Publication Abstract

The utility of habitat mapping techniques in the asssessment of anthropogenic disturbance at aggregate extration sites

D.S. Limpenny, S.E. Boyd, W.J. Meadows and H.L. Rees

Marine benthic habitats are vulnerable to the influence of a wide range of anthropogenic activities (e.g. aggregate extraction, dredged material disposal and trawling). Recent developments in seabed mapping techniques offer the potential to radically alter approaches to monitoring the impacts of such activities. In this paper we report on an integrated mapping approach, using geophysical and faunal sampling techniques, in order to assess the impacts of marine aggregate extraction at the seabed.

Studies at two aggregate extraction sites in the southern North Sea utilised sidescan sonar and single beam bathymetry to produce maps of the distribution of sediment types and associated natural and anthropogenic features. These acoustic maps were used as an exploratory tool to facilitate the generation of effective site-specific sampling designs and for locating representative reference sites against which changes at impacted locations may be compared in the longer-term. The longevity of the physical impacts of dredging activity at the seabed were also assessed.

The employment of geophysical techniques to map the extent, magnitude and persistence of the effects on the seabed arising from marine aggregate is fundamental for the interpretation of wider cause and effect relationships. The outcome of recent survey work is presented, together with a generic strategy for generating habitat maps.

Reference:

D.S. Limpenny, S.E. Boyd, W.J. Meadows and H.L. Rees, 2002. The utility of habitat mapping techniques in the asssessment of anthropogenic disturbance at aggregate extration sites. ICES Copenhagen, CM2002/K:04, 20pp