Relationships Between NearSurface Plankton Concentrations, Hydrography, and SatelliteMeasured Sea Surface Temperature

In situ measurements of surface chlorophyll and zooplankton concentration are compared with in situ hydrographic measurements and infrared satellite images of the west coast of British Columbia for early winter and midsummer study periods. Maximum winter concentrations ofchlorophyll (1.0 mg m-3) and zooplankton (2900 counts m-3) were found in colder, more stratified nearshore water. Warmer water over the middle and outer shelf consistently had the lowest chlorophyll and zooplankton concentrations (< 0.2 mg m3 and < 1700 counts m3, respectively). Correlations between winter log e transformed zooplankton concentrations and surface temperature demonstrated that infrared satellite imagery explained 49'/,, of the sampled zooplankton concentration variance. The winter association of specific chlorophyll concentrations with identifyable hydrographic regimes enabled the satellite imagery, in conjunction with an image-derived salinity model, to explain 55% of the sampled chlorophyll variance. Maximum summer chlorophyll concentrations (>20.0 mg m -3) coincided with intermediate temperatures around the edge of an upwelling frontal zone with lower concentrations (• 5.0 mg m-3) in the coldest, most recently upwelled water. Lowest concentrations (< 1.0 mg m-3) were present in vertically stratified regions of the shelf. A least squares fit nonlinear equation showed that satellite-measured surface temperature patterns explained 72% of the 1oge transformed chlorophyll variance. In contrast with the above relationships, summer zooplankton concentrations were not consistently related to satellite temperature patterns. While peaks showed a qualitative association with higher chlorophyll concentrations at the outer edge of the upwelling area, surface temperature was a poor predictor of zooplankton concentration over the study area as a whole.