The relative contribution of chemosynthesis in heterotrophic fauna at seeps is known to be influenced by depth and by habitat. Using stable isotopes of carbon and nitrogen, we investigated macro- and megafaunal nutritional patterns in Norwegian margin cold seeps by comparing food webs both among habitats within a seep site and between different sites. The very active Håkon Mosby mud volcano (HMMV) is characterized by geochemical gradients, microbial activity and faunal zonation from the centre to the periphery. The Storegga Slide (600–900 m depth) has pockmarks with patchy less active seeps, and also shows concentric zonation of habitats but at much smaller spatial scale. The dominant carbon source for macrofaunal nutrition in both areas was... |