Meeting Abstract

P1.86  Thursday, Jan. 3  Response to haloclines might depend on seastar larval form and rearing salinity EL-SHAFFEY, Hisham M*; GEORGE, Sophie B; Georgia Southern University, Statesboro, GA georges@georgiasouthern.edu

The purpose of this study was to determine the effect of rearing salinity (21� or 31�) on the response of larvae of the seastars Pisaster ochraceus and Dermasterias imbricata to a halocline; the salinity of the bottom water layer was at 32� and the salinity of the top 22�. Six artificial water columns made up of Plexiglas cylinders, 4cm in diameter and 45cm tall, marked off in five cm increments were used. Columns were covered with Plexiglas caps containing 3 holes – two of which contained Plexiglas tubes, one 45 cm long, extended to the bottom of the column and the other 22.5 cm long, extended to the halocline. The tubes were used to measure the salinity at the top, middle, and bottom of the column without disturbing the haloclines. Larvae reared at high (31�) or low (21�) salinity were introduced through the remaining hole. The experimental design consisted of two treatments, a pair of controls and four sets of haloclines (22/32�). Ten trials were run for each larval rearing salinity and for each species; with observations made at two-minute intervals for a total of ten minutes. Results varied between species. Pisaster larvae went significantly deeper in the controls than in the haloclines regardless of larval rearing salinity. For Dermasterias larvae, those reared at 21� went significantly deeper in the controls than in the haloclines. Those reared at 31� went to similar depths in controls and haloclines. This study shows that larval form and larval rearing salinity might play a role in larval dispersal and the distribution of adult populations in the Puget Sound region.