size structure abundance 10 Atlantic Ocean 8 biomass 8 zooplankton 8 Atlantic Ocean (Southwest) 6 South America 6 community structure 6 crustacean 6 seasonality 6 Argentina 4 Brazil-Malvinas Confluence 4 Southwestern Atlantic 4 chlorophyll 4 copepods 4 dominance 4 normalized biomass size spectra 4 picoplankton 4 population density 4 population distribution 4 summer 4 trophic level 4 upper ocean 4 Adesmia volckmannii 2 Aegla platensis 2 Aeglidae 2 Allometric equations 2 Animalia 2 Anomura 2 Appendicularia (class) 2