Abstract
Abstract: We observed that a small number of embryos in brood tubes of the lecithotrophic capitellid, Capitellasp. I, remained and metamorphosed into crawl-away juveniles in the parental brood tube after the parent and other larvae had left. In order to investigate whether this behavior might have a genetic basis, we rearedthe planktonic and non-planktonic individuals separately in population cages for three consecutive generations. In each generation, three food levels were used, producing mature worms of different sizes. Food supply appeared to have no direct effect on the number of non-planktonic larvae per first brood produced. Brood size ranged from 3 to 371 embryos per brood tube over the different food treatments, and was closely correlated with the size of the female parent. We found 2 to 8 non-planktonic individuals per brood irrespective of brood size. High proportions of non-planktonic larvae per brood(>20%)were only found in the smallest broods(<50 embryos per brood). In all broods with >100 embryos, >95% of the individuals were planktonic. Since the proportion of non-planktonic individuals did not increase with short-term selection for this trait over two generations, we concluded that it does not have a genetic basis. Nevertheless, the small number of non-planktonic individuals in this lecithotrophic species may be important over relatively small scales(on the order of 100m)in the recovery of relict populations decimated by the hypoxic conditions which often develop in organically enriched sediments.
