Tropical ascidian communities in Panama-Pacific waters: Structure of undisturbed communities and potentials for invasion


Mary Carman, Geology and Geophysics Department, Woods Hole Oceanographic Institution
Stephen Molyneaux and Stefan Sievert, Biology Department, Woods Hole Oceanographic Institution

Ascidians are benthic marine filter feeders that occur worldwide in nearshore and offshore invertebrate habitats. There is growing awareness that some introduced ascidians are highly invasive and can rapidly spread to new habitats. Increasing anthropogenic development along the Panama coastline, including the chain of islands between Isla Canales de Tierra (Liquid Jungle Lab site) and Isla Coiba, may contribute to a change in the ascidian population, as increasing human coastal development is associated with increasing non-endemic ascidian species. Transport of exotic species around the world is increasing due to further liberalized international trade, new global markets and an accelerated movement of goods and people, collectively affecting natural environments.

During an exploratory survey in January 2006, we documented 3 species of native ascidians living deeper than 3 m in the Liquid Jungle Lab (LJL) area. We propose to return to LJL with Stephan Bullard, Biology Department, University of Hartford, and Anne Goodwin, Zoology Department, Simmons College, and undergraduate students, in January 2008, to conduct extensive surveys and plankton tows along a 16 km transect running from Isla Canales de Tierra to the south southwest, past the islands of Pacora, Afuerito, Canal de Afuera, and Coibito toward Coiba. The specific questions that we propose to address are:

1) How abundant and diverse are the ascidians occurring in the chain of islands between LJL and Coiba?
2) Are there ascidian larvae in the water column and are they the same species as previously documented?
3) Does the composition of the ascidian fauna differ with the degree of development along shoreline areas?

We have discussed complementary interests with Rubao Ji, who has proposed to TRI to survey and model hydrodynamics in the LJL region. The results of our proposed study can then be directly linked with his in an interdisciplinary manner to relate the distribution of acidians in the LJL area to physical factors and to develop a model to predict larval movement. Additional hydrographic data obtained from the OLI supported Panama Liquid Jungle Laboratory Underwater Tropical Observatory (PLUTO) will further enable us to focus on whether species transfer into and out of local habitats will be encouraged or whether physical barriers will promote species stability in local habitats. Prediction of the most likely direction of species transfer between the LJL region and Coiba should be possible, as well as the likelihood for invasion of the waters of the LJL.