Copepod community ingestion, respiration and length-dry mass relationships in the southern Benguela upwelling system during METEOR cruise M153

Small copepod genera play an important role in marine food webs and biogeochemical fluxes but have been neglected in many studies. Abundance, biomass and carbon consumption rates of small- (<1 mm prosome length (PL)), medium- (1-1.5 mm PL) and large-sized (>2 mm PL) copepods along a cross-shelf transect in the southern Benguela upwelling system were determined using rather high taxonomic resolution. Zooplankton samples were collected with a Multinet (Hydrobios Multinet midi, 5 nets with 200 µm meshsize) during the Meteor cruise M153 in February/March 2019. Calanoids contributed on average 55 ± 19% to total copepod abundance and 82 ± 13% to total copepod biomass. Small-sized Oithona spp. (119/114 mg C m-2 d-1) and Clauso-/Paracalanidae (87/263 mg C m-2 d-1) as well as large-sized Calanoides natalis (47/193 mg C m-2 d-1) were the dominant consumers at the most inshore stations. Small and medium-sized copepodite stages of Metridia lucens were also important, especially towards the continental slope. At offshore stations, Para-/Clausocalanidae (17-27 mg C m-2 d-1), Oithona spp. (9-16 mg C m-2 d-1), Pleuromamma spp. (0-16 mg C m-2 d-1), Calanus agulhensis (0-15 mg C m-2 d-1), Acartia spp. (0-12 mg C m-2 d-1), C. natalis (0-10 mg C m-2 d-1) and M. lucens (2-6 mg C m-2 d-1) were dominant consumers. Hence, usually small- and medium-sized copepods dominated total copepod ingestion, emphasizing that inadequate representation of small copepods will lead to significant underestimations and misinterpretations of the functioning of zooplankton communities, and finally to inadequate biogeochemical models.