Habitat 'at risk' in estuaries

ESTUARIES across England and Wales are at risk of losing important habitat as it is “squeezed” out by rising seas and human development, a study warns.

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Estuaries are key for wildlife such as wading birds, as breeding and nursery grounds for commercially important fish, and for storing carbon and improving water quality by filtering nutrients, contaminants and sediment.

However, a combination of rising seas and lower summer river levels as a result of climate change, and man-made barriers such as weirs and dams are putting freshwater habitat at the top of estuaries at risk, according to scientists who have previously coined the phenomenon “estuarine squeeze”.

Now researchers have identified and mapped the tidal freshwater and brackish zones with low salt levels - important areas which provide habitat and corridors for nutrients and wildlife - at the top of all 85 estuaries in mainland England and Wales.

Nearly 70% of these estuaries are blocked by barriers such as weirs or sluices where the estuary meets the river, and around half contain tidal freshwater and brackish zones, the analysis shows.

Some 19 estuaries with tidal freshwater and brackish zones had barriers preventing them shifting inland as the seas rise and push salty water further in.