activities is
recognized as a leading threat to aquatic ecosystems throughout the world. Increased
activities associated with the movement of humans and commodities have allowed
barriers to naturally occurring biological invasions, such as the isolation of the Hawai‘i
Archipelago, to be overcome more readily. Examples of these activities are maritime
19
vessel traffic, live seafood and bait shipments, aquaculture and fisheries activities,
shipments of commercial and institutional aquarium species, and activities of education
and research institutions. In the MHI, 343 alien marine species have been documented
and inventoried (Eldredge and Carlton, 2002). Invertebrate species dominate with 287
species, follo wed by algae (24), fishes (20), and flowering plants (12). Based on
historical literature and recent surveys, the pathways of introduction for non-native
marine invertebrates to Hawai‘i have been determined (Table 2.2-1).
Organisms may reach the NWHI as larvae in vessel ballast water or as adults or
larvae associated with biofouling and sediments of vessel hulls and piping systems (e.g
Apte et al. 2000, Godwin and Eldredge 2001, Godwin et al. 2004). Therefore the
likelihood of non- indigenous species reaching the NWHI is a function of the proximity
and pattern of ship movements associated with the MHI.
Table 2.2-1. Hawai‘i non-indigenous species introduction mechanisms for marine
invertebrate (Eldredge and Carlton 2002).
Mechanism
Species Number
Hull fouling
212
Solid ballast
21
Ballast water
18
Intentional release: Fishery
18
Parasites associated with AIS
Organisms associated with commercial
oyster shipments
Aquarium release
8
7
3
Oahu is the hub of the commercial harbor system in the state of Hawai‘i. All
overseas maritime traffic, with only a few exceptions, enters and departs Honolulu
Harbor and Barber’s Point Harbor. Cargo destined for the all other main island ports
arrives at Honolulu Harbor first and is then shipped to the receiving destinations (Godwin
& Eldredge, 2001a). Honolulu Harbor, the major port for the state, handles over 11
million tons of cargo every year. The harbor serves as the primary distribution center for
the state of Hawai‘i. Over 80% of all resources consumed in the state are imported. Of
this, 98% is shipped in from locations throughout the world. In 1998, 1,100 foreign deep
draft ships entered Honolulu Harbor. Hawai‘i is considered the “Crossroads of the
Pacific” and receives a variety of cargo for import and trans-shipment to other
destinations. Therefore the primary receiving areas in Hawai‘i for non- indigenous species
are Honolulu and Barber’s Point Harbors.
20
2.2.1 Ship Movement
2.2.1.1 Ballast Water
From the early history of seafaring to the present, ocean- going vessels have needed
ballast. All vessels before the middle of the 19th century used solid ballast in the form of
sand, rocks, and other heavy materials. As ships became larger it became necessary to
design ballast systems into vessels, in the form of dedicated tanks that could be filled
with water. The need to use the aquatic environment for a transportation medium in the
growing global economy has lead to the increases in vessel size and ballast water volume.
This increased ballast water volume combined with faster ship speeds allows the uptake
and survival of an increased number of organisms.
Ballast is taken aboard through piping systems that are connected to the ocean
through the seachest. The seachest is a system of paired recesses that are below the water
line and typically run along the keel. The recess areas provide a "prime" for pumps that
pull in water and distribute it through piping that serves the ballast system, the engine
cooling apparatus, and the fire fighting hoses on deck. The seachest is covered with a
grate with openings of 2-5 cm to prevent large objects from being pulled into the pumps.
The same pumps are used for deballasting operations, with the water released through
discharge valves located above the water line for some types of ballast tanks and below
the water line for other types. Ballast water systems vary in design but are all based on
ballast tanks arrayed in such a way as to provide the maximum stability.
Organisms that are associated with marine plankton communities can be pulled into
the ballast tanks of vessels during ballasting operations. These organisms are
characterized as holoplankton, meroplankton, and tychoplankton. The holoplankton are
the species that live entirely in the water column their entire life. Holoplankton are
further divided into the phytoplankton, which includes unicellular algae and various
bacteria, and the zooplankton. This latter grouping includes small crustaceans, gelatinous
species and a variety of other organisms. Meroplankton are the larval forms of marine
species that use the water column to feed and disperse before becoming adult organisms.
The larvae and eggs of crabs, barnacles, snails, clams, starfish, worms, fish and many
other species are present in meroplankton and represent a large part of the biomass of
plankton communities. Tychoplankton are species that normally live in bottom
communities and become suspended in the water column temporarily. Additionally, adult
organisms of animals such as fish and crabs can become entrained in ballast tanks by
being in close proximity to seachest intakes or as attached organisms on debris.
Bacteria that have the potential for causing human health problems can also be
found in ballast water. In the early 1990s shellfish beds in the southeastern United Sates
along the Gulf of Mexico had to be closed because of the presence of cholera bacteria
(Vibrio cholerae). This occurrence of Vibrio cholerae was traced back to ballast water
discharges from vessels arriving from South America. The strain present in the Gulf of
Mexico was the same that triggered an epidemic in South America that caused 10,000
deaths. The vibrios are waterborne bacteria that cause cholera when humans ingest
contaminated water or raw or poorly cooked seafood taken from contaminated areas.
21
There are 139 serogroups of Vibrio cholerae but only two - (01 and 0139) - cause cholera
of epidemic proportions. The association of cholera bacteria with ballast water began to
be realized more widely following the study of McCarthy & Khambaty (1994) in the Gulf
of Mexico. Further research has detected both 01 and 0139 serogroups in ballast water
being discharged in the United States Mid-Atlantic ports of Baltimore and Norfolk in the
Chesapeake Bay (Ruiz et al., 2000a).
2.2.1.2 Sediments
Vessels generally ballast in coastal areas or ports that have a great deal of particulate
matter suspended in the water column. This suspended matter is made up of organic and
inorganic detritus and plankton. After ballast water is pumped into tanks particles begin
to settle to the bottom and form a sediment layer. These layers can be up to 8cm thick
(Godwin, personal observation) and can provide a habitat for benthic fauna. A portion of
the sediments can become re-suspended and discharged during ballasting and
deballasting operations. Ballast tanks will always retain water and sediments in
unpumpable sections of the tank until it is re-suspended by ballasting operations or
movement of the vessel during transit. This material is removed from the tank
periodically to prevent damage to pumps, and is undertaken by members of the crew
during port visits and sea transits or by shipyard workers during service periods. In both
cases the material can be either intentionally or unintentionally dumped overboard.
These ballast water sediments can harbor communities of adult organisms that
result from the settlement of larvae and eggs from the meroplankton. These organisms
can mature and become a source for new larvae that become suspended within the water
column of the ballast tank. Another common component of the sediment is the resting
stages of phytoplankton species such as dinoflagellates and diatoms. Only a few of the
studies listed have dealt with ballast sediments. The most notable are the studies by
Hallegraeff et al. (1990), Hallegraeff & Bolch (1992), and Kelly et al. (1993) that
demonstrated the presence of viable resting stages of phytoplankton species in ballast
sediments. These studies connected the introduction of the toxic dinoflagellates that are
transported as cysts to ballast sediments. In the first two studies, the toxic dinoflagellates
Gymnodinium catenatum and Alexandrium catenella, which cause paralytic shellfish
poisoning, were identified from ballast sediments sampled from commercial cargo
vessels arriving to southern Australia. These sediments can also harbor bacterial
communities that can flourish by deriving nutrients from the abundant organic matter
settling out to the bottom of the ballast tank.
There are sediment accumulations associated with maritime vessel activity that are
not due to ballast water operations. A source common to any type of vessel is the
sediment found on anchors and anchor chains, which can accumulate in the chain locker
compartment. These areas of the vessel can provide a sheltered habitat for a variety of
animals that are adapted to an intertidal existence along coastlines and others that can
exist in an encysted stage, such as the microalgae mentioned earlier. Vessels that conduct
unique operations such as dredging and those that function as work platforms (i.e.,
barges, floating drydocks) have to be considered as well. These vessels can transport
sediments associated with deck surfaces and the gear associated with their unique
22
operations. Very little has been done to survey this typ e of sediment transport due to the
random nature of these arrivals to port systems.
2.2.1.3 Hull Fouling
Ballast water is the pathway that has been the major focus of investigation as a marine
invasion vector, and the biofouling that occurs on the surfaces of vessel hulls has been
given less attention. Historically, wooden sailing ships provided an ideal surface to which
marine fouling organisms could attach. Common fouling organisms on these vessels were
the wood-boring shipworms (Teredo). The cosmopolitan range of this organism is
thought to have resulted from worldwide spread by wooden vessels, especially as trade
routes opened up between the Atlantic and the Pacific. Hull fouling has been dramatically
reduced with the advent of steel hulls combined with anti- fouling coatings. The steps
taken by large ocean going vessels and personal craft to eliminate hull fouling are not
completely effective though, and organisms are still being transported by this means.
The organisms that generally foul vessel hulls are the typical species found in
natural marine intertidal and subtidal fouling communities. The typical invertebrate
organisms associated with marine fouling communities are arthropoda (barnacles,
amphipods, and crabs), mollusca (mussels, clams, and sea slugs), porifera (sponges),
bryozoa, coelenterata (hydroids and anemones), protozoa, annelida (marine worms), and
chordata (sea squirts and fish), as well as macroalgae (seaweed). If these fouling
communities become very developed they can also provide micro-habitats for mobile
organisms such as fish. Initial settlement of fouling organisms tends to be in sheltered
areas of the hull, such as sea chest intakes and rudder posts, and develop in areas where
anti- fouling coatings have been compromised (Ranier, 1995; James & Hayden, 2000;
Godwin, 2003; Coutts & Taylor, 2004; Godwin et al., 2004). Anti- fouling coatings wear
off along the bilge keel and weld seams, and are inadequately applied in some cases, all
which make the surfaces susceptible to settlement by fouling organisms. Further work
has focused on the transport of hull fouling organisms on personal craft throughout the
tropical Pacific (Floerl and Inglis, 2001).
Recent non- indigenous species introductions to Hawai‘i are directly attributed to
hull fouling. The bivalve mollusk Chama elatensis and the sponge Gelliodes fibrosa both
were introduced from the fouling community on the hull of a floating drydock towed to
Hawai‘i from the Philippines in 1992 (DeFelice, 1999). The barnacle Chthamalus
proteus, which is listed in Table 3.1-1, is native to the Caribbean, was not recorded in
Hawai‘i before 1973 (Southward et al, 1997). The larvae of C. proteus would not have a
good chance at surviving the journey from the Caribbean in a ballast tank, and were
likely introduced by larvae spawned from adults that were part of a vessel hull fouling
community. Apte et al., (2000) recorded such a scenario with blue mussels (Mytilus
galloprovincialis), which were part of the fouling community on the hull of the U.S.S.
Missouri (Defelice and Godwin, 1999), which was towed to Pearl Harbor from
Bremerton, Washington. These mussels, which are alien to Hawai‘i, were observed
spawning upon arrival to Pearl Harbor; three months later, settled juveniles were
recorded in the harbor, and identified as M. galloprovincialis through molecular
techniques. Establishment of this species in Hawai‘i has not been determined.
