MARINE ECOLOGY PROGRESS SERIES Mar. Ecol. Prog. Ser. Vol. 60: 185-203, 1990 Published February 8 REVIEW Reproduction and recruitment of corals: comparisons among the Caribbean, the Tropical Pacific, and the Red Sea* Robert H. Richmond, Cynthia L. Hunter Marine Laboratory, University of Guarn, UOG Station, Mangilao, Guam 96923, USA ABSTRACT. Detailed reproductive data are now available for 210 of the ca 600 identified scleractinian reef coral species. The majonty (131 species) are hermaphroditic broadcast spawners, although hermaphroditic brooders (11 species), gonochoristic broadcasters (37 species), and gonochoristic brooders (7 species) have also been reported. Characteristics of sexuality and mode of reproduction are generally conservative within species, genera, and even families, although some exceptions occur. Variation in timing or mode of reproduction in allopatric populations may represent adaptations to local environmental conditions or indicate problems in the taxonomy of some groups. Synchronous spawning of numerous species occurs on the Great Barrier Reef, while asynchrony among and withln species has been observed in the Red Sea, Caribbean, Central Pacific, Hawall, and southern Japan. Sexual reproduct~onis the primary means for successful recruitment for some coral populations, while asexual processes may be the dominant or sole means of recruitment for these same species at the limits of their ranges. Recruitment success of different reproductive strategies may vary within and between localities, and is mediated by both biotic (predation, competition) and abiotic (environmental variability, disturbance) factors. Data on reproductive patterns and recruitment success may be applied to coral reef management practices. INTRODUCTION Until the last decade, the majonty of data on coral reproduction were anecdotal and incomplete observations based on short-term and sporadic studies (see review by Fadlallah 1983). This situation is not surprising, in light of the remoteness of tropical coral reefs from most universities and research facilities, and the logistical difficulties of studying corals in situ. However, a number of recent investigations have been published based on continuous monitoring of field populations, as well as histological and laboratory examination of individuals. Previous generalizations This review originates from a UNESCO/COMAR workshop held in Fiji comparing Atlantic and Pacific tropical coastal ecosystems 8 Inter-Research/Printed in F. R. Germany and perceived trends may now b e re-examined, as data for a greater number of species over a wide geographic range have become available. Detailed reproductive data have been reported for ca 4O0/0 of the known species from the tropical Pacific (studies from the Great Barrier Reef, Guam, Palau, Enewetak, Hawaii, Okinawa, a n d Panama), 3 0 % of Caribbean coral species, and 6 % of Red Sea species. These studies provide information on coral sex (hermaphroditism vs gonochorism), mode of reproduction (brooding vs broadcast spawning), and timing of reproduction (seasonality, periodicity, a n d synchrony). Certain patterns of reproduction and recruitment are now discernible from these data. In this paper, w e review data for 210 scleractinian species, a n d compare reproductive processes observed in the Caribbean, eastern Pacific, Hawaii, Central Pacific, southern Japan, Great Barrier Reef, and Red Sea. As data for more taxa and 186 Mar. Ecol. Prog. Ser 60: 185-203, 1990 regions become available, additional (or different) patterns and trends may emerge. The study of coral reproduction has advanced through numerous theses and dissertations over the last 10 yr, as well as from concerted group efforts, most notably on the Great Barrier Reef of Australia. The major pattern that has developed from the Great Barrier Reef studies is one of remarkable similarity and synchrony of reproductive activity among coral species. The majority (90 %) of species studied there broadcast spawn gametes annually, during the week following the full moon in the austral spring (Harrison et al. 1984, Willis et al. 1985, Babcock et al. 1986). Data from other regions (the Caribbean, Red Sea, Central Pacific, Hawaii, and southern Japan) show different patterns, with considerable variation in mode, timing, and synchrony among species. In addition, populations of the same species reported from 2 or more regions may display different reproductive traits. Globally, corals display great plasticity in their life history characteristics. These data are summarized for each region in Table 1, and across regions in Tables 2, 3 and 4. REPRODUCTION IN GENERAL Corals reproduce both sexually and asexually. Sexual reproduction involves the process of gametogenesis, which may require from a few weeks for sperm, to over 10 mo for eggs. Spawning and subsequent fertilization of eggs by sperm results in small, presumably genetically unique, dispersive propagules (planula larvae) which may settle, metamorphose and develop into primary polyps. Asexual reproduction is also common in many scleractinian species, and may occur through fragmentation (see review by Highsmith 1982), polyp bail-out (Goreau & Goreau 1959, Sammarco 1982), or asexual production of planulae (Stoddart 1983). Asexual processes result in clonal propagules (genetic replicates of adult colonies) which, if derived from fragments, have the apparent advantages of large size and locally adapted genotypes. Stylophora pistillata; Loya 1976, Rinkevich & Loya 1979a). Corals can be simultaneous or sequential hermaphrohtes (see discussion in Fadlallah 1983). Two species, Stylophora pistillata and Goniastrea favulus, exhibit protandrous development (Rinkevich & Loya 1979b, Kojis & Quinn 1981a).The only report (Duerden 1902) of true protogyny, in which the colony functions first as a female and becomes hermaphroditic in subsequent years, has been questioned (Szmant 1986). Most hermaphroditic corals exhibit annual protogyny, where eggs develop prior to spermary formation during a reproductive season. Mixed breeding systems have been described for a brooding species, Pontes astreoides, in which 26 % of colonies examined were hermaphroditic, 28 O/O had only female gonads, and 46% were sterile (Chornesky & Peters 1987). In Galaxea