Preliminary study of the influence of current velocities on estuarine benthos, especially Anisogammarus confervicolus, in the Fraser River estuary (South Arm)

Field studies in the lower Fraser River (South Arm) were conducted during July to August 1976 to provide data on the abundance of benthic species at habitats subjected to different river flow regimes. Freshwater organisms, especially oligochaetes and chironomids, dominated quadrat samples in the Ladner marsh. Oligochaetes and chironomids were most common in grab samples in Ladner and Sea Reaches, and largest numbers were founda t stations characterized by leaf debris. An isopod (Gnorimosphaeroma oregonensis), the amphipods Corophiun spinicorne and Anisogamnarus confervicolus, and chironomid larvae dominated drift samplers. Benthic organisms were more abundant in side channels where current velocities were reduced. A reconnaissance survey of Steveston Island showed that benthic organisms have colonized some habitats of this partially man-made island. Preliminary laboratory studies with the amphipod Anisogammarus aonfervicolus