23
2.2.2 Marine Debris Transport
Marine debris such as plastics, glass bottles, packing crates, fishing net debris, and
smaller components that are products of physical degradation of these items can cause
injury and death to marine organisms. This debris can injure marine organisms through
physical contact or cause mortality through ingestion, entanglement or smothering
(Andre and Ittner, 1980; Conant, 1984; Balaz, 1985). Net debris affecting the Hawaiian
archipelago comes from commercial fishing activities throughout the Pacific. Oceanic
currents transport net debris from as far away as Alaska (Kubota, 1994). This creates a
situation in which drifting debris can act as a pathway for non- indigenous species. This
unique pathway can affect remote locations with little other anthropogenic influence,
such as the NWHI, as well as populated regions such as the MHI. Drifting net debris can
overcome the barriers of isolation and management by providing a mechanism of
transport for marine non- indigenous species (Godwin, 2001b).
2.2.2.1 Biofouling on Marine Debris
Since 1996 a multi-agency effort [National Oceanic and Atmospheric Administration
(NOAA), Ocean Conservancy, University of Hawai‘i Sea Grant, US Coast Guard, U. S.
Navy and others] has been removing derelict marine debris from Hawaiian waters in
order to prevent damage to the reef and entanglement with endangered marine species.
Efforts have been focused on French Frigate Shoals, Maro Reef, Lisianski Island,
Midway Atoll, Kure Atoll, and Pearl and Hermes Reef. Over 100 metric tons per year
has been removed over the past several years, but debris is continually drifting onto the
reefs. Results from the 2000 NOAA, National Marine Fisheries Service (NMFS) effort
identified marine invertebrate biofouling on net debris. Most species were common
species indigenous to Hawai‘i that are well known in fouling and benthic communities.
The majority of the organisms recorded likely took up residence or recruited to the nets
after arrival in the NWHI (Godwin, 2000). The one non- indigenous species, the sea
anemone Diadumene lineata, found associated with net debris provides evidence that
derelict fishing gear can act as a mechanism of transport for invasive species to the
NWHI (Zabin et al., 2004). Approximately 100 individuals were found in 2000 in Pearl
and Hermes lagoon on a commercial trawl net. Since there are no commercial fishing
vessels in Hawai‘i that use trawl nets it could have originated anywhere from Japan to the
Pacific Northwest. Since it is not known whether this anemone could survive such a long
journey, it is possible that it had passed through the MHI where this species has been
identified in Kane‘ohe Bay. Diadumene lineata has been globally successful, possessing
many of the traits necessary to survive and spread in diverse conditions. In order to
survive adverse conditions, this anemone can encase itself in a hard cyst surviving a wide
variety of unfavorable conditions until more favorable circumstances prevail. This
response to lack of resources, high water temperatures, or fluctuations in salinity can give
this organism the advantage to survive long periods of transport (Zabin et al., 2004).
Diadumene lineata has not been observed since the original sighting but full scale species
inventories are not conducted in marine habitats in the NWHI. Two other species of
introduced anemones have been described from O‘ahu, Diadumene leucolena, originally
from the Western Atlantic and D. franciscana of unknown origin but previously
described from California. The danger that these two alien anemones will reach the
NWHI by similar means is highly probable and concerning.
24
2.2.2.2 Rafting of Organisms with Debris.
Rafting describes the behavior of marine organisms, usually fish, when they aggregate
near or under natural or anthropogenic sourced debris (Jokiel, 1992; Day and Shaw,
2003). A great deal is known about the sources, distribution and fate of anthropogenic
marine debris (Shomura and Godfrey, 1990). There is information on the quantitative
distribution and characteristics of marine debris in the North Pacific (Day and Shaw,
1990), and there is information on patterns of circulation and drift. Derelict nets can
definitely act as an anthropogenic pathway for the transport of marine organisms,
especially fishes. The ocean current regime in the area allows nets to be readily
transported from a variety of locations. Over the past few years several large Fish
Aggregation Devices (FADs) that broke away from mooring in the main Hawaiian
Islands have come aground on the reefs of the NWHI, demonstrating the potential for
rafting of marine invasive species from the main Hawaiian Islands into the NWHI.
Management activities and protocols currently in use by NOAA-NMFS and the US
Fish and Wildlife Service (USFWS) are ineffective against such disturbances. Although
the obvious effects of entanglement of wildlife and physical damage to benthic marine
habitats are easy to convey to the general public, the transport of non- indigenous species
is less apparent. The problem must be dealt with at the international level and must
involve public sector resource managers and commercial fishing interests. The
consequence of irresponsible disposal and accidental loss of fishing gear and research and
fisheries buoys to wildlife must be brought to the attention of the commercial fishing
industry and the public sector so that solutions can be formulated that will decrease the
magnitude of this significant problem.
2.2.3 Fisheries Activities and Other Pathways
Extractive fisheries activities using gear such as floats, nets, traps, trawls, and dredges
can unintentionally transport introduced species by biofouling or entrainment of mobile
species or propagules. Fresh or frozen bait may harbor introduced organisms in form of
the primary organism but can also include its epibionts and parasites. During efforts to
introduce new species of snappers to Hawaii in the 1950’s there were additional
introductions of fish unintentionally included in transport tanks (See section 3.1).
A variety of algae, crustaceans, mollusks, echinoderms and fish have been intentionally
introduced to the MHI for the purpose of aquaculture. These activities have been
responsible for unintentional introductions of epibionts associated with the primary
species. Examples are the mud blister worm Polydora websteri that arrived on oyster spat
from U.S. west coast hatcheries and another polychaete worm Polydora nuchalis, which
was probably transported here from Mexico with live shrimp (Eldredge, 1994).
Other means of transporting non-native species to the Northwestern Hawaiian Islands
Marine National Monument falls under the rubric of research and conservation activities.
The increase in coral reef monitoring efforts forces the inclusion of small boat outboards,
diving equipment, instrument platforms, and towboards previously used in the MHI as
vectors for non- indigenous species transport. This is possible through the unintentional
transport of apical cells or fragments of macroalgae and encysted invertebrate larvae on
surfaces or within sediments. Additionally, sand, soil and construction materials (i.e. rip25
rap, sheet pilings) transported for maintenance and terrestrial conservation activities
should also be considered for its potential for aquatic non-indigenous species transport to
the Northwestern Hawaiian Islands Marine National Monument. All of the vectors within
this section should be thought of as mechanisms for transportation from the MHI but also
interisland within the Northwestern Hawaiian Islands Marine National Monument.
3.0 MARINE NON-INDIGENOUS SPECIES IN THE HAWAIIAN
ARCHIPELAGO
Recent compilations of marine alien species in Hawai‘i (Eldredge and Carlton, 2002)
include some 343 species: 287 invertebrates, 24 algae, 20 fish, and 12 flowering plants.
Ecological and economic consequences for these alien species invasions remain unclear
but examples of negative impacts by introduced aquatic invertebrates in other areas of the
Pacific have been documented:
•
The tube dwelling polychaete Sabella spallanzanii introduced to Australia from the
Mediterranean overgrows commercially important shellfish populations.
•
Asterias amurensis, a starfish introduced into Australia from Japan is a major
predator on commercially important species and has caused major ecological impacts.
•
The hydroid Eudendrium cameum was introduced into the Republic of Palau and its
spread could have ecological effects on coral reef resources.
For Hawai‘i, some examples of alien marine invertebrates are the following:
•
The bivalve mollusk Chama macerophylla and the sponge Gelliodes fibrosa both
were introduced from the fouling community on the hull of a floating dry-dock towed to
Hawai‘i from the Philippines in 1992.
•
The barnacle, Chthamalus proteus, which is common in the high littoral zone in
Hawai‘i, is native to the Caribbean, and was not recorded in Hawai‘i before 1973.
•
The snowflake coral Carijoa riisei was once believed to be introduced from the
Caribbean and has recently been shown to have originated from the Indo-Pacific
(Toonen, pers. comm.) now appears to be poised to impact unique deep-water habitats by
overgrowth of endemic corals.
The remainder of this section will provide a synopsis of fish and invertebrates, and an indepth coverage of algae, as related to both the MHI and NWHI.
3.1 Marine Non-indigenous Species and the NWHI
The activities that have provided information concerning marine aquatic invasive species
of NWHI are recent, and the judgments as to whether organisms are invasive or native
are based on the knowledge of marine aquatic invasive species that has been gained in the
MHI over the last decade. This is due both to the status of the taxonomy for many
invertebrate groups and the historical sampling effort in the NWHI. The status of the
taxonomy of many non-coral marine invertebrate groups and algae is not fully developed
for the NWHI and this does not allow comprehensive species inventories to be produced,
although efforts to correct this are presently underway. In addition, when large scale
26
faunal surveys began in shallow water coral reef habitats in the NWHI in 2000 only two
expeditions with such a focus had ever been to the area during the previous 100 years.
The data concerning marine aquatic invasive species in the NWHI was collected
from a single focused marine invasive species survey by the Bishop Museum at Midway
Atoll and from multidiscipline efforts conducted under the auspices of the Northwestern
Hawaiian Islands Rapid Assessment and Monitoring Program (NOW-RAMP) in 2000,
2002 and the National Oceanic and Atmospheric Administration-National Marine
Fisheries Service, Coral Reef Ecosystem Division (CRED) efforts in 2000, 2002 and
2003.
The results of these efforts have recorded a total of 11 aquatic invasive marine fish,
invertebrate, and algae species in the NWHI. Table 3.1-1 shows the species, the native
range of each, their present status in the NWHI, and the hypothesized or documented
mechanism of introduction.
Table 3.1-1. Marine non-indigenous species in the NWHI. NIH=Nihoa, NEC= Necker Island, FFS=French Frigate
Shoals, MAR=Maro Reef, PHR=Pearl and Hermes Reef, LAY=Laysan Island, LIS=Lisianski Island, MID=
Midway Atoll KUR=Kure Atoll, (Zabin et al., 2004 Godwin 2002, DeFelice et al. 2002, Godwin 2000, DeFelice et
al. 1998).
