Combined Effects of Temperature and Algal Concentration on Filtration and Ingestion Rates of Crassostrea gigas: Bivalvia

The effect of varying algal cell concentration, food items and temperature on the filtration and ingestion rates of the eyed larva of Crassostrea gigas were investigated under laboratory condition. The filtration and ingestion rates were measured according to the indirect method in which the flow of water into the passage cavity is inferred from the rate of removal of suspended particles. Cultures of the unicellular alga Isochrysis galbana and Pavlovia lutheri were used in the test solutions. Three different concentrations of the two algal species (100,50 and 25 cells/mu l) and three temperature degrees (25 degrees c, 20 degrees c and 13 degrees c) were used to study the effect of these factors at different time intervals from starting the experiments (1, 6 and 12 days) on the filtration and ingestion rates of the eyed - larvae. The filtration and ingestion rates of the larvae of C. gigas that recorded by using I. galbana were large than that of P. lutheri. These results might depend on the size of the filtered particles. Moreover, the larvae of C. gigas regulate filtration rates according to the particle concentration in the surrounding medium, filtration was more actively in lower concentrations (25 x 10 (6) L-1I. galbana) than at the higher ones (100 x 10 (6) L-1I galbana). The mean value of filtration and ingestion rates of C. gigas were significantly increased by the increase in temperature degree and 25 degrees c were considerable the perfect temperature to achieve high values of both filtration and ingestion rates if it is compared by 20 degrees c and 13 degrees c. These results help to explain the feeding behavior of C. gigas. {[}Mona, M. H., Elkhodary, G.M. and Khalil, A.M Combined Effects of Temperature and Algal Concentration on Filtration and Ingestion Rates of Crassostrea gigas: Bivalvia] Life Science Journal, 2011; 8(4):805-813] (ISSN: 1097-8135). http://www.lifesciencesite.com.