July 2010

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ENVIRONMENT: BP’s deep troubles

The far and future effects of the oil spill

By Dr. Azad Mohammed and Dr. Judith Gobin

On April 20th 2010, an explosion occurred at BP’s Deepwater Horizon drilling rig, unfortunately killing 11 platform workers, injuring 17 others and triggering an oil spill in the Gulf of Mexico (GOM). Little did we know that this would potentially be one of the worst spills in history, even as the flow continues to date (Day 76). Latest estimates from US scientists suggest that approximately 160-380 million litres (between 42 to 100 million gallons) of oil have already entered the GOM. The Exxon Valdez disaster of 1989 which was earlier considered the largest spill now pales in comparison–it released 41 million litres of oil.

Impacts of the spill: The impacts of this disaster are compounded by the sheer size and scope of it. The picture is indeed grim, not only for the Gulf of Mexico’s environment and proximal areas–their coastal and marine ecosystems–but for the cascading effects, and ultimately on human beings in terms of loss of livelihoods and severely affecting the tourism industry. The longer-term socio-economic impacts are therefore expected to be severe.

On the ocean’s surface is the obvious oil slick while beneath the sea’s surface there is now a toxic soup of hydrocarbons and dispersants (being used to disperse and/or break down the oil). It is this combination of processes which will potentially harm many sensitive parts of the ecosystem. The millions of barrels of oil being released enter the water and begin to break up or scatter into the marine environment. This occurs as a result of a number of chemical and physical processes related to the oil itself (chemical make-up) and the environment (ambient conditions). These processes begin to change the compounds that make up the oil. The main factors that influence the fate of oil include: the type of oil, the direction of ocean currents, wind speed, turbulence, temperature, solar radiation and tidal flows. These factors influence the rate at which the oil spreads and the areas that are subsequently affected.

The impacts of oil can be realised at different levels and may be either short or long term as it relates to petroleum toxicity and oxygen depletion. Ecological and environmental effects arise as a result of exposure to the oil itself or to the components of the oil. The most visible effects of oil are associated with the direct coating of animals and the environment as we have seen in the numerous GOM photos presently on the web and newspapers. Oil interferes with insulation, respiration and mobility of many animals and this is the primary cause of mortality during the initial phase of a spill. The immediate negative impacts are also on the millions of translucent zooplankton which, being a food source for other marine organisms, ultimately end up having cascading effects up the food chain. Additionally, oil reduces the amount of light penetration in the water and thus significantly affects primary productivity, one of the main driving forces of all ocean productivity.

The GOM spill has already reportedly killed over 1500 animals, although this may not be a true estimate as many carcasses would have sunk and may not yet be found. GOM reports have indicated that dolphins were seen blowing oil from their blow holes. Some GOM fauna will die as a result of ingestion of toxic components of the oil itself or from oil-covered carcasses. Juveniles or sensitive life stages are even more susceptible and losses in these populations are expected to be greatest. In this respect, losses will be exacerbated since this event has occurred at the height of the reproductive season (spring) in the GOM which was teeming with larval stages and coincided with the nesting season for sea turtles.

In the GOM, various shell fish species which rely on the oceans for fertilization and dispersal are particularly at risk because of depleting oxygen and exposure to the toxic oil fractions. Surface oil reduces the amount of oxygen in the water, resulting in rapid oxygen depletion, while toxic components may be incorporated (bio-accumulated) in animal tissue and transferred through the food chain. Sedentary fauna and shellfish, such as oysters, are usually more at risk as they routinely filter large volumes of water to extract food, and are therefore more likely to accumulate oil components.

Oil exposure effects will not only be felt in the water but also in coastal environments of the GOM such as beaches, wetlands and coral reefs. In addition to their contributions of biodiversity these environments also provide ecosystem services–those direct or indirect contributions that the environment makes to the well-being of humans. For example, wetlands, reefs and beaches protect our coastal communities from natural disasters by reducing storm surges. A destroyed wetland or coral reef will reduce this natural barrier. Another negative effect comes directly from the massive quantities of dispersants being used. The estimated volume of dispersants is now 1.67 million litres: 1.06 m litres on the surface and just over 600,000 undersea. On the one hand, while dispersants assist in breaking up the oil (by accelerating microbial activity) and often reduce the toxicity of the oil, at the same time (being chemicals) they also cause additional negative impacts on biological organisms.

