Spatial and temporal variability of the zooplankton community in Valdés Biosphere Reserve, Patagonia, Argentina: Nuevo Gulf case study

Zooplankton diversity has been identified as one of the biological Essential Ocean Variables to detect temporal and spatial changes in marine biodiversity and ecosystem health. The present study evaluated the mesozooplankton community composition and abundance associated with oceanographic variables in Nuevo Gulf (NG, 42° 42′S, 64° 30′W), a World Heritage Site in Argentinian Patagonia and part of the Valdés Biosphere Reserve. We found that >43% of total mesozooplankton community abundance was composed by copepods, followed by cladocerans (24%) in spring, while copepods represented more than 98% in summer. Variability of the abundances in most mesozooplankton groups was associated with chlorophyll a and temperature values. Among copepods, Calanoida predominated in the community, mainly reflecting high densities of Ctenocalanus vanus, especially in summer. In addition, we report for the first time the presence of the copepod Drepanopus forcipatus in this Gulf. Zooplankton information for this region is scarce and fragmented, thus a short review of previous mesozooplankton studies from nearby areas is included for context. Our work emphasizes the importance of continuous and long-term monitoring to better understand the zooplankton community under expected environmental changes. •Mesozooplankton community is represented mostly by calanoid copepods, contrasting with previous studies in the Nuevo Gulf (NG).•Community composition varies from spring to summer within the NG.•Large copepods (but not their sex ratio) were the only group showing differences between depth layers and seasons.•Drepanopus forcipatus was registered for the first time in the study area.