Publication Abstract

Integration of ground-truthing approaches to characterise an area licensed for dredge material disposal off the Northeast coast of the UK

Integration of ground-truthing approaches to characterise an area licensed for dredge material disposal off the Northeast coast of the UK

S.N.R. Birchenough, S.E. Boyd, R.A. Coggan, D.S. Limpenny, W.J. Meadows and R. Foster-Smith

Traditional sampling methods were combined with acoustic techniques, video images and Sediment Profile Imagery (SPI) to assess spatial and temporal changes in macrobenthic communities at a dredged material disposal site off the North East Coast of the UK. Annually over 150,000 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 such impacts are developing. The site of approximately 3.5 x 8.7-km was surveyed with a high-resolution sidescan sonar system producing a mosaic with 100% coverage of the survey area, which revealed a clear footprint of the disposal operations in the centre of the licensed area. 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 reduction in species richness and total abundance and biomass of organisms in the vicinity of the disposal site. The use of SPI provided additional ground-truth 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 R. Foster-Smith. 2004. Integration of ground-truthing approaches to characterise an area licensed for dredge material disposal off the Northeast coast of the UK. ICES Copenhagen. ICES CM 2004/T:03

S.N.R. Birchenough*, S.E. Boyd*, R.A. Coggan*, D.S. Limpenny*, W.J. Meadows* and R. Foster-Smith

ICES Copenhagen, ICES CM 2004/T:03