Meeting Abstract
P2.87 Wednesday, Jan. 5 Salinity fluctuations induce morphological changes in larvae of Pisaster ochraceus PIA, Tanya/S*; GEORGE, Sophie/B; Georgia Southern University, Statesboro; Georgia Southern University, Statesboro tp00569@georgiasouthern.edu
A regular occurring event in the coastal waters of the Pacific Northwest is a decrease in salinity (to < 15ppt in some areas) as a result of increased precipitation and ice melts. Salinities as low as 20ppt can suppress feeding activity and act as a barrier to the vertical movement of adult Pisaster ochraceus. P. ochraceus is a keystone predator in the rocky intertidal zone of the Pacific Northwest. How larvae of this species would respond to a sudden decrease in salinity is unknown. The purpose of the present study was to determine whether low salinity affects larval growth, development and survival of P. ochraceus. Seastar larvae at different stages of development were kept either at 32ppt salinity for 51 days (controls) or exposed to fluctuating salinity (that is transferring gastrulae, bipinnaria or brachiolaria larvae from 32ppt to 20ppt for 3, 7 or 14 days and then back to 32ppt for 31, 38 or 45 days respectively). Total larval length and width were measured when the bipinnaria larval stage developed, and the posterolateral arm length, stomach length and width measured when the brachiolaria larval stage developed for 10 larvae per jar once a week. A total of 150 larvae were measured weekly. Gastrulae exposed to 20ppt for 3 days and bipinnaria larvae exposed to 20ppt for 14 days were most affected. Larvae exposed to 20ppt for 14 days were shortest, widest, had the smallest stomachs, developed slowly and produced the smallest juveniles. However, larval mortality rates did not differ significantly among treatments. This study indicates that the timing, magnitude and duration of icemelts and rainfall in the Pacific Northwest alters larval morphology, could affect larval feeding and swimming efficiency and ultimately the quality of new recruits into populations of P. ochraceus.
