Seasonal cycle and population dynamics of the sea hare Aplysia oculiferain the northern Gulf of Eilat (Aqaba), Red Sea

摘要

Populations of the sea hare, Aplysia oculifera (Adams & Reeve, 1850) (Gastropoda: Opisthobranchia), were studied in the northern coast of the Gulf of Eilat (Aqaba) between April 1988 and March 1992. Recruitment occurred from December to February, synchronized with the blooming of green algae (Enteromorpha intestinalis and Ulva sp.). A single recruitment event occurred each year, while a secondary recruitment was rarely observed and was related to acute catastrophic disturbance of the habitat. Adult sea hares inhabited the inter-and subtidal zones from December-January to April-June, feeding on E. intestinalis and Ulva sp. Populations disappeared in April-June which coincided with disappearance of these green algae. Mean maximum body live mass of adult sea hares (MMBLM, that is the highest mean body mass recorded at specific site within the season) ranged from 0.77 to 33 g MMBLM, varied significantly among populations inhabiting the various study sites, and was significantly and inversely correlated with water movement intensity. Abundance of sea hares varied among sites and among years and was related to the amount of green algae during the recruitment season.