NOTES ON FRESHWATER MOLLUSKS OF FRENCH POLYNESIA, SOCIETY ARCHIPELAGO

 

Observation of 11 freshwater mollusk species in the Society Islands:

Tahiti, Moorea, Huahine, Raiatea and Bora Bora during a field trip made in 2003-2004.

 

Article first published in Journal de la Société Linnéenne de Bordeaux, 2006

 1-2: Neritina turrita / 3-4: Clithon spinosum / 5-6: Septaria porcellana / 7-11: Melanoides tuberculata / 12-13: Neripteron dilatatum / 14-15: Physa acuta / 16: Pseudosuccinea columella / 17-18: Clithon dispar / 19-21: Helisoma duryi / 22: Neritina canalis / 23-24: Neripteron tahitensis / 25-26: Neripteron auriculatum (Indonesia) / 27: N. turrita operculum / 28: N. tahitensis operculum / 29: N. canalis operculum / 30: S. porcellana operculum

1-2: Neritina turrita / 3-4: Clithon spinosum / 5-6: Septaria porcellana / 7-11: Melanoides tuberculata / 12-13: Neripteron dilatatum / 14-15: Physa acuta / 16: Pseudosuccinea columella / 17-18: Clithon dispar / 19-21: Helisoma duryi / 22: Neritina canalis / 23-24: Neripteron tahitensis / 25-26: Neripteron auriculatum (Indonesia) / 27: N. turrita operculum / 28: N. tahitensis operculum / 29: N. canalis operculum / 30: S. porcellana operculum

 

A: Melanoides tuberculata

(O. F. Müller, 1774) Thiaridae

Species mainly nocturnal, burrows into the substrate during the day and can move behind. Observations of very active individuals during the day were carried out in closed biotopes with strong plant and / or animal decomposition (ditch type with food waste). No typical habitat, found in artificial or natural environments, zones with or without current, polluted or unpolluted zones, with or without vegetation. Relative stability of the shapes and patterns of the shell within the same population; great variability of patterns from one locality to another. Introduced species.

Field reports:

  • January 13, 2004

Huahine, Society Archipelago. North of Fare, private road towards Vaihonu Ocean, Vaihonu. Population of about 120 individuals, concentrated in the still flooded part of a ditch near the road. Friches in the neighborhood, bottom of the ditch in coral soup (limestone). Long zone of 12m, width of 80cm and depth of water 60 to 90cm. Freshwater from rain; no visible pollution, little traffic on the road and no food crops in the vicinity; no macro waste. Vegetation: Hygrophilla, Nuphar, reeds, pandanus. Dead branches and decomposing coconut, bottom of trench covered by thin layer of sediment and dead leaves (acidic apport). Gambusia fishes on the surface, larvae of mosquitoes and dragonflies in sediments. Presence of other mollusks: see Lymnaea columella and Physa acuta. Specimens of M. tuberculata adults and juveniles moving on wood, which are essentially dead, always near the surface and in higher concentrations on surfaces covered with filamentous green algae in carpets (short and fine thallus, max. also develop on shells live mollusks. Greenish-brown coloring almost uniform after cleaning, some specimens with red brown spooks on the first towers. Very little variation in color and shape in this population. Few specimens with marks of breakage and reformations; apex and first few spins, except for some individuals exceeding 30mm. Average length 39mm (measurement of 45 specimens).

  • January 25, 2004

Raiatea, Society Archipelago. 100m north of camping Peter's Place, about 5km south of Uturoa, mouth of the Mitimitiaute river. Small colony of 36 individuals observed, in calm zone of the mouth of the river. Sandy bottoms covered with dead leaves and fine sediments. 4 other individuals observed on a basaltic stone upstream. Tarmac road nearby, the river passes under a small bridge. Shorelines with dense wild vegetation, observation area exposed to the sun about 2 hours a day. Two upstream dwellings occasionally show traces of detergent in the quiet areas of the river. No aquatic vegetation except carpet of fine green algae on smooth substrates. M. tuberculata observed moving or not on and under dead leaves, dead wood and smooth basaltic stone. Coloring of the shell very clear with some brown spooks, columellar zone often dark. Average size of the shells: 34mm (40 specimens measured). Some specimens slightly darker; apex often eroded, some marks of reformation of the shell. Periostracum fine, without algae except sometimes on the first towers. Observation of groups of 3 to 6 individuals, sometimes agglutinated.

