Intertidal, benthic samples were taken at 67 sites on the estuaries of Essex and Suffolk in the autumn 1990, as part of the NRA's 1990 National Estuaries Survey. Most sites had typically estuarine fauna, with the exception of the seaward end of the Deben estuary which had low species diversity and abundance, which is thought to be related to the low levels of organic carbon in the sediments of the area. The upper estuaries all had large populations of oligocheates. However, the total number of species found at the upper estuarine sites was about average for the area as a whole. Some species, notably Hediste and the bivalves, were represented by large specimens so that the relative biomass of oligochaetes was low. The conclusion reached was that although the organic load in the areas studied may be high, it is unlikely that there are any gross pollution effects. A 10cm corer was used to sample to a depth of 15cm at each site. Three replicates were taken at each site and sieved through a 500 æm sieve. A sediment core of 44mm diam and 15cm deep was used to take samples from each site, but only those from the Suffolk estuaries were analysed for particle size, and organic carbon content.
