Abstract

Intragonadal injections of serotonin (5-HT), dopamine (DA), noradrenaline, and prostaglandin (PG) E2 (PGE2) were assayed as inducers of spawning in the hermaphrodite scallop Argopecten purpuratus. The three monoamines were effective in inducing the release of sperm but not of oocytes PGE2 did not induce the release of either gamete. When a mixture of 5-HT or DA with PGE2 was injected, gametes of both sexes were released. The injection of DA, followed (within 30 min) by an injection of PG2, also induced the release of both gametes. This was not the case for 5- HT. The percentages of gamete fertilization and of larvae survival were much higher for the gametes spawned by an injection of DA combined with PGE2 than for those gametes spawned as a result of increasing temperature and adding microalgae. These results support the hypothesis that PGs and dopaminergic mechanisms may be implicated in female spawning. This study shows that the injection of DA combined with PGE2 may be successfully used in hermaphrodite scallops for obtaining viable gametes for fertilization and consequent larval development.