Projects in the Collin Lab: Reproductive Timing Under Variable Environmental Conditions: Implications for Metapopulation Dynamics Kecia Kerr PhD student, McGill University and STRI short-term fellow (2006-2011) Predation risk appears to drive many factors in the life history and ecology of marine organisms. The timing of synchronous larval release, timing of postlarval return to adult habitat and diel vertical migrations are all considered adaptations to decrease predation risk, particularly by plankivorous fishes. Estimates of rates of planktonic predation vary drastically from 0% to nearly 100%. Predation risk in general has been understudied and very few studies have addressed variation in risk across diurnal and seasonal cycles. To determine how planktonic predation risk varies across diurnal, tidal amplitude and seasonal cycles, we are using a tethering technique devised by Stephan Bullard allowing us to deploy and retrieve individual plankton in the ocean. We deploy tethered brine shrimp from docks and from a canoe in during the day and night. Preliminary results indicate that predation risk is higher at night than during the day for adult brine shrimp deployed from a dock. This result is contrary to theory and previous results that state that planktonic predation risk is lowest at night. Most planktivorous fish are visual hunters that are most active during the day. Therefore predation risk from these fish is expected to be higher during the day. However, some …
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