An analysis of abundance, ecology and life history of the lettuce sea slug Elysia crispata on the island of Bonaire

With the exception of Elysia crispata, shell-less Sacoglossa species (Order: Mollusca), have been widely studied. Within the Caribbean, these small bodied organisms occur in low population densities, making them hard to find and, in turn, difficult to study. This project served to assess E. crispata abundance, ecology and life history traits on the island of Bonaire. Data collected for this study was conducted by observations from ten 40 m2 transects located at depths of 2.2 m, 7.9 m and 10.7 m. A pair of surveyors recorded the number of individuals found, size of individuals, substrate individuals were located on, and color intensity of individuals within each transect. Overall abundance of individuals found at the study sites were much higher than anticipated. Of the 275 individuals found, the highest population densities were found in shallow transects. The average size of individuals was between 3.0 ± 2.6 cm to 5.0 ± 3.8 cm (mean ± SD) in length, with no correlation between size of individual and coloration. Overall abundance of smaller individuals found on shallower transects could indicate higher densities of preferred substrate within these areas. Roughly 94% of individuals were found on various compositions of turf algae. These results implied that E. crispata were biased towards occupying substrates with turf algae compositions as opposed to other available substrates.

This student research was retrieved from Physis: Journal of Marine Science XVII (Spring 2015)19: 26-33 from CIEE Bonaire.