There is little detailed information available on the invertebrate macrofauna of the Usk and Wye Estuaries. This report describes the Distribution and abundance of the benthic invertebrate macrofauna and examines a number of factors thought most likely to influence the organisms concerned. 1. Studies were initiated during 1977 and winter and summer surveys were undertaken on each estuary. Grab samples from sites at approximately one kilometre intervals were taken for quantitative estimates of the sediment fauna. 2. Sediment characteristics and particle size analysis were measured and tidal water quality data including temperature, salinity and suspended solids were measured. 3. Quantitative estimates of the sediment macrofauna were analysed by a biological index of similarity and classified by an agglomerative cluster analysis. The sublittoral sediments of both the Usk and Wye Estuaries support a reduced fauna, consisting mainly of annelids and some molluscs, compared with the Outer Bristol Channel. Site details have not yet been entered.
