Structure and Spatial Distribution of Mesozooplankton Communities in the Atlantic Sector of the Southern Ocean

Abstract

In this paper, the composition and patterns of spatial distribution of mesozooplankton communities in the waters of the Bransfield Strait, the Antarctic Sound, the Powell Basin of the Weddell Sea and the waters off the Antarctic Peninsula and South Orkney Islands during the austral summer of 2022 are presented. Among the mesozooplankton communities two groups were found to be the most abundant: copepods Calanoides acutus, Metridia gerlachei and Oithona spp., and euphausiids Euphausia superba. The maximum abundance and biomass of the mesozooplankton were found in the warm Antarctic surface deep-sea water off the South Orkney Islands. The minimum values, respectively, were found in the cold modified Weddell Sea waters off the Antarctic Peninsula. Copepods was concentrated in the Bransfield Strait near the South Shetland Islands with sea surface temperature (SST) of –0.5–0.5°С and sea surface salinity (SSS) of 34.5–34.6‰; and the krill E. superba eggs and larvae at different development stages was concentrated in the waters off the South Orkney Islands with SST values of 1–2°С and SSS values of 34.3–34.5‰. Four groups of mesozooplankton communities at different composition, abundance, and taxa dominance were identified. The results of this and future study have practical implications for monitoring the state of the changing ecosystem of the Southern Ocean.