fascicularis, some colonies are female and some are hermaphroditic, but eggs in the latter apparently serve only to provide buoyancy for the sperm packets (Heyward et al. 1987, Hamson 1989). Hermaphroditism is advantageous when the probability of finding (or, in the case of sedentary corals, proximity to) members of the opposite sex is low, and self-fertilization is possible. Heyward & Babcock (i986) found varying levels of success in self-crosses in 4 coral species (0% in Montipora digitata, 1.5 to 1 6 % in Acropora tenuis and Goniastrea aspera, and 26 to 89 % in Goniastrea favulus). In experiments performed during spawning events on Guam during the summers of 1987 and 1988, no viable planulae developed from mixing gametes from the same individuals in Acropora irregularis or A. humilis, while nearly 100 % of the embryos resulting from self-fertilized eggs of Acropora tenuis developed successfully (Richmond 1989, unpubl.). Barriers to self-fertilization apparently break down with time after spawning for some species, but not for others (Heyward & Babcock 1986, Richmond unpubl.) Numbers of gonochoristic and hermaphroditic species within each region are summarized in Table 2. Within regions, hermaphrodites range from 60 to 100 % of reported species. Globally, the majority (68 %) of coral species studied are hermaphroditic (Table 3). Sexual reproduction in corals Hermaphroditism vs gonochorism Brooding vs spawning In hermaphroditic species, ovaries and spermaries may develop on the same mesentery (most favids and mussids), on different mesenteries within the same polyp (most pocilloporids and acroporids; see Fig. l ) ,in different polyps within the same colony (e.g. Cladopsammia rolandi; de Lacaze-Duthiers 1897 in Fadlallah 1983),or at different times within the same colony (e. g. Fertilization may take place within the maternal polyp (brooding), or externally in the water column after gametes are shed (broadcast spawning). Species which broadcast spawn outnumber brooders in the Pacific regions and the Red Sea (Table 2 ) . However, brooding may be the predominant mode of reproduction in the Caribbean. Overall, for the present data h c h m o n d & Hunter: Reproduchon a n d recruitment of corals 187 T a b l e 1. Reproduchve charactenstics of corals from t h e Caribbean S e a , Great Barner Reef, Central Pacific, Hawaii, O i u n a w a , eastern Pacific, a n d Red S e a . Symbols - Sex: H, h e r m a p h r o d l t ~ c ;G , gonochoric, X , u n k n o w n . M o d e : S , s p a w n e r , B, brooder; possibly stenle. Timing: month a n d lunar d a y of g a m e t e release (spawners) or planulation (brooders) [ m o n t h is divided into p h a s e s 1 , n e w moon, 3, first quarter, 5 , full moon, 7 , last quarter; 2, 4 , 6 a n d 8 indicate intermediate lunar p h a s e s (after Shlesinger & Loya 1985));W , winter, s p , s p n n g ; sr, s u m m e r ; f , fall; yr, year-round; X, u n k n o w n Species Sex Mode Timing Source Caribbean ACROPORIDAE Acropora cenricorn~s Acropora palmata H H S S JuVAug, 6-7 Aug Szmant-Froelich (19841, Szmant (1986) Szmant-Froelich (1984). Szmant (1986) H SP SP sr Yr Duerden (1902), Van Moorsel (1983) Vaughan (1910) Mavor (1915) Van Moorsel (1983) AGARICIDAE Agaricla agancltes Agaricia crassa Agaricja fragills Agarjcia humihs FAVlIDAE Diploria stngosa Favia fragum H B B B B H H S B Aug, 7 Yr yr, 3-5 ~Manicinaareolata H B ~Montastreaa n n d a n s Mon tastrea ca vernosa H G S S SP Yr Aug, 7/Sep, 7 A"g Szrnant-Froelich (1984) Duerden (1902),Vaughan (1910) Szmant-Froelich (1984), Szmant (1986) Szmant-Froelich et al. (1985) Wilson (1888) ~n Fadlallah (1983) Duerden (1902) Szmant-Froehch (1984),Szmant (1986) Szmant-Froelich (1984). Szmant (1986) MEANDRINIDAE Meandnna ( = ~Meandra)areolata X B JulIAug, 3-8 Boschma (1929),Yonge (1935) in Fadlallah (1983) G? H B B SP Feb-Mar Duerden (1902) Szmant-Froelich (1984). Szmant (1986) H B May-Jun Jan-Sep yr, 6 8 Nov-Feb Vaughan (1910),Szmant-Froelich (1984) Szmant (1986) Chomesky & Peters (1987) Tomascik & Sander (1987) MUSSIDAE Isophyllia sp. Mycetophyllia ferox PORITIDAE Pontes astreo~des Porites pontes SIDERASTREIDAE S~derastrearadians X X (or female only) B G7 (some hermaphroditic) H G G B B S F yr? Jul-Sep Duerden (1902) Szmant-Froelich (1984), Szmant (1986) Szmant-Froelich (1984),Szmant (1986) G 6G 10H:3x S 12B 7 s Aug Szmant-Froelich (19841, Szmant (1986) Pacific Great Barrier Reef ACROPORIDAE Acropora aculeus Acropora aspera Acropora austera Acropora cereaLis Acropora cuneata Acropora cytherea Acropora digitifera H H H H H H H S S S S B S S Acropora divancata Acropora elseyl H H S S Acropora flonda H S Nov, 6 seasonal Nov, 6 Nov, 6 sp-sr Oct/Nov, 6 sp-sr Oct, 6 Oct, 6 Nov, 6/Dec, l Oct, l/Nov. 6 Nov, 6 Acropora formosa H S Acropora gemmifera Acropora grandis H H S S Babcock et a1 (1986) Bothwell (1981) Babcock et al.(1986) Babcock et al.(1986) Bothwell (1981) W~llise t al. (1985), Babcock et al. (1986) Bothwell (1981) Wlllis et al. (1985) W ~ h et s al.(1985) Babcock et al. (1986) W i h s et al. (1985) Willis et al. (1985),Wallace (1985b), Babcock et al. (1986) Babcock et al. (1986) W d l ~ set a1 (1985) Wlllis et al. (1985), Babcock et al. (1986) W i h s et a1 (1985). Babcock et al. (1986) S~derastreasiderea TROCHOSMILIIDAE Dendrogyra cylindrus Nov. 5-6 Oct, 6/Nov, 6 Nov, 6 Nov, 6 8 M a r . Ecol. Prog. Ser 60: 185-203, 1990 T a b l e l (continued) pecies Sex acific reat Barrier Reef CROPORIDAE cropora granulosa cropora horrida cropora humlLis cropora hyacjnlhus cropora laOstella cropora longlcyathus cropora loripes cropora l u t k e n ~ cropora rnlcropthalrna cropora rnlllepora cropora nasuta cropora nobdis cropora pahfera cropora pulchra cropora robusta cropora sarnoensls cropora sarmen tosa cropora cropora cropora cropora secale selago sol~tanensls tenuis cropora v a l e n a e n n e s ~ cropora valida cropora cf varia bills cropora cf vaughanl cropora yongei streopora rnlcrophthalma ontipora aequ~tuberculata ontlpora dlgltata on lipora fol~osa onlipora hisplda ontipora lnforrnis ontlpora rnonaslenata ontlpora spurnosa ontlpora tu berculosa ont~poraturgescens GARICIIDAE chysens rugosa Mode Timing Feb/Mar sr? sp-sr Oct, 6 Nov. 5-7 sp-sr Oct/Nov, 6 Nov, 5-6 Sep. 6/0ct, 6 Nov, 1 Nov. 5 Source sp-sr Oct, 6-7 Nov. 5 sp-sr Nov, 6 Nov, 6 Nov, 6 Feb/Aug/Nov? Nov, 7 Nov. 6 7 Nov. 6 Oct, 6 Oct, 6-7/Nov, 6 Nov, 5-6 Nov, 6 Oct, 6-7/Nov, 6 Nov, 5-6 sp-sr Nov, 6 Nov, 6 Nov, 6 Oct, 6 Oct, 5/Nov. 5 Nov. 5 Nov. 5 Oct/Nov, 6 Nov. 6 Oct, 5 Nov, i Nov, 5 Nov, 6 Nov, 6 Wallace (1985b) Wallace (1985b) Bothwell (1981) \M~ll~s et a1 (1985) Babcock et al. (1986) Bothwell (1981) Willis et al. (19851, Wallace (1985b) Babcock et al. (1986) Wilhs et a1 (1985) Babcock et al. (1986) Willis et a1 (19851, Wallace (1985b) Babcock et al. (1986) Wallace (1985b) Babcock et a1 (1986) Babcock at a1 (1986) Willis et a1 (1985) Babcock et a1 (1986) Bothwell (1981) CVillis et al. (1985) Babcock et a1 (1986) Willls et a1.