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Epibenthic community analyses

Sampling of the epibenthic invertebrate community was undertaken using a 2m-beam trawl at stations sampled for fish by IBTS and DBTS (Dutch Beam Trawl Survey). Organisms taken in the samples were identified to species, measured and weighed, allowing size-based approaches to be applied to the resulting abundance data to provide estimates of productivity of the epibenthic community at each sample location. The diversity indices applied to the data were Hill's N0 (species richness), N1 (exponential of Shannon-Weiner Index) and N2 (reciprocal of Simpson's Index).

The spatial distribution of species tended to be relatively restricted according to a range of different environmental parameters. Cluster analysis suggested two main communities; a northern and southern community, which exist in very different environmental conditions. Strong latitudinal and longitudinal trends were observed in all three indices. Total epibenthic biomass varied considerably, being lower where particle size was less than 200m and consequently productivity tended to also be lower in these muddier habitats. Productivity was positively correlated with bottom water temperature and depth, although this is unsurprising as temperature is one of the parameters in the models used to estimate productivity and temperature is related to depth. All three diversity indices were negatively related to productivity. Considerable variation in spatial patterns of biomass, and productivity were evident between different sized invertebrates. The biomass productivity of the larger epibenthic invertebrates was least in the southern North Sea.

Once the MAFCONS consortium have made use of these data and been written up into a number of scientific papers, making the results available to a wider audience, the databases containing these data will be made available to the general public via our website.


John LANCASTER, (Project Co-ordinator)
Tel.: +44-01792-295451
Fax: +44-01792-295452
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