Species
Hypnea musciformes
(algae)
Diadumene lineata
(anemone)
Pennaria disticha
(hydroid)
Amathia distans
(bryozoan)
Schizoporella errata
(bryozoan)
Balanus reticulates
(barnacle)
Balanus venustus
(barnacle)
Chthamalus proteus
(barnacle)
Lutjanus fulvus
(fish)
Lutjanus kasmira
(fish)
Cephalopholis argus
(fish)
Native Range
Unknown;
Cosmopolitan
Present Status in NWHI
Unknown; in drift and on lobster
traps (MAR and NEC)
Mechanism of Introduction
Intentional introduction to MHI
(documented)
Asia
Unknown; on derelict net only
(PHR)
Established (FFS, PHR, LAY,
LIS, KUR and MID)
Established (MID)
Derelict fishing net debris
(documented)
Fouling on ship hulls (hypothesized)
Established (MID)
Fouling on ship hulls (hypothesized)
Established (FFS)
Fouling on ship hulls (hypothesized)
Atlantic and
Caribbean
Caribbean
Not Established; on vessel hull
only (MID)
Established (MID)
Fouling on ship hulls (documented)
Indo-Pacific
Established (NIH, FFS)
Indo-Pacific
Established (NIH, NEC, FFS,
MAR, LAY, and MID)
Established (NIH, NEC and
FFS)
Intentional introduction to MHI
(documented)
Intentional introduction to MHI
(documented)
Intentional introduction to MHI
(documented)
Unknown;
Cosmopolitan
Unknown;
Cosmopolitan
Unknown;
Cosmopolitan
Atlantic
Indo-Pacific
27
Fouling on ship hulls (hypothesized)
Fouling on ship hulls (hypothesized)
3.2 Fishes
3.2.1 Introduction
In the MHI, 21 marine fishes were intentionally introduced although few survived and
reproduced. Yet, along with those intentional introductions came five unintentional alien
fishes. The introduction of the Kandu, Valamugil engeli, the striped goatfish, Upenneus
vittatus, and the gold-spot herring, Herklotsichthys quadrimaculatus were associated with
the unsuccessful introduction of the Marquesan sardine, Sardinella marquesensis.
Presently, most intentional introductions now require safeguards to assure history isn’t
repeated.
3.2.2 Lutjanus kasmira
Description
Ta‘ape, was introduced from the Marquesas in 1958 and although only 3,200 ta’ape were
released on the island of O‘ahu, they have increased their range to include the entire
Hawaiian archipelago. Of six species of serranid fishes (groupers and their relatives)
purposely introduced to Hawaiian waters for economic reasons in the 1950’s only one
(Cephalopholis argus) was successful, despite the fact that the serranid fauna in the area
are not well represented.
Figure 3.2.2-1. Blue-Lined Snapper (also known as Ta‘ape or Lutjanus kasmira ). Photo by K. Stender
History
Since most snappers occurring in Hawai’i have historically been highly prized food fish
(‘opakapaka, ehu, onaga), but inhabit depths of over 60 m, the Hawai‘i Fish and Game
introduced three shallow water snappers from the South Pacific and Mexico in the mid
1950s and early 1960s in hopes of stimulating the commercial fisheries. These are
among the 11 demersal species introduced within a 5-year period. Lutjanus kasmira
(ta‘ape) and L. fulvus (to’au) have become widely established in the MHI, while the third
28
species, L. gibbus is extremely rare. None of these species has been widely accepted as a
food fish among the local population or become successful in the commercial fisheries
and the ecological effects of these aliens have only recently been realized.
Current Distribution
Three species of reef fish introduced in the MHI L. kasmira, L. fulvus, and C. argus have
become established in the NWHI. The only species to have successfully expanded along
the entire NWHI chain is the ta‘ape L. kasmira.
Ecology
This species occurs throughout the Indo-Pacific region and is known from depths of 2265 meters but generally is found in depths no greater than 15 meters. It is a common
coral reef species that feeds mainly on crustaceans and forms stationary schools by day
and feeds individually at night.
Threats
Histological reports from Work et al. (2003) found that nearly half of the ta’ape
examined from O‘ahu were infected with an apicomplexan protozoan. Furthermore, 26%
were infected with an epitheliocystic-like organism with potential transmission to
endemic reef fishes. In addition, ta‘ape from Hilo were found to host the nematode
Spirocamallanus istiblenni (Font and Rigby, 2000). Species of goatfish (weke and
kumu), a popular food fish for humans, may be displaced by ta’ape, which has also
expanded its range into deeper water where ‘opakapaka reside. Friedlander and Parrish
(1998) looked at patterns of habitat use to determine predation and resource competition
between ta’ape and several native species within Hanalei Bay, Kaua’i, but found no
strong ecological relationships.
3.2.3 Cephalopholis argus
Figure 3.2.3-1. The Peacock grouper, Cephalopholis argus introduced to Hawai‘i in the 1950’s. Photo by J. Randall
Description
Groupers are solitary predators that are poorly represented in the Hawaiian Archipelago.
The peacock grouper, Cephalopholis argus (roi) is covered with blue spots with a series
of light colored vertical bars towards the rear half of the body (Figure 3.2.3-1).
29
History
This species, which was intentionally introduced by the state for commercial purposes in
1956 from Moorea, French Polynesia, initially had more popularity as a food fish than the
introduced snappers, the Bluestripe Snapper, Lutjanus kasmira, (ta‘ape) and the Blacktail
Snapper, L. fulvus (to‘au). Its attractiveness as a food fish rapidly declined as cases of
ciguatera poisoning increased. This opportunistic feeder is perceived by many local
fishermen as unsafe to consume.
Current Distribution
Cephalopholis argus can be found throughout the MHI but has only been recorded at
Nihoa Island, Necker Island, and French Frigate Shoals in the NWHI.
Ecology
The peacock grouper occurs in both lagoon and seaward reef habitats at depths up to 40
m, particularly in areas of high coral growth and clear water. They feed both day and
night, primarily on small fish and occasionally on crustaceans.
Threats
Dierking et. al (2005) investigated the feeding biology and levels of ciguatoxins in C.
argus at sites on the islands of O‘ahu and Hawai‘i. According to this study, roi impact on
native species is less than formerly believed but could be a function of their low
population numbers. Contrary to popular belief, they found that the majority of roi are
relatively safe to consume, with approximately 4% containing levels of toxin high
enough to cause ciguatera poisoning. However, 20% of samples contained some level of
ciguatoxin. Although a strong site specific correlation occurred with the highest
percentage of toxic roi found on the island of Hawai‘i, nearly all of the 28 locations on
both islands contained fish that tested positive for ciguatoxins. Toxin concentration in
tissues were found to be only slightly higher in larger individuals, resulting in findings
that smaller roi are not significantly safer for consumption than fish of larger size.
3.3 Invertebrates
3.3.1 Introduction
In sharp contrast to the MHI that harbors 287 introduced and cryptogenic (unknown
origin) invertebrate species, only five introduced invertebrates have become established
and two more have been recorded but do not appear to be established in the NWHI
(Friedlander et al., 2005; Eldredge, 2005). Not surprisingly, the majority of invertebrate
introductions (4) are found on Midway Atoll, which has a long history of anthropogenic
activity. These include the hydroid, Pennaria disticha, two bryozoans, Amathia distans
and Schizoporella errata, and the barnacle, Chthamalus proteus. Pennaria disticha is the
only species that has spread to multiple locations within the NWHI (Godwin, 2002;
Friedlander et al., 2005). The anemone Diadumene lineata was recorded as associated
with a derelict fishing net in the NWHI (Godwin, 2000) but has not been confirmed as
established but appears to be established in a discrete location within Kaneohe Bay on
Oahu in the MHI (Zabin et al., 2004). A single record of the barnacle Balanus venustus
30
was recorded at Midway Atoll on the hull of a vessel in 2003 but is unlikely to be
established (Godwin et al., 2004).
Figure 3.3.1-1. The anemone Diadumene lineata. Photo credit R. Manuel
The majority of the invertebrate introductions found in the MHI are recorded from
bays and harbors and are thought to have arrived through fo uling on vessel hulls or
through ship ballast water from the Indo-Pacific. The distribution of introductions in the
NWHI provides evidence to support this, with most of the non-native species found in the
only harbor in the NWHI at Midway. The majority of these invertebrate introductions
found in harbors have not been described from Hawai‘i’s coral reefs. In the guide to
invasive invertebrates in Hawai‘i (DeFelice et al., 2001), only four have been reported on
coral reefs and only one of these is considered invasive. Coles and Eldredge (2002)
believe that unlike invasive algae, this dearth of invertebrate species may be attributed to
either a lack of opportunities to invade these highly diverse communities or a deficiency
of surveys. The lag period that exists between establishment and actual invasive behavior
must also be taken into account.
There being such a large number of established AIS in the MHI there is the
potential for the introduction of other species from both natural and anthropogenic
means. Two introduced invertebrates established in Hawai‘i, Carijoa riisei and
Chthamalus proteus, will be reviewed more in-depth. The octocoral Carijoa riisei has
recently begun exhibiting invasive qualities in the MHI after a lag period of many
decades. Also covered will be the barnacle Chthamalus proteus, which exhibits a disjunct
distribution on an interisland and archipelago scale.
3.3.2 Carijoa riisei
Description
Each polyp of Carajoa riisei is white in color with eight tentacles resembling a tiny
snowflake. It is often found growing on pier pilings where it can readily cover all
exposed parts of the structures. This soft coral is not a reef builder. Its skeleton is a
rigid structure composed of spicules, similar to material found in sponges, and
microscopic needles of calcium carbonate, imbedded in a chitin- like material. Carijoa
31
riisei is utilized by many other organisms that colonize this octocoral, living on or within
the skeleton.
Figure 3.3.2-1. The octocoral Carijoa riisei. Photo by S. Khang.
History
The “snowflake coral” originally observed in Pearl Harbor was thought to have arrived
from the Caribbean but genetic research has shown that it may have originated in the
Indo-Pacific region and arrived as part of ship hull fouling or in ballast water.
Current distribution
In the Caribbean, it is only found in shallow waters as part of the fouling community on
pier pilings. It is also found in the western Pacific, Australia and Asia. In Hawai‘i, along
with this preferred habitat, it has also spread rapidly to invade deeper waters. This eight
tentacled coral attaches with a root-like structure in areas where light doesn’t fully
penetrate.
Ecology
C. riisei avoids well lit habitats, preferring dark cracks, undersides of rocks, shaded pier
pilings and deeper waters. It is a suspension feeder, consuming tiny zooplankton from
the water column.
Threats
Initially, it was not considered a threat to the ecosystem since it was thought to inhabit an
underutilized habitat. Yet in just seven years, C. riisei has expanded its range to include
sites from Koko Head to Haleiwa. Expansion continued and by 1990 it was recorded
from all islands in the MHI chain. Results from a 2001 survey using the Hawai‘i
Undersea Research Laboratory’s Pisces V, found C. riisei had spread into waters up to
110 meters and is competing with the native black corals. They both feed on the same
32
zooplankton and are competing for space. This octocoral is overgrowing the black coral
at an alarming rate. Carijoa riisei can grow up to 8 cm a month while the precious black
coral takes over a year to match that growth rate. As it blankets anything in its path, the
biodiversity of the area is drastically reduced. It has been reported that black corals are
completely decimated in some areas in the deep trench (75-110 m) between West Maui
and Lana‘i (Grigg, 2003). The black coral industry generates over $15 million annually
in revenues for the state of Hawai‘i (Grigg, 2001). Hawaiian corals are especially
susceptible to displacement by fast-growing octocorals since few are native to the area. It
is usually found approximately 60 m. from shore in moderate water motion and has no
known predators. This prolific rate of spread illustrates the need to determine the
ecology, distribution, abundance, range, and tolerances of this potentially devastating
invasive.
