Inter-seasonal and inter-annual changes in the zooplankton community structure in a coastal station from Patagonia, Argentina (2018–2023)

HERNÁNDEZ MORESINO, R.; DE CIAN, A.; EPHERRA, L.; MARTELLI, A.; CRESPI-ABRIL, A; PISONI, JUAN PABLO; BARBIERI, E.; HALTER, B.

Plymouth

Simposio; Symposium Trends, Reflections, Evolution, and Visions in Ocean Research ? A celebration of the scientific life of Trevor Platt; 2023

Trevor Platt Science Foundation

Environmental conditions around the world ocean are drastically changing in response to greenhouse gases from anthropogenic activities. Continue time-series measurements at fixed locations are necessary to monitor ocean trends. The Nuevo Gulf Oceanographic Station (GNEO, 42°45'43.99"S - 65°1'29.97"W) is a coastal monitoring effort in Patagonia, Argentina, measuring the temporal variability of physical, chemical, and biological variables in these waters and supplying data to the NANO-DOAP project (A global study of coastal Deoxygenation, Ocean Acidification and Productivity) since 2021. At this time, we will present trends in mesozooplankton community structure from 2018 to the present. Vertical trawls were performed monthly, with a Hensen net from the dock of Puerto Madryn City. Taxonomic identification and quantification were conducted by semi-automatic analysis of digital images with ZooImage software. Changes in the community structure reflect changes in taxonomic composition among seasons, but no differences were evidenced among years up to date. There is an increase in the abundance from autumn to summer. Slopes of the size structure are similar from autumn to spring, where small copepods dominate with 60%. In summer, the abundance duplicates, increasing the proportion of small copepods to 70%, stepping the slope of the size spectra from -3 to -4 compared with the rest of the seasons. Small copepods dominated all seasons, followed by large copepods and appendicularians, the last ones mainly during the cold seasons. These surveys of zooplankton communities using semi-automatic tools are an effective and low-labour effort way of assessing the health status of urban coastal marine ecosystems.