Northern Ireland

Fresh warning after blue-green algae detected further along north coast beaches

A member of the public enters the water at Portstewart on Saturday, despite warnings in place over the presence of potentially toxic blue-green algae. Pictures by Margaret McLaughlin
A member of the public enters the water at Portstewart on Saturday, despite warnings in place over the presence of potentially toxic blue-green algae. Pictures by Margaret McLaughlin
By Ryan McAleer

Fresh warnings have been issued further along the north coast after a potentially toxic blue-green algae was detected at more locations.

Red flags are already in place at Portstewart and Castlerock beaches after water tests confirmed the presence of a blue-green algae ‘Microcystis sp’, which the Northern Ireland Environment Agency (NIEA) says has the potential to produce harmful toxins.

The Department for Agriculture and Environmental Affairs (DAERA) confirmed on Sunday that red flags are now in place at Downhill, following a further detection of blue-green algae on Sunday morning.

DAERA said Benone beach was clear as of 11am on Sunday, but urged the public to remain vigilant for any sightings of algae, which moves with the tide and wind.  

Despite warning signs erected by the National Trust and the Causeway Coast and Glens Borough Council in recent days, asking people and their pets to stay out of the water, some members of the public were spotted in the water at Portstewart over the weekend.

DAERA said blue-green algae is a type of bacteria that naturally inhabits freshwater, coastal and marine waters.

The algae has been linked to the death of a number of dogs in Co Fermanagh last month.

Read more:

  • Public urged to be vigilant of toxic blue algae when visiting the north coast
  • Lough Neagh could take two decades to return to 'good' ecological status, agency warns
  • Toxic algae blamed for dog deaths in Co Fermanagh
People pictured on Portstewart Strand on Saturday, where a red flag warning remains in place due the detection of blue-green algae along the shoreline. Picture by Margaret McLaughlin
People pictured on Portstewart Strand on Saturday, where a red flag warning remains in place due the detection of blue-green algae along the shoreline. Picture by Margaret McLaughlin

It can thrive on abundant sunlight, still or slow-flowing water and sufficient levels of nutrients, such as nitrogen and phosphorus.

DAERA said nitrogen and phosphorus are naturally present in our waterways, but they can also come in excessively from agricultural fertilisers, sewage effluent, household products and storm water runoff.

The department said when the algae ‘blooms’, the water becomes less clear and may look green, blue-green or greenish-brown.

The National Trust warning at Portstewart strand, warning people and their pets to keep out of the water.
The National Trust warning at Portstewart strand, warning people and their pets to keep out of the water.

“Scums can form during calm weather when several bloom forming species rise to the surface.

“This can look like paint, mousse or small clumps. The duration of blooms may last for a few days to several weeks until conditions in the water body change and the algae die and decompose.”