  • February 22, 2004

Raiatea, Society Archipelago. Second waterfall of the river Mitimitiaute, in the mountains, south of Uturoa. Approximately 300 individuals observed on the entire cauldron, juveniles and adults. Distributed over the whole zone (about 8m in diameter, from 0 to 110cm deep), on smooth stones, immersed wood, on vegetation close to the surface of the water and zones watered by the projections of the cascade. No house or culture upstream, very fresh water after rain (12 ° C), high flow, fairly clear water, low sedimentation. Access to the waterfall through the forest, on foot only. Dense vegetation, sloping soil, cauldron exposed to the sun about 3 hours a day. Smooth basalt stones and pebbles at the bottom of the basin, covered with a thin layer of green algae. Mosses and ferns on vertical walls, in less watered areas. Very calm zones on the edges of the basin, very agitated under the cascade, very current near the flow. Presence of fish "eels with ears" and crustaceans "chevrettes" in large numbers. Other mollusks: see Neritina canalis and Neritina tahitensis. Shells very eroded, numerous bursts and reformations, thick periosteum, first absent turns or broken apex. Light brown color almost totally uniform. Average size 26mm (measuring 60 specimens).

  • February 11, 2004

Raïatea, Society Archipelago. Ditch near the only road from Utufara Point, south of Uturoa. Approximately 70 individuals observed along the length of the ditch (about 800m). Recent residential area, with concrete drainage ditches regularly cleaned of stringy green algae that grow there to excess. Rainwater and waste water supply. High water temperature (31 ° C), area exposed to the sun mostly throughout the day. Other mollusks: Physa acuta, Helisoma duryi and Lymnaea columella. Slightly eroded shells, thick periostracum, little reformations or splinters, apex or first towers often broken. Dark brown color almost completely uniform, sometimes some darker spots. Average size 31mm (measuring 30 individuals).

B: Pseudosuccinea columella

(Say, 1817) Lymnaeidae

Species encountered only in calm, closed environments (type basin, ditch or pond). No observation of specimens exceeding 13mm, many juveniles. Always in the presence of Physa acuta, often with Helisoma duryi. Introduced species.

Field reports:

  • January 13, 2004

Huahine, Society Archipelago. North of Fare, private road towards Vaihonu Ocean, Vaihonu. Biotope: still flooded part of a ditch near the road. Friches in the neighborhood, bottom of the ditch in coral soup (limestone). Long zone of 12m, width of 80cm and depth of water 60 to 90cm. Freshwater from rain; no visible pollution, little traffic on the road and no food crops in the vicinity; no macro waste. Vegetation: Hygrophilla, Nuphar, reeds, pandanus. Dead branches and decomposing coconut, bottom of trench covered by thin layer of sediment and dead leaves (acidic apport). Gambusia fishes on the surface, larvae of mosquitoes and dragonflies in sediments. Presence of other mollusks: see Lymnaea columella and Physa acuta.. 26 individuals observed and measured, average size 11mm, very fine shell, translucent. Only observed on stems and leaves of living plants.

  • February 7, 2004

Raiatea, Society Archipelago. Utufara, seafront near the city center, wharf of steamships. Artificial basin of concrete planted with water lilies and ornamental reeds, with carasses. Approximately 30 individuals observed, under leaves and on water lily stalks. A few bunches on the reed stalks, near the surface. Average size 12mm (measuring 15 specimens).

  • February 11, 2004

Raiatea, Society Archipelago. Ditch near the only road from Utufara Point, south of Uturoa. Biotope: see record 4 Melanoides tuberculata. Other mollusks: see Physa acuta and Helisoma duryi. Observation of 6 individuals in the seaweed waste from the ditch and put to dry. 2 individuals still alive, the others dried up. No observation of live specimens in water. Average size 8mm.

C: Physa acuta

Draparnaud, 1801 Physidae

Introduced species. In the same media as Lymnaea columella and Helisoma duryi. Point presence of periostracum, which may be very thin or thicker, opaque or translucent depending on its pigment content.

