The Erme Estuary MCZ is an inshore site that covers an area of approximately 1 km². The Erme is located on the south coast of Devon and opens into the Western Channel and Celtic Sea region.
The site covers the whole estuary from the mouth of the river to the limits of the tidal influence near the village of Ermington. The MCZ falls within the Erme Estuary Site of Special Scientific Interest and at the mouth of the river it overlaps with the Prawle Point to Plymouth Sound and Eddystone Site of Community Importance.
The Erme Estuary contains a wide variety of habitats from rocky shores to intertidal mud flats. These support a large number of important species including several that are rare, such as the nationally scarce tentacled lagoon worm. This is a tiny bristleworm which grows up to 5 mm in length and creates and lives in tubes within the mud habitats of the estuary. These worms have tentacles around their mouths used for gathering food from the surrounding muddy sediments. The tentacled lagoon-worm is particularly vulnerable to activities that cause changes in its habitat. Estuaries play an important role in the environment, creating areas for wading and migratory birds to feed and rest and forming nurseries for juvenile species of fish. The large mudflats and areas of muddy gravel that are exposed at low tide produce films of algae that are foraged upon by many species.
Areas of intertidal rock within the estuary form the feature ‘Estuarine rocky habitats’. These areas of rock provide a hard surface for algae and animals to attach in an area dominated by sand and mud with variable salinity. At low tide these areas become foraging grounds for birds and crustaceans and at high tide they create shelter for juvenile species of fish.
At the mouth of the river, exposed rocks are pounded by waves and currents washing away sand and mud leaving only bedrock or boulders. Mussels, limpets and barnacles can be found clinging to the rocks with patches of brown and red seaweeds growing in the crevices and on the landward side of the rocks.