PARENT SESSION
Oral Session #57: Aquatic Ecology: Wetlands, Estuaries, Marine. Presiding: T. Klinger.
Wednesday, August 8, 2001. 1:00 PM to 5:15 PM. Hall of Ideas J.
Rocky intertidal community dynamics across a major oceanographic discontinuity: precipitous changes in recruitment and growth .
Freidenburg, Tess1, Menge, Bruce1, Foley, Melissa1, 1
ABSTRACT- Rocky intertidal community structure and dynamics vary with changes in nearshore oceanographic patterns. Processes such as coastal upwelling can influence intertidal communities by affecting the delivery of larvae, phytoplankton, and detritus. Along the central Oregon coast upwelling is intermittent during the summer whereas at Cape Blanco, a prominent headland on the southern coast, upwelling is more persistent. To evaluate the influence of this oceanographic discontinuity on rocky intertidal community structure, we studied recruitment and growth patterns of sessile invertebrates at sites spanning Cape Blanco. Results suggest that recruitment of mussels and barnacles and growth of mussels are generally lower at Cape Blanco than at sites on the central Oregon coast. We also observed a sharp gradient in recruitment around the headland with a site 6 kms north of the headland consistently receiving more recruits than a site 20 kms south of the headland. Chlorophyll-a concentration also decreased strikingly from north to south of the headland. These studies suggest that the changes in biophysical coupling associated with a shifting oceanographic regime at Cape Blanco can potentially impact the structure and dynamics of rocky intertidal communities.
KEY WORDS: upwelling, recruitment, rocky intertidal, oceanography