ANTROMARE-1 Cruise, RV García del Cid

Abstract

Natural variability and changes induced by the ANTHROPOGENIC impact on diversity and TROPHIC networks in the deep SEA in the Mediterranean; Food web structure of deep-sea megafauna in the Balearic Basin (NW Mediterranean) was investigated using carbon and nitrogen stable isotopes. A total of 71 species (including 26 fish species and 19 decapod species) were analysed from samples collected with a semi-balloon otter-trawl in 2 contrasting oceanographic settings: the Catalonian Slope (CS), a continental slope area indented by several submarine canyons and an insular slope area north of Mallorca (the Balearic Slope, BS). Three faunally distinct depth zones were sampled in each area in July 2010: 450 to 600 m (upper slope), 1000 to 1300 m (middle slope) and 1400 to 2200 m (lower slope). Different physical- chemical variables and potential food sources were analysed as possible explanatory variables of trophic web variability.Eighteen CTD casts were performed during the ANTROMARE survey, approximately coinciding with the biological sampling stations, using an SBE 32 coupled with a fluorometer, a transmissometer and an oxygen sensor. Values of temperature (T), salinity (S), oxygen, fluorescence and turbidity were recorded for each CTD profile. The values of these variables at 5 m below the surface (5m) and at 5 m above the sea bottom (5mab) were obtained, although only 5mab values were then used for analyses