Scientists monitor algae bloom after Donegal fish kill
- Published
Members of the public took photos of the dead fish on Downings Beach on Saturday
Irish marine scientists are closely monitoring an algae bloom off the Donegal coast after thousands of fish washed up dead on Downings Beach.
However, because only one species of fish died in the mystery incident, the Marine Institute has not ruled out recent storms as a possible cause.
´óÏó´«Ã½ News NI contacted the institute on Saturday after receiving images of thousands of dead sprat along the sand.
Staff since confirmed a high presence of a "harmful phytoplankton species".
'Red tide'
Phytoplankton are microscopic marine algae that need sunlight to survive.
Large blooms of phytoplankton can be harmful to marine life and can cause water discolouration along shorelines, a natural phenomenon known as a red tide.
Large algae blooms or red tides caused extensive damage to marine life on the Donegal coast in 2005, 2012 and 2015.
The Marine Institute said the bloom of summer 2005 was "particularly devastating" as it affected the whole coastline along the west of Ireland.
'Elevated levels'
Over the past week, seawater samples submitted to the institute's phytoplankton laboratory have shown a high presence of the "harmful phytoplankton species Karenia mikimotoi".
Karenia mikimotoi does not pose any risk to humans but dense blooms can kill fish and other sea creatures.
The Downings incident only killed one species of fish, which suggests it is not linked to a red tide
The phytoplankton species has "been observed in a number of sites at elevated levels," the institute said.
The highest level was 2.5m cells per litre, which was recorded at McSwynes Bay, County Donegal.
The bay is about 45 miles (74km) from Downings Beach, on the other side of the county.
'Other causes'
Dave Clarke of the Marine Institute's Phytoplankton and Biotoxin Unit said Karenia mikimotoi "can produce dense blooms which occasionally results in large simultaneous mortalities of finfish, shellfish and invertebrate species".
"The mortalities observed in Downings, however, are of a single species (sprat)," he added.
"For this reason, there may be other causes such as recent storms."
The fish were strewn across Downings beach
The Marine Institute said the bloom "is however being closely monitored" by its staff who "carry out a weekly national monitoring programme to identify potentially harmful or toxic producing phytoplankton species present in coastal areas".
The institute is a state agency responsible for marine research and provides scientific and technical advice to the Irish government on marine resources.
- Published31 August 2019
