Quantifying fecundity in Macoma balthica using an enzyme-linked immunosorbent assay (ELISA)

Monoclonal antibodies specific to a heat shock protein 70-like protein expressed in the eggs of Macoma balthica (mb-HSP70) were employed to develop an enzyme-linked immunosorbent assay (ELISA) to quantify fecundity in females. The assay was specific to egg tissue, with no demonstrable reactivity with juvenile or male tissues. The concentration of mb-HSP70 increased as the female gonads matured, necessitating the determination of a calibration curve for future experiments. The number of eggs in females was positively correlated with body mass index (BMI), and clams with a BMI <1.4 did not produce eggs. The estimated number of eggs per clam during the fall spawning period was similar to that observed in eastern North Atlantic populations in clams of similar size; clams with shell lengths from 16 to 18 mm had from 7000 to 60 000 eggs apiece. Larger clams had up to 450 000 eggs. This assay effectively quantifies eggs at any stage of gonadal development in which eggs can be distinguished microscopically and is easier and cheaper to perform than other techniques of comparable precision.