IMIS - Marine Onderzoeksgroepen

During April and May 1993, and in February and May 1994, samples of the benthic macrofauna were collected from MAFF research vessels at each of the 25 "intermediate" and "offshore" stations around the England and Wales coastline. One station in the SW Approaches (S48) was sampled in December 1992, i.e. outside the recommended February and May sampling window, but this offshore, deep-water environment was included as a clean-water "reference" point. (An attempt to sample S48 in February 1994 had to be abandoned due to bad weather.) An additional station off the Tees Estuary was sampled to provide information on the shallow coastal environment in this area. At each location, five sediment samples for macrofauna analysis were collected using a 0.1 m² day grab from the central point of a 500 m grid of 9 stations, the latter being sampled for contaminant analyses only. The five replicates were collected from within a 100 m range ring, using SEXTANT software and DGPS position-fixing. The depth of sediment in the closed jaws of the grab was determined, as an indication of sample volume. Very small samples (i.e. less than about 5 cm depth) were discarded. A visual description of the sediment type was recorded, together with the location and times at which the sample was collected, and the prevailing sea state, wind strength, and water depth. A small subsample for sediment particle size analysis was removed using a 2 cm diameter perspex corer inserted to a depth of about 5 cm. The contents of the grab were transferred to a hopper, and gently washed over a 1 mm mesh brass sieve. The retained material was preserved for analysis in 5% formaldehyde in seawater with added Rose Bengal. 430 taxa were identified, consisting of 186 polychaetes, 112 crustaceans, 76 molluscs, 19 echinoderms, and 37 in the catergory "other groups".