Exotic species pose danger to marine life

DUBAI - The introduction of exotic species in the waters of the Arabian Gulf, through ballast water from cargo vessels, is one of the major threats to the region's marine environment, Dr Waleed Hamza, Head of the Department of Biology at the UAE University, said yesterday.

By A Staff Reporter

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Published: Sun 30 May 2004, 9:20 AM

Last updated: Thu 2 Apr 2015, 11:32 AM

He was delivering a presentation on the "Status of the Marine Life in the Arabian Gulf - Towards Effective Protection and Management", at a workshop on artificial reefs, titled Challenges in the Oceans: The Runde Reef System.

Dr Hamza explained that there are several other factors that have an impact on the region's marine environment, such as increase in coastal population density, desalination plants and discharge of sewage, and oil transportation activity, but noted that ballast water has a key role in eutrophication and fish kill phenomenon. "According to figures available some 50,000 cargo vessels, including tankers, operate in the Arabian Gulf annually. They discharge a total of 30 million cubic metres of ballast water each year, introducing exotic species of marine life that compete with and wipe out those species that occur here naturally," he said.

According to Dr Hamza bacteria have play a very important role in somewhat balancing the marine environment of the Gulf. "There has been a natural seepage of oil in the Arabian Gulf and the bacteria have come to adapt themselves to the environment, and have become specialised at degrading and breaking down the pollutant," he said. Ballast water is the water that large ships fill up their ballast tanks with when they unload their cargo in order to attain balance. The quantity of ballast water could be as much as a quarter of a vessel's full capacity.

This water is pumped in from around the unloading area, which is usually polluted and infested with invasive marine organisms. When these ships dock in to reload they dump the ballast water, without treating it.

Dr Hamza shed light on the characteristics of the Arabian Gulf, which he noted has a limited input of fresh water, about 10 to 46 cm per year and mainly from the Shat Al Arab and Iranian rivers, as a result of which its salinity is higher. He revealed that the Gulf, which has a depth of 100 metres, had dried up during the last ice age when the sea level dropped by over 150 metres. "So the biomass in the Arabian Gulf is just 20,000 years old," he said.

Dr Hamza added that Gulf experiences an average annual rainfall of three to eight centimetres and an evaporation of about 140 to 500 centimetres annually.

"The freshwater deficit in the Gulf is ten-fold and the water is renewed between every two to five years," Dr Hamza added.

The lack of information in the region is a major issue in marine management, Dr Hamza said, adding that while there is information available country-wise, there are gaps in the data in one or the other aspect, making analysis and understanding of the Gulf as a whole difficult.

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