Coastal mesozooplankton respond to decadal environmental changes via community restructuring

Long-term ecological research has revealed the impact of climate on marine ecosystems at multiple time scales. Changes in pelagic system have been detected LTER-MC site Gulf Naples (Tyrrhenian Sea, western Mediterranean) since 1984. Here we analyzed series to determine whether zooplankton had significantly changed over three decades 1984–2015. In addition seasonal cycle as main mode temporal variability, observed long-term trends functional groups and species. Copepods, most abundant group, declined years owing a decrease abundance Acartia clausi, Centropages typicus, Paracalanus parvus complex, Oithona spp. Increasing were for strict carnivores (chaetognaths) typical filter feeders (cladocerans, appendicularians, thaliaceans); latter may be linked higher density <5 μm phytoplankton. Two shifts detected: (i) 1985–87, similarly regime registered other basins Northern Hemisphere, (ii) after 2011, likely related local atmospheric forcing. The disappearance or some neritic copepods increased offshore species seem reflect enhanced influence open Tyrrhenian waters sampling site. Despite these changes, no significant total overall composition, which indicates restructuring within whole community. These results underline need examine entire diversity spectrum improve our knowledge their traits detect interpret variability.