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Tropical ascidian communities Pacific Panama

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

We propose to survey tropical ascidian communities along the west coast of Panama in a transect starting at the LJL and running to the NE coast of Isla de Coiba (7o37’N, 81o43W) and to develop a conceptual framework to assess the risk of invasive ascidians spreading from the direction of Coiba along the island chain toward Isla Canales de Tierra.

These surveys will form a baseline dataset of 1 ascidian abundance and diversity of the undisturbed state of the area and will allow us to compare ascidian communities at the LJL to those at Coiba (a location that has been affected by high nutrient load). The model will allow us to develop testable hypotheses about the probability of invasive ascidians spreading to the area. We propose to conduct the field-based portion of this project during two weeks in January 2008.

The apparent low diversity and low abundance of ascidians in the Pacific waters adjacent to the LJL is in stark contrast to the high diversity (58 species) and high abundance of ascidians in the Atlantic-Caribbean waters of similar latitude at Bocas del Toro, Panama (Rocha et al., 2005).

Seventeen species of ascidians, including both native and introduced species, were found in Panama City in 2000 (G. Lambert, unpublished data). However, additional species of ascidians may be found at the LJL when more extensive SCUBA surveys are conducted at deeper sites.

In this context, specific questions that we will address:
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?