Green tides on the rise as blooming waters bedevil the coastline

A "green tide" of sea lettuce discolours Clonakilty bay in Co Cork
A "green tide" of sea lettuce discolours Clonakilty bay in Co Cork
LIAM MORRISON/NUIG

Shamrock it isn’t: Ireland’s global image as a clean Emerald Isle could be compromised by creeping “green tides” on parts of the coastline.

Pollutants from urban development in Dublin and from intensive agriculture in Cork are feeding extensive blooms of green seaweeds, researchers at NUI Galway have found.

Dublin’s Tolka estuary and Courtmacsherry and Clonakilty in Cork are badly affected, according to a study for the Environmental Protection Agency.

Unlike “red tides”, caused by harmful microalgae, “green tides” are macroalgal blooms, Liam Morrison, the lead researcher at the university’s earth and ocean sciences department, said.

The tides are not generally toxic to humans, but their size discourages recreational use of the shoreline, along with navigation, inshore fishing and angling, he said.

The research found that