A joint effort by the State of Hawai‘i Department of Land and Natural Resources,
Division of Aquatic Resources and the University of Hawai‘i to eradicate C. riisei is
currently under way. Divers, utilizing two strategies, manually cleared two sites on
Kaua’i. In some areas, large clumps of the octocoral were removed while in others, the
entire area was cleared of the invasive by smothering with plastic sheeting. The
effectiveness of the methods will be evaluated during subsequent monitoring of sites.
The rationale to concentrate eradication efforts on the Island of Kaua‘i is two- fold. Since
it has only been documented from two sites, it may be possible to contain its spread and if
its spread is not contained it is highly probable that it will advance to the NWHI, with
Kaua‘i creating a stepping stone to this near pristine environment. Although there exists
a possibility that ship traffic from O‘ahu can also potentially extend the reach of C. riisei
to the NWHI, attempts at eradication on O‘ahu is futile due to the extent of its spread.
3.3.3 Chthamalus proteus
Description
Chthamalus proteus is a small grayish-white barnacle that grows to about 1cm in
diameter. It has a conical shape that is varied depending on the age and level of crowding
with other conspecifics. Older C. proteus resemble the native barnacle Nesochthamalus
intertextus, which lives in the same habitat. The interleaving shell plates of N. intertextus
and its purplish color differentiate it from C. proteus.
Figure 3.3.3-1. The barnacle Chthamalus proteus. Photo by C. Zabin
33
History
Due to the supratidal nature of this species it is unlikely it was overlooked in barnacle
surveys conducted in the Pacific prior to the mid-1900’s (Pilsbry, 1927; Hiro, 1939;
Henry, 1942; Edmondson, 1946; Gordon, 1970). It also was not recorded during a
comprehensive survey of intertidal barnacle fauna of Hawai‘i in 1973 (Matsuda, 1973).
Chthamalus proteus was well established on Oahu, Maui, and Kauai by the time it
was noticed in 1995 (Southward et al., 1998). It was recorded in the NWHI in the harbor
at Midway Atoll in 1998 (DeFelice et al., 1998), and was later discovered in Guam
(Southward et al., 1998).
Current distribution
Chthamalus proteus is native to the Caribbean, Gulf of Mexico and the Western Atlantic
and has several congeners throughout the Atlantic and Pacific. It has become established
in a disjunct pattern between islands and within the archipelago. Intertidal faunal surveys
have been conducted on all MHI except Ni‘ihau, and is found on all except Kaho‘olawe.
Ecology
This barnacle colonizes supratidal anthropogenic structures such as pier pilings and sea
walls but has spread to natural intertidal boulder habitat. The native chthamalid barnacle
Nesochthamalus intertextus inhabits similar natural habitats but is rarely found in harbors
and man-made embayments. Chthamalus proteus can grow in high densities on both
natural and man- made surfaces. These barnacles are hermaphrodites but crossfertilization can occur in high density populations. Specialized paired appendages called
cirri extract food particles directly from the water with continuous motions in and out of
the shell.
Threats
A potential threat of this species is alteration of natural substrates through dense
colonization. This would alter settlement patterns of native species and exclude algal
grazers such as opihi. This species has shown a propensity for settlement on vessel hulls
(Godwin, 2003; Godwin et al., 2004) and its disjunct distribution along the Hawaiian
Archipelago is likely due to this mechanism of transport. This mechanism of transport is
difficult to manage and can involve any size of vessel. Its establishment in the harbor at
Midway Atoll has provided a “stepping stone” within the NWHI that cannot be
discounted. The original establishment site in the MHI was within the harbor system on
Oahu and it has expanded within and beyond this to both natural and man-made habitats.
This potential exists for the population established on Midway Atoll and measures have
to be taken to minimize expansion.
34
3.4 Algae
3.4.1 Introduction
Since 1950, at least nineteen species of algae have become established on O‘ahu.
Through commercial, experimental and accidental introductions from several South
Pacific locations, Florida, California, and Japan, many of these invasives have spread to
the outer islands (Russell, 1992). Three of the most successful in expanding their
abundance and distribution are Acanthophora spicifera, Hypnea musciformis, and
Gracilaria salicornia (Table 3.4.1-1 ).
Aliens with the extraordinary capabilities of rapid growth and reproduction and
the ability to change their form have spread out to compete among the natives. Many
expand their territories through fragmentation, by regeneration of small pieces, or attach
themselves to other species as epiphytes. Other reasons for their success may be their
escape from their natural predators or reduced grazing pressure in their new home. These
ecological invasions can advance rapidly and have negative effects on marine
ecosystems. Since 1950, 19 species of seaweeds that were either intentionally or
accidentally introduced to Hawai’i, have become permanent or unwelcome residents.
Many were first identified in harbors or bays, where ships from foreign destinations
visited, escaping from ballast water or fouling on hulls. Some spread throughout the
archipelago, while others have remained exclusively at the origin of introduction on
O’ahu. Although over half of these species were introduced into Kane’ohe Bay, only a
few have become widespread and invasive, displacing native seaweeds and overgrowing
corals in some areas.
Native seaweeds can also gain a competitive advantage over corals and become
invasive when excess nutrients are available. A “phase shift” from a coral to an algal
dominance occurred in Kane’ohe Bay, beginning in the 1950’s and peaking in the 1970’s,
due to sewage discharge, slowly allowing the take over of the “bubble algae”,
Dictyosphaeria cavernosa. Overfishing may also favor seaweeds over corals when fewer
herbivorous fishes are available to subdue fast growing algae.
Each species has unique biological and ecological characteristics that affect their
probability of establishment, rate of spread, reproductive success and interaction with
native species. Investigating and understanding these distinctive traits is critical to
ecosystem conservation and ecological management.
Rapid growth rates, morphological plasticity, and effective propagation can
accelerate the spread of alien algal species into areas where they have not previously been
established (Carpenter, 1990).
35
Table 3.4.1-1. Partial list of macroalgae that were intentionally introduced into O’ahu since 1950 (Russell, 1992; UH Botany, 2005).
Species
Acanthophora spicifera
Avrainvillea amadelpha
Origin
Success
Product
Value
Competition
Guam
highly
successful
none
Laurencia spp.
West Pacific?
successful
none
many reef spps ?
Philippines
not successful
kappa
carrageenan
unknown
1/74
Florida
No
iota
carrageenan
none
marginal
agar
unknown
carrageenan
unknown
agar
many reef spp
O’ahu locale
Date
Pearl Harbor
and/or Waikiki
Koko Head, Kahe
Pt
After
1950
After
1981
from
10/70 to
late 1976
Eucheuma denticulatum
Honolulu Harbor,
Kane’ohe Bay
Eucheuma isiforme
Kane’ohe Bay
Gracilaria epihippisora
Waikiki &
Kane'ohe Bay
4/71 9/78
Big Island
(Hawai'i)
Kane'ohe Bay
mid
1970's
Philippines
unknown
4/71 9/78
Big Island
(Hawai'i)
highly
successful
Gracilaria eucheumoides
Gracilaria salicornia
Waikiki &
Kane’ohe Bay
Kane’ohe Bay &
Kahuku
Honolulu Harbor
mid
1970's
1971
Florida
successful
Philippines
Kane’ohe Bay
1/74
Florida
unknown
highly
successful
9/74 to
late1976
8/70 to
late1976
Philippines
successful
Pohnpei and
Philippines
successful
1976
California
No
California
No
Nemacystus decipiens
Honolulu Harbor
& Kane’ohe Bay
Honolulu Harbor
& Kane’ohe Bay
Makapu’u &
Kahuku
Makapu’u &
Keahole Pt
Waikiki
unknown
Pilinella californica
Makapu'u Kahuku
1976
California
Porphyra sp.
O'ahu
unknown
Japan
Wrangelia bicuspidata
Kane'ohe Bay
1974
unknown
Gracilaria tikvahiae
Gracilaria sp.
Hypnea musciformis
Kappaphycus alvarezii
Kappaphycus striatum
Lola lubrica
Macrocystis pyrifera
1972
1980's
1950's
carrageenan
fresh produce
carrageenan
kappa
carrageenan
kappa
carrageenan
kappa
carrageenan
many reef spp
none
none
unknown
unknown
unknown
unknown
successful
Abalone food ;
alginates
none
unknown
No
none
none
unknown
nori
unknown
successful
none
unknown
none
3.4.2 Algal Invasion Patterns
Along with biological characteristics of the seaweeds themselves, environmental
conditions in the donor and recipient regions play a role in the establishment and spread
of marine invasives (See Table 1.1.2-1). Where new habitat becomes ava ilable,
introductions not only become established but can move to nearby regions. These areas
can act as stepping stones to accelerate the spread of invasions. This was the mechanism
for the introduction of the zebra mussel, Dresseina polymorpha into the Laurensian Great
Lakes where it is not commercially exported (Carlton, 1996). Changes in the donor
regions can also accelerate the spread of otherwise innocuous species. Nutrification,
sedimentation, removal of herbivorous fishes and other anthropogenic impacts can
initiate phase shifts that can trigger unprecedented growth of algal species. This in turn
may increase the chances of transport outside the donor region as was the case with the
clam, Theora lubrica. Pollution in the Inland Sea of Japan triggered a population
explosion of this clam that was connected to its increase in San Francisco Bay. An
interaction of a number of factors can result in inoculation and dispersal events
(Johnstone, 1986). Changes in physical factors such as salinity, temperature, and water
motion can create optimum conditions for invasion. These environmental fluctuations
36
are occurring at unprecedented rates. Technological advances in shipping have further
aggravated the problem. Larger vessels carrying more ballast water are traveling faster to
more ports of call than in any previous time, continually increasing the chances of
invasion.
Herbivory can be an important factor in the success of introduced algae. Many
algae have developed defenses to reduce the effects of hervivorous fishes. These include
spatial and temporal adaptations. Some seaweeds inhabit cracks and crevices that are
difficult for grazers to reach. Others such as Halimeda, produce uncalcified young blades
at night when herbivorous activity is at a minimum. Other algae have developed
chemical defenses making them unpalatable to fishes. Secondary metabolites not only
resist pathogens and fouling organisms but also have been shown to reduce predation
(Faulkner, 1984). Morphological adaptations can also deter predators.
3.4.3 Growth Rates
Specific physical and oceanic conditions can play an important role in the distribution
and abundance of invasive algal species. Water motion explained the most variability in
distribution, abundance and productivity in invasive algal species in Kane‘ohe Bay
(Doty, 1971; Glenn, 1992; Rodgers and Cox, 1999). Kappaphycus thalli have thick
branches, which have been shown to reduce diffusion of materials into the center of the
thallus, therefore requiring greater water motion than alga with thinner thalli (Glenn,
1992). In field growth experiments by Glenn (1992) in Kane‘ohe Bay, water motion was
the only environmental factor consistently correlated with growth rates of Kappaphycus
alvarezii and K. striatum. Maximum growth rates occurred at the highest rates of water
motion (15 cm s-1 ) with 81% to 98% of the variability attributed to water motion. Under
ideal conditions, Kappaphycus sp. can double their size in 15 to 30 days or less (AnanzaCorrales et al., 1992). In the Main Hawaiian Islands, Russell (1983) found a year-round
average growth rate of 5%. Many algal species have genetically and environmentally
adapted to different water motion regimes.
