Eastern English Channel fish assemblages: measuring the structuring effect of habitats on distinct sub-communities
Multivariate and spatial analyses are used to identify and locate fish, cephalopod, and macrocrustacean species assemblages in the eastern English Channel from 1988 to 2004. Four sub-communities with varying diversity levels were identified in relation to depth, salinity, temperature, seabed shear stress, sediment type, and benthic community nature. From 1997 to 2004, some 25% of overall community structure variance could be related to the available environmental descriptors and 20% to persistent factors such as depth, seabed shear stress, sediment, and macro-invertebrate community type. Although there may be significant interannual shifts in overall community structure and composition, the sub-communities identified persisted over time, reflecting the relative stability of the environmental conditions in this area. The diversity levels of the community appeared to have increased over the past 2 decades and to be higher in areas with soft sediments and wide temperature and salinity variations, typically coastal river plumes and estuaries where bentho-demersal species dominated. The strong spatial structure of the fish communities in the eastern English Channel reflects the different types of habitats shared by differing species assemblages. Such persistence may be useful for spatially explicit planning of human use and resource management.
Keyword(s)
Structuring environment, Spatial patterns, Fish community, Eastern English Channel, Diversity