FRESHWATER SNAILS IN FIJI

Presentation on theme: "FRESHWATER SNAILS IN FIJI"— Presentation transcript:

1 FRESHWATER SNAILS IN FIJI
By Alison Haynes

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3 Main Families NERITIDAE Genera:Neritina, Clithon, Septaria 22 species
Male and female individuals THIARIDAE Genera: Melanoides, Thiara 10 species Origins in South East Asia

4 Distribution of Neritids and Thiarids
Originated in South East Asia Island hopped northwards (less) & southward (most) and a few eastwards Solomon Islands 28 species, 24 Fiji, 16 Samoa, 9 French Polynesia

5 USP Concrete Drains Diversity and abundance of neritids & thiarids
40 m stretch 600m from sea both genera reach 800 individuals per m.

6 Thiarids in drain

7 Neritids in drain

8 Neritina & Clithon Difficult to tell apart
If spines present, must be Clithon But not all Clithons have spines All have operculum with longitudinal ridge/groove Penis with penis sac

9 Clithon Male head with penis and penis pouch Spermatophore Operculum

10 Neritina E. Male head with penis Spermatophore operculum

11 Septaria 5 species in Fiji, 13 worldwide
Prefer fast flowing streams (Ovalau, Taveuni) Distribution in stream depends on shape

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13 Septaria

14 Thiarids Found in ponds, drain, rivers and strteams
Melanoides tuberculata now worldwide Reproduction by parthenogenesis – all female

15 Other Species Species with southern,
Australian or New Zealand relatives Physastra nasuta Fluviopupa pupoidea is endemic to Fiji 4 mm high Genus in Vanuatu, New Caledonia, Rapa Island Lord Howe Island

16 Endemic Thiarid, Fijidoma maculata
Found in inland Viti Levu in headwaters of Rewa & Ba rivers. Shaped like a neritid for living in swift current. Population in Wainibuka, Wailoa & Ba rivers Endangered

17 Endemic Species, Acochlidium fijiense
Found only in Nasekawa R., Vanua Levu Related to marine nudibranchs One of the rare species found in freshwater. Other species in Palau & Flores (Indonesia)

18 Snails used as food

19 Conservation of Freshwater Snails
Main threats 1. Siltation caused by logging of forests road making cultivation of steep hillsides 2.Cause silt and grit to cover stream bottom and the algal film on which the snails feed E.g. cleaning tail race at Wailoa power station decimated F. maculata population downstream in the Wailoa R.

20 Conservation of Freshwater Snails
2. Cyclones and storms F. maculata population in Wainibuka R. reduced to 250 m-2 from 1475 per m-2 after 2 cyclones in 1985