THE ENVIRONMENTAL Protection Agency (EPA) and a leading Irish marine biologist have both challenged the findings of a report by a US/Swedish scientific team which claims that excessive pollution has created 20 "dead zones" around the Irish coastline.
The report in a recent issue of the US journal Science identified 20 areas extending from north Dublin right around to Belfast lough as "dead" or hypoxic, due to depletion of oxygen levels.
The study by Robert J Diaz of the Virginia Institute of Marine Science, USA, and Rutger Rosenberg of the University of Gothenburg, Sweden noted that dead zones have spread "exponentially" since the 1960s, affecting some 400 coastal systems internationally, and have "serious consequences for ecosystem functioning".
The scientists relied on data from the OSPAR Commission, the northeast Atlantic marine environment body involving 15 contracting parties and the European Commission, to confirm the status of the Irish areas.
However, in a letter to the journal Science the EPA says that the majority of Irish areas identified in the article are not hypoxic, and questions the scientists' source material.
Ireland had not identified any area as suffering from acute hypoxia in its report to a 2003 study on the eutrophication status of the OSPAR maritime area, the EPA says.
"It is therefore incorrect and misleading to use this report to identify the presence of hypoxic areas around the Irish coast," the agency says.
Dr Brendan O'Connor of the Galway-based environmental consultancy Aqua-fact, has also disputed the scientists' findings. He told The Irish Times that he had worked on all except one of the areas listed in the Science report, and none of the areas would merit "dead zone" status.
He says that water chemistry data was used to assess sites for the OSPAR report, and no reference was made to benthic communities or organisms living in the sediment as an indicator of status.
Dr O'Connor says that many of the zones identified are in "reasonably good condition", and several locations are due to benefit from construction of waste water treatment plants.
"With the full implementation of the EU Water Framework Directive, I would be fairly sure that conditions in the estuarine systems should improve," he said.
Chemical fertiliser run-off and the burning of fossil fuels have been identified as the main contributors to eutrophication, and depletion of marine life in so-called "dead zones", due to low oxygen levels.