MEPS 439:181-192 (2011)  -  DOI:

Drivers of deep Mediterranean megabenthos communities along longitudinal and bathymetric gradients

Samuele Tecchio1,*, Eva Ramírez-Llodra1, Francisco Sardà1, Joan B. Company1, Isabel Palomera1, Ariadna Mechó1, Rut Pedrosa-Pàmies2, Anna Sanchez-Vidal2

1Institut de Ciències del Mar (CSIC), 08003 Barcelona, Spain
2GRC Geociències Marines, Universitat de Barcelona, 08028 Barcelona, Spain

ABSTRACT: The Mediterranean deep sea, being isothermal and longitudinally trophic-graded, is an optimal natural benchmark to test for macro-ecological patterns of species distribution. The relevance of environment−biota interactions on deep-sea megafauna in the Mediterranean Sea, a matter still neglected, is addressed here along longitudinal and bathymetric axes. Benthic and nektobenthic megafauna were collected in the 3 basins of the Mediterranean: the western (Catalan Sea and southern Balearic), central (western Ionian) and eastern (south of Crete) basins, with an otter-trawl Maireta system and an Agassiz dredge between 1200 and 4000 m depth. Simultaneously, environmental data were collected on surface production, near-bottom physical parameters, sediment grain size and carbon content. Megafaunal biomass was higher in the Catalan Sea, decreasing eastward and with depth. Species diversity and evenness were relatively constant in the western and central Mediterranean at all depths, whereas these indices decreased with depth in the eastern Mediterranean. β-diversity analyses indicated a high species turnover between areas. The 3 basins presented significantly different environmental conditions. Sediment particulate organic carbon, surface fluorescence and sediment grain size were the 3 environmental variables that best explained the distribution of megabenthos along the longitudinal Mediterranean axis. These results show that the food supply, from either the surface or from the adjacent deep-sea floor, is critical in regulating the biodiversity of deep-sea Mediterranean megafauna and that this diversity is pooled region-wide. The heterogeneity of resources may be essential in maintaining these high levels of local and regional diversity.

KEY WORDS: Deep-sea · Mediterranean · Megafauna · Environmental factors · POC · Biodiversity

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Cite this article as: Tecchio S, Ramírez-Llodra E, Sardà F, Company JB and others (2011) Drivers of deep Mediterranean megabenthos communities along longitudinal and bathymetric gradients. Mar Ecol Prog Ser 439:181-192.

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