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A summer studying snails in the Caribbean

Cpica_webI am a graduate student with the UCMP and the Department of Integrative Biology at Berkeley, and I study the biogeography, conservation biology, and microevolution of molluscs. From July through August of 2009, I traveled to nine islands in the Eastern Caribbean looking for Cittarium pica, a large, marine gastropod, or snail. This species has many common names, including West Indian Topshell, burgao, burgos, cingua, magpie shell, wilke, and “whelk”, which is why knowing the scientific name is so important!

Cittarium pica is the largest snail that lives along rocky coasts, reaching a maximum width of 13.6 cm! Since at least the Pliocene, about 5.2 million years ago, the species has lived in the West Indies and along the Caribbean coasts of South and Central Americas. Humans have fished this snail since they first arrived in the region, eating the meat and using the shell for both jewelry and as tools.

Conducting research on the islands of the Caribbean and Northwestern Atlantic is a breathtaking experience, both because of the spectacular views and because it’s hard work! When I found locations on the islands with C. pica populations, I recorded the size and location of individuals within the intertidal zone. I will use this information to assess the fishing pressure on island populations, determine the habitat preferences of the species, and map the distribution of habitat during the Pleistocene. This map can then be used to predict the future distribution of C. pica habitat as the sea level rises due to global warming. During the Pleistocene, sea level fluctuated from ~130m below to ~6m above present day sea level!

At each site, I also collected tissue samples from 25-30 snails (taking them does not fatally harm the animals) to determine the genetic variation of the species on both local and regional scales. These data will provide information on the patterns of larval dispersal within the region and help to identify populations that are at high-risk of local extinction (due to low genetic diversity).

During six weeks of fieldwork, I collected 385 tissue samples from 13 different field sites, conducted ten population surveys, recorded habitat and size information for 2,542 individuals, and collected shells from each site. Whew! I had a busy six weeks! While exploring the rocky coastlines, I also found C. pica fossils in Barbados and several locations with fossil corals. I didn't have a permit to collect fossils, so I'll have to return to those sites in the future.

This trip was the third of four field seasons for my dissertation research. To read more about my summer adventures, please check my research blog.

My 2009 fieldwork was funded by the American Museum of Natural History, Unitas Malacologica, and the Reshetko Family Scholarship Fund.

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