Development of an Immunological Probe to Quantify Reproductive Effort in the Suminoe Oyster,Crassostrea ariakensis(Gould 1861)

Abstract

A polyclonal antibody specific to an egg protein of the Suminoe oyster, Crassostrea ariakensis, was developed to assess reproductive effort. After 2 mo of immunization, rabbit antiserum showed strong specificity to the egg protein in an enzyme-linked immunosorbent assay (ELISA). The rabbit antioyster egg immunoglobulin G detected as little as 0.2 µg/mL of Suminoe oyster egg protein by ELISA. The quantity of eggs present in an oyster was estimated using ELISA and was expressed as a gonadosomatic index (GSI). Gonadosomatic index values of Suminoe oysters were assessed monthly from January to July 2007 at the Seomjin River estuary off the south coast of Korea. Histology indicated that most oysters were mature and ready to spawn by the middle of July. Mean GSI values for oysters collected in April, when most female oysters are in early developmental stages, varied between 0.6% and 14.0%. In July, most oysters were ready to spawn and GSI values ranged from 17.5–67.0%, with a mean of 47.7%. The potential fecundity of ripe oysters was determined by dividing the number of eggs, which was estimated by ELISA, by the mean dry weight of a single egg (14 ng); fecundity ranged from 162–910 million eggs. The immunological technique used in this study was affordable and sensitive enough to measure variation in the number of eggs present among gametogenic stages.