Sheltered gravelly mud shores, subject to reduced salinity. The infaunal community consists of the ragworm Hediste diversicolor, as well as the spire shell Hydrobia ulvae and the baltic tellin Macoma balthica. The presence of the gravel in the sediment is unlikely to have a large influence on the infaunal composition, which is driven mainly by the estuarine sandy mud conditions. Coarse material on the sediment surface may however enrich the biota with additional epifaunal species such as barnacles and algae. Given the low sample numbers for this biotope, more records are needed to confirm the characterising species list. Situation: It is probable that there are broad transition areas between this biotope, and the corresponding muddy sediment biotope, unit A2.312. The boundaries may be very indistinct, with A2.4111 present in patches of gravelly mud on areas of mudflat, where the main biotope is A2.312. This biotope has been found alongside its mud equivalent in the Stour estuary.