Publication Abstract

Cumulative impacts of aggregate extraction on seabed macro-invertebrate communities in an area off the east coast of the United Kingdom

An assessment of the impacts of a multiple aggregate extraction licence on seabed macro-invertebrate communities in an area off the east coast of the United Kingdom

K.M. Cooper, S.E. Boyd and H.L. Rees

Accumulations of licensed marine aggregate areas are a feature of a number of areas off the coast of the United Kingdom. The purpose of this study was to determine whether there was any evidence of a large-scale cumulative impact on benthic macro-invertebrate communities as a result of the multiple extraction licences located off Great Yarmouth in the western North Sea. Analysis of the precise location of dredging revealed a cumulative increase in the area of seabed dredged over the period 1993-2001. A broad-scale spatial survey, with sampling sites within and beyond the extraction area, was designed to characterise the sediments and benthic communities across the region and to look for evidence of any large-scale cumulative impact. A subset of these stations was also sampled for a further three years and confirmed that results from the broad scale survey were stable over time. Results showed the study area to be characterised by sands, in the northern half of the survey area, and sandy gravels in the south. The low diversity communities found across much of the survey area are typical of mobile sandy sediments and the naturally disturbed conditions, characteristic of this area, result from a combination of the exposed coast, shallow water, strong tides and sandy sediments. However, compared to the central region of the survey area, areas of higher diversity were also identified in the north and south of the region. This higher diversity suggests that sediments in these areas are more stable, and this stability is thought to result 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. The extent to which aggregate extraction activities may have contributed to the distribution of communities is discussed.

Reference:

K.M. Cooper, S.E. Boyd and H.L. Rees (2007) Cumulative impacts of aggregate extraction on seabed macro-invertebrate communities in an area off the east coast of the United Kingdom. Journal of Sea Research, 57(4): 288-302

K. Cooper*, S. Boyd* , J. Aldridge* and H. Rees*

Journal of Sea Research, 57(4): 288-302