x Abu Dhabi, UAEFriday 21 July 2017

Red tide ebbs, then rises again

Despite hopes that cooler weather would help rid Dibba's waters of its red tide of algal bloom, the phenomenon has not yet subsided.

Algae-infested water surround one of the UAE's most popular diving and snorkelling spots in Dibba.
Algae-infested water surround one of the UAE's most popular diving and snorkelling spots in Dibba.

Despite hopes that cooler weather would help rid Dibba's waters of its red tide of algal bloom, the phenomenon has not yet subsided and is continuing to kill fish and threaten the region's tourism industry. Little is yet known about the algae responsible or why the tide has so far lasted two months, far in excess of its normal seasonal lifespan. An official from the Ministry of Environment and Water said that while he believed the algae was not toxic, people should not eat shellfish or shrimp from the area.

The east coast waters cleared up briefly at the start of last week but by midweek, the ocean again took up a brown-red hue, indicating the presence of algae. Satellite images produced by the Kuwait-based Regional Organisation for the Protection of Marine Environment (Ropme), show the bloom is affecting more than 200km of the coastline from Muscat in Oman, through the Musandam Peninsular, and down to Dibba in Sharjah.

Dr Ibrahim al Jamali, director of the Marine Resource Research Centre in Umm al Quwain, said scientists had still not identified the species responsible for the red tide. "We sent some samples to France and some to Ropme in Kuwait and are awaiting their answers," said Mr Jamali. The samples, he said, were taken two weeks ago. He said he did not believe the red tide in Dibba was toxic but had still urged residents to avoid eating sea food as they acted as de facto filters for the water.

Another question which officials still cannot answer is why the red tide is lasting for such a long time. "This [phenomenon] occurs naturally in the UAE but it goes away usually after two or three days," said Mr Jamali. It is still not known whether human activity could be contributing to the problem, he said, adding that Cyclone Gonu, which hit Oman and the UAE in the summer of 2007, could be another contributor.

Jeffrey Catanja, a manager at the Sandy Beach Dive Centre, said there were signs it was subsiding last week. "The sea was back to normal on Monday and Tuesday. Then, all of a sudden, on Wednesday it became red again." By Friday, Mr Catanja and his customers had lost hope that the bloom was subsiding. "People cancelled all bookings because of this," he said. "Next week is the public holiday. I hope it will not be like this, a lot of people will be disappointed."

"The water was rusty brown - like mud," said Gernot Dobida, who went scuba diving on the East Coast on Friday. "It got clear after a depth of seven metres but it was really dark as the algae seemed to be blocking the sunlight from penetrating. It was like a night dive." Beach-goers were not happy either. "My family went for a picnic near the Royal Beach Hotel and Resort and all around us, the water was dark brown," said a Dibba resident who asked not to be named.

"There was such a bad smell coming from the sea that I got a headache 40 minutes after arriving at the beach? This smell is all over Dibba, especially when the wind is blowing from the sea." Algae are microscopic organisms which serve as an important marine food source. Under certain natural or man-made conditions, algae can multiply so rapidly that they form dense patches in the water. Depending on the colour of the organisms, they can cause the water to appear murky in shades of brown, red, pink, yellow or green.

If the algae multiply too fast, they deplete the oxygen dissolved in water causing fish to suffocate. Some algae are toxic. They can kill fish and are also a threat to the people who swim in algae-infested water or who eat sea food from such areas. Of the 20 species of algae common in the UAE, nine are toxic and represent a health concern. vtodorova@thenational.ae