SPAWING INDUCTION, FERTILIZATION AND LARVAL DEVELOPMENT OF HEDISTE DIVERSICOLOR(NEREIDIDAE, POLYCHAETA) UNDER DIFFERENT EXPERIMENTAL CONDITIONS

A suite of experiments with the polychaete Hediste diversicolor were performed to assess the induction of gamete spawning byendogenous substances, to evaluate the percentage of fertilised and hatching eggs in two different conditions (“natural” and in vitrofertilization), and to measure the density effects on larval growth and survival. The results showed that mature females were induced to spawn by adding mature male tissue homogenate in the medium. The percentages of fertilised and hatching eggs were higher in the in vitro fertilisation and larval/juvenile survival was affected by density