Brazilian studies of Hypnea musciformis found an 87% recovery rate after harvest
for its Kappa-carrageenan. Cultivation experiments determined a 15% growth rate per
day (Faccini and Berchez, 2000).
3.4.4 Means of Dispersal
Other species are less restricted in their ecological requirements than Kapaphycus sp.
Acanthophora spicifera, the most successful and widespread alien algae in the Main
Hawaiian Islands, has become well established in a wide variety of habitats from
sheltered bays to exposed coastlines occurring from the lower intertidal to the eulittoral
zone. It spans a range of oceanic conditions, occurring in moderate to strong water
motion and survives in a wide range of salinities. A. spicifera attaches to stable
substratum such as basalt and carbonate platforms or large rocks or to shifting shells,
sand or rubble, facilitating its spread. Once established, A. spicifera can spread rapidly
throughout the NWHI chain as it has in the Main Hawaiian Islands. This species has
been documented to attach to stationary buoys and ropes as well as to mobile boat hulls
and floating objects that can act as vectors of spread to extend their distributions.
37
Vegetative fragmentation is an extremely effective means of propagation, which
can result in widespread establishment. Algae can break into pieces from waves,
predation or other means of disturbance. It was found that fragments as small as a few
apical cells can regenerate to start new populations. Fragments of Kappaphycus striatum
as small as 0.05 g were found to exhibit positive growth (Woo, 2000). Many species that
exhibit this form of reproduction have successfully invaded new areas (Mshigeni, 1978;
Kilar and McLachlan, 1986; Meinesz et al., 1993). In Hawai‘i, several invasive
rhodophytes have spread extensively through vegetative fragmentation. Through
successful ecological strategies such as vegetative fragmentation, Acanthophora
spicifera, has become widely established on all the main Hawaiian Islands since its
introduction in 1950.
3.4.5 Spread
There is growing concern about the impacts of invasive marine species on a global scale.
In the United States alone, least 4,500 non- indigenous marine species have become
established (U.S. Congressional Office of Technology Assessment, 1993), with severe
ecological impacts incurred by at least fifteen percent of these (Ruiz et al., 1997). The
rate of introduction has rapidly escalated in the last half of the century, initiating
increasing research and management action.
Many alien species arrive in new areas but do not expand and persist (Mollison,
1986). Once a species settles and becomes naturalized to the surrounding environmental
conditions there is possibility for expansion. Species may expand naturally or by
anthropogenic means of transfer (Ribera, 1994). Once a species persists in new
environments it has the potential to become invasive, competing with native species for
resources such as space and nutrients.
Alien, invasives have already demonstrated the potential to spread rapidly
throughout the Main Hawaiian Islands. Kappaphycus alvarezii was introduced on the
shallow reef flat on Moku o lo‘e in 1974 and was not expected to spread. It was
hypothesized that the lack of a sexual reproductive cycle would limit its spread. Based
on its distribution in shallow waters, it was further suggested that its introduction onto the
shallow reef flat would keep it contained since it was believed that Kappaphycus could
not survive in the deeper waters surrounding the island. Its apparent inability to cross
channels and deeper dredged reefs was thought to prevent its dispersal into new areas
(Russell, 1981). Russell also concluded that K. alvarezii would not compete with native
algal species since it had been documented to inhabit sandy grooves on the reef edge
where native algal abundance was low. Eighteen years after the documentation of the
distribution of K. alvarezii in 1978 (Russell, 1983), Rodgers and Cox (1999) assessed its
rate of spread. It was documented to have spread throughout Kane‘ohe Bay, extending
its range 5.7 km from 1974 to 1996, with an estimated rate of spread of 260 m yr -1 .
Although each invasive species responds differently to physical, biological, and
environmental conditions in new habitat, Woo (2000) found that Kappaphycus striatum is
not limited by environmental conditions but rather by dispersal, herbivory, and substrate
availability.
Other introduced species have even higher rates of spread. The rate of spread
varies with species and environmental conditions. The chlorophyte, Caulerpa
38
scalpelliformis was documented to have spread 300 m yr-1 in Botany Bay, New South
Wales (Davis et al., 1997). A few species have exhibited extremely rapid rates of spread.
In the Mediterranean, Caulerpa taxifolia, a popular marine aquarium species due to its
fast growth, was reported to have spread 53 km yr -1 (Meinesz et al., 1993) and displaced
the native seagrass Posidonia oceanica (Ribera & Boudouresque, 1995). Similarly,
Carlton and Scanlon (1985) estimated the rate of spread of Codium fragile to be 55 km
yr-1 . The ability of these algae to spread rapidly is in large part due to the reproductive
strategy, vegetative fragmentation. The aquaculture industry has made good use of this
ability for seaweeds to grow rapidly (Glenn and Doty, 1990). Other successful invasives
on O‘ahu have been documented to reproduce through fragmentation. These include the
weedy species Acanthophora spicifera (Kilar and McLachlan, 1986), Hypnea
musciformis (Russell and Balaz, 1992), and Kappaphycus striatum (Glenn and Doty,
1990). This ecological advantage over many native species allows them to increase their
distribution and abundance rapidly.
The economic and ecological impact of species that become invasive can be great.
In algae, some of the competitive strategies that make these weedy macrophytes so
successful have been identified. They reproduce readily through vegetative
fragmentation and have the ability to fragment easily and regrow rapidly. They can alter
their photosynthetic performance to compete successfully in new areas. They can even
change their morphologies to take advantage of specific nutrient conditions.
Understanding these adaptive strategies can influence the approach management takes to
preventing and predicting its introduction and spread.
It has already been documented that Hypnea musciformis has invaded the NWHI
(Tenbruggencate, 2005). Hypnea musciformis has recently been reported from samples
collected from the leeward side of Mokumanamana (Necker Island). These samples were
collected from lobster traps deployed at depth of 30 to 90 meters. The first reports of this
invasive alga in 2002 found very low quantities. Samples from subsequent years
continued to include small amounts of this invasive alga. The most recent reports from
2005 samples found much higher quantities than any previous years. This verifies that H.
musciformis has not only become established but is increasing in abundance. It has
expanded its distribution from its last known point 350 miles northwest on the island of
Kaua‘i. High biomass of this species has been correlated with areas with high levels of
nutrients such as locations off Maui that are affected by agricultural runoff or sewage
seepage. Possible contributions of nutrients to waters surrounding Mokumanamana
include guano droppings from resident bird populations. The documentation of the
spread of this invasive to the NWHI highlights the high probability of continued island
hopping along the chain.
Most introduced specie s do not become established, yet those that do can upset
marine biodiversity, change successional patterns, compete with native species, and alter
habitat complexity. These few persistent invasives can have large ecological and
economic impact. Most of these macrophytes can be easily identified in the field, aiding
in monitoring and management efforts.
Although data on characteristics of alien macrophytes is sparse, there are certain
life strategies that favor growth and spread of these invasives.
39
§
§
§
The ability to reproduce easily through vegetative fragmentation
The ability to adjust their photosynthetic capabilities in a wide range of light
environments
To ability to modify their morphologies to adapt to differing wave and nutrient
regimes
It has been well documented that invasive algae can outcompete native species,
reducing endemism (Woo, 2000). The possibility also exists for hybridization of nonnative with native species.
Recent inventories show a high rate of error in some regions. Accurate records
exist in very few places. Yet in response to worldwide algal invasions at an alarming
rate, research on introduced algae has grown. In the Mediterranean, at least 60 invasive
macrophytes have become widely established. Along the Atlantic coast of the United
States, nearly 30 non- native algae have spread extensively and over 20 invasives have
spread in New Zealand. Algal invasions have also been reported from Australia and
Brazil (Ribera and Boudouresque, 1995). Here in Hawai‘i, 19 non- indigenous species of
algae have become established and are spreading throughout the state (Russell, 1992).
3.4.6 Ecological Consequences
Algal invasions can have an impact on biodiversity, community structure, species
richness, competition, and genetic diversity. Diversity of species and species richness
may initially increase following invasions with a consequent decrease in the number and
abundance of native species. Community composition may be altered dramatically when
the spread of an invasive alga reduces the heterogeneity of the environment by reducing
endemic native species. On a cellular level, increases in gene flow and the success of
particular genotypes can also alter genetic diversity. The difficulty in preventing
invasions includes identifying possible algal candidates, regions they may invade and the
rate of spread. Spatial and temporal variation prevents accurate predictions.
Development of strategies to avoid introduction is critical. By the time an invasive has
been reported, it has spread extensively. Once they have begun to advance it is extremely
difficult to eradicate.
Descriptions of some species with the potential to spread to the Northwestern
Hawaiian Islands Marine National Monument are included in the following sections,
(Hypnea musciformis already spread to Necker Island):
40
3.4.7 Hypnea musciformis
Figure 3.4.7-1. Hypnea musciformis. Photo by L. Preskitt
Description
Hypnea musciformis can be found in clumps or intertwined cylindrical branches that
become progressively thinner towards the tips. This highly branched species processes
tendrils that attach easily to other species. The holdfasts are either extremely small or
lacking. Its coloration ranges from red to yellowish brown in high light or nutrient poor
regions. Hypnea musciformis is easily distinguished from other species in this genus
including the native Hypnea cervicornis by broad, flattened hooks at the end of branches.
It can be epiphytic, attaching easily to other algal species with hooked tendrils that twist
around algal axes.
It can be found on hard bottom substrate or attached to rocks, coral, or shells. It
can also commonly be found attached to other macrophytes including Sargassum spp.,
Ulva fasciata and another invasive, Acanthophora spicifera.
History
The invasive algae, Hypnea musciformis was intentionally introduced from Florida to
Kane‘ohe Bay, Hawai‘i in 1974. Following a three-year lag, it expanded its range to
several reefs within the bay. It subsequently spread rapidly to intertidal zones spreading
to Waikiki in 1980 and continuing to extend its range to include most of O‘ahu by 1982
(Abbott, 1987). The original intention was to market it as a product in the carageenen
trade. Although the project was subsequently abandoned and it was presumed that this
species would die out, it has spread prolifically to most of the main islands. It was first
recorded in Pa‘ia on the island of Maui in 1987. More recent observations determined
that in the winter on both windward and leeward Maui beaches, H. musciformis is
responsible for two-thirds of the drift algal biomass. These nuisance blooms can result in
large drifting mats that can result in over 20,000 lbs. of algae washing up weekly. The
rotting algae on the beaches have reduced property values and occupancy reductions in
41
Kihei, Maui resulted in losses of over $20 million dollars (HCRI, 2002). Clean-up efforts
have also cost taxpayers thousands of dollars.
Current Distribution
Figure 3.4.7-2. Data from www.botany.hawaii.edu/GradStud/smith , used with permission.
Hypnea musciformis is distributed throughout most of the world. In Hawai‘i, it is one of
the few invasive algal species whose range has been followed since its initial
introduction. It is currently reported to have extended its range to all of the main
Hawaiian Islands with the exception of the island of Hawai‘i and Kaho‘olawe. It has
recently spread to Mokumanamana (Necker Island) possibly through island hopping or
transport by the commercial lobster fisheries traps.
