Caerphilly Castle Moat - Information and a Warning to our Visitors

Wednesday 24 July 2013

Caerphilly Castle Moat - Information and a Warning to our Visitors

We want to warn our visitors that the waters in the moat at Caerphilly Castle contain blue green algae bloom that may be toxic to humans and animals.

What are blue-green algae?

There’s a wide range of blue-green algae(cyanobacteria). In fresh waters, they’re suspended within the water or attached to rocks and other surfaces.

Blue-green algae and other algal groups are important contributors to the aquatic biology of fresh and marine waters.

They are primary producers that:

• convert sunlight to energy by photosynthesis
• release oxygen and carbon dioxide into water
• take up minerals
• produce food chain supporting substances

Blue-green algae need nutrients to grow which exist in various forms in freshwater. The algae use them directly.

John Edwards, Cadw's Assistant Director of Properties in Care  said: ' Natural Resource Wales have tested the waters and comfirmed that the blue-green algae which naturally occur in inland waters, estuaries and the sea is present once again in the waters at Caerphilly Castle.

This shouldn't affect visitors enjoyment of the surroundings at this outstanding medieval castle but although the algal scum isn't always harmful it is safer to avoid contact with it and the water close to it.'

Contact hasnt led to long term effects but in some cases illnesses have been severe. Illnesses including skin rashes, eye irritation, vomiting, diarrhoea, fever and muscle and joint pain have occurred in people who have swallowed or swam through algal scum. 

We strongly urge our visitors to stay away from the water and keep their pets away as the toxins the algae may produce are also toxic to animals and can cause severe illness and death.

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