Browsing Marine Biology by Title
Now showing items 198-199 of 199
Zooplankton abundance, community structure, and oceanography northeast of Kodiak Island, AlaskaZooplankton community dynamics and correlations with physical characteristics of the water were studied in the northwestern Gulf of Alaska. Zooplankton were collected systematically northeast of Kodiak Island, Alaska in March, May, August and November of 2002 to 2004. Species composition, total abundance and spatial community structure were correlated to physical variables. Small copepods (numerically>50%) dominated the zooplankton composition and were most abundant in August. Average biomass was 48.7 g WW m⁻² in May and 52.0 g WW m⁻² in August in Kodiak region. Interannual zooplankton abundance variations were large, with May 2003 having a dramatically higher abundance (2x10⁴ individual m⁻³ higher) than 2002 and 2004, probably due to the higher temperature (1° C higher) and lower salinity in May 2003. Small to moderate correlations (r<0.7) were found between temporal zooplankton abundance and selected physical variables. Spatial patterns in zooplankton composition among stations were more discernable in May than in August, likely due to water column stability in the spring and more dynamic influences in the summer, but revealed no consistent spatial patterns. The zooplankton community patterns in this region thus appear to arise due to complex oceanographic and bathymetric interactions, and suggest high variability can occur in the availability of prey for higher trophic levels.
Zooplankton ecology of Norton Sound, AlaskaThe zooplankton distribution in Norton Sound was monitored for the Outer Continental Shelf Environmental Assessment Program. Salinity, temperature, and predation were investigated as factors controlling species composition and community structure. Sampling was concentrated along the eastern coast of Norton Sound during July and August, 1976. The copepod Acartia clausi and the cladocerans Evadne sp. and Podon sp. were numerically dominant in the samples. These species are able to tolerate the widely ranging salinities and temperatures of the coastal waters. The A. clausi population abundance was correlated with water temperature, while cladoceran and larval mollusc populations were correlated with salinity. No differences in species composition were discerned between stations along the shallow coast; however, the seaward community contained a greater diversity of organisms supporting a larger planktonic carnivore biomass. Zooplankton was a numerically dominant item in the diets of many fish species, although the epibenthic mysid community was volumetrically most important.