Infaunal Macroinvertebrate Diversity of East and West Sound Orcas Island: use of Multibeam and In-Situ sampling to characterize soft-sediment communities

Abstract

East Sound and West Sound, Orcas Island WA, are two glacially cut fjords dominated by mud and silty/mud substrates (Endris et. al., 2010). Fine grained substrates are typically dominated by deposit feeding organisms, specifically polychaetes (Lenihan and Micheli, 2001). Estuaries, with influx of fine grained material and alteration of water chemistry, exhibit lower overall diversity (Constable, 1999). This study aims to evaluate differences in the infaunal macroinvertebrate communities in East and West Sound Orcas Island Washington State. A possible controlling factor on the communities within East Sound is a glacially deposited partial sill at the mouth that restricts flow and likely creates differing physical conditions from West Sound. This question is addressed by 1) collecting and characterizing the infaunal macroinvertebrates within East and West Sound. 2) Measuring physical parameters such as dissolved oxygen, pH, temperature, and grain size distribution. 3) Using multibeam backscatter data and in-situ sampling to delineate the boundaries between different communities in the two sounds.