Ecology
This species possess traits favorable over native species. It has a high growth rate,
propagates effectively, exhibits morphological plasticity, resists herbivory, is an effective
epiphyte, and has high surface to volume ratios (Carpenter, 1990). Growth rates in field
studies in Kane‘ohe Bay recorded 10-12% day-1 increases (Russell, 1992). Earlier field
studies found even higher growth rates from 20% day-1 (Dawes, 1987) to 50% day-1
(Humm and Kreuzer, 1975). These may be underestimated due to the difficulty in
determining growth rates in situ due to loss by fragmentation and predation.
42
Figure 3.4.7-3. Mokumanamana (Necker Island), Northwestern Hawaiian Islands. Photo Credit: M. Costa
Typical of many macrophytes, H. musciformis reproduces both sexually and
asexually. Through vegetative reproduction it is highly successful in all size classes,
especially the smallest pieces. Fragmentation studies have shown that the tiny hooks left
behind after physical disturbance can increase up to 200% in a less than a week (Smith et
al., 2002). Currents disperse the drift algae removed by high wave action to new
locations.
Along with another invasive algae, Acanthophora spicifera, H. musciformis is a
prominent food source of the endangered green sea turtle, Chelonia mydas.
Threats
Spreading rapidly through reproductive fragmentation and prolific spore development, H.
musciformis has become one of the most prevalent species in the shallow reef
environment. Russell (1992) demonstrated a competitive dominance of this weedy
species over the native macroalgae Laurencia nidifica and Hypnea cervicornis.
3.4.8. Avrainvillea amadelpha
Figure 3.4.8-1. Avrainvillea amadelpha. Photo Credit: L. Preskitt
Description
A. amadelpha is comprised of one to four small, thin wedge-shaped blades. Plants do not
normally exceed 4 cm in width and 3 cm in height. Its short stature is due to horizontal
growth from the basal region rather than upward expansion from the blades. The surface
43
of each blade has a velvety texture. Although the color of this alga is a green to greenish
gray, it often appears brown due to fine silts which can get trapped and lightly cover
blades or aggregations of blades. Other macroalgae is often found attached to more
established plants.
History
Although the mechanism of introduction is unknown, the most recent of the described
invasive algae in the Main Hawaiian Islands, Avrainvillea amadelpha is hypothesized to
have arrived after 1981. The possible origin of this introduction includes the Mauritius,
Tuamotus, Fiji, or the Philippines. It was first identified on O‘ahu’s leeward coast. It has
spread rapidly along O‘ahu’s south shore where it currently inhabits similar communities
as Acanthophora spicifera. Its recent extension of its range to the island of Kaua‘i
confirms its ability for interisland dispersal.
Current Distribution
Figure 3.4.8-2. Data from: www.botany.hawaii.edu/GradStud/smith, used with permission
Invasive algae surveys conducted in 1999 and 2000 by the University of Hawai‘i’s
Botany Dept. show the distribution of A. amadelpha to include the islands of O‘ahu and
Kaua‘i. Although it primarily inhabits shallow coastal waters, it has been collected from
14m depths off Waikiki. It can thrive in sandy or rubbly areas. On the island of O‘ahu,
its range extends from Kahe Point to Diamond Head. It has similarly been reported from
Kaua‘i’s south shore. This may be of some concern to the NWHI since it is capable of
44
interisland dispersal whether through natural mechanisms such as currents or through
anthropogenic vectors including ship traffic. With its spread occurring in a northwesterly
direction, the possibility of island-hopping exists.
Threats
Given the current rate of spread of A. amadelpha, the threat of dispersal to new areas is
highly probable. In areas where it has become established, it covers a wide expanse of
substrate, eventually acting as substrate for attachment of other algae. Competition with
native species has already been described. Overgrowth of Halophila hawaiiana, a
significant native seagrass has occurred in large sandy regions. H. hawaiiana is a
relatively rare seagrass found in the subtidal environment. The roots of this important
species traps and holds sediment. Within these meadows a rich community of organisms
are supported. A variety of sessile and mobile invertebrate species take advantage of the
food and shelter provided. Fishes also utilize these seagrass beds. In addition, they
provide a significant portion of the endangered green sea turtle’s (Chelonia mydas) diet.
A. amadelpha may also be competing with Halimeda spp., a calcified chlorophyte that
contributes to sand production. Loss of habitat may influence certain fisheries.
3.4.9 Kappaphycus and Eucheuma spp.
Figure 3.4.9-1. Kappaphycus. Photo by K. Rodgers
Description
Kappaphycus alvarezii has been referred to as the “licorice algae” due to its ropy
appearance and rubbery texture. It is easily distinguished by its large branches, often
extending over 6 feet in length with a diameter of up to an inch, making it one of the
largest species of seaweed. It varies in coloration from yellow to green to golden brown.
The morphological plasticity and lack of sexually mature adults of species within the
Kappaphycus and Eucheuma genus make differentiation difficult.
45
History
The genus Kappaphycus and Eucheuma occur naturally throughout the Indo-Pacific
although the most commonly cultured species are from the Philippines. Thus far, species
from these two genus have been introduced to 32 countries for aquaculture purposes with
a current annual value of $270 million (Ask and Azanza, 2002). Several Kappaphycus
and Eucheuma species were intentionally introduced from Florida and the Philippines to
Honolulu Harbor and Kane‘ohe Bay in the early 1970’s for experimental aquaculture
studies, to assess the feasibility of producing kappa-carrageenan, used for medicinal
purposes and as a thickener for many foods. These included K. striatum, K. alvarezii, E.
denticulatum, and E. isiforme. Three of these four species became highly successful,
extending their distributions and increasing their abundance. The exception was E.
isiforme, which has not been reported since shortly following its introduction into
Kane‘ohe Bay in 1974.
Kappaphycus alvarezii (formally described as Eucheuma striatum) was initially
introduced into Honolulu Harbor on O‘ahu’s south shore in September 1974. It was later
transplanted to Moku o lo‘e (Coconut Island) on the northwest reef in late 1976 (Russell,
1992). It was again transplanted to several other locations within Kane‘ohe Bay.
Glenn and Doty (1990) conducted research on growth, photosynthesis, and
respiration, while Russell (1981) documented the introduction and establishment of K.
alvarezii in a doctoral dissertation with subsequent ecological studies.
Current Distribution
Figure 3.4.9-2. Data from: www.botany.hawaii.edu/GradStud/smith , used with permission
46
K. alvarezii also transplanted to Moku o lo’e (Coconut Island) in Kane’ohe Bay in 1974
has since become highly successful, spreading as far as Kualoa at the far north end of the
Bay. Although its distribution has expanded to include the whole bay, it is found in
highest abundance on the fringing reef and patch reefs in the south and central sectors.
Ecology
Kappaphycus spp. can spread rapidly through fragmentation, growing from even the
smallest pieces. In recent years, extensive scientific and community efforts have been
undertaken to control its distribution and limit its abundance.
Threats
Invasive marine algae have displaced native algal species throughout the world. In
temperate marine regions, Caulerpa taxifolia, Codium fragile tomentosoides, Grateloupa
turuturu, Sargassum muticum, and Undaria pinnatifida have spread rapidly to invade
new territories. In the tropics, the most well-documented case of displacement of natives
is the Kappaphycus spp. from Hawai’i. It has demonstrated the potential to successfully
invade new territory (Rodgers and Cox 1999, Conklin and Smith 2005) and its ability to
compete directly with native species has been documented (Woo 2000). By 1996,
eighteen years after its original introduction on Moku o lo‘e, Kappaphycus spp. had
spread nearly 6 km from the point of its origin to the northwest sector of Kane‘ohe Bay
(Rodgers and Cox 1999). Subsequent surveys in 2003 found Kappaphycus spp. had not
only continued its progression but has invaded new territory (Conklin and Smith 2005).
This further extension of its distribution reflects an additional 3 km spread from 1996 to
2003, a nine-year period. Thus, in the 25 years since its arrival, it has spread 9 km. An
additional concern is the abundance of Kappaphycus spp. near the channels where
currents can potentially carry fragments outside the bay. It was also documented that
Kappaphycus spp. has invaded new habitats (Conklin and Smith 2005). Once restricted
to the outer margins of reef flats it has extended its geographic range to include the reef
slopes.
The documented ability of Kappaphycus spp. to invade new territory and overgrow
and kill native species has become a serious concern as has the results of recent research
demonstrating its rapid re-growth following removal (Conklin and Smith 2005).
Experimental plots on three different habitat types show extensive growth rates after only
two months. A year following manual removal of all Kappaphycus spp. from plots, it
averaged 62% cover. Residual tissue left at attachment points are responsible for this regrowth. These microscopic cells are impossible to manually remove. This can pose a
problem in control and eradication efforts. An extensive program has been underway to
control the spread of Kappaphycus spp. outside Kane‘ohe Bay. Research projects to link
its ecology with methods of control are diverse. These include studies focusing on
competition with native species, re-growth studies, effectiveness of biocontrol agents,
and herbivorous fish preference tests.
These studies aid in understanding the ecology of Kappaphycus spp. and evaluating
the possible measures of control. A manual removal attempt utilizing a modified dredge
and suction is currently being tested as a joint effort between the University of Hawai’i,
the Nature Conservancy, and the Division of Aquatic Resources. Manual removal had
47
previously been demonstrated to be ineffective in preventing re- growth. Woo (2000)
found Kappaphycus spp. to spread rapidly from only a few apical cells not even visible to
the human eye. Conklin and Smith (2005) have documented substantial re- growth after
removal from experimental plots.
Research involving the role of herbivorous fishes in controlling invasive species is
disappointing. Kappaphycus spp. is not a preferred algae and is not being grazed heavily
by fishes frequenting the bay (Stimson et al. 2001). An herbivorous invertebrate has
however shown some promise in biocontrol of Kappaphycus spp. Unlike the local fishes,
the sea urchin, Tripneustes gratilla appears to prefer this invasive algae over native
species. Studies using experimental enclosures found a substantial decrease in
Kappaphycus spp. although no increase in coral cover was observed (Conklin and Smith
2005). T. gratilla occurs in low abundance in Kane’ohe Bay and would have to be
brought into the bay in large numbers to effectively control the Kappaphycus
populations. The negative effects of biocontrol agents in terrestrial environments are
well documented. Their wide-ranging effects are usually irreversible, creating more
problems than they solve. Biocontrol as a method of introducing a species in an attempt
to control a destructive species can have devastating effects. There can be synergistic
effects with other species and non-target effects can results. Host switching may occur
when the targeted species becomes limiting. The host may expand their range since they
are self-propagating and self-dispersing. Competition with native species can arise. A
common carnivorous snail introduced to control the African snail populations and the
Indian mongoose as a biocontrol for rats are just two examples of failed attempts at
controlling invasive species. Introduced in 1955, the biocontrol agent Euglandina rosea
drastically reduced the remaining endangered Achatinelline tree snails populations. The
mongoose, Herpestes auropunctatus was similarly introduced as a biocontrol for rats on
the sugar plantations in 1883 from Jamaica. It has since reduced bird populations
through predation on eggs and hampered efforts to reintroduce the endemic nene goose,
Nesochen sandvicensis, back to its native environment. In addition to reduction and
competition with native species it has assisted in the spread of other introductions such as
the guava (Psidium spp.) (Stone and Loope 1987). Although biocontrol agents have not
been widely used in the marine environment, effects of marine introductions have been
well-documented. The introduced snapper, Lutjanus kasmira carries an internal parasite
that may spread to native fishes and may also displace deeper water snappers. Even
introducing native species into areas with low abundances such as is suggested with T.
gratilla, can dramatically alter the ecosystem.
