Physical drivers of phytoplankton production in the southern Benguela upwelling system

摘要: Abstract Investigations of primary production (PP) were undertaken in the southern Benguela ecosystem during two research surveys October 2006 and May 2007. Significant differences environmental conditions, as well biomass PP, observed between May. During October, integrated PP significantly higher, ranging from 20.43 to 355.01 mg m −2 , 0.71 6.98 g C m  d −1 respectively, than May, where range was 47.92–141.79 mg m 0.70–3.35 g C m respectively. Distribution patterns indicated low newly upwelled water along coast, higher mid-shelf region, while lower values at beyond shelf edge. Latitudinal variations showed consistently St. Helena Bay region compared south Cape Town. both surveys, phytoplankton communities comprised primarily diatoms small flagellates, with no significant differences. Phytoplankton adaptation variability characterised by increased P m B E k under elevated temperatures irradiance, clear relationships evident for α . Generalised Additive Models (GAMs) that photosynthetic parameters all predictors photosynthesis rates ( z ), being most important, accounting 36.97% deviance However, levels conditions exerted a much greater influence on irradiance explaining largest proportion (68.24%) deviance. Multiple predictor GAMs revealed 96.26% could be explained model which included nitrate, chlorophyll irradiance.