Dredge, grab and diving survey. Divided into 2 areas: a) upstream with muddy substrate; b) downstream with coarser sediments. 'Upstream Area' epibenthos dominated by mobile species - large numbers of Carcinus, and also of the juveniles and adults of a number of fish species including P. flesus, C. harengus, P. pollachius and A. anguilla, such that the channels are a significant nursery area. 'Downstream Area' - despite the absence of stable bedrock suitable for colonization, the biological communities are characterised by high-biomass epibenthic communities, including well over 100 sessile and semi-mobile biota. Records currently considered sensitive have been removed from this dataset.