The Harte Research Institute (HRI) at Texas A&M University, Corpus Christi, completed an all-species inventory of the GOM in 2009. Data from that study show that the area containing the Deepwater Horizon oil spill contains 8332 species of plants and animals. Having that information in the face of this disaster is fortunate and timely as this data set will be invaluable in helping to assess the effects of the spill and ecosystem recovery following cleanup activities. Despite the dreadful circumstances, it is an almost ideal situation, as there is excellent “pre-spill/impact” data which will be used to compare with “post-spill/impact” data.

Another critical impact of the GOM spill is a human health one, as oil contains a mixture of volatile hydrocarbon compounds (such as benzene and xylene) which are known carcinogens. Exposure to these compounds–especially by response teams–may lead to dizziness, nausea, headaches and chest pains. Over 143 cases of exposure-related illnesses have been reported for the GOM spill and we can expect this value to significantly rise as response efforts continue.

The Deepwater Horizon spill therefore brings far-reaching and multi-pronged devastation since there is an associated billion-dollar value of annual economic activity as well as the ecosystem services at risk. Many livelihoods revolve around harvest from the sea (fish, lobster, shrimp, oysters, etc.). The Louisiana fishery has been devastated with the banning of fishing and damage to property such as boats and fishing gear. Oily beaches will also have a direct negative impact on tourism in the affected coastal areas.

According to Drs. Shirley, Tunnell, Jr., Moretzsohn, and Brenner (of HRI) loss as a result of the GOM spill “includes ecosystem services of $1.2 billion; recreational fishing ($114 million), commercial fishing ($30.3 million) and tourism ($77.6 million).”

As expected, tropical storm activity (given the hurricane season) will increase turbulence and wind speed, accelerating the spread of the oil, which of course, extends the points of impacts. At the same time, oil with an asphaltene content greater than 0.5%, can form stable emulsions which may persist for months after the spill. In effect, the long term effects of this spill may not be fully realized for some time to come.

The Caribbean islands do not appear to face any immediate threats by the GOM oil spill, although concerns were raised (June 18th 2010) by Caribbean Ministers to the US Secretary of State, Hillary Clinton in Barbados. Around the same time in Port of Spain, the Association of Caribbean States (ACS) held its 11th meeting of the Caribbean Sea Commission whose chairman, Barbados Minister of Health Donville Inniss, was also voicing concerns.

“It is very important to preserve our marine space. The Caribbean Sea is not only vital for recreation but for economic benefits as well. Many of our industries utilise the sea, such as the tourism and fishing industries,” he said.

Based on oceanographic studies, the US National Oceanic and Atmospheric Administration (NOAA) suggested that “oil bearing currents will follow an offshore course past the north of the Cuban coast, before turning and passing to the west of Bahamas and away from the Caribbean.”

Trinidad and Tobago is the largest oil producer in the Caribbean with our immediate neighbor (approx. 13km) Venezuela being the fifth largest producer in the world. The possibility of an oil spill of such magnitude in our area is perhaps not far-fetched. In terms of preparedness for such a situation, Trinidad and Tobago recently updated (Feb. 2010) it’s National Oil Spill Contingency Plan (NOSCP of 1997). The responsibility of co-ordination now lies with the Organization for Disaster Preparedness Management (ODPM). In the event of a spill being beyond the local and regional resources, the ODPM will “contact relevant operators to engage the services of Tier 3 equipment providers (ie substantial resources and support, including worldwide co-operation).” Our Caribbean marine biodiversity is now reasonably well known with the most recent contribution by Milosavich et al. (2010). This work is the first complete report on the status of marine biodiversity including island inventories for the Caribbean. This and other inventories will indeed serve as appropriate data sets for possible comparative impacts (following an oil spill for example), although there are still many data gaps which need to be addressed.

It is therefore timely that the Caribbean heeds this GOM incident as a warning and ensures that we implement an appropriate regional plan of action to address such a potential disaster. This is critical in order to protect our coastal and marine ecosystems (biodiversity and other services) which play a major role in sustaining our economies.

-Dr Judith Gobin is a Lecturer (Marine Biology) and an Environmental Scientist, and Dr Azad Mohammed is a Lecturer (Physiology) and a Toxicologist, Department of Life Sciences, UWI St. Augustine.