Microplankton and zooplankton respiration were calculated from ETS activity measurements in the upwelled waters off Cape Blanc, Mauritania. The mean respiration was 14.4 mgC h-1m-2 for microplankton and 6.4 mgC h-1m-2 for zooplankton. Mixing kept the microplankton from accumulating in the surface waters so that vertical profiles were nearly uniform with depth. High levels of ETS activity below the euphotic zone reflected this mixing....