(1985), Babcock et a1 (1986) Willis et al. (1985) Wallace (1985b) Babcock et a1 (1986) Bothrvell (1981) Bothwell (1981) W~lliset al. (1985) Babcock et al. (1986) Bothwell (1981) Babcock et a1 (1986) Willis et al. (1985) Willis et al. (1985) Wallace (1985b) Babcock et a1 (1986) Babcock et a1 (1986) Will~set al. (1985), Babcock et a1 (1986) Willis et al. (1985) Willis et al. (1985) Babcock et a1 (1986) Willis et a1 (1985) 'I,V~lliset a1 (1985). Wallace (1985b) Babcock et a1 (1986) Bothwell (1981) Willis e t a1 (1985) Babcock et a1 (1986) Babcock et a1 (1986) Will~set al. (1985) Willis et al. (1985) Babcock et al. (19861, Heyward & Collins (1985) Babcock et al. (1986) Willls et a1 (1985) Babcock et al. (1986) Willis et a1 (1985) Babcock et al. (1986) Babcock et a1 (1986) Babcock et a1 (1986) Babcock et al. (1986) Nov, 5-6 Nov, 6 GV~lllset a1 (1985) Babcock et a1 (1986) Nov/Dec Nov. 6 Nov, 6 Oct, 6 Nov, 5 sp-sr Oct, 6/Nov, 5-6 Nov. 5-7 Nov, 6 7 Oct, 6 Oct/Nov Nov. 5-6 X R~chmond& Hunter. Reproduction and recruitment of corals Table 1 ( c o n t ~ n u e d ) Species Sex Pacific Great Barrier Reef AGARICIIDAE Pachyseris speciosa Mode T~ming Source S Oct. 67/Nov. 5-6 Nov. C 7 Willis et al. (1985) Babcock et al. (1986) Marshall & Stephenson (1933) Pavona cactus CARYOPHYLLIDAE CataIaphyUia jardinen Euphyllia ancora Euphyllia div~sa S(sperm) X S S S Physogyra lichtenstelni S Oct, 6 Oct. 6 Oct. 6 Nov, 6 Nov, 6 Willis et al. (1985) Willis et al. (1985) Willis et al. (1985) Babcock et al. (1986) Willis et al. (1985) Babcock et al. (1986) B S S B S S Dec. I Jan-Jun Apr-Jun Nov. 6 7 Oct, 6 Nov. 7 Babcock et al. (1986) Fisk (1981) in Hamott (1983a) Fisk (1981) in Harriott (1983a) Babcock et al. (1986) Willis et al. (1985) Willis et al. (1985) Nov. 6 Nov. 5-7 Nov. 5 Oct, 6 Nov. 6 Oct, 6 Nov, 6 Oct, 6 Dec OcWNov, 6 Nov. 6 Nov. 6 Nov. 6 Nov, 5-7 Nov. 6 Nov. 5-6 Nov, 5-7 Nov, 6 Nov, 6 Nov, 6 Nov, 6 Oct. 6 Nov. 6 Nov. 6 Oct. 5-7 Oct. 6-?/Nov, 6 Nov. 5-6 Nov. 6 Oct/Nov. 5-6 Willis et al. (1985), Babock et al. (1986) Babcock et al. (1986) Willis et al. (1985). Babcock et al. (1986) Willis et al. (1985) Babcock et al. (1986) Willis et al, (1985) Babcock et al. (1986) Willis et al. (1985) Harrison (1985) Babcock et al. (1986) Babcock et al. (1986) Willis et al. (1985) Babcock et al. (1986) Harriott (1983a) Babcock et al. (1986) Babcock et al. (1986) Willis et al. (1985) Babcock et al. (1986) Marshall & Stephenson (1933) Willis et al. (1985) Babcock et al. (1986) Willis et al. (1985) Babcock et al. (1986) Babcock et al. (1986) Kojis & (luinn (1982). Babcock et al. (1986) Willis et al. (1985) Babcock et al. (1986) Willis et al. (1985) Willis et al. (19851, Babcock et al. (1986) Willis et al. (19851, Babcock et al. (1986) Willis et al. (1985). Babcock et al. (1986) Willis et al. (1985) Babcock et al. (1986) Babcock et al. (1986) Babcock (1984) Willis et al. (1985) Babcock et al. (1986) Babcock et al. (1986) Kojis & Quinn (1981a). Kojis & Quinn (1982) Oct, 6/Nov, 5-6 Nov, 5-6 Willis et al. (1985) Babcock et al. (1986) DENDROPHYLLIDAE Dendrophyllja sp. Heteropsammia cochlea Heteropsarnrnia aequicostatus Tubastrea faulkneri Turbinaria frondens Turbinaria reniformis FAVIIDAE Australogyra zelli Barbattoia amicorurn Caulastrea furcata Cyphastrea chalcidium Cyphastrea micropthalrna Cyphastrea Diploastrea Echinopora Echinopora Ecliinopora seraiha heliopora gemmacea hornda lamellosa Favia favus Favia lizardensis Favia mathaii Favia pallida (as F. doreyensis) Favia pallida Favia rotumana Favia stelligera Fa vla veronl Favites abdita Favites bennettae Favites chinensls Favites complanata Favites nexuosa Favites halicora Favites pentagona Fa vites russelli Goniastrea aspera Goniastrea edwardsi Goruastrea favulus (as G. australensis) Goniastrea favulus X Nov, 6 Nov. 6 Oct, 6/Nov, 5 Nov. 6 Nov/Dec Nov. 6 Nov. 6 Nov. 5-6 189 J T T m (Am WV] m m J T T T Z T 0000 00 X X X T 3:T T J J T J T T 3: V] - - ( U - m - - - - 3 - m n r u r r - r w w - w - r r r + 3 r - r y r w w w w w w w mmzEzggKgzgzgzg m m - . m m m 2 U ru n n 0 0 n o (U m 9 - - ru n 0 n (U n 0 n - ru n 0 n X 22% 'D U U U h X X 'D 'D r" C" m - m r n r n r n " ~ 9 U U X X 0 n X .E E . E . ---r". w w w w - c + m m m m m m U - - L m m m 9 hchrnond & Hunter: Reproduction a n d recruitment of corals 191 Table l (continued) Species Sex Mode Tirnlng Source Pacific Great Barrier Reef PECTINIDAE Pectinia lactuca H S Pectinia paeonia H S Oct, 6 Nov, 6 Oct. 6-7/Nov, 6 Nov, 6 Willis et al. (1985) Babcock et al. (1986) Willis et al. (1985) Babcock et al. (1986) yr. 1-5 Marshall & Stephenson (1933) -. POClLLOPORlDAE Pocillopora damicornis (as P. bulbosa) Pocillopora damicornis Seria topora h ystrix H B X B sp-sr Harriott (198313) Sammarco (1982) PORITIDAE Goniopora columna Goniopora dijboutiensis Goniopora lobata G G G S S S G G G G G G S S S S S S Oct/Nov. 6 Nov. 6 Oct. 6 Nov. 6 Nov. 5-6 Oct, 6 Nov. 6 Nov. 5-7 Nov. 6 Oct-Jan Willis et al. (1985) Willis et al. (1985) Willis et al. (1985) Babcock et al. (1986) Babcock et al. (1986) Willis et al. (1985) Willis et al. (1985) Babcock et al. (1986) Babcock et al. (1986) Harriott (1983a) Dec. 5-7 Kojis & Quinn (1981 b) Goniopora minor Goniopora norfolkensis Goniopora tenuidens Gonipora sp. 1 Gonipora sp. Poriles australiensis Porites cylindrica (as P. andrews~) W.S/sr, G (24 O/O S hermaphroditic) 1 Nov. 6 Dec, 1, 4-7, 8 Nov. 6 G S Jan, 4-8 Porites lu tea Nov-Jan Nov, 5-7 G B sp-sr-f Porites m urrayensis S Nov. 5-7 Porites solids G B sr-f Porites stephensoni (as P,haddonj) X 34G-109H:2x 8B:136S.lx Central Pacific (Gu_aam,MarGaL,-Islands,Palau) ACROPORIDAE X B Yr Acropora bruggernanni H X sr Acropora cerealis S Jul. 4-5 X B Jun/Jul. 1 4 Acropora corym bosa a Acropora delica tula X B Jun/Jul. 1-3 Acropora humilis H S Aug. 7 H S sr Acropora h ystrixC X sr Acropora irregularisd H Aug. 4-7 S Acropora nasuta H S Jul, 7 Acropora ocellata H S Jul. 5-6 X B X Acropora pala wensis X sr Acropora smithie H S JuVAug. 