Coast

Mudflats form in sheltered coastal areas and can be seen on estuaries at low tide. Despite their barren appearance, mudflats are rich in wildlife.

Microscopic algae, such as diatoms, thrive in these habitats and form the foundation of this nutrient-rich ecosystem. The algae coat the surface, fuelling a food web that supports a variety of invertebrates including bristle worms, mussels, shrimps and mud snails. These invertebrates are critical food sources for fish and attract internationally important numbers of wintering birds. From geese and ducks to waders such as bar-tailed godwit, avocet, curlew and dunlin, mudflats become bustling feeding grounds, especially during the winter. The iconic black and white avocet with its curled beak and the haunting call of the curlew echoing around the estuaries are just two of the sights and sounds that make these areas so special.

Beyond their role in supporting wildlife, mudflats are vital breeding and nursery grounds for fish and shellfish, helping to sustain coastal fisheries and boost the biodiversity and productivity of our seas.

Seagrass beds develop in sheltered intertidal and shallow subtidal areas, often growing on mudflats. Devon’s seagrass beds are primarily composed of two species of eelgrass. Dwarf eelgrass (Zostera noltii) grows on higher areas often adjacent to saltmarshes. Common eelgrass (Zostera marina) is typically found underwater in subtidal zones. However, in Devon it has also been recorded at the edges of the intertidal area.

All seagrass beds are incredibly valuable for wildlife. They provide shelter, feeding grounds and nursery areas for a wide range of marine life, including fish, invertebrates and birds. Birds, such as brent geese, feed on the eelgrass (in nationally important numbers on the Exe, Tamar and Taw Torridge estuaries) and others feed on the invertebrates and fish that live in this habitat. Seagrass beds are especially important for juvenile fish and even support rare species such as seahorses.

Key areas for intertidal seagrass beds are the more sheltered south Devon intertidal areas such as the Exe Estuary, the Kingsbridge Estuary and Torbay (non-estuarine). Subtidal seagrass beds are also present in areas such as Plymouth.

Seagrass beds are under pressure from poor water quality, including increased sedimentation and turbidity, which reduce the light that’s available and essential for growth. Anchoring and mooring activities physically damage the beds, breaking up the plants and leaving them more exposed to erosion and disease. See Key pressures and opportunities below for more information.

Saltmarshes are made up of salt-tolerant plants that have adapted to regular immersion by tides. They develop on mudflats in sheltered areas at the upper edge of the intertidal zone, where sediment gradually builds up. As plants colonise these areas, they help stabilise the sediment, allowing the saltmarsh to grow until only the highest tides cover it.

Saltmarsh species include native small cordgrass (Spartina maritima), glasswort, sea purslane, sea aster and common sea lavender. Saltmarshes are rich in invertebrates and provide important high-tide refuges and feeding grounds for birds, especially during the winter months.

In Devon, saltmarshes are found in most estuaries, with key areas including the Exe Estuary, Taw-Torridge Estuary and the Kingsbridge Estuary.

Historically, large areas of saltmarsh were drained for agriculture or reclaimed for development, permanently changing the natural landscape. Today, with rising sea levels and limited space for inland migration, remaining saltmarshes are increasingly at risk of permanent submersion. See Key pressures and opportunities below for more information.

Organic reefs are structures formed by living organisms such as mussels, oysters and reef-building worms. They can be found in both estuarine and rocky shore environments.

Blue mussel beds are primarily composed of Mytilus edulis and often form on rocks or firm mud, which the mussels attach themselves to using strong threads called byssus. Native oyster (Ostrea edulis) beds are mainly found along the south Devon coast. They grow on hard surfaces or old oyster shells and create layered, reef-like structures.

Mussels and oysters reproduce by releasing eggs and sperm into the water. The fertilised larvae float for a while before sinking and settling on a surface. Over time, as more individuals settle and grow, they form dense clusters. Crabs, shrimp, worms and small fish often live among the shells and seaweed grows on their surfaces. These habitats also attract birds and wading animals that forage for food.

The honeycomb worm (Sabellaria alveolata) is a reef-building marine worm found across Devon in places such as Westward Ho!. The worms build protective tubes from sand and shell fragments, creating dense, honeycomb-like structures that can form large reefs up to several metres across and a metre deep. They thrive in more exposed areas where wave action and currents supply the sand needed to maintain and expand the reef.

The Pacific oyster is an invasive species with an aggressive growth rate that threatens native habitats. It can rapidly blanket coastal areas, outcompeting native species and changing the structure of these delicate ecosystems. See Invasives for more information.

Dense forests of seaweed or large marine algae are vital components of the coastal ecosystem. These underwater habitats provide shelter and food for a wide variety of marine life, including fish, crabs and sea urchins.

Seaweeds are broadly grouped into three main types: green, red and brown algae, each thriving in different conditions and depths. Among the most iconic are the kelps, large brown algae that form extensive underwater forests in deeper waters.

