SCHIOPU, Daniela; GEORGE, Sophie B.; University of South Florida; Georgia Southern University: Ingestion rates of Dendraster excentricus larvae

The ability of D. excentricus larvae to capture and ingest different-sized algae was determined in two consecutive summers by assigning larvae to either single or mixed algal diets. The single algal diets of I. galbana, D. tertiolecta or Rhodomonas sp. and the mixed algal diets I. galbana-D. tertiolecta, I. galbana-Rhodomonas sp., D. tertiolecta-Rhodomonas sp. and I. galbana-D. tertiolecta-Rhodomonas sp. were used. Algal cell size varied between years with I. galbana increasing in cell size and D. tertiolecta and Rhodomonas sp. decreasing in cell size. In both years, the volume of algal cells ingested varied significantly among algal diets and among larval stages. The volume of algal cells ingested was greater for single algal diets than for mixed algal diets. Four-arm stage larvae ingested large volumes of I. galbana from the I. galbana-Rhodomonas sp. and I. galbana-D. tertiolecta combinations and small volumes of the larger algal cells in the mixture. In both years, the volume of D. tertiolecta and Rhodomonas sp. (in single algal diets) increased from the 4-arm to the 8-arm larval stage. Four, 6-arm and 8-arm larvae ingested almost equal volumes of the Rhodomonas sp. and D. tertiolecta in the mixed algal diet in both years. When fed a diet containing all three algae, 6-arm larvae ingested equal volumes of Rhodomonas sp. and D. tertiolecta and higher volumes of I. galbana and 8-arm larvae ingested large volumes of I. galbana and D. tertiolecta and small volumes of Rhodomonas sp. The present findings suggest that cell size and ratios play an important role in ingestion rates at various stages of development.