Swim groups and water sports clubs are being asked to “keep bleach off the beach” by finding nature-friendly ways of removing algae from seaside steps and piers.
Environmental organisation Coastwatch says the use of chemical cleaners is killing the very creatures that can help keep access points clear.
“Limpets and periwinkles eat the algae,” said Elise Merckel, who oversaw a trial of alternative cleaning methods for Coastwatch.
“When you find them on walls and steps, there is often a white circle around them where the wall is clear because they have eaten it.”
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The little molluscs graze slowly, however, and public safety concerns mean slippery access points to bathing areas and harbours need to be cleaned quickly and comprehensively.
Specialist liquid chemical cleaners are available which contain bleach and plain bleach is sometimes used, too. But Coastwatch says it may be illegal to use them under the Water Pollution Act.
It also warns that bleach can burn bare feet and hands and is extremely harmful to marine life – not just limpets and periwinkles but barnacles, mussels and other shellfish.
“We are asking people to just brush away the algae,” said Coastwatch founder Karin Dubsky.
The organisation conducted a trial with Dún Laoghaire Rathdown County Council in recent weeks using steel brushes, natural fibre brushes and sand on different steps to see which method worked best.
The steel brushes were more effective but could be hard to handle. However, adding sand improved the abrasive power and the first brushing was the hardest.
“After the first cleaning, it became much easier to go back and remove any regrowth,” Dubksy said.
The council has adopted a no-bleach policy but Dubksy said even if councils do the right thing, local people and clubs often help keep their regular access points clear.
Coastwatch is putting up posters on piers to raise awareness and ask people to report any suspected bleach use to the Environmental Protection Agency through a QR code on the page.
“There are cleaning products which promise great cleaning action on slipways but when you look at the label you see they contain bleach, expressed as chemical sodium hypochlorite, or NaOCl, or NaClO,” said Dubksy.
“Long after that characteristic bleach smell is gone, you will see a notable absence of marine life on and below the sea steps where the bleach has washed off and killed them.”
Merckel urged regular maintenance of facilities to help prevent algae from growing, which could cause a slip risk.
“If there is continuous seepage of water on to an area, the algae will grow faster,” she said.
“It’s important to seal cracks or drain the water away so that the concrete can dry fully at low tide and not be continuously wet.”
