Document: CAR-3-82-21

West Coast rocky intertidal diversity: Invertebrates, algae, anchors, a gun and three spark plugs.

SCHOCH, G.C.*, G.ALLISON, S.ETCHEMENDY, S.WOOD, B.MENGE and J.LUBCHENCO

Oregon State University, Corvallis, OR 97331 USA ¹

Abstract:
Evidence suggests that patterns of community structure in rocky intertidal communities are functionally linked to oceanic processes and physical characteristics of the shoreline. However, there is a lack of information on biotic patterns across large spatial scales (100's of km) that would allow rigorous assessments of the relationship between intertidal community patterns and the physical and biological interactions on rocky shorelines, and in the nearshore and offshore ocean. As a major research component of PISCO (Partnership for the Interdisciplinary Study of Coastal Oceans), a consortium of four West Coast Universities, a multi-scale dataset is being developed to evaluate these associations. Rocky shorelines at 14 areas along the Eastern Pacific upwelling system from Northern Washington to Southern California were partitioned into relatively homogeneous alongshore segments of 10-100 m based on slope angle, topographic complexity, nearshore bathymetry, and wave runup. Within each of the 14 areas, three sets of three replicate segments were selected for annual biological sampling. Macro-organisms (primarily invertebrates and algae) were sampled along horizontal transects at three elevations within each replicate alongshore segment. We compared the abundance and frequency of each taxon (nested ANOVA's), and community structure (NMS ordinations) among each set of three replicates, among the three sets of replicates within each area, and among the 14 areas. Results suggest that nearshore bathymetry, wave energy dissipation, and the presence of sand are strongly correlated with low zone patterns and that physically similar low zone habitats supported similar biological communities even when separated by distances of 100's of kilometers. We conclude that this supports the hypothesis that rocky intertidal community structure is predictably associated with physical characteristics of the shoreline and the physical and biological characteristics of the nearshore ocean. This information is being used to guide process-oriented research on the roles of upwelling, productivity, larval transport, recruitment, and species interactions aimed at understanding the mechanisms underlying the observed patterns, thus providing a unique source of relevant information for managers and policy makers.

Keywords: biodiversity assessments, rocky intertidal, community patterns, invertebrates, algae

This abstract is being presented at: 10:15 AM in session:
Oral Session #37: Phytoplankton.