6 7 Pontes cylindnca Porites lobata G " S Willis et al. (1985),Babcock et al. (1986) Kojis & Quinn (1981b) Babcock et al. (1986) Kojis & Quinn (1981b) Hamott (1983a) Babcock et al. (1986) Kojis & Quinn (1981b) Babcock et al. (1986) Marshal1 & Stephenson (1933) Atoda (1951a) Heyward (1989) this study Stimson (1978) this study Stirnson (1978) this study Heyward (1989) Heyward (1989) this study this study this study Kawaguti (1940) in Fadlallah (1983) Heyward (1989) this study Note: all taxonomic assignations for Central Pacific are according to Randall (1983, pers. comm.) and samples of each species are deposited in the University of Guam Marine Laboratory reference collection Synonymized with A. cytherea by Veron & Wallace (1984) Synonymized with A. selago by Veron & Wallace (1984) L Synonymized with A. cerealis by Veron & Wallace (1984) %ynonymized with A. danae by Veron & Wallace (1984) ' Synonyrnized with A. robusta by Veron & Wallace (1984) M a r Ecol. Prog. Ser. 60: 185-203. 1990 192 Table 1 (continued) Specles Sex Pacific Central Pacific (Cuam, Marshall, Islands. Palau) ACROPORIDAE Acropora squarrosa' H X Acropora striata Acropora surculosag Acropora ten uis Acropora valida H H H Acropora varia bilish Astreopora randalli Montipora foveola fa Montipora verrucosa H H H H CARYOPHYLLIDAE Euphyllia glabrescens DENDROPHYLLIDAE Balanoph yllia sp. FAVIIDAE Fa via rna thaii Favia steUigera Favites abdita Favites flexuosa Goniastrea aspera Goniastrea e d w a r d s ~ Goniastrea retiformis Leptoria phrygia Montastrea curta Pla tygyra daedalea Pla tygyra pini FUNGIIDAE Fungia fungites Heliofungia actiniform~s OCULINIDAE Acrhelia horrescens Galaxea fascicularis (as G. aspera) POCILLOPORIDAE Pocillopora damicornis (as P. caespitosa) Pocillopora elegans (P. meandrina?) Pocillopora verrucosa Stylophora pistjlla ta Sen'atopora h ystrjx PORITIDAE Goniopora fruticosa Porites cylindrica X X X Mode Timing Source Jul. 2-3 Jun/Jul, 3-4 J a n . 1-8 Jul, 7-8 Jul. 7-8 sr Jul. 6 7 sr Jul. 8/Aug, 1 Jul. 2-3 Jun. 7-8 Sep. 2-? this study Stimson (1978) this study this study Heyward (1989) this study Heyward (1989) this study this study this study X Kawaguti (1941) Yr Abe (1937) sr JunIJul, 6 8 Jun/Jul. 5-7 sr sr Oct/Nov, l sr Jun/Jul, 7-8 Jul. 1-2/7-8 sr Jul, 7-8 Aug, 6-7 Jul, 7-8 sr Heyward (1989) this study this study Heyward (1989) Heyward (1989) Abe (1937) Heyward (1989) thls study this study Heyward (1989) this study this study this study Heyward (1989) sr Sep-Apr, 1 Heyward (1989) Abe (1937) Yr Jul/Aug, 1-3 Yr Kawaguti (1941) this study Atoda (1951b) Yr yr. 1-3 Jun/Jul/Jan, 7-3 yr, 2-3 Jan, 3-4 Hada (1932). Kawaguti (1941) Atoda (1947a) Stlmson (1978) Richmond & Jokiel (1984) Stimson (1978) Jun/Jul, 1-3 J a n , 1-4 yr, 5-7 sr/\v, 1-5 S t ~ m s o n(1978) Atoda (1947b) Kawaguti (1941),Atoda (1951c),Stlmson (1978) this study this study Note. all taxonomic assignations for Central Paclf~care according to Randall (1983, pers. comm.) and samples of each species are deposited In the University of Guam M a n n e Laboratory reference collection Synonyrn~zedwith A. loripes by Veron & Wallace (1984) g Synonymlzed with A. hyacinthus by Veron & Wallace (1984) h Synonymlzed with A. valida by Veron & Wallace (1984) ' R ~ c h m o n d& Hunter: Reproduction a n d recruitment of corals 193 Table l (continued) Species Sex Mode Tlm~ng Pacific Central Pacif~c(Guam. Llarsh&lI-Isla~,-~a~a_u], PORITIDAE G S Jul. 7-8 Porites lobata G X sr Pontes lutea G X X Por~tes(Synarea) rus 4G 28H-3-3'12x 14B.28S.3':2x -H ACROPORlDAE Acropora cytherea Acropora hurnilis Acropora valjda Monhpora dilatata S X B B sr-f sr-W Edmondson (1929).Edmondson (1946) Edmondson (1929). Edmondson (1946) X B Yr Edmondson (1929). Edrnondson (19461, Stlmson (1978) FUNGllDAE Fungia scutarm G S Jul-Sep, 5 Krupp (1983) POCILLOPORIDAE Poc~lloporadan~icomis H B yr. 5-1 Jun/Jul/Aug, 1 1''. 5 yr. 6-8 yr. 3-5 Edrnondson (1946),Harrigan (1972) Reed (1971) St~mson(1978) R~chmond& J o k ~ e (1984) l G G G Jun-Aug. 5 Aug-Sep, 5-6 Aug, 7-8 sr Hunter Hunter Hunter Hunter Jun. 5 Jun. 5 Jun, 5 Jun. 5-8 Jun. 5-8 Jun, 5 Jun. 5 Jun, 7 Jun. 7 Jun. 5 Jun. 5 Jun. 5 Jun, 5 Jun. 5-6 Jun. 5-6 Jul, 6/Aug, 6-7 R~chmondpers. obs. Heyward e t al. (1987). Richmond pers obs. Richmond pers. obs. Heyward e t al. (1987). Richmond pers. obs. Heyward et al (1987) Heyward e t al (1987) Richmond pers. obs. Heyward et al (1987) Heyward e t al. (1987) kchrnond pers. obs. k c h m o n d pers. obs. K Sakai pers. comm. K Sakai pers. comm. Heyward e t al. (1987) Heyward e t al. (1987) Heyward e t al. (1987) 'Type Y' 'Type B' PORITIDAE Porites compressa Porites e vern~anni Pontes loba fa Por~ tes brigharni H H H S S S H X Grigg et al. (1981) Gngg et a1 (1981) Gngg et al. (1981) Heyward (1985) Heyward (1985) Hunter (1989) Heyward (1985) Heyward (1985) Heyward (1985) Hunter (1989) Heyward (1985) DENDROPHYLLIDAE Dendrophyllia rnanni Tubastrea coccinea (as T aurea) FAVlIDAE Cyphastrea ocellina S thls study Heyward (1989) thls study Jul. 5-6 Jun/Jul/Aug Jul/Aug, 5-7 Jul. 1 sr-f Jul, 5-6 Jul, 1 Jun/Jul, 1 Jul, 5-6 Montipora flabella fa Montipora s t u d e q i A4on hpora verrucosa (sensu Vaughan 1907) Mon t~poraverrilli H Source 4G:6H:3' 4x S S S B 5B:9S:3' Oklnawa ACROPORIDAE Acropora an thocercis Acropora cytherea Acropora dig1tifera Acropora florida Acropora formosa Acropora g r a n d ~ s Acropora hyacyn thus Acropra la tistella Acropora micropthalma H H H H H H H H H S S S S S S S S S Acropora nob~lis Acropora tenuls Acropora vahda A4ontipora aequ~tuberculata Montipora digita fa Montipora effusa H H H H H H S S S S S S X (1988). Hunter & Hodgson unpubl & Hodgson unpubl. & Hodgson unpubl. & Hodgson unpubl. Mar. Ecol. Frog. Ser. 60: 185-203, 1990 194 Table l (continued) I Species Sex Pacific Okinawa ACROPORIDAE Mon hpora turgescens FAVIlDAE Favia pallida Favites chinensis Goniastrea aspera Platygyra pini Platygyra ryukuensis Mode Timing Source Jun. 5 Heyward et al. (1987) Jun. 5 Jun. &7/Jul, 7 Aug, 7 JunlJul, 5-6 Jun. 2 Jul, 7/Aug, 6-7 Heyward Heyward Heyward Heyward