Other suggested methods of controlling invasive species that have proven effective
elsewhere include insitu killing using salt, copper sulfate, and chlorine (Thibaut and
Meinesz 2002). Experiments would have to be replicated in Hawaiian environments to
include Kappaphycus spp. If these chemicals prove to be effective in the control of
Kappaphycus spp. it is still highly likely that they may inflict serious damage on adjacent
native species.
Phase shifts from coral to algal dominated reefs have been associated with loss of
biodiversity, reduction in value, and the erosion of reef structure. The spread of
Kappaphycus spp. to other areas in the MHI is highly probable. As a possible NWHI
48
invader, steps can be taken to slow its expansion beyond its present distribution and
prevent its accidental import outside the MHI.
3.4.10 Acanthophora spicifera
Figuure 3.4.10-1 . Acanthophora spicifera . Photo by J Smith
Description
Acanthophora spicifera is a Rhodophyte or red algae. Its coloration varies with exposure
to sunlight, from yellow in shallow waters exposed to bright light, to green, red or dark
brown in areas with lower irradiation. The distinctive solid, cylindrical, spiny branches
can grow up to a foot high. The short main branches are hook- like and brittle,
fragmenting easily in high water motion. Its large holdfast is irregularly shaped to attach
to hard substrate. Branch morphology can change under varying conditions. Under low
wave energy conditions, it can reach greater heights. Kilar and McLachlan (1986) found
that A. spicifera in Panama reached only about one-third the height in heavily wave
influenced fore-reefs as those residing in low energy back reef areas.
History
Believed to have arrived accidentally from Guam to either Pearl Harbor or Waikiki, this
highly successful species has spread throughout the state since its arrival in the 1950’s.
Current Distribution
Acanthophora spicifera is widely distributed throughout tropical and subtropical regions
in tidal and subtidal zones (Kilar and McLachlan, 1986). It is typically found in shallow
reef flats between 1-8 m although has been reported to depths of 22 m in Florida, the
Virgin Islands and Puerto Rico. In Hawai‘i, A. spicifera can be found on all main islands
particularly in shallow intertidal zones and has been reported as one of the most abundant
rhodopyhtes occurring on reef flats (Jokiel and Morrissey, 1986). It can be found on a
49
diversity of substrate type. It is particularly abundant on hard bottom substrate, attached
as an epiphyte on other algae or unattached as drift algae.
Figure 3.4.10-2. Data from: www.botany.hawaii.edu/GradStud/smith, used with permission
Ecology
Typical of most macrophytes, A. spicifera exhibits both sexual and asexual reproductive
strategies. Sexual tetrasporaphytes were found to be extremely common on reef flats in
Panama but dropped dramatically from 80% to 5% of the plants during prolonged periods
of tidal immersion (Kilar and McLachlan 1986). Asexually, fragmentation accounts for
most of the standing crop. High wave energy will fragment algae and local currents
distribute them to adjacent areas. Fragments can securely attach to substrate in about two
days. Its morphology is ideal for recruitment into new areas due to its hook- like branches
that can snag on rocks, corals, or other species of algae.
Distributed throughout the tropics and subtropics, its temperature range is quite
broad and has also been found to tolerate levels of salinity both higher and lower than
ambient. It cannot survive repeated exposure to air (Russell 1992). However, its survival
rate increases when it co-occurs with other species. This beneficial co-existence is due to
the tolerance of the other algal species to wave energy and their retention of water to
prevent desiccation.
The major predators on A. spicifera are reef fishes and the green sea turtle,
Chelonia mydas. Russell and Bala z (1992) found in examining stomach contents that
over 20% of their diet is comprised of A. spicifera.
50
Threats
Branches often break off easily and grow rapidly into extensive free-floating mats or
attach to several species of native seaweeds. Competition with native algae was
demonstrated by Russell and Balaz (1992).
4.0 MANAGEMENT OPTIONS
4.1 Prevention
In the aquatic environment it is considered unrealistic in most cases to be able to
eradicate a non- indigenous species once it has become established. The best strategy is to
minimize the likelihood of initial introduction through prevention and outreach efforts.
The most common approach for prevention is to target individual species that are
potentially invasive to an area. This is a method proven to be effective in terrestrial
systems, however, a more comprehensive approach in aquatic environments is to identify
major pathways that can expose habitats to non- indigenous species and determine ways
to control their potential effects. These pathways have been identified in earlier sections.
There are many pathways that can transport non- indigenous species to aquatic systems
and a variety of management tools and treatment options aimed at prevention. In contrast
to historic introductions, present introductions are seldom intentional. Measures to avoid
unintentional introductions must now be addressed. Education and legislation can help
control introductions associated with maritime shipping, live seafood and bait shipments,
aquaculture, shipments of commercial and institutional aquarium species, the activities of
education and research institutions and marine debris transport. The major vectors that
can impact the Northwestern Hawaiian Islands Marine National Monument are covered
in the following sections.
4.1.1 Ballast Water
Ballast water treatment and management can decrease inadvertent introductions
associated with this vector. Several treatments have been suggested to treat ballast water.
These include filtration, mechanical agitation, salinity alteration, exposure to radiation,
microwaves, heat, removal of oxygen, construction of facilities to supply treated water,
and facilities to discharge water into (Carlton et al. 1995). Several of these methods have
been successfully employed. Using the heat from the engines to raise the temperature of
the ballast water resulted in the mortality of all zooplankton and partial mortality of
phytoplankton (Rigby et al. 1999). The use of nitrogen to remove oxygen to prevent
ballast tank corrosion has also proved to be successful in eliminating most of the marine
organisms (Tamburru et al. 2002). Another deoxygenating technique using a vacuum had
similar results (Gordon and Horeth 2001). Presently, the most widespread method is the
exchange of ballast water before arrival to a destination. This is the method that is in
widespread use due to its inclusion in administrative rules on the national and
international scene (see section 4.2).
4.1.2 Sediments
The measures taken to minimize the transport of organisms by sediments associated with
maritime activities are varied. If an area has a potential for uptake of abnormally high
51
levels of sediment, it should be avoided as a ballasting site. Addition of large quantities
of sediment to a ballast system is generally avoided due to the potential damage to pumps
and to minimize the number of times tanks have to be cleaned between shipyard service
periods. Guidelines exist for disposal of this sediment (International Maritime
Organization, 1998) and state that it should be disposed of in land-based facilities or in
open ocean environments. Sediments associated with deck surfaces and closed spaces
such as anchor chain lockers and bait wells are easier to manage. These areas associated
with sediment accumulation can easily be surveyed and the material eliminated by
physical removal before departure from source ports to the Northwestern Hawaiian
Islands Marine National Monument.
A synopsis of preventative measures to minimize transport of non- indigenous
species by ballast water and sediments from source ports to the Northwestern Hawaiian
Islands Marine National Monument are as follows (Based on Godwin and Eldredge
2001):
§
§
§
§
§
§
Ballast water exchange in water deeper than 2000 m should be performed to
flush out any surviving organisms taken in at ports, if pre- intake measures are
not in place.
Pre-intake measures such as filtration, ultraviolet treatment, sonic treatment,
or other measures that exist should be implemented.
Do not take in water from global hotspots where organisms that may be a
threat to the environment exist, such as from areas that are experiencing toxic
algal blooms or waterborne disease outbreaks.
Do not take in ballast water at night since a more diverse assemblage of
organisms may be present.
Avoid areas with high sedimentation or shallow waters, poor water quality, or
regions near sewage discharge.
Post-intake extermination of organisms with biodegradable chemicals, heat, or
electrical treatment should be conducted.
§
Clean ballast tanks regularly and dispose of sediments properly.
§
Inspect deck surfaces and enclosed voids for sediment accumulations and
remove and dispose of properly.
4.1.3 Hull Fouling
Of all the vectors associated with maritime vessels, hull fouling is the most problematic
to control and monitor. Modern anti- fouling coatings prevent a great deal of fouling.
Maintenance of these coatings is the best preventative measure for transport of organisms
by this means. Increasing the frequency of shipyard service to hulls is the optimal way to
maintain the integrity of hull coatings, but would be prohibitively costly to the vessel
owners, and hence an unrealistic option. Hull fouling occurs in areas where the antifouling coating has been compromised due to physical damage, but it occurs more
frequently in sheltered areas such as the seachest. Fouling that occurs in accessible
regions of the hull can be spot cleaned by commercial divers, but the seachest can only be
accessed during drydock service in a shipyard. This seachest fouling can spread and clog
or restrict flow through the piping that supplies water for engine cooling, fire fighting, as
well as the ballast water system. As a control measure, the United States Navy has tried
52
the placement of slow-release biocide devices in the seachests of some vessels (Godwin,
personal observation).
Efforts to identify vessels with high potential for hull fouling introductions could
be taken by port authorities. Vessels that have a high incidence of hull fouling are barges,
floating drydocks and vessels from decommission yards. Towed cargo barges are used by
many companies to cheaply carry small quantities of bulk and general cargo. Floating
drydocks are generally surplus military platforms that have been purchased by private
shipyards to supplement land-based drydock facilities. Vessels from military
decommission yards are purchased to be used as war monuments, scrap metal, and as
hardware for the navie s of developing nations. The cargo barges tend to spend more time
in port and move at slow speeds when being towed, which create a situation more
conducive to settlement and establishment of fouling organisms. Cargo barges are
maintained in the same way as other commercial vessels, in respect to hull maintenance.
This is not the case for vessels from decommission yards, which ha ve been idle for many
years and poorly maintained. These vessels and cargo barges are the extreme cases for
hull fouling and should be targeted by port authorities as high risk vessels for marine
non- indigenous species introductions. Requiring hull maintenance records for the vessels
and denying port entry to those vessels deemed high risk based on these records would be
one approach. Another method could be to provide quarantine areas in water greater than
2000 meters in which remote video inspections could be done on the hull of vessels
unable to produce recent maintenance records. All ports need to create policies
concerning hull fouling introductions that will educate the maritime shipping industry
and provide vessel owners clear guidelines to follow. The port could create an
infrastructure that assists in development of hull monitoring programs with commercial
divers and remotely operated video inspection equipment. Awareness of this issue by the
industry and port officials is the best method for prevention.
A synopsis of high risk vessel platforms is as follows:
1. Towed vessel platforms: this category includes a variety of platforms towed by tug
boats such as cargo and crane barges, drilling platforms, and pontoon bridges. The tug
boats for this and the second category would also be included as high priority vessels.
