Habitat point records from 1987 OPRU HRE Dart Estuary survey

The Dart Estuary is situated on the south coast of Devon and opens into Start Bay. The estuary itself runs through a steep sided channel from Totnes, some 18 km to the north, to Dartmouth and Kingswear at the mouth. It then opens out, through a vry narrow entrance, and with a bend in the channel, into a bay called the Range. The freshwater flow to the estuary is comparitively greater than most other inlets on the south Devon coast and the water is therefore considerably less than fully marine until it reaches the Range. The shores and subtidal in the upper and middle estuary are predominently of mud with occasional bedrock outcrops on the shore. The lower estuary also has muddy shores and subtidally but usually incorporating shingle and with more frequent bedrock and other hard substrata. The shores adjacent to Dartmouth and Kingswear are man-made walls, but in the entrance to the estuary and in the Range they are of predominently steep Dartmouth slate bedrock. The subtidal in the Range is mostly of muddy sand with outcrops of bedrock in places. The area is very popular for sailing and around Dartmouth there are many hundreds of boats in marinas and on moorings. These have had an inevitable effect on the concentrations in the water of the antifouling paint TBT. The concentrations of this pollutant are very high in the Dart. Due to the height and steepness of the coast the area has been poorly developed for industry, but this also creates disadvantages for the marine environment - in particular the poor disposal methods of sewage and refuse. Fishing activity is small and mostly confined to salmon netting and periwinkle collecting. Access is differcult to most shores or diving sites without a boat, and minimal use is made of the marine habitats for education or research. There have been very few previous marine biological studies, although in recent years there have been two baseline environmental impact studies in the lower estuary. Seventeen intertidal and fifteen subtidal habitats and associated communities have been described from this survey. Descriptions are given of these and lists of species found are tabulated. The habitats and communities in the Range are of open coast type but are not very diverse. The communities on the bedrock outcrops were quite rich and interesting. The narrow entrance and bending channel creates a very rapid transition from exposed marine conditions to sheltered estuarine conditions. The subtidal communities in the entrance are unusual. Within the estuary there is a gradual salinity gradient and communities are generally typical of estuaries elsewhere. The communities on the Anchor Stone are quite rich and make a very interesting dive site. Bedrock on the shore in the upper estuary was colonised by communities rarely recorded from elsewhere. The scientific interest and conservation importance of the area has been assessed using standard criteria and the conservation importance of habitats and communities in the area have been provisionally graded as of Local, Regional or National importance. Species of particular scientific interest have been tabulated and their conservation importance provisionally graded as of Regional or National importance. Records currently considered sensitive have been removed from this dataset.

Organization: Joint Nature Conservation Committee