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May/June 2023 - Fieldwork in Rurutu, Austral Islands
[English version/Tahitian version (coming soon)/French version]
Yu Kai Tan, Diana Vergara, and Tom Duda visited Rurutu during the Austral winter of 2023 to characterize feeding ecologies and presence/abundance of shallow water cone snail species. To determine diets of individual snails, they collected animals from field sites, placed each snail in a cup with seawater (as shown below), and then collected feces from the specimens that defecated. They also searched for egg capsules to determine if any cone species are currently reproducing, collected tissue clips from a selection of animals to detect potential cryptic species by examining DNA sequences, and measured shells of each snail to determine size frequency distributions of species.
Sampling work occurred in the shallow water, lagoon/inner reef area in the northwest part of Rurutu, towards the southwest from the western edge of the airport (click here to see this location on Google Maps). The principally sampled area was largely comprised of an intertidal to subtidal bench with thick algal bound sand on a basalt foundation with depressions and small channels filled with sand, rubble, and larger rubble and coral fragments. The bench extended to a fringing reef where various macroalgae (e.g., Turbinaria ornata) nearly completely covered all hard substrates. The fore reef area has a gradual slope and included large boulders and sandy areas. Cone snails occurred in all parts of the back reef area, but abundance appeared to be greatest closest to shore and in areas that were occasionally exposed during extreme low tides and when swells/winds were weak. A view of the main sampling area (at low tide) is shown in the photo below.
Although some snails were found completely buried in sand or rubble or underneath large rubble or coral chunks, many of the snails, like the individuals of Conus sanguinolentus and Conus sponsalis shown below, were partially buried in small sand pockets on the bench but fairly easy to find.
Yu Kai, Diana, and Tom collected more than 2000 cone snails during the sampling period. They obtained fecal samples and tissue clips from several hundred of these individuals. All but 65 snails (which were preserved to represent voucher specimens) were returned to their site of collection. The photos below show the large number of specimens of various small-sized cone snail species (top image; e.g., Conus aristophanes, Conus coronatus, Conus ebraeus, Conus lividus, Conus nanus, Conus sponsalis, etc.) and large-sized species (bottom image; e.g., Conus leopardus) that were briefly grouped together and then returned on the final day of fieldwork.
Māuruuru roa to Frédéric Riveta, Mayor of Rurutu, and General Secretaries of Rurutu, Purea Parau and Gaston Chung; Christophe Brocherieux from the Direction de l'environnement de la Polynésie Française; Tamatoa Bambridge, Serge Planes, Béatrice Tanseau, and Tiphanie François from CRIOBE; Jenny Kahn and Erin Cearlock from William and Mary; Ben Hess and Taehwan Lee from UM; and Virginia, Jean Claude, Io Line, Soraya, Araia, and Poe from Vaitumu for helping to make this work possible.
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