Field reports:

  • January 13, 2004

Huahine, Society Archipelago. North of Fare, private road towards Vaihonu Ocean, Vaihonu. Biotope: see record 1 Melanoides tuberculata. 62 specimens observed and measured, average size 7mm. On any support, also on the surface of the water. Individuals all very active, many eggs beneath the leaves of Nuphar. Translucent shell very fine, senescent; a black specimen (periostracum?) observed under identical conditions.

  • February 11, 2004

Raïatea, Society Archipelago. Ditch near the only road from Utufara Point, south of Uturoa. Biotope: Recent residential area, with concrete drainage ditches regularly cleaned of stringy green algae that grow there to excess. Rainwater and waste water supply. High water temperature (31°C), area exposed to the sun mostly throughout the day. Other mollusks: see Helisoma duryi and Lymnaea columella. Observation of two dead, dried-up individuals in seaweed waste from the ditch and put to dry. Sizes 6 and 7mm. An individual (6mm) observed in the water, on a wall of the ditch.

D: Helisoma duryi

Wetherby, 1979 Planorbidae

Introduced species. In the same media as Physa acuta and Lymnaea columella. Particularly favored are stringy green algae with very long and thin thallus. Mimetism produced by the development of these same algae on the shell.

Field reports:

  • February 11, 2004

Raïatea, Society Archipelago. Ditch near the only road from Utufara Point, south of Uturoa. Biotope: Recent residential area, with concrete drainage ditches regularly cleaned of stringy green algae that grow there to excess. Rainwater and waste water supply. High water temperature (31 ° C), area exposed to the sun mostly throughout the day. Other mollusks: see Physa acuta and Lymnaea columella. Observation of 7 individuals living in water, on plastic bags; 2 live animals and 19 dead in the seaweed waste from the ditch and put to dry. Average size 6mm (measurement of 20 specimens). Shell fine, whitish to translucent with fine periostracum and fine green algae, especially in the umbilicus.

E: Clithon dispar

(Pease, 1867) Neritidae

This species is found in brackish waters with low salinity and seawater. Variable shell patterns: uniformly black or with gray dots.

Field reports:

  • December 29, 2003

Bora Bora, Society Archipelago. Mouth of the Vaitape River, south of Vaitape. Observation of a large colony (about 250 individuals) on basaltic rocks, in cavities. Some individuals out of the water, close to the surface. Brackish brackish water, no vegetation. Mean size 4mm (measuring 50 specimens), the largest individuals (max.6mm) are found towards the bottom of the colony. Shell uniformly black on the outside, white to yellowish aperture, often eroded.

F: Neritina turrita

(Gmelin, 1791) Neritidae

Field reports:

  • December 1, 2003

Moorea, Society Archipelago. 500m north of the quay of Haapiti, stream alongside the campsite, mountain side. Small stream with low flow, fed by rainwater and wastewater of some houses upstream. Pebble bottom, very clear waters, dense vegetation on the edges, filamentous green algae on the stones. Shallow (from 0 to 15cm). Observation of 12 individuals on the emerged part of smooth basaltic stones covered with a fine carpet of algae. Average size 22mm. Yellow brown shell with black bands, fine periostracum brown, apex always eroded, some marks of reformation.

  • February 13, 2004

Raiatea, Society Archipelago. Ditch near the road, PK 5,5, south of Uturoa. Ditch fed by rainwater and wastewater, opening into the lagoon. Coral soup background and pebbles with dead leaves and waste. Very clear waters, absence of current, vegetation composed of Hyacinths and grasses, with fine green algae on the pebbles. Observation of 3 adult specimens (21 to 24mm) and 6 juveniles (16 to 20mm) on the smooth pebbles. Shells in perfect condition, fine periostracum, no erosion or marks. Black strips finer and more numerous than the Moorea specimens.

