Habitat Selection Response of Small Pelagic Fish in Different Environments. Two Examples from the Oligotrophic Mediterranean Sea |
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| Authors: | Angelo Bonanno Marianna Giannoulaki Marco Barra Gualtiero Basilone Athanassios Machias Simona Genovese Sergey Goncharov Sergey Popov Paola Rumolo Massimiliano Di Bitetto Salvatore Aronica Bernardo Patti Ignazio Fontana Giovanni Giacalone Rosalia Ferreri Giuseppa Buscaino Stylianos Somarakis Maria-Myrto Pyrounaki Stavroula Tsoukali Salvatore Mazzola |
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| Affiliation: | 1. Consiglio Nazionale delle Ricerche, Institute for Coastal and Marine Environment (IAMC), Detached Units of Capo Granitola (TP), Mazara del Vallo (TP) and Naples, Italy.; 2. Hellenic Centre for Marine Research, Institute of Marine Biological Resources, Iraklion, Greece.; 3. Russian Federal Research Institute of Fisheries and Oceanography (VNIRO), Moscow, Russia.; 4. Consiglio Nazionale delle Ricerche (CNR), Roma, Italy.; Technical University of Denmark, Denmark, |
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| Abstract: | A number of scientific papers in the last few years singled out the influence of environmental conditions on the spatial distribution of fish species, highlighting the need for the fisheries scientific community to investigate, besides biomass estimates, also the habitat selection of commercially important fish species. The Mediterranean Sea, although generally oligotrophic, is characterized by high habitat variability and represents an ideal study area to investigate the adaptive behavior of small pelagics under different environmental conditions. In this study the habitat selection of European anchovy Engraulis encrasicolus and European sardine Sardina pilchardus is analyzed in two areas of the Mediterranean Sea that largely differentiate in terms of environmental regimes: the Strait of Sicily and the North Aegean Sea. A number of environmental parameters were used to investigate factors influencing anchovy and sardine habitat selection. Acoustic surveys data, collected during the summer period 2002–2010, were used for this purpose. The quotient analysis was used to identify the association between high density values and environmental variables; it was applied to the entire dataset in each area in order to identify similarities or differences in the “mean” spatial behavioral pattern for each species. Principal component analysis was applied to selected environmental variables in order to identify those environmental regimes which drive each of the two ecosystems. The analysis revealed the effect of food availability along with bottom depth selection on the spatial distribution of both species. Furthermore PCA results highlighted that observed selectivity for shallower waters is mainly associated to specific environmental processes that locally increase productivity. The common trends in habitat selection of the two species, as observed in the two regions although they present marked differences in hydrodynamics, seem to be driven by the oligotrophic character of the study areas, highlighting the role of areas where the local environmental regimes meet ‘the ocean triad hypothesis’. |
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