Heyward Heyward et et et et et et al. (1987) al. (1987) al. (1987) al. (1987) al. (1987) al. (1987) FUNGIIDAE Fungia sp. MUSSIDAE Loboph yllia corym bosa Symphyllia recta Jul. 7 Heyward et al. (1987) Jun, 6 Jun. 5 Heyward et al. (1987) Richmond pers. obs. OCULINIDAE Galaxea fascicularis JudJuYAug, 6-7 Heyward et al. (1987) PORITIDAE Gonipora queensland~ae Yamazato et al. (1975) Eastern Pacific - work in progress After 2 yr, only immature ovaries observed (spring). No complete gametogenesis, spawrung or Pocillopora damicornis planulation observed (Richmond 1985) Spermanes and ovaries observed near maturity during summer (A. Yedid pers. comm.) Pocillopora elegans Planulated Jun through Nov during both 1984 and 1985 (Richmond unpubl.) Tubastrea aurea Red Sea ACROPORIDAE Acropora eurystorna Acropora hempn'chii Acropora humilis Acropora hyacinthus Acropora scandens Astreopora myriophthajma May/Jun, 5 X May/Jun. 7 Jul, 3 JunIJul, 5 JuVAug/Sep, 5 FAVIlDAE Fa via fa vus Favites abdita Goniastrea retiforrnis Pla lygyra lamellina OCULINIDAE Galaxea fascicularis POCILLOPORIDAE PociUopora verrucosa Seriatopora caliendrurn Stylophora p~stillata PORITIDAE Alveopora daedalea H OG:15H Shlesinger & Loya (1985) Rinkevich & Loya (1979a) Shlesinger & Loya (1985) Shlesinger & Loya (1985) Shlesinger & Loya (1985) Shlesinger & Loya (1985) Jun/Jul, 6-7 Aug. 6 Shlesinger & Loya (1985) X Jul/Aug, 7 Jun/Jul, 1-2 Aug. l Rinkevich & Loya (1979a) Shlesinger & Loya (1985) Rinkevich & Loya (1979a) Shles~nger& Loya (1985) JuVAug/Sep, 6-7 Shlesrnger & Loya (1985) May. 1 Jul/Aug. 1 May-Dec, 8-1 Dec-Jul, 1-8 Fadlallah (1985) Shlesinger & Loya (1985) Rinkevich & Loya (1979a).Shlesmger & Loya (1985) Loya (19761, Rinkev~ch& Loya (1979a, b), Shles~nger& Loya (1985) f-W B 3B:llS:lx base, spawners outnumber brooders 168:37 (Table 3). Spawning is usually associated with higher fecundity, while brooding produces fewer, larger larvae (Fadlallah 1983). Shlesinger & Loya (1985) Szmant-Froelich (1984) proposed that brooders experience the greatest recruitment success in the Caribbean, while spawners (particularly acroponds and poritids) are the more successful recruiters in the Pacific. Richmond & Hunter: Reproduction and recruitment of corals 195 Table 2. Global comparisons of reproductive characteristics in scleractinian corals from the Caribbean, Red Sea, and Pacific regions. See individual entries under regional headings for literature citations Caribbean No, of species for which reproductive data are recorded Gonochoric Hermaphroditic Not reported Brood Spawn Not reported No. of species in region Hawaii Central Pacific GBR Okinawa Red Sea 19 17 47 145 26 15 6 10 3 4 6 7 4 28 l5 34 109 2 2 24 0 0 15 0 12 7 0 62' 5 9 1 25 3 11 1 2446 3 452 14 28 5 3533 8 136 1 3564 0 242' Sources: (1) Goreau & Wells (1967). (2) Jokiel (1987), (3) R. Randall, pers. comm., (4) Willis e t al. (1985). (5)Veron (1985). (6) Sheppard (1987) Table 3. Summary of reproductive mode for 210 species of scleractinian corals for which data are available. Entries reflect cumulative counts, omitting repeats for species found In 2 or more regions Hermaphroditic Spawn Brood Unknown Gonochoric Unknown 390+ She also noted that Caribbean Porites, which are brooders, have small adult colony size, while the spawning gonochoric Pacific Porites are large and long-lived. Pacific Porites species which brood form small, encrusting colonies (P. stephensoni [as P. haddoni], Marshal1 & Stephenson 1933; P. rnurrayensis, Kojis & Quinn 1981 b; P. brighanii, Hunter & Hodgson unpubl.). Timing, seasonality, synchrony, and periodicity Sexual reproduction in corals may occur yearly (Willis et al. 1985, Babcock et al. 1986), seasonally (Rinkevich & Loya 1979a, b , Szmant 1986, Tomascik & Sander 1987), monthly (Marshal1 & Stephenson 1933, Kawaguti 1941, Atoda 1947a, Richmond & Jokiel 1984), or not at all (Grigg et al. 1981, Richmond 1985, Richmond & Hunter unpubl.). Annual multispecies synchronous spawning has been observed for over 140 species on the Great Barrier Reef (Harrison et al. 1984, Willis et al. 1985, Babcock et al. 1986, Harrison pers. comm.), while asynchrony is exhibited among coral species in the Central Pacific. Hawaii, Okinawa, and the Red Sea (Table 1).Synchronous development and release of gametes among individuals in a population are important to maximize the probability of successful cross (and/or self) fertilization. Conversely, a presumed advantage to multiple spawnings or planulations is to minimize the effects of a single catastrophic event on an individual's or population's reproductive success. Temperature, photoperiod, and nocturnal illumination all appear to be important in providing temporal cues which may allow synchrony within populations (Kojis & Quinn 1981 a , Jokiel et al. 1985, Willis et al. 1985, Hunter 1989). The expanding database suggests that the degree of multispecies synchrony may b e correlated with the annual temperature range experienced by the corals (Shlesinger & Loya 1985, Babcock et al. 1986). Annual variation in seawater temperature is 2.2 "C in the Central Pacific (Guam; Emery 1962), 3.2 "C in the Caribbean (Barbados; Tomascik & Sander 1987), 4.0 "C in Hawaii (Oahu; Jokiel 1985), 6.0 "C in the Red Sea (Eilat; knkevich & Loya 1979 b), 9.8 "C in Okinawa (Nakamura 1984),and 12.0 "C on the Great Barrier Reef ( M a g n e t ~ cIsland; Babcock et al. 1986).The percentage of reported coral species spawning within the same month and lunar phase for each of these regions is 18, 26, 29, 20, 65, and 88 '10,respectively. Oliver et al. (1989) reported that reproductive seasonality and synchrony among a n d within coral species distributed from the southern Great Barrier Reef to Papua New Guinea diminishes at lower latitudes. The trend appears to b e one of tighter interspecific synchrony with increased temperature range. A similar pattern of less restricted spawning patterns with increasing proximity to the equator was reported for echinoderm species by Pearse (1968). Differences in reproductive seasonality can occur within a species over its distributional range (Table 4). Most Great Barrier reef species spawn in the austral spring, while spawnings in the Central Pacific, Hawaii, Mar Ecol. Prog. Ser 60: 185-203, 1990 196 Table 4. Global comparisons of reproductive