Oil spill blamed for mass coral mortalities

When news broke out of the Deepwater Horizon oil spill in the Gulf of Mexico last April, it was clear that the environmental consequences would be catastrophic. Yet reports last week that coral communities may have been killed as a result of the spill come as unwelcome surprise. A team of scientists used a submersible robot, named Jason II, to explore more than thirty coral and seep sites in the Gulf. The discovery of a 40 by 15 metre site where approximately 90% of gorgonian soft corals were either dead or dying comes to the dismay of environmentalists worldwide, as initially it was hoped that corals may be safe from damage by the oil. This is the latest piece of evidence to indicate that the oil has indeed sunk in the waters, a worst case scenario for coral reefs.

The expedition led by marine biologist Charles Fisher, investigated depths of 1,400 metres. The dead coral site was located 11 kilometres southwest of the oil spill and although the cause is currently uncertain, circumstantial evidence strongly points towards the oil spill. Fisher stated that the corals were covered in a slimy brown substance, thought to be mucus which corals release when they are experiencing stress, as opposed to the oil itself. Alternatively, it is possible that oil- and gas-consuming microbes in the water have caused oxygen levels to deplete, thus leading to the death of corals, but there is no conclusive proof for this.

Coral reefs are renowned for both their beauty and their growing demise. Corals are crucial in providing food and shelter for many fish species, yet they are under threat from climate change and various human activities, such as dynamite fishing and mining.

Frontier has long been monitoring coral reefs in Tanzania and Fiji, predominantly by conducting baseline surveys on coral reef biodiversity. These surveys help us to monitor the reef’s health and checks for signs of damage from human activities, such as destructive fishing practices and pollution. Such work may help prevent the loss of coral reefs, which could destabilize entire marine communities.

By Flora O’Brien

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