x Abu Dhabi, UAETuesday 23 January 2018

A red clay could stem the red tide

A red clay that could provide a solution to red tides is being tested for use in the UAE, where it could help revive fish stocks.

DUBAI // A red clay that could provide a solution to red tides is being tested for use in the UAE, where it could help revive fish stocks and protect beaches and desalination plants. But concerns about how it might hurt coral reefs mean the process, being developed in Iran, might not be widely used. "We are working closely with other countries in the region to find solutions to the red tide problem and are monitoring the success of the clay method in Iran," said Ebrahim Jamali, director of the Marine Resources Centre. "We have coral reefs in the UAE that are sensitive to environmental impacts, and so we have reservations about the widespread use of the method. However, we are considering its use it controlled and concentrated areas to protect aquaculture fishing and desalination plants."

The clay binds with the algae blooms, causing them to sink to the seabed. But the material can form a blanket that deprives marine life of vital oxygen. Red tides, however, killed 900,000 tonnes of fish in UAE fish farms in 2007, lending urgency to the search for a solution. Mr Jamali said today that experiments using local clays were being conducted to learn more about their impact on the seabed and marine life.

"A key factor will be in finding a suitable local clay that will minimise the environmental impact of the method," he said. "Mapping of the sea bed will need to be conducted to see what species are present at the selected sites and how they will be affected before use of the method is approved." The technique, which is in widespread use in Korea, mixes a fine clay with seawater, which is then sprayed onto the algae bloom. One of the benefits of the method is that small areas, such as the gates of fish farms or desalination plants, can be specifically targeted.

Abdulla Abdulrazzaq, consultant to the assistant deputy minister for fisheries, said that more information about what caused red tides was needed. "The red tide was brought to the region by tankers arriving from areas where the oceans are polluted. The ships use water for ballast and when they release it, nutrients flood the sea and attract the algae blooms. "Changes and fluctuations in the temperature and current will have an effect on red tide, and it is possible it could clear through natural processes. However, it is important that potential solutions are identified and tested, and clay may be suitable in concentrated areas, including some beaches."

Dealing with red tides was at the top of the agenda at the Regional Commission for Fisheries, held in Dubai last week. The algae blooms were identified as one of the factors behind a dramatic decrease in fish stocks seen across the region, particularly in coastal aquaculture. Those projects, which help meet high demand by farming fish and releasing them into the sea, are seen as key to reviving populations of threatened species, such as hammour and bream. But the operations are susceptible to red tides because they are located in shallow waters, where the algae can rob the water of oxygen, killing the fish.