In shallower areas, species like thongweed (Himanthalia elongata) create striking, ribbon-like structures that are a distinctive and beautiful feature of the Devon coastline.

Consultation Q: Is there a better term for this habitat?

The steep wooded banks in Devon’s estuaries are a distinctive and ecologically valuable feature. Native trees, such as oak, alder, willow and ash, often grow right up to the water’s edge. Their branches overhang the estuary, where the highest tides ‘salt-prune’ the lower twigs, creating a distinctive, level line of foliage during the growing season.

Fallen branches, limbs and even entire trees, provide shelter, spawning grounds and nursery habitat for a variety of estuarine fish, including bass and mullet. Rare bryophytes (mosses and liverworts) and fungi thrive in the humid, shady conditions.

Devon is considered a national stronghold for these habitats as over 40% of the UK’s temperate mangroves are found here.

Saline lagoons are shallow coastal water bodies that are partially separated from the sea by natural barriers or (as in Seaton Wetlands) by engineered structures called ‘self-regulating tidal exchange gates.’ They contain a mix of seawater and freshwater, creating brackish conditions that vary with tides, rainfall and evaporation.

The best example of saline lagoons in Devon is found at Seaton Wetlands, which includes an intertidal lagoon adjacent to the Axe Estuary.

Consultation Q: Are there any other examples in Devon? Plymouth?

Brackish reedbeds are unique wetland ecosystems primarily dominated by common reed (Phragmites australis) and other salt-tolerant plant species. They’re used as a refuge for fish, including young eels, and provide vital roosting and feeding sites for birds. Brackish reedbeds can be found across all of Devon’s estuaries.

Coastal grazing marshes are low-lying, wet grasslands that have generally been created from intertidal habitats for grazing livestock. They’re characterised by a network of ditches and pools that hold water throughout the year, creating a mosaic of wet and dry areas.

Ditches and pools in the marshes provide habitat for amphibians, fish and aquatic invertebrates. Marshes are particularly important for birds, providing breeding sites for waders and waterfowl and feeding grounds for migratory birds. Breeding avocets became extinct in the UK in the 19th century due to habitat loss and hunting. They re-colonised the Suffolk coast in 1947 and in 2023 returned to Devon to breed at Seaton Marshes. Pintail feed on plants in grazing marshes and other estuarine habitats, particularly on the Exe Estuary with smaller numbers at Kingsbridge and the Taw-Torridge.

Wildlife-rich grazing marshes in Devon include Exminster Marshes, an RSPB reserve on the Exe estuary, and extensive marshes on the Axe estuary managed by East Devon District Council.

Consultation Q: Are there any other examples in Devon?

Sand dunes form when wind-blown sand accumulates above the high tide line. They’re shaped by natural forces and vegetation, gradually developing into a series of ridges and slacks that support a rich variety of plant and animal life. In Devon, sand dunes are vital habitats for rare and specialised species, including sea holly, sand spurges and the elusive petalwort. These dynamic landscapes also support a rich variety of insects and provide a crucial refuge for ground-nesting birds.

Sand dunes are found across Devon’s coastlines. Five of the largest sand dune systems include Braunton Burrows SSSI and SAC, Northam Burrows SSSI, Croyde and Woolacombe dunes along the north coast, and Dawlish Warren SSSI and SAC on the south coast. Other smaller dunes can be found at places such as Bantham, as well as remnant dune features in areas like Exmouth. 

Add more info on species and links to Focus Species (inverts, plants, lichens).

Vegetated shingle is a unique coastal habitat found on shingle beaches. It supports a variety of specialised plants that can tolerate the harsh conditions of salt spray, wind and shifting stones. These plants help stabilise the shingle, providing a habitat for invertebrates, birds and other wildlife.

Common species include sea kale, yellow horned-poppy and various lichens and mosses. Focus Species include the scaly cricket found on the shingle at Branscombe and sea spurge tortix moth on the shingle at Slapton. Devon Species of Conservation Concern include the grey bush-cricket and Cepero’s groundhopper (both also found on sand dunes).

See the Devon Species of Conservation Concern spreadsheet for more species and links to species below.

Rockpools form in natural hollows and man-made crevices along the shore, trapping seawater as the tide recedes. These miniature marine worlds offer a fascinating window into coastal biodiversity, teeming with life such as crabs, starfish, sea anemones, and small fish and shellfish.
The shores around Lundy Island are especially rich in rockpool life, thanks to the island’s designation in 1973 as the UK’s first Marine Protected Area.

Sea caves are fascinating natural formations created by the relentless action of waves eroding the coastal cliffs over millennia. Found along rugged coastline, particularly in areas like Torbay and the north coast, sea caves are typically carved into soft sedimentary rocks such as limestone or sandstone. Many are accessible only by boat or at low tide, revealing intricate patterns and textures formed by geological processes. Sea caves provide habitats for species such as sponges, molluscs, small fish, crustaceans and even bats. They’re also significant features in several of Devon’s protected sites.

To be added in the next few weeks.