penodicity in coral species which have been reported from 2 or more regions. Abbreviations are for month and lunar day. Month is divided into 8 phases: 1, new moon, 3, first quarter, 5, full moon, 7, last quarter; 2, 4 , 6 and 8 indicate intermediate lunar phases (after Shlesinger & Loya 1985); W : winter, sp: spring, sr: summer, f: fall, yr year-round; ' possibly sterile GBR ACROPORIDAE Acropora cerealis (as A. hystrixIa Acropora cytherea (as A. c o r y r n b ~ s a ) ~ Acropora digitifera Acropora florida Acropora formosa Acropora grandis A cropora h umilis Acropora hyacinth~rs (as A. surculosajc Acropora latistella Acropora loripes (as A. ~ ~ u a r r o s a ) ~ Acropora rnicropthalma Acropora nasuta Acropora nobilis Acropora robusta (as A. smith.iIe Acropora selago (as A. de~icatula)' A cropora ten uis Acropora valida (as A. variabi1is)g Montipora aequituberculata Montipora digitata iMon tipora turgescens FAVIIDAE Fa via fa vus Central Pacific Okinawa Jun/Jul, 1-4 Jun, 5 Jun, 5 Oct, 6 Nov, 6 Oct, 6/Nov, 5-6 Nov. 6 Oct, 6/Nov, 5-7 (spawn) Jun/Jul, 1-3 (brood) Aug, 7 (spawn) Jul, 7-8 - Jul, 7-8 Aug, 6-7 Oct/Nov, b Nov, 6 J u n , 5/7 Jun. 5 Nov. 6 Oct, 6 NOV.5-6 Oct, 6-7 NOV.5-6 sp-sr Oct, 6 OcVNov, 5 Nov, 6 Jul. 6 Jun, 5 Jun, 5 Jun, 5-6 Jun, 5-6 Jun, 5 Nov. 6 Favites flexuosa Goniastrea aspera Nov. 6 Oct, 5-7 NOV,5-6 (spawns) Nov, 6 Nov, 6 Nov. 6 sr Oct/Nov, 1 (broods?) Synonymized with A. cerealis by Veron & Wallace (1984) "Synonymized w ~ t hA. cythcrea by Veron & Wallace (1984) 'Synonyrnized with A. hyacinthus by Veron & Wallace (1984) Synonymized with A. loripes by Veron & Wallace (1984) " Synonymized with A. robusta by Veron & Wallace (1984) Synonymized with A. selago by Veron & WaIIace (1984) g Synonymized with A. valida by Veron & Wallace (1984) ' Jun, 3 Jul. 2-3 Oct/Nov, 6 Nov. 6-7 Jul. 7-8 Jul, 7-8 sr - " J u n , 5?8 Jun, 5?8 Jun, 5 Jun, 7 NOV.5-6 Oct/Nov. 6 Nov, 6 NOV.5-6 Nov. 6 a Red Sea Nov, 6 Favia mathaii Fa via pallida Fa via stelligera Favites abdita Favites chinensis Goniastrea edwardsi Goniastrea retiformis Leptoria p h r y g ~ a Hawaii Jun, 5 Jun, 6-7/Jul, 7 Aug, 7 Jun/Jul, 5-6 Jul, 3 Richmond & Hunter Reproduct~ona n d recruitment of corals 197 Table 4 (continued) FAVIIDAE Montastrea c ~ l r t a Platygyra daedalea Platygyl-a lamellina Pla tygyra plni FUNGIIDAE Fungia fungl tes Heliofungla actinifo~-mls MUSSIDAE Lobophyllia c o r y n ~ b o s a Symphyllla recta OCULINIDAE G a l a s e a fascicularis POCILLOPORIDAE Poc~lloporadanllcornis GBR Central Pac~f~c Nov, 6 Oct/Nov, 6-7 Nov, 6-7 Aug. 6-7 Jul, 6-7 Nov, 6 sr Oct/Nov, 6 Oct/Nov, 5 sr Sep-Apr, 1 Por7tes lutea Red S e a - Jul/Aug/Sep, 6-7 (spawns) Jun. 6 Jun. 5 Oct/Nov, 6 (spawns) Jul, 2-3 (spawns) Y' (broods) yr, 1-5 yr, 1 yr, 3-8 Jun/Jul, 1 4 J a n , 1-4 (bloods) SI-/W,1-8 y r , ., 7 sp-sr Hawaii Jun, 2 Nov. 6 Nov, 6 Pocillopora verrucosa Seriatopora hystnx St)~lophorapist~llafa PORITIDAE Poriles cylin dl-ica Pal-~tes loba ta Okinawa Jun/Jul/Aug, 6-7 (spawns) yr. 5-3 (spawns) Dec-Jul. 1-8 Nov, 6 Nov, 6 Dec, 1, 4-7, 8 J a n , 4-8 Nov-Jan NOV,5-7 Okinawa, and the Red Sea occur mostly during summer. For many species, variations in t ~ m i n gand synchrony of spawning have been observed within as well as between the regions summanzed in thls paper (Table 1). Seasonal (latitudinal) variability withln regions (e.g. between Palau, Enewetak and Guam) may be of sufficient magnitude to cause differences in reproductive timing. In addition, spawning may occul- at different times for different sections of a single colony, or for different colonies within a population (Willis et al. 1985, Babcock et al. 1986, Hunter & Richmond unpubl.). While temperature may be the seasonal cue, nocturnal illumination (lunar phase) may provide the 'fine tuning' for the particular night or nights of gamete or planula release. Both brooding and broadcasting species have been shown to cue on night-time illumin a t ~ o n(Jokiel et al. 1985, Hunter 1989). It has also been suggested that tidal regime and onset to darkness may play roles as 'forcing functions', determining the actual time of day when spawning will occur (Harriott 1983 a , Babcock et al. 1986, Hunter 1989). A distinct lunar planulation cycle was reported for Stylophora pistlllata in Palau (Atoda 1947 b ) , while Red Sea populations of thls specles show no lunar synchrony (Rinkevich & Loya 1979 b). Lunar periodicity of planulation was found to d~fferbetween populations of Pocillopora darnicojnis at Enewetak and Hawaii, and within populations in Hawaii ( h c h m o n d & J o k ~ e l 1984). The 'Type B' morph of P. darnicornis planulated consistently at first quarter moon, while 'Type Y' planulated at last quarter. Van Moorsel (1983) proposed identification of a new species of Agaricia based partly on its distinct planulation schedule. Differences in timing among allopatric populations of a species may represent adaptations to local environmental parameters and cues. Richmond & Joluel (1984) suggested that asynchrony among sympatric populations of an identified 'species' may b e the result of the immigration of planulae from one region into another. Reproductive isolation, in this case via temporal mechanisms, allows for divergence and eventual specia t ~ o n .Such reproductive differences within nominal 198 Mar Ecol. Prog Ser 60: 185-203, 1990 Fig. 1 Acropora tenuis. Section through a ripe colony of a s~multaneoushermaphrodite, 1 wk prior to spawning. Egg and sperm are found within the same polyp. Egg diameter is ca 0.5 mm I species raise questions concerning taxonomy based on morphological characteristics alone. Asexual reproduction in corals Corals possess the ability to reproduce asexually, which is displayed by a variety of mechanisms. Asexual reproductive processes include formation of 'polypballs' (Rosen & Taylor 1969), polyp bail-out (Goreau & Goreau 1959, Sammarco 1982, Richmond 1985), asexual production of planulae (Stoddart 1983), and fragmentation (Highsmith 1982). Asexual reproduction via fragmentation appears to be important for many coral species, and especially for populations living at the extremes of their physiological limits. Grigg et al. (1981) reported lack of mature gonads in populations of 3 species of A c r o p o r a from the Northwest Hawaiian Islands. Reproduction via fragmentation