re found naturally in many inland waters, estuaries and the sea.
They generally grow in non-flowing fresh water such as lakes, ponds, and slow-moving streams during hot weather when there is less rainfall - but can also occur at other times of the year.
The algae are very small and can’t be seen with the naked eye unless they are concentrated into clumps when they can look like green flakes, greenish bundles or brown dots in the water.
When the algae blooms, it can look like a blue-green scum has appeared on the surface of the water - almost like pea soup.
Blooms of the organisms often build up around the edges of ponds and lakes, which may look like foam.
According to Natural Resources Wales' information leaflet, bloom and scum-forming blue-green algae can produce harmful toxins.
What are the health risks to humans?
According to Public Health Wales these toxins can be potentially harmful to humans.
A statement on their website said: "People may be exposed to these toxins through contact with the skin (e.g. when swimming), through inhalation (e.g. when motor boating or water skiing), or by swallowing contaminated water.
"These toxins can cause skin rashes, nausea, vomiting, stomach pains, fever and headaches. Occasionally they can cause more serious illness such as liver and brain damage.
"Children are at greater risk than adults of developing problems because of their comparative lower body weight."
How can the health risks be minimised?
Not all blue-green algae blooms and scums are toxic but it is not possible to tell from appearance and so here are some precautions to take:
- Do not swim in the water
- Do not swallow the water
- Avoid contact with the algae
- Do not eat fish caught from the water
- Observe and abide by any warning notices positioned around the water
Public Health Wales encourage anyone who has come into contact with water containing blue-green algae to shower with fresh water immediately.
Anyone who comes into contact with affected water and becomes ill should obtain medical attention immediately.
Why is blue-green algae dangerous to dogs?
The toxins which may be produced by blue-green algae can be poisonous to animals and can cause severe illness and death, reports Public Health Wales.
Dogs can develop poisoning when they drink from such water, or lick themselves after swimming in it, and this in turn has a toxic effect on the stomach and internal organs - which could prove fatal.
Animal welfare charity, Blue Cross, has warned dog owners against walking their pets near to bodies of water confirmed to have blue-green algae.
A statement on their website read: "Blooms of blue-green algae can produce harmful toxins which stop a dog’s liver from functioning properly. However, not all types of blue-green algae are dangerous.
"Sadly, exposure to toxic blue-green algae is often fatal, and can also cause long term health problems in dogs that survive after drinking or swimming in algae-contaminated water.
"Some types of blue-green algae can kill a dog just 15 minutes to an hour after drinking contaminated water.
"Dogs who have been swimming in water can get the algae caught in their fur, and can ingest it while cleaning themselves later on.
"Concentrations of the algae vary throughout the year and may not always be harmful - but you can’t tell simply by looking at them whether or not they are dangerous, so it is best not to run the risk of allowing your dog to come into contact with water where the algae may be present."
The symptoms of blue-green algae toxicity in dogs
If your dog shows any of the following signs after drinking from, or swimming or paddling in water, contact your vet immediately and tell them you are concerned about blue-green algae:
- Vomiting/being sick
- Breathing difficulties
There is no antidote for the toxins produced by the bacteria, but if caught early enough, your vet will likely try to make your dog sick and attempt to flush the toxins from the body before they take hold.
How to protect your dog
Sadly, blue-green algae poisoning often eventually causes fatal liver failure.
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