Aln Estuary MCZ

Status: Designated


Site overview

Aln Estuary is an inshore site on the Northumberland Coast, which extends from the estuary mouth to the upper tidal limit. It is a small area covering just 0.39 km2. This estuary provides a vital link between the land and sea. ┬áConditions in estuaries are typically more sheltered than other coastal areas; this creates an environment which can support some species that are not found in more exposed places. This estuary contains within it a rocky habitat which is relatively uncommon and is home to kelps, wracks, anemones, barnacles and sea squirts. These habitats also support a range of migrating and wintering water birds including gulls, dunlins and other waders such as redshanks, curlews, snipe and wigeons. Coastal salt-marshes and saline reedbeds, such as those found here, are recognised as being one of the world’s most productive ecosystems with many birds, juvenile fish, crustaceans and molluscs using marshes as nurseries. Salt marshes are also important in the fight against climate change. They are known to accumulate sediment and other organic matter at a rate that may keep up with sea level rise. They also provide carbon storage at approximately 10 times the rate measured in temperate forests.

MPA Type

Marine Conservation Zone

Marine Conservation Zones (MCZs) are designated under UK legislation (Marine and Coastal Access Act 2009) and have been established around England, Wales and Northern Ireland to contribute to the UK MPA network protect a range of nationally important marine wildlife, habitats, geology and geomorphology, and can be designated anywhere in English and Welsh territorial and UK offshore waters.

Surface Area

0.39 km2 (0.15 mi.2)


12.16 km (7.56 mi.)

  • Intertidal mud

    The quiet water in sheltered estuaries and harbours allows very fine silt and clay to settle and form a layer of mud that can be exposed at low tide. These glistening muddy expanses can be packed ful of life and are sometimes called the ‘larders of the s

  • Coastal saltmarshes and saline reedbeds

    Saltmarshes link the land and the sea and create very specialised conditions for particular plants. They form a natural coastal defence and are home to a large variety of life. Associated reedbeds are equally rich and improtant and support iconic species

  • Estuarine rocky habitats

    Estuaries are usually soft, muddy places, so rock and stable boulders in estuaries are rare and offer a great habitat for a wide variety of plants and animals.

  • Sheltered muddy gravels

    Muddy gravels occur mainly in estuaries, drowned river valleys and sea lochs, in areas protected from wave action and strong tidal streams. They can be found both on the shore and in the shallows.

Did you know?…

To the shelf limits, Scotland has 61% of UK waters, of which 23% are now in existing or new ‘marine protected areas’

Over 500,000 records of undersea species and habitats have been collected by volunteer Seasearch divers