appeared to be the major means of population growth. Likewise, Pocillopora d a m i c o r n i s populations in the eastern Pacific had not produced mature gonads nor planulae during a 2 yr study, yet were the dominant reef species off the coast of Panama (Richmond 1985). Eastern Pacific P. d a m i c o r n i s exhibit highc,r colony growth rates than Central Pacific populatiuns, which enhances population growth via fragmentation (Richmond 1985). High bioerosion rates on corals in the eastern Pacific are proposed as making fragmen- tation important for massive species such as P a v o n a c a c t u s (Highsmith 1982). Asexual reproduction of corals is found in all r e g o n s covered in this review, but appears to dominate in areas which are marginal for coral growth, including the eastern Pacific (Richmond 1985), the northwest Hawaiian Islands (Grigg et al. 1981), southwestern Australia (Stoddart 1984), and possi.bly Bermuda (Wyers 1985). Within regions with optimal conditions for coral growth, asexual processes may dominate specific habitats including areas of high wave energy (Tunnicliffe 1981), soft or unconsolidated substrata (Gilmore & Hall 1976), and stable, undisturbed sites (Hunter 1988, unpubl.). In areas where sexual reproductive processes are prevalent, asexuaI reproduction may augment recruitment at any time, especially during periods of environmental stress or disturbance (Highsmith et al. 1980). Enhanced colony growth rate and subsequ.ent fragmentation may result from allocation of energy away from production of sexual products, notably in environments where sexual processes may be physiologically constrained (Richmond 1987 a ) . The occurrence of sterile populations has been described for other invertebrate taxa as well (Mileikovsky 197 1). Asexual reproduction has the advantages of not requiring a partner, propagating locally adapted genotypes, and providing a refuge-in-size from predation and burial by sediments. Richn~onti& Hunter Reproduct~onand recruitment of corals PLANULA LARVAE Coral planulae can result from elther internal fertilization and brooding, or external fertilization of spawned gametes and subsequent development outside the parent colony (Harrigan 1972, Babcock & Heyward 1986). Stoddai-t (1983) suggested that planulae of Poc~llopora damlcornls may also be produced asexually, based on similarities of parental a n d planular multllocus genotypes and adult population structure. Two other species, Tubastl-ea cocclnea and T. dlaphana, were also found to have planulae with lsozyme patterns identical to their broodparents, while planulae of Acropora pallfera and Serjatopora hystnx had genotypes consistent with sexual origin (Ayre & Resing 1986). The brooded planulae of Pocillopora damicornis contain symbiotic zooxanthellae upon release from the parent, as well as a large quantlty of lipid (Fig. 2). With the additional ability to feed whlle planktonic, these planulae remain competent for over 100 d , a period sufficient to allow dispersal over large distances (Richmond 1981, 1987 a ) . Planulae resulting from spawned gametes (Fig. 3) may lack zooxanthellae upon fertilization (known exceptions being poritids and Montipora spp., whose eggs contain maternal zooxanthellae), but eventually acquire the algal cells from the environment, usually after settlement and metamorphosis (Babcock 1989). Planulae of Fungia scutaria acquire zooxanthellae after release from the parent colony but before metamorphosis (Krupp 1983). The spawned larvae of Acropora tenuis do not contain zooxanthellae, and have a shorter competency period (ca 20 d ) than the brooded larvae of Poallopol-a Fig. 2 Poc~llopol-a damlcornis. Brooded planula of a coral Note the bands of zooxanthellae, and the oral opening. T h e larva 1s ca l mm In length 199 dan~icornis(Richmond 1989). Larval competency (the abllity of larvae to successfully settle and metamorphose) is a major factor affecting the distrlbution of coral species, particularly for reefs in the eastern Pacif~c.I t has been proposed that the present coral fauna of the eastern Pacific is the result of long-distance dispersal of planulae from Central Paclflc stock (Dana 1975, Rlchmond 1987 b). Some instances of llnlited distrlbution patterns and endemlsln may b e the result of abbreviated larval competency periods. RECRUITMENT Reproductive success may best b e measured by recruitment. Recruitment of both sexual and asexual propagules is medlated by biotic factors, such as predahon and competition, and by abiotic factors such as environmental variability and disturbance. Sexual recruitment of corals is a function of several parameters including the timing of reproduction, competency periods of planula larvae, current regimes, availability of substrata, and densities of predators and competitors (Bii-keland et al. 1981, FItzhardlnge 1985, Babcock 1989). Several studies have found evidence for 'open populatlons' with non-localized sources of coral planulae (Wallace 1985 a , Babcock 1989), but others have suggested that reefs can be self-seeded (Baggett & Bright 1985, Sammarco & Andrews 1988, 1989, Andrews et al. 1989).In some areas, juvenile abundance 1s directly related to adult cover (Bak & Engel 1979, Fig. 3 Acropol-a tenuls. Spawned clusters of e g g s sul-I-ounding sperm from a coral. Each cluster contalns between 9 and 16 eggs around a single sperm packet Cluster diameters range between 1.3 and 1 6 mm 200 Mar Ecol. Prog. Ser 60: 185-203, 1990 Rylaarsdam 1983), although this is not always the case (Fitzhardinge 1985, Harriott 1985).Relative recruitment rates have been shown to vary from year to year, and among sites on the Great Barrier Reef (Wallace 1985 a ) . There appears to b e a n inverse correlation between success of larval recruitment and propagation by fragmentation in some coral species (Kojis & Quinn 1981 b, Highsmith 1982, Wallace 1985b). Sammarco (1985, 1987) reported that, while planular recruitment of Acropora spp. on the Great Barrier Reef is high, juvenile recruits are rare in the Caribbean a n d populations there are structured primarily by asexual processes. Temporal and regional variations in biotic and environmental factors can cause differences in reproductive a n d recruitment patterns of coral communities. The pan-Pacific coral Pocillopora