Cross Sands broadscale survey 1998 (EUROBIS)

The low diversity communities found across much of the survey area were typical of mobile sandy sediments. However, stations located in the southern half and northern extreme of the survey area tended to support higher numbers of species and individuals. This may be due to marginally enhanced stability arising from the higher proportion of gravel found in samples to the south of the extraction licences and to the presence of Sabellaria spinulosa reef in the north.

Analysis of data in relation to areas of predicted dredging impact revealed proportionally less gravel and more sand within the 'direct' impact zone, compared to the 'indirect' impact zone. Whilst multivariate analyses of macrofaunal data were unable to discriminate between dredging impact zones, a comparison of univariate measures revealed significantly lower numbers of species and individuals in areas which have been subject to 'direct' dredging impacts in comparison with 'reference' areas.

This provides good evidence of the near-field consequences of dredging. Values of these measures in the 'indirect' zone were intermediate, although not significantly different from the 'reference' zone. We conclude that, although the dominant influence on assemblages in the region is that of sediment instability induced by tidal currents, we cannot dismiss the possibility of a subsidiary influence of dredging activity in the near vicinity of the licensed block and further investigation is warranted.

Size reference: 40 localities, 201 species [Source: The information provided in the summary was extracted from the MarBEF Data System at "marbef.org/data/eurobisproviders.php"]