Variation in Planktonic Predation Risk: A Tethering Study

KECIA KERR; ANABELLE CORNEJO; AUGUSTO CÉSAR CRESPI ABRIL; RACHEL COLLIN

Quebec

Congreso; SQEBC (QUEBEC SOCIETY FOR THE BIOLOGICAL STUDY OF BEHAVIOUR): 36th Annual Conference; 2011

Université de Sherbrooke

Predation risk appears to drive many behaviours of marine organisms. The timing of synchronous larval release, timing of postlarval return to adult habitat, diel vertical migrations and even the presence of a larval stage are all considered adaptations to decrease predation risk. Despite the fact that predation risk is believed to vary with environmental cycles, predation risk across diurnal, tidal amplitude and seasonal cycles has been understudied. We conducted 142 predation risk assays using tethered adult and larval brine shrimp during day and night, large and small amplitude tides and across seasons in Panama. We found significant effects of season, prey type (adults or larvae) and the interaction between these factors on the proportion of prey items recovered at the end of each assay. Diurnal state also affected predation risk under some conditions but its effect was strongly modulated by season. Contrary to expectation, risk of predation can be quite high at night, particularly for larger plankton. Our results demonstrate a temporal gradient in predation risk across the seasonal cycle that differs for different sized plankton.