  • February 6, 2004

Raïatea, Society Archipelago. Vairahi River, near PK 7. River broad of about 5m, widening up to 8m near the bridge of the road. In this zone the depth also increases, passing from a few centimeters to about 2 meters. The current, medium upstream, disappears almost totally in this part. Vertical walls reinforced with limestone blocks, bottom of smooth basaltic stones and pebbles, with strong sedimentation and filamentous green algae. Turbid waters, very slightly brackish. Dense to very dense vegetation on the banks, with branches and submerged roots. Dead wood on the bottom; some waste on the edges; two houses and a vanilla greenhouse upstream. Presence of juvenile fish in schools. Other mollusks: see Clithon spinosus and Neritina auriculata. Observation of 48 individuals in the widened and calm part of the river, especially near the bridge, and 7 individuals in the turbulent part with current. On smooth stones and dead woods covered with algae, especially in deep areas, never close to the surface; except for individuals in the stream, on smooth stones practically out of the water. Generally immobile in the sedimentary layer, and moving on cleaner surfaces. End periostracum, shells always eroded, often with splinters and marks of reformation. Average size 23mm (measuring 25 specimens). Reasons similar to specimens in RL - 2.

G: Neritina canalis

Sowerby 1825 Neritidae

Ovoid, yellow, wrapped in transparent mucus. The gelatinous assembly is laid in the form of plates, glued under smooth stones in high current areas. Periostracum mimetic on smooth black stones. Small number of individuals observed at each survey.

Field reports:

  • December 19, 2003

Tahiti, Society Archipelago. Venue The Three Cascades, Tefaarumai. Zone downstream from the 1st waterfall, river with strong current, shallow (from 0 to 30cm), bottom of blocks and smooth basaltic pebbles with fine carpet of green algae. Very soft and fresh water, no traces of pollution. Dense vegetation on the banks, some dead wood stuck in the stones. Other mollusks: see Septaria porcellana. Observation of 12 individuals on the protected side of the stream of smooth stones close to the surface. Two individuals under stone, motionless. Thick black periostracum brown, opening orange-yellow to bright orange; Apex most often eroded, some specimens with splinters and punctual absence of periostracum. Average size 29mm (measuring 14 specimens).

  • February 22, 2004

Raïatea, Society Archipelago. Second waterfall of the river Mitimitiaute, in the mountains, south of Uturoa. Biotope: Second waterfall of the river Mitimitiaute, in the mountains, south of Uturoa. On smooth stones, immersed wood, on vegetation close to the surface of the water and zones watered by the projections of the cascade. No house or culture upstream, very fresh water after rain (12 ° C), high flow, fairly clear water, low sedimentation. Access to the waterfall through the forest, by foot only. Dense vegetation, sloping soil, cauldron exposed to the sun about 3 hours a day. Smooth basalt stones and pebbles at the bottom of the basin, covered with a thin layer of green algae. Mosses and ferns on vertical walls, in less watered areas. Very calm zones on the edges of the basin, very agitated under the cascade, very current near the flow.. Other mollusks: see Neritina tahitensis. Observation of 2 individuals under smooth stones at the bottom of the basin, motionless. Sizes 22 and 28mm, eroded apex.

H: Neritina tahitensis

(Lesson, 1830) Neritidae

Probably a local form of Neripteron auriculatum (Lamarck, 1816)

Field reports:

  • February 6, 2004

Raïatea, Society Archipelago. Vairahi River, near PK 7. Description of the biotope: see Neritina turrita risé 3. Other mollusks: see Clithon spinosus. Observation of 16 individuals on smooth stones emerged or not, in the part with strong current of the river. 3 individuals observed moving on immersed tree roots, close to the surface, in the current-free zone. Average size 22mm (measurement of 19 specimens). Periostracum thick, gray brown, with very fine and short hairs. Reformation markings, base and white opening with light cream.

  • February 22, 2004

Raïatea, Society Archipelago. Second waterfall of the river Mitimitiaute, in the mountains, south of Uturoa. Description of the biotope: see Melanoides tuberculata surveyed 3. Other mollusks: see Neritina canalis. Observation of a single colony of 32 individuals on the vertical wall near the waterfall, between 5 and 25 cm above the surface. Juvenile and adult specimens grouped on a small area of about 100cm by 20cm. Strong erosion of the shell, especially on large specimens and at the beginning of the coil. Average size 19mm.

