Meeting Abstract

9.5  Saturday, Jan. 4 09:00  Slowly but surely: Avoiding heat stress at a snail’s pace HAYFORD, H.A.*; CARRINGTON, E.; Univ. of Washington, Friday Harbor Labs; Univ. of Washington, Friday Harbor Labs hayford@uw.edu

The regulation of temperature through behavior is often overlooked when predicting the effects of climate change. Ectotherms use behavior to cope with environmental temperature shifts, while meeting nutritional demands. These needs conflict when a mobile predator feeds upon immobile prey of higher thermal tolerance. Nucella ostrina, an intertidal snail of the Eastern Pacific, risks aerial exposure at low tide to feed on the barnacle, Balanus glandula. We hypothesized that N. ostrina foraging in the San Juan Islands, Washington, would be constrained by low tide exposure. We added N. ostrina to concrete islands in the intertidal and forced snails to choose between feeding in exposed areas and taking refuge. Snail behavior and barnacle consumption were monitored daily for two months. N. ostrina foraging peaked during neap tides, when aerial exposure time and temperature were consistently minimized. Barnacle consumption mirrored foraging behavior. To determine if experimental patterns held true for organisms in their natural habitats, we marked free-ranging snails with radio frequency identification (RFID) tags and tracked using a hand-held tag reader. We observed periodic abundance on exposed high shores that followed the 14-day lunar tidal cycle. RFID allowed us to track small animals over large stretches of shoreline and to confirm that non-feeders were retreating to refuges. These results suggest that N. ostrina alters its behavior to capitalize on differences in microclimate, maintaining a foraging pattern that consistently minimizes its exposure to hot aerial temperatures. Consequently, predation pressure on barnacles is dynamic through space and time. Mechanistic climate change models should include ameliorative behavior when predicting changes in both population distributions and dynamics of species interactions.