2. Floating Drydocks: a category of large towed vessel platforms that can change
ownership quite frequently and are subsequently moved throughout the oceans of the
world. Purchasing and transporting floating dry docks to new locations is a cheaper
alternative to constructing new shipyard facilities.
3. Stochastic Events: a general category that puts focus on arrivals that are not part of
the regular suite of vessel arrivals to a port system. Examples would be unscheduled
arrivals for medical and mechanical emergencies, salvaged vessels, and decommissioned
military vessels. Personal craft from overseas locations are also included in this category
due to the fact that arrivals are quite unpredictable. The exception would be regularly
scheduled sailing races that use Hawai‘i as a stop-over or finish point.
In order to prevent transfer of introduced species by vessel hull fouling the
inspection of all vessels planning to enter the Northwestern Hawaiian Islands Marine
National Monument is imperative and should include all surfaces at and below the
waterline. This requires some specialized training and needs to be done by specialists.
Levels of fouling vary and this makes the level of compliance variable. Fouling ranges
53
from concentrations in discrete locations to uniform coverage. Discrete levels of fouling
can be dealt with easily but uniform coverage requires a labor intensive and costly
procedure performed by commercial diving companies. Potential operators/owners of
vessels operating in the Northwestern Hawaiian Islands Marine National Monument
should be made aware of this cost so that it can be figured into contract proposals. Public
and private sector vessels that will be operating regularly in the Northwestern Hawaiian
Islands Marine National Monument should adopt the following approaches to safeguard
against non- indigenous species transport:
§
§
§
§
Frequent underwater visual or video inspections
Proper maintenance
Regular cleanings at shipyards
Sea che st and piping time-released biocides
4.1.4 Other Sources
Marine debris has been shown to have the ability to transport non- indigenous species to
the Northwestern Hawaiian Islands Marine National Monument. Modes of transport such
as derelict fishing nets are problematic to manage but the impact of other anthropogenic
debris, such as Fish Aggregating Devices (FAD) deployed by the State of Hawai‘i, can be
minimized. Increased attention to the care and maintenance of FAD’s will minimize the
likelihood of them drifting into the Northwestern Hawaiian Islands Marine National
Monument.
The increase in focused research in the Northwestern Hawaiian Islands Marine
National Monument has created a situation in which more vessel traffic and extractive
activities are influencing a variety of habitats. A suite of potential non- indigenous species
vectors associated with research activities related to small boat and diving operations
need to be considered. The large vessel platforms are included under the guidelines of
other maritime traffic but the small boats launched from them need to be considered as
well. Before loading onto the transport vessel, a full survey of outboard motor apparatus
and bilges for live organisms, sediments and propagules should be completed.
Appropriate cleaning with freshwater should be required in all cases. Dive gear,
instrument arrays and other equipment should also be subjected to inspection and
freshwater rinsing before being loaded for transport to the Northwestern Hawaiian
Islands Marine National Monument.
Many other vectors associated with fisheries and conservation activities exist and a
brief synoptic list of measures to minimize inadvertent exposure of the Northwestern
Hawaiian Islands Marine National Monument to aquatic non- indigenous species is as
follows:
§
§
§
§
§
§
§
No aquaculture or small scale rearing of algae, invertebrates or fish
No intentional introductions for any purpose
No disposal of bait or seafood
Sanitation of live wells and fishing gear prior to entry
No release of any organism collected on another island
Proper storage and disposal of marine debris
No sand or soil transport
54
§
Inspection and cleaning of marine construction material
4.2 Legislation and Administrative Rules
U.S. Federal Government Management Efforts
Due to the impacts of AIS documented in the United States , Congress passed the Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990 (NANPCA). The
NANPCA legislation created mandatory ballast water management guidelines that
applied only to the Great Lakes. A reauthorization of NANPCA in 1996 created the
National Invasive Species Act of 1996 (NISA), which expanded the legislation to cover
all U.S. ports. Under NISA, the U.S. Coast Guard (USCG) developed voluntary ballast
water management guidelines and mandatory ballast water management reporting and
record keeping. NISA required the USCG to submit a report to Congress to evaluate the
effectiveness of the voluntary ballast water management program. This report was
submitted in June 2002 and concluded that compliance was too low to allow for an
accurate assessment and proposed regulations that would make the voluntary guidelines
mandatory. The proposed mandatory guidelines would require all vessels equipped with
ballast water tanks entering U.S. waters after operating beyond the Exclusive Economic
Zone (EEZ) to use one of the following approaches:
§ Complete exchange of ballast water intended for discharge in U.S. waters.
This exchange must take place no less than 200 nautical miles from any shore.
§ Retain ballast water on board the vessel
§ Prior to entry into U.S waters, use an environmentally sound ballast water
management method that has been approved by the USCG
§ Discharge ballast water to an approved reception facility
This legislation covers ballast water only and has no provisions for dealing with
sediments or hull fouling, although they are mentioned as issues for the future.
Presently, the NISA 1996 legislation is being reauthorized as the National Aquatic
Invasive Species Act 2005 (NAISA). This is expanded legislation that seeks to provide
tools and coordination to manage AIS threats more broadly. The NAISA legislation will
implement a framework for an effective AIS management program. The components of
this framework will be coordinated between all levels of government in partnership with
private sector stakeholders.
State of Hawai‘i Aquatic Invasive Species Management Effort
In 2003 the development of administrative rules dealing with the vectors of ballast water
and ballast sediments were drafted by the State of Hawaii and pending rules for hull
fouling are in development. The administrative rules for ballast water and ballast
sediments were based on a rules and regulations from the International Maritime
Organization resolution A.868(20) within MEPC 47, and State of California Assembly
Bill 703. The rules were developed, reviewed and agreed upon by a multiple stakeholder
task force.
In the Session Laws of Hawai‘i 2000, the Legislature established Act 134, which
subsequently became Chapter 187A-31, Hawai‘i Revised Statues (HRS), titled Alien
55
Aquatic Organisms. Chapter 187A-31, HRS, designated the Department of Land and
Natural Resources (DLNR) as the lead agency for preventing the introductions and
carrying out the eradication of alien aquatic organisms through the regulation of ballast
water discharges and hull fouling. It also gives DLNR the authority to establish an
interagency task force to address concerns relating to alien aquatic organisms and adopt
administrative rules, including penalties, to carry out the intent of this law.
The administrative rules for ballast water mirror the rules generated by the USCG
for mandatory ballast water management and reporting. In the case of ballast sediments
all vessels (including vessels at dry dock) are required to dispose of ballast sediment in a
proper manner. Ballast sediment is defined as any settling particulate matter (organic or
inorganic) that is found inside a ballast tank.
In 2003 a research project funded by the Hawai‘i Coral Reef Initiative Research
Program focused on the initial efforts for hull fouling management for Hawai‘i. The
focus of the effort was to develop an information framework that provides a baseline to
support the development of management strategies for hull fouling introductions. A
baseline risk assessment strategy based on priority vessel types was put together to guide
the DLNR in preliminary decision-making. The vessels that received the highest priority
were towed platforms, floating drydocks, and unscheduled arrivals of salvaged vessels,
decommissioned military vessels, and private boats from overseas locations. Presently,
the DLNR is pursuing funding to support efforts to expand the information as a tool for
minimizing the introduction of marine AIS by hull fouling of commercial and private
vessels. Although designed for the MHI, a similar approach for the NWHI could be
developed.
4.3 Limitations and Information Needs
Before a prevention plan can be formulated it is imperative to know which species are
involved, and their distribution and abundance. One of the main problems in taxonomic
identification of introduced species in the NWHI is that a full assessment of species has
not been completed. New species continue to be described. Although great strides have
recently been made in describing new species, there are still few comprehensive surveys
to determine endemic status. Descriptive taxonomic studies are crucial to understanding
which species are native to a particular locale. The description of taxonomic groups is
often biased by the size of the organism. For example, perhaps the most widespread
organism in the marine environment, the nematode has been poorly described relative to
mollusks or fishes. This size dependent information is highly correlated with commercial
and recreational interests. To add to this problem, there has been a steady decline in the
number of taxonomists (Winston and Metzger 1998). This shift away from systematics
to cellular and molecular studies may hinder the description of marine organisms (Wilson
1989).
The lack of species distributions and abundance and an incomplete taxonomic
database make identification of invasive species difficult. In order to determine if a
species is introduced, baseline abundance and distribution data is necessary. The origin
of many species is unknown and reported as cryptogenic.
56
4.4 Eradication
Only two attempts at eradication of a potentially invasive species have been reported in
the literature. A mussel, Mytilopsis sp. was eliminated from Darwin Harbor in Australia
Bax et al. 2002). Four marinas were quarantined and treated with sodium hypochlorite
and copper sulfite and all boat hulls were cleaned. This was possible because the marinas
were isolated from other waters by a set of double locking gates. Follow-up monitoring
verified the success of the project.
The second success story involved the polychete, Terebrasabella hetrouncintata in
Cayucos, California. Introduced with a shipment of South African abalone, it spread to
an intertidal area near the mariculture facility. A two- fold eradication plan was initiated
preventing further spread by placing screens over effluent pipes and eliminating its native
host, the Black turban shell, Tegula funebralis (Culver and Kuris 2000).
These two successes were only possible because of the small spatial scale and early
detection of the invasive species. Regrettably, this is the exception in the vast majority of
cases. This is why extensive monitoring must be initiated to detect these aliens in the
colonization phase before they have the time and opportunity to spread. Yet, monitoring
large areas is not often feasible due to the time and expense involved.
Historically, most attempts at eradication of invasive species have not been
successful as reported earlier. Physical or chemical removal can be very costly.
Attempts to remove invasive Japanese sea stars (Asterias amurensis) from Tasmania
were unsuccessful. The Asian mussels (Mytilopsis sp.) cost Australians millions of
dollars to eradicate from a small artificial marina.
If an introduction is identified early before it has had a chance to spread and
become invasive, it is possible to control or even eradicate it. Rapid response to incipient
invasives is essential. Monitoring efforts and widespread assessment in the Northwestern
Hawaiian Islands Marine National Monument may have the ability to identify
§
§
§
§
§
§
§
Similar environment to the source of the invasive species
Recently disturbed environment
Low natural diversity
Absence of predators of the invasive species
No similar native species
Simple food-web
Anthropogenic disturbance
To implement a rapid response would require a core team composed of members
that not only represent specialists familiar with disturbances but also include individuals
from the variety of jurisdictions represented in the Northwestern Hawaiian Islands
Marine National Monument.
Since it is difficult to predict which species may become invasive, identification of
the habitats that may foster these species is often used (Williams and Meffe, 1999).
Some of the characteristics of these habitats where introduced species are likely to invade
can aid in minimizing the likelihood of introductions.
Recent scientific data has increased our knowledge and awareness that has
amplified the focus on these invasive introductions. Through education and effective
57
management strategies, the threat of invasion can be drastically reduced. In order to
preserve and continue the legacy of the Northwestern Hawaiian Islands Marine National
Monument it is imperative to take the necessary steps to protect its native biota from
these non- indigenous species threats.
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Scott Godwin