  • December 17, 2003

Tahiti, Society Archipelago. Pointe Venus River, Mahina. Wide river (about 5m) and shallow with fine black sand bottom. Low current, traces of detergent (foam) and waste. Some of the edges are made of vertical concrete. No vegetation, dead wood and some smooth basaltic stones. Other mollusks: see Neritina dilatata. Observation of 7 individuals on smooth stones, average size 21mm.

I: Neripteron dilatatum

(Broderip, 1832) Neritidae

Fine and fragile shell with variable motifs. Observation of many freshly dead individuals in an area where Neritina tahitensis does not experience the same mortality rate under identical conditions. N. dilatata may be more sensitive to point-source water pollution.

Field reports:

  • December 17, 2003

Tahiti, Society Archipelago. Pointe Venus River, Mahina. Biotope: Wide river (about 5m) and shallow with fine black sand bottom. Low current, traces of detergent (foam) and waste. Some of the edges are made of vertical concrete. No vegetation, dead wood and some smooth basaltic stones. . Observation of 3 juvenile individuals (9 to 11 mm) on smooth stone, 2 adult individuals under dead wood (15 to 16 mm) and 11 adult individuals (13 to 15 mm) moving on concrete walls, close to the surface. 27 shells observed at the mouth of the river.

J: Clithon spinosum

(G. B. Sowerby I, 1825) Neritidae

Larger specimens often have very eroded thorns. Variable patterns: marbles, points or bands more or less dense.

Field reports:

  • February 6, 2004

Raïatea, Society Archipelago. Vairahi River, near PK 7. Biotope: River broad of about 5m, widening up to 8m near the bridge of the road. In this zone the depth also increases, passing from a few centimeters to about 2 meters. The current, medium upstream, disappears almost totally in this part. Vertical walls reinforced with limestone blocks, bottom of smooth basaltic stones and pebbles, with strong sedimentation and filamentous green algae. Turbid waters, very slightly brackish. Dense to very dense vegetation on the banks, with branches and submerged roots. Dead wood on the bottom; some waste on the edges; two houses and a vanilla greenhouse upstream.

Observation of two individuals on immersed roots (10 and 12mm), a juvenile specimen. Periostracum brown, patterns in black sparks on a yellow brown background. Slight erosion of the spines and apex. Marks of reformation.

K: Septaria porcellana

(Linnaeus, 1758) Neritidae

The operculum is rudimentary, and completely covered by the foot. Periostracum mimetic on smooth black stones. They do not form large colonies, often isolated individuals.

Field reports:

  • December 19, 2003

Tahiti, Society Archipelago. Venue The Three Cascades, Tefaarumai. Biotope: Zone downstream from the 1st waterfall, river with strong current, shallow (from 0 to 30cm), bottom of blocks and smooth basaltic pebbles with fine carpet of green algae. Very soft and fresh water, no traces of pollution. Dense vegetation on the banks, some dead wood stuck in the stones. Internal cover. Observation of 12 individuals on protected parts of smooth basaltic stones. Average size 30mm. Periostracum black thick, early turn always eroded, sometimes with large shrinkage of material. Numerous fragments and marks of reformation, punctual absence of periostracum. Some specimens have deformations of the shell, perforations and / or blisters caused by parasites.

 

References:

Burch, J. B. (1980), North American freshwater snails, Species List, Ranges and Illustrations. Walkerana, Michigan.

Goodwin D. R. (2006), The use of mollusks as biological indicators in assessing climate and environmental change. Visaya net, March 22.

Hubendick, B. (1951), Recent Lymnaeidae. Their variation, morphology, taxonomy, nomenclature, and distribution. Kungl. Svenska Vetensk. Akad. Handl., 3, 1-223.

Pfleger, V. (1989), Guide to shells and mollusks. Hatier.

Pointier, J.P. & Marquet, G., 1990. Taxonomy and distribution of freshwater mollusks of French Polynesia. Venus 49 (3): 215-231

Supian Z. and Ikhwanuddin A. M. (2002), Population dynamics of mollusks (Gastropods Melanoides tuberculata) in Crocker Range Park, Sabah. ASEAN review of biodiversity and environmental conservation. July - September.

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