Sea snakes around the UAE are contaminated with chemical pollutants, some of which are known to affect the reproductive capacity of other animals, notably reptiles and birds.
A chemical derivative of the pesticide DDT, the use of which was banned in agriculture in the US half a century ago because of its effect on wildlife, was among those detected.
In a paper, published in July in Marine Pollution Bulletin, scientists at Sharjah’s Environment and Protected Areas Authority (EPAA) and the American University of Sharjah carried out a detailed analysis of 13 sea snakes found dead.
Researchers looked for two groups of pollutants, organochlorine pesticides (OCPs) and polycyclic aromatic hydrocarbons (PAHs), which are types of persistent organic pollutants, branded forever chemicals because they remain in the environment for a considerable length of time.
OCPs and PAHs were found in all specimens, suggesting that exposure of sea snakes around the UAE to chemical pollutants is common.
“We believe that this exposure is chronic, with effects comparable to the health impacts experienced by people when they are exposed to pollutants in areas with reduced air quality, such as congested cities,” said the first author of the study, Fadi Yaghmour, a scientific researcher at the EPAA.
“With an increasing population, it is inevitable that some pollutants will enter the water, which may lead to a decline in the overall health of marine animals.”
The animals, mostly found on Sharjah’s west coast, had been collected through the Sharjah Strandings Response Programme, which picks up dead marine reptiles, mammals and seabirds. The group also rescue injured and unwell animals, nursing them back to health and releasing them.
The researchers carried out tests on 10 Arabian Gulf coral reef sea snakes, two ornate sea snakes collected from the west coast, and a single spine-bellied sea snake found on the east coast.
“Overall, the concentrations reported in this study surpass those documented in other marine reptiles within the UAE or sea snakes from different geographic areas,” the researchers wrote.
The effect of this contamination on the health of the sea snakes, including their ability to reproduce, is poorly understood because scientists have not carried out detailed studies on this.
Mr Yaghmour said that it was known that some of the substances could affect the reproductive success of other reptiles and birds, suggesting that sea snakes too may be harmed.
Chemical build-up
Older specimens, which are heavier or longer, typically had higher concentrations of the pollutants, demonstrating that the chemicals build up over time, a phenomenon known as bioaccumulation.
“As the sea snake gets older and older, it accumulates more pollutants over time, similar to how a chain smoker or a person exposed to reduced air quality accumulates pollutants from the air they breathe,” said Mr Yaghmour, who works at the EPAA’s Hefaiyah Mountain Conservation Centre.
Co-authors of the study include Prof Fatin Samara, of the American University of Sharjah, and Johannes Els and Susannah Philip, both of the EPAA’s Breeding Centre for Endangered Arabian Wildlife.
Researchers from the University of Melbourne and the Australia Zoo Wildlife Hospital in Beerwah, Queensland also contributed.
One chemical detected was DDD, which is produced when organisms metabolise the insecticide DDT.
DDT became well known after the American biologist Rachel Carson’s 1962 book Silent Spring, which highlighted the environmental damage that the chemical caused and was pivotal in the US decision to outlaw its use in agriculture in 1972.
Many other countries also banned DDT, and in 2004, a worldwide agriculture prohibition was introduced. The substance is still sometimes used to kill mosquitoes that may spread malaria.
The life of a snake
Sea snakes live to about 10 years old, so the study’s findings reflect contamination present in the environment now or in recent years.
Determining when or where the pollutants were released is, however, difficult, as so-called forever chemicals remain in the environment for many decades and may spread widely.
Some pollutants are passed down from one generation of marine animals to the next, such as through dolphin milk or turtle eggs.
“The lesson is perhaps to respect and observe environmental regulations in the region and the country,” Mr Yaghmour said.
“In the country and the region, there are good laws in place. If followed, these laws will reduce environmental exposure to pollutants, leading to significantly healthier ecosystems and animals that we rely on and are part of.”
The EPAA is keen to spread the message that sea snakes, although venomous, do not typically pose a threat to the public and should not be harmed.
“There is a fear that exists from the public of sea snakes and it is mostly an unfounded fear,” Mr Yaghmour said.
“Sea snakes are not inherently dangerous, but their bite can be. Bites typically result from irresponsible behaviour.
"Therefore, sea snakes should not be considered a menace.”
Sea snakes will not approach and attack swimmers, although the advice is to move away from them if they are spotted in the water.
If a sea snake is found on the beach, Mr Yaghmour said a lifeguard or the authorities should be informed and the animal should not be touched, even if it is dead.
