Comparison of Diet of Chlamys hastata and Chlamys rubida from Shallow and Deep Waters off the San Juan Islands

Abstract

Gut contents of two species of sea scallops, Chlamys rubida and C. hastata, were compared for individuals from the San Juan Channel collected in shallow (20m) and deep (~80m) habitats. Gut contents were preserved in paraformaldehyde and an Olympus microscope with 10x and 20x lenses was used to view phytoplankton. Food constituents of different categories were counted using an ocular micrometer transect. No noticeable trends regarding dietary constituents were seen across species or habitat which supports our null hypothesis. A count of identifiable diatoms showed that Thalassiosira and CF Melosira were the most abundant diatoms. In addition, CF Melosira was more abundant (~2x greater) in shallow animals from both species relative to deep animals. The results imply that both species of scallops are consuming similar organic and inorganic matter at different depths.