Zooplankton structure and dynamics in two estuaries from the Atlantic coast in relation to multi-stressor exposure

The aim of this research was to investigate the response of pelagic zooplankton to different levels of abiotic multi-stressors in the North Atlantic coast, taking advantage of the comparison of the communities of two adjacent estuaries in the Portugal NW coast with different levels of historical pollution (Minho and Lima estuaries). The zooplankton community structure, composition and temporal variation were comparatively investigated for 15 months, using different net meshes. Abiotic factors were measured in situ and water samples were simultaneously collected for determination of nutrients and chlorophyll a. The overall results revealed a diverse community represented by species that have been cited for subtropical and temperate zones. Although the higher diversity levels were observed in Lima estuary, supported by higher contributions of marine taxa, the total zooplankton biomass was found to be significantly higher in the Minho estuary. The contrasting salinity gradient between estuaries, associated to significant differences in water nutrients levels, were found to be the main forcing factors affecting micro and mesozooplankton. Considering the importance of the impacts resulting from abiotic variation on the basis of aquatic food webs, the present investigation represented a case-study, based in two contrasting estuaries, strongly influenced by freshwater discharges (Minho estuary) versus higher salinity levels (Lima estuary), contributing to a better understanding of the effects of these extreme events on pelagic plankton communities, providing useful information for studies of climate change impacts, biogeography, conservation programs and to the improvement of pelagic fisheries management models.

Vieira L. R., Guilhermino L. & Morgado F., in press. Zooplankton structure and dynamics in two estuaries from the Atlantic coast in relation to multi-stressor exposure. Estuarine, Coastal and Shelf Science. Article (subscription required).


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