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Coloured patches of algae seen off UAE coast not red tide — experts

Authorities in contact with fishermen to monitor situation.

Gulf News

Dubai: Satellite imagery showing patches of algae off the east coast are not a harmful algal bloom, marine biologists from the Ministry of Environment and Water have confirmed, though the threat lingers.

The fishing community on the UAE's eastern region suffered severe economic loss during 2008 and 2009 when a harmful algal bloom (HAB) struck the coastline for about eight months, killing fish and affecting coral reefs.

An increase in a certain type of algae, or phytoplankton, in the water that occurs naturally can make the water appear murky or discoloured from pink to red.

Ebrahim Al Jamali, director of Ministry of Environment and Water's marine environmental research centre, said large areas of algae were reported on December 8, but this is not HAB.

"There was a high level of chlorophyll in the waters off the east coast. This is a form of algae but not red tide, and it is not toxic," he said.

Close communication

"We are in close communication with the fishermen in Fujairah and they have also not reported any harmful algae."

A report released by the Ministry of Environment and Water (MOEW) said "biological activity" had been spotted in the form of threads and intermittent patches which indicates a possibility of red tide. The ministry stressed that this type of phytoplankton does not cause toxic or harmful impacts to fish or other marine organisms at this time.

Initial monitoring by MOEW showed that algae is present at a rate of 5 thousand to 10 thousand cells per litre. Only when this quantity reaches a certain critical mass of about 1 million cells per litre is HAB said to occur, according to a preliminary study conducted in 2009 by Dr Muthanna Al Omar, Head of Environmental Studies Department, National Energy and Water Research Centre at Abu Dhabi Water and Electricity Authority. In his presentation, Al Omar states that the harmful algae, called C. polykrikoides, is one of 337 species of phytoplankton living in the Gulf's waters.

A study of red tide in 2008 conducted off Dibba and East Musandam in the Gulf of Oman by a team of marine biologists from several universities including the United Nations University published in Marine Pollution Bulletin show that harmful algae will likely lead to significant changes in both coral and fish community structure.

"Although the causative agents of this C. polykrikoides bloom are unknown, increased coastal enrichment, natural oceanographic mechanisms, and the recent expansion of this species within ballast water discharge are expected to be the main agents. With rapid changes in oceanic climate, ... and increased global distribution of HAB species ... HAB events are predicted to increase dramatically." the report says.

Toxic growth: Threat to marine life

- Algal blooms occur when there is a large concentration of micro-organisms.

- Some algal blooms are associated with the production of natural toxins, depletion oxygen or other harmful effects, and are generally described as harmful algal blooms, or HABs.

- Scientists are moving away from calling harmful algal blooms a red tide, as the occurrence of an increase in toxic or non-toxic phytoplankton has nothing to do with the movement of the water or tides.

Source: National Oceanic and Atmospheric Administration