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October/November 2023 - Fieldwork in Makemo, Tuamotu Archipelago
[English version/Tahitian version/French version]
PolyCone project members Alessandra Shea, Sebastien Dutertre, Diana Vergara, and Tom Duda performed fieldwork at Makemo during October and November of 2023. They collected several species of fish and mollusc-eating cone snails that were brought to the cone snail rearing facility at CRIOBE in Mo'orea. They also evaluated the local abundance of cone snail species and obtained feces, egg capsules, and tissue clips from snails to characterize their diets, determine which species were actively reproducing, and evaluate the presence of cryptic species. Field studies and collections took place at several sites along the seaward and lagoon sides of Makemo (click here to see this general area on Google Maps).
Seaward sites were dominated by a bench with algal bound sand, very little macroalgae, and a fringing reef where waves less than 1 m in height broke (see photo above). The habitat was highly complex and heterogeneous with numerous boulders and large rubble closer to shore and corals and deeper depressions with small rubble and coarse sand near the fringing reef. Only the portion of the platform nearest to the shore was exposed during extreme low tides. Several species, including Conus catus, Conus coffeae, Conus retifer, and Conus tulipa, occurred under the small boulders/large rubble near the shore (typically in less than 0.5 m of water). Otherwise, the platform included lots of individuals of Conus ebraeus and Conus sponsalis as well as a variety of other cone snail species.
Lagoon sites contained large sandy/silty areas with occasional large corals and regions near the shore with small platforms. Little to no macroalgae was present at sites that were surveyed. As observed at Rangiroa, cone snail species occurring in the lagoon were considerably larger and much less abundant than those at seaward sites, although only a few cone snail species were found at lagoon sites at Makemo (unlike what was observed at Rangiroa). Below is a photo of one of the lagoon sites where numerous individuals of relatively large-sized Conus ebraeus individuals were found. Conus leopardus was fairly abundant in shallow water areas (i.e., 1-3 m) of the lagoon.
Members of the research team sampled cones along a transect across a small hoa (or channel) that connects the lagoon to the sea (click here to see the hoa on Google Maps). Here they observed that the abundance of snails increases and the size of snails decreases as one moves in the hoa from the lagoon to seaward side of the atoll. Below are photos showing the view to the lagoon (top) and ocean (bottom).
In total, the group collected more than 3800 cone snails during the fieldwork, although most of these individuals (~80%) were of the two most commonly observed species (Conus sponsalis and Conus ebraeus). In addition, they obtained hundreds of fecal and tissue samples as well as samples of more than 30 egg capsules. Although some of the capsules tentatively appear to be empty, most of them contained developing embryos and so should provide intact DNA to determine which species deposted them.
Māuruuru roa to members of the Makemo town hall and community; Lucien Ragivaru from Pouheva; Christophe Brocherieux from the Direction de l'environnement de la Polynésie Française; Tamatoa Bambridge, Serge Planes, Béatrice Tanseau, and Tiphanie François from CRIOBE; Ben Hess and Taehwan Lee from UM; and Fabrice, Veena and Alec and Veronica and family at Hello Makemo for helping to make this work possible.
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