Zooplankton electron transport system activity and biomass in the western Ross Sea (Antarctica) during austral summer 2014

The present study provides insight into specific zooplankton oxygen and carbon demands (per unit biomass) and community zooplankton respiration and carbon requirements in the Ross Sea (Antarctica). In the literature, there is a lack of data in this area. The role of mesozooplankton in carbon remineralisation in coastal and pelagic environments was evaluated. The zooplankton composition, abundance and biomass were analysed. In the marine carbon cycle, zooplankton from the epipelagic realm has a key role. Estimation of the electron transport system activity represents a specific and highly sensitive method to evaluate the zooplankton carbon requirements from the sinking flux as an indication of the respiratory activity. We focus here on 26 sampling stations in the western sector of the Ross Sea, in which the 0–250-m layer was investigated during the austral summer of 2014. The oxygen consumption from the electron transport system analysis was converted into carbon demand. Differences in carbon requirements were observed, and their relationships to zooplanktonic composition and abundance were investigated, along with their relationships to seawater temperature, food availability, non-living specimens and pteropod faecal pellet abundance. A positive correlation between carbon demand and temperature was highlighted. The change in copepod community composition was relevant in terms of species and relative size ranges. The zooplankton biomass ranged from 41.25 to 171.46 mg m-3 among the stations, which is in agreement with the late summer trophic condition, with higher values for the more coastal stations. Positive correlation between zooplankton biomass and community metabolism per day was revealed. With its recycling of the particulate organic material that originates in the epipelagic layer, the zooplankton compartment participates in the decrease in the input of material, mainly in the two coastal areas investigated, with respect the more pelagic zone.