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No early end in sight to Red Tide menace

MUSCAT -- A massive Red Tide outbreak that has been plaguing large stretches of Oman's northern coastal waters is unlikely to disappear for at least another two months, according to an Omani scientist studying the phenomenon. Dr Adnan al Azri, a marine researcher at Sultan Qaboos University (SQU), believes that the algal blooms, which first surfaced last November, are likely to thrive until the onset of the southwest monsoon, when a shift occurs in marine conditions that underpin their current growth.

Since the outbreak in November, the blooms have been responsible for incidents of fish mortality and a pervasive foul odour that has all but driven swimmers and strollers from several beachfront hotspots. Many popular beaches, particularly in Muscat have also been temporarily sullied by copious deposits of foam blamed on the blooms and brought ashore by waves. Worse, the phenomenon has menaced many shore-based installations that depend on seawater intake for their operations, it is learnt.

"This is the first time that this particular type of phytoplankton -- Cochlodinium polykrikoide -- has been recorded in Omani coastal waters," said Dr Al Azi, who has been instrumental in identifying the species at the heart of the current outbreak. "Unlike other phytoplankton that periodically surface in Omani waters, this species has thrived for so long because of its peculiar characteristics that allow it to reproduce when marine conditions are conducive," he stated in comments to the Observer.

Dr Al Azri, who is a member of an international team of scientists funded by Nasa to investigate the impact of global warming on the ecosystem of the Arabian Sea, is currently supporting the Ministry of Fisheries, among other bodies, in their study of algal blooms in the Sultanate. An outbreak of Cochlodinium polykrikoide, according to the scientist, is characterised by three distinctive features: the colour of the bloom, which ranges from red to brown and even black depending upon the stage of its growth; the foul smell it emits as a result of its breakdown by bacteria; and finally the foam it generates when the species reaches a certain stage of its growth.

Indeed, much of the beachfront at Shatti al Qurum was carpeted with a thick coat of such foam last week, keeping away many visitors. Worryingly, the algal blooms are sweeping further down Oman's coast, says Dr Al Azri, with reports of outbreaks as far afield as Masirah. "The blooms are moving in an anti-clockwise direction along the Gulf of Oman and Arabian Sea. They began in September with satellite images showing them initially off the Pakistan and Iranian coasts, and later along the Strait of Hormuz and the UAE, before they began slowing moving towards Sohar and now Muscat. We now have information that the blooms have reached Masirah, and I worry that if prevailing wind conditions continue to persist, they will eventually reach Salalah."

Although classified internationally as a toxic species, the extent of toxicity associated with the Cochlodinium polykrikoide phytoplankton is still "debatable", according to the scientist. Still, he advises caution with regard to the consumption of fish potentially contaminated by the algal bloom. The many fish kills attributed to the species at the outset of the outbreak in November were caused by the release of "reactive oxygen" which damages fish gills. Equally harmful to fish is the large volumes of mucus produced by the blooms, which clog the gills and cause them to suffocate.

"Although there is no clear scientific evidence that the species is harmful to human health, my advice to people is to avoid eating fish that is either found dead or stressed in Red Tide contaminated waters. It is also best to avoid swimming in such waters, given the possibility of ingesting the algal microorganisms, or even handling the foam that washes up in areas affected by the bloom," Dr Al Azri said. The marine researcher is currently working alongside officials of the Ministry of Fisheries and Ministry of Environment and Climate Affairs, in delving into the causes behind the prolonged nature of the current Red Tide outbreak. "We need to look at the sources of the nutrients sustaining the current bloom, as well as study the peculiar conditions that favour their growth: wind patterns, water circulation, eddies, and other land-based factors," he added.

By Conrad Prabhu

© Oman Daily Observer 2009