freshwater snails in fiji by alison haynes. main families neritidae genera:neritina, clithon,...
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FRESHWATER SNAILS IN FRESHWATER SNAILS IN FIJIFIJI
By Alison HaynesBy Alison Haynes
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Main FamiliesMain Families
NERITIDAENERITIDAE Genera:Neritina, Clithon, Genera:Neritina, Clithon,
SeptariaSeptaria 22 species22 species Male and female Male and female
individualsindividuals THIARIDAETHIARIDAE Genera: Melanoides,Genera: Melanoides, ThiaraThiara 10 species10 species Origins in South East AsiaOrigins in South East Asia
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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
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USP Concrete Drains Diversity and abundance of neritids &
thiarids 40 m stretch 600m from sea both
genera reach 800 individuals per m.
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Thiarids in drainThiarids in drain
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Neritids in drainNeritids in drain
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Neritina Neritina & & ClithonClithon
Difficult to tell apartDifficult to tell apart If spines present, must If spines present, must
be be ClithonClithon But not all But not all Clithons Clithons
have spineshave spines All have operculum All have operculum
with longitudinal with longitudinal ridge/grooveridge/groove
Penis with penis sacPenis with penis sac
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Clithon
Male head with penis and penis pouch
Spermatophore
Operculum
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Neritina
E. Male head with penis
Spermatophore
operculum
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SeptariaSeptaria
5 species in Fiji, 13 5 species in Fiji, 13 worldwideworldwide
Prefer fast flowing Prefer fast flowing streams (Ovalau, streams (Ovalau, Taveuni)Taveuni)
Distribution in stream Distribution in stream depends on shapedepends on shape
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Septaria
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ThiaridsThiarids
Found in ponds, drain, Found in ponds, drain, rivers and strteamsrivers and strteams
Melanoides Melanoides tuberculatatuberculata now now worldwideworldwide
Reproduction by Reproduction by parthenogenesis – all parthenogenesis – all femalefemale
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Other SpeciesOther Species
Species with southern,Species with southern, Australian or New Zealand Australian or New Zealand
relativesrelatives Physastra nasutaPhysastra nasuta Fluviopupa pupoidea is Fluviopupa pupoidea is
endemic to Fijiendemic to Fiji 4 mm high4 mm high Genus in Vanuatu, New Genus in Vanuatu, New
Caledonia, Rapa IslandCaledonia, Rapa Island Lord Howe IslandLord Howe Island
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Endemic Thiarid, Endemic Thiarid, Fijidoma maculataFijidoma maculata
Found in inland Viti Found in inland Viti Levu in headwaters of Levu in headwaters of Rewa & Ba rivers.Rewa & Ba rivers.
Shaped like a neritid Shaped like a neritid for living in swift for living in swift current.current.
Population in Population in Wainibuka, Wailoa &Wainibuka, Wailoa &
Ba riversBa rivers EndangeredEndangered
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Endemic Species, Endemic Species, Acochlidium Acochlidium fijiensefijiense
Found only in Found only in Nasekawa R., Vanua Nasekawa R., Vanua LevuLevu
Related to marine Related to marine nudibranchsnudibranchs
One of the rare One of the rare species found in species found in freshwater.freshwater.
Other species in Palau Other species in Palau & Flores (Indonesia)& Flores (Indonesia)
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Snails used as foodSnails used as food
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Conservation of Freshwater SnailsConservation of Freshwater Snails
Main threatsMain threats 1. Siltation caused by1. Siltation caused by logging of forestslogging of forests road makingroad making cultivation of steep hillsidescultivation of steep hillsides 2.Cause silt and grit to cover stream bottom2.Cause silt and grit to cover stream bottom and the algal film on which the snails feedand the algal film on which the snails feed E.g. cleaning tail race at Wailoa power station E.g. cleaning tail race at Wailoa power station
decimated decimated F. maculata population F. maculata population downstreamdownstream in in the Wailoa R.the Wailoa R.
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Conservation of Freshwater SnailsConservation of Freshwater Snails
2. Cyclones and storms2. Cyclones and storms F. maculata F. maculata population in Wainibuka R. population in Wainibuka R.
reduced to 250 mreduced to 250 m-2-2 from 1475 per m from 1475 per m-2-2 after 2 after 2 cyclones in 1985cyclones in 1985