Gradients in benthic community structure and bioturbation potential along the Nordic Seas continental margin

The Nordic Seas region, extending north from the Wyville-Thomson Ridge, west of Scotland to the Fram Strait, north of Svalbard, marks a transitional zone between the temperate North Atlantic Ocean and the polar Arctic Ocean. The influence of contrasting fluxes of organic matter on benthic community structure and function within the deep waters of the region were investigated. Previous studies have sampled the macrofaunal community throughout the region but it is difficult to draw comparisons between studies due to differences in the sampling gear and sorting methods employed. Therefore samples of the macrofaunal community were collected throughout the region employing a standardised method. In the summer of 2002, during the RRS James Clark Ross 75 cruise, replicated samples were obtained with the 5MBA multiple corer and the USNEL boxcorer from four stations located at similar sampling depths along a latitudinal transect at the Norwegian Sea contjnental margin. Additional replicated samples were obtained with a megacorer at six stations located along two bathymetric transects across the Norwegian Sea continental margin in the summer of 2005 during the RRS James Clark Ross 127 cruise. Contrasting fluxes of organic matter influenced benthic community structure, functional ecology and bioturbation potential. Species known to adopt the feeding strategy of the sub-surface storage of organic matter occurred in areas characterised by a seasonal input of organic matter. Species richness and diversity was highest at the Svalbard Margin, located within the marginal ice zone. Bathymetric patterns of macrofaunal biomass were comparable with previously reported global patterns. However, bathymetric patterns of macrofaunal abundance were higher than global patterns. The previously reported rapid subduction of organic matter by the sipunculan Neplzasoma sp. and associated deep burrow networks on the ring Plateau was linked to the species Neplzasoma lilljeborgi. It is proposed that N. lilljeborgi is an ecosystem engineer. Keywords: Nordic Seas, macrofauna, benthic, community structure, bioturbation, organic matter.EThOS - Electronic Theses Online ServiceGBUnited Kingdo