Search

Sabellaria spinulosa reefs are considered to be sensitive and of high conservation status. This article evaluates the feasibility of using remote sensing technology to delineate S. spinulosa reefs. S. spinulosa reef habitats associated with the Thanet Offshore Windfarm site were mapped using high resolution sidescan sonar (410 kHz) and multibeam echo sounder (

Publisher Summary The Northern Palaeovalley is an open shelf valley system in the English Channel. It is a distinctive erosional feature within the northern half of the eastern English Channel with a particularly well-defined margin on its northern side and an upper break of slope at a depth of 25–30 m with the valley floor generally at depths of 55–75 m. The valley is >100 km long and varies in width from 8 to 20 km. Its floor lies at depths of 45–90 m, with margins up to 30 m high. Net sediment transport is west to east, with rock and coarse sediment in the valley floor in the west and a gradual eastward increase in sand cover and volume, culminating in two large linear sandbanks up to 28 km long along the northeast margin of the valley. The Palaeovalley supports a rich diversity of infaunal and epifaunal communities. Considerable overlap exists in the infaunal communities associated with the different geomorphic features, while the epifaunal communities exhibit far greater variability in response to the environmental gradients. Interstitial polychaetes dominate the macrobenthic communities across the area reflecting the dominance of mobile sediment deposits. The Palaeovalley as a whole is characterized by comparatively rich macrofaunal communities comprising infaunal and epifaunal species in varying proportions. There is significant overlap between the infaunal communities associated with the five geomorphic features in this area, as all are dominated by interstitial polychaetes, many of which are tolerant of a wide range of sediment classes.

The tunnel-valleys of the southern North Sea are arcuate and linear seabed depressions. The origin of these features has been the subject of much discussion, but they are generally considered to have been formed by subglacial erosion and sediment backfill beneath the outer margins of a receding ice sheet. We present here a study of two tunnel-valleys, the Silver Pit and the Sole Pit. Extensive areas of Sabellaria spinulosa reefs have been identified on the western flanks of the Silver Pit that extend down to the valley floor, representing a resource of significant conservation interest. The eastern flanks were found to support a diverse faunal assemblage with widespread hydroid and bryozoans turfs and abundant ascidians. The seabed of the Sole Pit is characterized by much sandier deposits than that of the Silver Pit, and it supports an abundant bivalve community, dominated by Abra alba. This bivalve assemblage also contains Coarcuta obliquata, which has only been recorded once before in the UK.

Many governments have recognised the need to utilise a blend of conventional and alternative energy sources to meet future energy demands, with an increasing focus upon producing clean and renewable energy, as well as investigating the offshore geological storage of carbon dioxide. The marine environment is likely to make a significant contribution to securing the future energy needs of many countries. Seabed site characterisation constitutes a critical part of the engineering design process; it contributes also to our understanding of the potential environmental impacts of marine energy generation and carbon capture and storage. Significant infrastructure is required also to support these emerging industries, including cables and pipelines to transfer energy and carbon dioxide across the seafloor: all of these add to the environmental footprint of renewable energy development. Consequently, the development of standards and best practices, for site and submarine transmission corridor characterisation and environmental impact assessment, are important requirements in developing national and international strategies to the transition to a world of lower carbon emissions.

Desprez, M., Pearce, B., and Le Bot, S. 2010. The biological impact of overflowing sands around a marine aggregate extraction site: Dieppe (eastern English Channel). – ICES Journal of Marine Science, 67: 270–277. The study investigates the physical impact of sediment deposition associated with aggregate dredging at a site off Dieppe, and the consequences for benthic fauna. Sampling stations were sited across potential zones of impact classified as high, moderate, and low deposition, depending on their proximity to dredging activities and their position relative to the net sediment transport route. Samples were also taken west of the dredge site outside the zone of likely impact (no deposition). A strong gradient was observed from the sediments dominated by fine sands in the high and moderate deposition zones, through to coarse sands and gravels in the low and no deposition zones. The benthic fauna sampled from the deposits of fine sand in the high and moderate deposition zones were sparse compared with the coarser deposits sampled from the low and no deposition zones. There was a strong correspondence between the distribution of different sediment fractions and the associated benthic fauna, with a weighted Spearman rank correlation of 0.638, higher than reported in related studies. This suggests that in deposition areas such as this, biological interactions play a less important role in shaping communities than the changes in the physical environment, which may have a greater impact on the biological communities.