The Helford River is a small marine inlet in south Cornwall which was formed by the flooding of a river valley subsequent to the last ice age. Historically the waterway has long been associated with human activities, providing a trade route for the surrounding villages and towns. At the present time however, activities are largely of a recreational nature, although some oyster farming and fishing still takes place. For several decades, the Helford River has been visited by collectors and scientists who were interested in the marine biota found in the vicinity. The biological reputation of the area grew, and was recognized by the Nature Conservancy Council as a result of there programme of intertidal surveys which took place during the 1970's. Since then, however, there has been a distinct deterioration in the quality of the majority of intertidal habitats and communities found within the Helford River, concentrating on sublittoral habitats, and to assess the nature conservation importance of the area using standard criteria. Survey work consisted of in situ recording of conspicuous species and collection of sediment samples for biological analysis, by using a pipe dredge and also a suction sampler. Abundances of conspicuous species were defined by the use of abundance scales and the information obtained was directly comparable to that for other areas. Sediment samples were sieved over a 1 mm mesh. Animals were picked out, identified and counted. Photographs were taken during fieldwork to illustrate habitats, communities and species. Habitats and communities present were classified into seven intertidal types and twenty subtidal types each of which is described. The distribution of habitats and communities is discussed, and for selected areas, the present biological data have been compared with ealier records. Features of the Helford River have been compared with those of other marine inlets. Communities have been provisionally graded as of Local, Regional, National or International conservation importance. It is generally acknowledged that many of the communities have been damaged and the assessment takes no account of their former condition. However, the recent designation of the Helford Voluntary Marine Conservation Area creates a potential for the rehabilitation of affected habitats. Records currently considered sensitive have been removed from this dataset.
