Publication Abstract

Lights, camera, acoustics: Assessing macrobenthic communities at a dredged material disposal site off the North East Coast of the UK

Lights, camera, acoustics: Assessing macrobenthic communities at a dredged material disposal site off the North East Coast of the UK

S.N.R. Birchenough, S.E. Boyd, R.A. Coggan, D.S. Limpenny, W.J. Meadows and H.L. Rees

Traditional sampling methods were combined with acoustic techniques, video images and Sediment Profile Imagery (SPI) to assess the spatial and temporal changes in macrobenthic communities at a dredged material disposal site off the North East Coast of the UK. Annually over 100,000 tonnes of maintenance dredgings from the Tyne Estuary are disposed of at a designated licensed site. It has been recognised that the disposal of these materials at sea can produce long-term environmental impacts with repercussions for the biota and sediments. Therefore, monitoring is required to determine whether unacceptable impacts are occurring or if conditions that could lead to inadequate impacts are developing. The site of approximately 2.7Km by 1.9Km in size was surveyed with a high-resolution sidescan sonar system producing a mosaic with 100% coverage of the survey area. A clear footprint of the disposal operations in the centre of the licensed area was revealed during the pilot survey. Benthic communities and sediments were ground-truthed using a Hamon grab fitted with a video camera. Results of the pilot survey and first year of the study indicated a decrease in total abundance of organisms, biomass and species richness in the vicinity of the dredged material disposal site. The use of SPI provided additional information on the status of the sediments and biogenic activities. This study demonstrates the advantages of combining conventional methods, acoustic techniques and optical imaging devices when assessing anthropogenic effects. Their collective contribution has allowed a thorough ecological assessment following anthropogenic activities at the seabed, which is a significant improvement over individual approaches.

Reference

S.N.R. Birchenough, S.E. Boyd, R.A. Coggan, D.S. Limpenny, W.J. Meadows and H.L. Rees (2006) Lights, camera, acoustics: Assessing macrobenthic communities at a dredged material disposal site off the North East Coast of the UK.  Journal of Marine Systems, 62(3-4): 204-216

S.N.R. Birchenough*, S.E. Boyd*, R.A. Coggan*, D.S. Limpenny*, W.J. Meadows* and H.L. Rees*

Journal of Marine Systems, 62(3-4): 204-216