Variation in filtration and ingestion rates among different microalgae species by hard clam, Mercenaria mercenaria, larvae and post‐set juveniles

Summary This study investigated filtration and ingestion rates of various microalgae species by hard clam, Mercenaria mercenaria, larvae (veliger, pediveliger) and post‐set. Four microalgae species, Tisochrysis lutea, Pavlova lutheri, Chaetoceros gracilis and C. muelleri were evaluated for larvae, and an additional species Cyclotella nana, were evaluated for post‐set. Flagellates (T. lutea and P. lutheri) were filtered and ingested at higher rates than diatoms (C. gracilis, C. muelleri and C. nana) by both larvae and post‐set. T. lutea was filtered and ingested at a higher rate than all other microalgae species evaluated. The filtration rate of T. lutea was 11.2 µl/ hr, 26.6 µl/ hr and 342.2 µl/ hr by veliger larvae, pediveliger larvae and post‐set respectively. Ingestion rate of T. lutea was 369 cells/hr, 1441 cells/hr and 10,357 cells/hr by veliger larvae, pediveliger larvae and post‐set respectively. In contrast, C. muelleri was filtered and ingested at lower rates by larvae, and C. nana was filtered and ingested at lower rates by post‐set compared with other microalgae species. The differences in filtration and ingestion rates among microalgae species were primarily attributed to the size, shape and dry weight of microalgae species.