(full paper is archived in the Miller Library)
Title: Braving the intertidal hailstorm: effects of wave-borne projectiles on survivorship of Lottia gigantea
Student Author(s): Sun, Bryan
Faculty Advisor(s): Denny, Mark W.
Location: Final Papers Biology 175H
Date: June 1996
Abstract: The effects of wave action on the dynamics of intertidal communities are often modeled viewing seawater as a pure fluid. This assumption overlooks the potential consequences of solid ocean debris, including rocks, animal shells, and other hard objects, which can be "thrown" into the intertidal zone at high velocities.
This study investigates the survivorship of the owl limpet Lottia gigantea in relation to its bombardment by wave-borne projectiles. Over a five-week period, the presence of new shell damage in 160 limpets was recorded at seven different rock faces that received varying levels of wave exposure and that contained varying levels of nearby rocks and debris. During the same period, maximum wave force measurements were taken daily, and Styrofoam targets placed at each rock face were used to record the projectile impacts.
Wave projectile action at directly wave-exposed areas can play a substantial role in the survivorship of L. gigantea. Limpets living on rock faces at directly-exposed sites experienced substantial levels of wave projectile damage on days with high wave action. Limpets living on rock faces that experienced deflected waves or waves that "ramped" off lower rock beds were significantly less affected by wave-projectiles. This suggests that the effects of wave action on limpet survivorship can depend on the local topography as well as the disturbance caused directly by hydrodynamic forces.