Diet, feeding intensity and stress markers in the henslow's swimming crab Polybius henslowi (Leach, 1820) from the Galician and Cantabrian Coasts (NW Spain)

Abstract

The diet and the feeding intensity of the portunid swimming crab, Polybius henslowi were studied during the spring of 2004, in an area comprising the Galician and the W Cantabrian Sea (NW Iberian Peninsula) at depths ranging from 78 to 327 m in the continental shelf. The entire area had been affected by the “Prestige” oil spill in November 2002, though the different sectors studied displayed different level of pollution/oil impact. A total of 342 specimens were collected in 25 bottom hauls and analyzed for diet composition. Stomach fullness was compared between three impacted sectors: (1) Miño River and Finisterre Cape (MF), (2) Finisterre and Estaca de Bares Cape (FE), and (3) Estaca and Peñas Cape (EP). Stomach fullness was lower in FE, although significant differences (Mann Withney test) between sectors were not reached. Diet (wet weight) consisted of a mixture of pelagic and benthic prey. Cephalopods (Ilex sp.), brachyurans (Polybius henslowi) and polychetes (e.g. Glycera spp.) were the main prey items found. Other important prey were Beloniform eggs and fish remains. Polychetes were especially abundant in MF, and Polybius henslowi in EP. Two stress markers were studied in twelve P. henslowi specimens from each of the 3 affected sectors. Neither acetylcholinesterase (a neurotoxic marker) nor lipid peroxidation (a marker of oxidative stress) were seen affected by the sampling area. Variations in the studied variables will be analysed in relation to changes in environmental factors (T, S, sediment nature), surface productivity (Chl a by satellite imagery) and tar aggregates concentration in the sediments