ALBERT

Notes: Abstract A major recruitment of the forcipulate asteroid Pisaster ochraceus was observed in September 1987 in the channel leading into Boca del Infierno, a semi-enclosed bay on the southeastern shore of Nootka Island, on the west coast of Vancouver Island, British Columbia, Canada. Newly settled recruits were observed at high densities subtidally in the channel (mean maximal density=1.23x104m-2) and at nearby sites. Subsequent surveys in 1988 to 1991 and size-frequency distributions of adults indicated strong yearly recruitment of P. ochraceus. Recruits of P. ochraceus were found on all available substrata, including hard and soft bottoms and on benthic algae. The initial food of the recruits included newly settled mussels (Mytilus sp.), snails and barnacles. Recruitment of the forcipulate Pycnopodia helianthoides was observed in 1987 to 1989 and in 1991, while recruitment of the spinulosan Dermasterias imbricata occurred only in 1988. High densities of planktonic bipinnaria larvae were found in the bay of Boca del Infierno in late May. We hypothesise that the high density population of adult P. ochraceus found in the channel of Boca del Infierno spawns synchronously and most of the resulting embryos and larvae are retained within the bay. This area may act as a “source” of larvae that then disperse locally. Post-recruitment mortality was estimated by comparing the density of recruits of P. ochraceus in 1987 with the numbers of juveniles presumed to be 1 yr old in 1988. Post-recruitment mortality was in excess of 97% with few individuals surviving to 1 yr. Moreover, even after the first year, mortality or emigration of the juveniles resulted in the almost complete loss of the 1-yr cohort at North Saavedra between 1988 and 1989. This study provides evidence that the P. ochraceus population in this area of Nootka Island may not be open, but may be regularly supplied from a “source” of larvae in the bay of Boca del Infierno. Post-settlement processes may, however, have significant effects on the local population, resulting in a poor correlation between the rate of recruitment and the incorporation of yr-1 + individuals into the adult population.

Notes: Abstract Reproduction in the viviparous apodid sea cucumber Leptosynapta clarki was examined in Grappler Inlet, Bamfield, Vancouver Island, Canada from July 1989 through July 1991. The reproductive cycle of L. clarki is annual with gonad growth during the summer months. Male sea cucumbers spawn during November and December and internally fertilize, through as yet undetermined means, the oocytes within the ovary. Embryonic development is rapid, so that within 2 wk fertilized eggs reach the pentactula stage. Pentactulae have an open mouth and anus and actively move in the ovarian tubules feeding on droplets and fluid derived from the resorption of unfertilized eggs. Histological examination of gametogenesis shows similar development to that found in non-brooding holothurians. However, the protandric sex change observed in some male L. clarki after spawning and changes to the overian wall structure prior to fertilization are previously undescribed in sea cucumbers.