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Long-term changes in the composition and diversity of deep-slope megabenthos and trophic webs off Catalonia (western Mediterranean): Are trends related to climatic oscillations?

TitoloLong-term changes in the composition and diversity of deep-slope megabenthos and trophic webs off Catalonia (western Mediterranean): Are trends related to climatic oscillations?
Tipo di pubblicazioneArticolo su Rivista peer-reviewed
Anno di Pubblicazione2009
AutoriCartes, J.E., Maynou F., Fanelli E., Papiol V., and Lloris D.
RivistaProgress in Oceanography
Volume82
Paginazione32-46
ISSN00796611
Parole chiaveAbundance, Alepocephalus rostratus, Arctic engineering, Aristeus antennatus, AS-links, Assemblage composition, Atmospheric pressure, benthos, Biodiversity, Calocaris macandreae, Catalonia, climate oscillation, Climatic conditions, Climatic oscillations, community composition, Conceptual model, Crustacea, crustacean, Decapod crustaceans, Decapoda (Crustacea), Depth range, Ecology, Feeding, Fish, Food additives, food web, Food webs, Hymenocephalus italicus, Lepidion lepidion, Long-term changes, macrobenthos, Meats, Mediterranean Sea, Megafauna, North Atlantic Oscillation, North atlantic oscillation indices, NW Mediterranean, Ocean habitats, Oceanographic process, Peracarida, Plankton feeder, Plesionika, Polychaeta, Pontophilus norvegicus, River discharge, Sediment surface, Sergestes arcticus, slope, spatial distribution, species diversity, trophic interaction, Western Mediterranean
Abstract

For depths ranging between 650 and 1700 m we have compared recent (2007-2008) to older (from 1988 to 1992) data, searching for long-term changes in the distribution, abundance and composition of deep megafauna (fish and decapods) off the central Catalonian coasts (western Mediterranean). Overall, in the depth interval between 600 and 1100 m, we found higher abundance of fish in 1988-1992 than in 2007, a decrease simultaneous with an increase of decapod crustaceans. Older and more recent haul replicates (after 20 years) had similar assemblage composition in the depth range 1300-1700 m, whereas we found significant changes at 1000 m. Diversity of fish was greater in 1988-1992 than in 2007, while diversity of decapod crustaceans increased between the two periods. Thus, there was a reorganization in benthopelagic communities, rather than a loss of biodiversity. This was in agreement with long-term changes described for diversity of (neritic) zooplankton in the western Mediterranean. We found a dominance of plankton-suprabenthos feeders (e.g. fish such as Lepidion lepidion, Hymenocephalus italicus and Alepocephalus rostratus; the decapods Plesionika spp. and Sergestes arcticus) in 1988-1992. In 2007 by contrast, dominance of plankton-suprabenthos feeders decreased, and assemblages were increasingly composed of benthos-feeding decapods (e.g. Aristeus antennatus, Pontophilus norvegicus and some hermit crabs) preying for instance on polychaetes. These results coincided with low/negative North Atlantic Oscillation index (NAO) in 2007 and in the period immediately before (2004-2006) 2007 (increase of benthos feeders), and with high average NAO in 1988-1992 (decrease of benthos feeders, which in turn may enhance abundance of plankton feeders). The benthic decapod Calocaris macandreae and suprabenthos (small crustaceans, mostly peracarids, living on and just beneath the sediment surface) are key prey in food webs off Catalonian margins, acting as links between surface oceanographic processes and abundance of benthopelagic predators. A conceptual model is presented relating changes in climatic conditions with changes in deep-sea, benthic-suprabenthic food webs. Calocari macandreae was more abundant in 2007, after 3 years of negative NAO. Under negative/low NAO, rainfall and river discharges increase in the NW Mediterranean, which may enhance advective food inputs for macrobenthos. This fits well with the higher abundance of benthos feeders in 2007, as well as with the significant deepening of decapod crustacean assemblages in that same period. Suprabenthos, being short-lived and annual species, were more abundant under positive NAO conditions (1988-1992), probably enhancing the abundance or aggregation of suprabenthic/pelagic feeders. © 2009 Elsevier Ltd. All rights reserved.

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URLhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-68349097465&doi=10.1016%2fj.pocean.2009.03.003&partnerID=40&md5=f73c0834268cf601df32d5a3083a20ce
DOI10.1016/j.pocean.2009.03.003
Citation KeyCartes200932