damicornis provides a n example of how life history characteristics may vary with respect to local conditions (Richmond 1985, 1987 a). Enewetak Atoll a n d Hawaii arc characterized as having low rates of p r e d a t ~ o non P. damicornis, relatively low seasonal variability, yet relatively high frequencies of mortality-causing disturbances (typhoons and winter storms). P. damicornis colonies planulate monthly throughout the year in Hawaii and the Central Pacific, a n d the oldest colonies observed are estimated to b e less than 10 yr old (branch lengths < 20 cm). The eastern Pacific of Panama is characterized as having high rates of predation on P. damicornis, high levels of seasonal variability, and low frequencies of mortality-causing events. In this area, P. damicornis has never been found to release planulae, has a higher colony growth rate, a n d is the dominant coral in terms of competitive interactions with other corals, with some colonies estimated as over 70 yr old (branch lengths > 240 cm). Theories on the evolution of life history characteristics have been proposed which suggest that under conditions of environmental instability, where lethal disturbances occur at a relatively high rate, formation of large numbers of motile propagules should occur, while under stable conditions, selection will favor clonal (asexual) growth (Williams 1975, MaynardSmith 1978).Likewise, under conditions of low juven~le versus high adult mortality, a n d relatively low competitive ability versus competitive dominance, selection will favor the sexual mode (Abrahamson 1980, Douglas 1981). Pocillopora damjcornis fits these predicted patterns over its distributional range. RESOURCE MANAGEMENT IMPLICATIONS As coral reefs throughout the world are showing signs of degradation, management of reef resources is becoming a growing concern. In the case of corals which spawn during a very brief period each year, the presence of contaminants such as petroleum products, pesticides, herbicides and heavy metals from soils may prevent successful fertilization of eggs by sperm, and hence, severely limit coral recruitment (fichmond unpubl.). It is suggested that pollution levels which may not affect adult coral colonies could still be responsible for the eventual loss of reefs if reproductive processes are disturbed. In Guam and in Okinawa (southern Japan), the peak coral spawning occurs during the rainy season, when levels of coastal contamination via runoff are at their highest (pers. obs.). With reef degradation and destruction occurring on a global scale, an application of the reproductive data is in the area of reef recovery. Areas of reef which have been destroyed may b e re-seeded, and the most efficient means will depend on local conditions. In areas where sedimentation is high, corallivores are present in large numbers, and/or disturbance rate is low, cementing larger numbers of smaller fragments may be more effective based on reproduction and recruitment data. In areas where environmental conditions support sexual reproduction of corals, juvenile mortality is expected to be relatively low, and suitable substratum is available, transplantation of gravid adult colonies into a n area may result in highest return of effort. Reef re-seeding is an expensive process (Harriott & Fisk 1989) and management efforts might best be expended in coral reef protection and conservation. SUMMARY Data on the reproductive biology of 200+ scleractinian corals indicate several apparent trends. Species which broadcast spawn outnumber those which brood planula larvae. Broadcast spawners typically have limited, annual spawning periods, while most brooders are iteroparous, releasing larvae over a large part of the year. Most corals reported to date are hermaphroditic, some of which have been found to self-fertilize readily in the laboratory; the capacity for selfing is low to nonexistent in other hermaphroditic species. There are reports of coral populations which are apparently sterile, particularly those at the extreme limits of their distributions. There appear to be several geographical trends in coral reproduction. The majority of species on the Great Barrier Reef participate in a n annual synchronous spawning event following full moon in the austral spring. In other areas of the Pacific, the Caribbean, and the Red Sea, there is a greater partitioning of spawning periods over more months, days, and lunar phases. Degree of synchrony among species may be related to seawater temperature ranges in each region. kchmond & Hunter: Reproduction and recruitment of corals M o d e of reproduction within a given taxa is g e n e r ally conservative, while timing m a y b e variable within a n d a m o n g species. Differences i n reproductive patterns m a y represent adaptations to local environmental conditions or m a y represent g r o u p s which h a v e not b e e n sufficiently taxonomically differentiated. A point w h i c h clearly e m e r g e s from t h e d a t a r e v i e w e d in this p a p e r is t h e n e e d for examination of reproductive characteristics i n conjunction with skeletal characters to elucidate w h a t m a y b e real p r o b l e m s i n coral taxonomy. Do o b s e r v e d reproductive differences indicate that speciation h a s occurred a m o n g populations? If w e a c c e p t t h e biological species definition, it is evident that morphological characters alone m a y fail to detect valid biological differences. As more studies of reproduction a r e p u r s u e d , resulting information will e n a b l e d e v e l o p m e n t of a m o r e a c c u r a t e u n d e r s t a n d i n g of t h e ecology a n d evolutionary biology of t h e Scleractinia. Acknowledgements. We gratefully acknowledge UNESCO for sponsoring the meeting on Interoceanic Comparisons, held at the University of the South Pacific, Suva, Fiji in March, 1986, for which this review was originally prepared. We thank Drs C. E. Birkeland, P. L. Jokiel, R. A. Knzie, D. A. Krupp and P. W. Sammarco for comments on manuscript drafts, R. Randall for taxonomic identifications, D. Hopper. F. Te, A. Kerr. and A. Goodis for assistance with field and laboratory examination of Guam corals, and Dr K. Yamazato for access to the corals of Ohnawa. 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