Mesozooplankton community distribution on the Agulhas Bank in autumn: Size structure and production

The Agulhas Bank on the tip of southern Africa, like other shelf seas, is a relatively productive environment which plays crucial role in biology and success many commercially valuable fish species. Fish their larvae depend zooplankton to feed but, despite importance, little known about distribution production Bank. Here we present results from survey conducted March 2019 East Central Bank, investigating mesozooplankton abundance, biovolume, taxonomic composition, size (normalised biovolume spectrum (NBSS) approach) secondary production. A clear cross-shore gradient was observed with inner-shelf having higher abundance dominated by small-size organisms, most likely mirroring overall productivity coastal waters, while outer-shelf showed opposite trend (i.e., low biovolume; shallow NBSS slopes). This general pattern was, however, disturbed one location (between 24 25°E) distinguishable community, linked passage meander inshore side Current. typified high biomass (?4 g C m-2), comparable upwelling areas copepods doliolids. High copepod this region before feature called “Cold Ridge”. However, during our survey, no such ridge observed. mixed layer depth deep (>20 m) Chlorophyll concentration measured at depth, net primary rates. We suggest that prone mechanisms as retention due cyclonic circulation or processes injecting nutrients upper require further research. Secondary same range seas (0.03–1.55 m-2 d-1) correlated biomass. comparison production, simultaneously, suggested exert significant control can, some areas, be food-limited (e.g., waters).