Q&A: Ecologists assess oil spill damage
An oil slick originating from a rig about 130 miles southeast of New Orleans, which is dumping oil into the Gulf of Mexico at a rate of approximately 25,000 barrels per day, is drifting toward the Alabama, Florida and Louisiana coasts, and scientists are still assessing the ecological impact that will result. According to The New York Times, BP—the company responsible for the rig explosion and resulting oil spill—moved today to install a shutoff valve on one of the three leaks and is preparing to deploy a system to siphon oil from the water. The company also vowed today to “appropriate” all necessary costs for cleanup, which is likely to be in the billions.
Meanwhile, the National Oceanic and Atmospheric Administration (NOAA) closed commercial and recreational fishing yesterday between Louisiana state waters at the mouth of the Mississippi River to waters off Florida’s Pensacola Bay. Also yesterday, President Obama visited Louisiana to assess the economic and ecological damage first hand. After a briefing by federal and state officials, Obama told reporters that the leak repair could take “several days” and “mitigating the damage” will be costly for BP but that it is essential the government and coordinating agencies take swift steps:
This is one of the richest, most beautiful ecosystems on the planet. And for centuries, its residents have enjoyed and made a living off of the fish that swim in these waters and the wildlife that inhabit these shores. This is also the heartbeat of the region’s economic life. We are going to do everything in our power to protect our natural resources, compensate those who have been harmed, rebuild what has been damaged and help this region persevere like it has done so many times before.
In the Q&A below, three members of the Ecological Society of America’s Rapid Response Team discuss the current and possible future damage of this spill and the effects it could have on the Gulf region. Felicia Coleman has served on several scientific advisory committees related to marine conservation including an appointment to the Gulf of Mexico Fishery Management Council, Alan Covich studies the effects of disturbances, including Hurricane Katrina, on aquatic ecosystems and food webs and Josh Schimel was involved in developing the Exxon Valdez Oil Spill Damage Assessment and Restoration program.
Q: Broadly speaking, what is the ecological impact we can expect from this type of oil spill in this particular region?
A (Felicia Coleman): Anything said about the likely ecological impact of the recent oil spill has to be put in context by acknowledging the immense biological productivity and diversity that characterize the northeastern Gulf of Mexico. This region has the most to give in terms of fisheries production, supporting recreational and commercial industries valued in the billions of dollars, and the most to lose when habitats essential to that production are compromised.
Those habitats off Louisiana have already experienced extensive wetland losses through subsidence due to decades of oil and gas extraction, coupled with low sediment accumulation caused by levees intended to halt flooding and the more recent catastrophic effects following Hurricane Katrina. The west Florida coast, while feeling the brunt of a number of hurricanes, has not experienced the other problems and has the biological diversity and relatively pristine habitat to show for it. That could change in a matter of weeks.
“The ecological impact from Louisiana to Florida could be the loss of extensive areas of wetlands, saltmarshes and seagrass beds wherever the oil makes landfall and at a time when productivity is just gearing up for the year.”
Q: Considering pre-existing damage from hypoxia and Hurricane Katrina, what further damage could the oil spill cause?
A (Alan Covich): After Katrina, there was an expanded set of studies on the wetlands and their roles in shrimp and fish life cycles. The ecosystem services of these already impacted wetlands will likely have new threats to sustaining these critical roles. There is limited good news: The governors in the U.S. and Mexico have organized an international network to study these coastal zones. The studies have been ongoing but really are just getting started and are not likely well enough along to evaluate the total impacts of the oil.
“Much of the research in this region has focused on increased nitrogen in the coastal waters and the Dead Zone that has already lost important habitat through lack of oxygen in the bottom waters from excessive algal blooms.”
In Apalachicola Bay, Florida, there is a multi-million dollar shell fish industry; if oil is carried that far east, oysters and shrimp will be greatly impacted. That one bay was not impacted before because it did not get a direct hit from Katrina.
Q: How does this disaster compare to the Exxon Valdez spill in terms of wildlife and ecosystem impact?
A (Alan Covich): It’s been a while since a big spill, so ‘drill baby drill’ sort of caught on. The first one going way back was the Santa Barbara spill in 1969 and a lot in the 70s and 80s in important places where people are living and were most concerned about oil on the beach and their boats. And then much of the public concern kind of went away for a while. Now it will be a hot topic issue. The thing that stands out will be we know the extensive efforts to do clean up on a rocky shore, but it’s not so clear on wetlands.
A (Josh Schimel): We won’t know that for some time. How fast can they stop the spill? How successful will they be in keeping oil off-shore? How far inland will the oil be driven? Until we know those things, we won’t have a good handle for assessing or estimating. The estimates I’ve heard is that it will have to keep gushing for over a month to equal the amount of oil [seen in the Exxon Valdez spill], and this is a light sweet crude that may be highly toxic but probably shorter lived in the environment. The brown mucky mousse that grounded in Alaska was nasty crud.
Given that, my suspicion is that a plausible ‘very bad case’ impact is that it could easily be worse. Prince William Sound was an important fishery and spawning ground, but it wasn’t the only one in the region. The Sound fisherman suffered badly (and still are I understand), but the Gulf of Alaska continues to be one the world’s major fisheries. Even within a few years of the spill, Kodiak was still one of the biggest fishing ports in the world. Southern Louisiana and the Mississippi Delta comprise something approaching one-fifth of U.S. fisheries and it is the core of the Gulf of Mexico fisheries. It could be wiped out economically. Particularly in economic damage to shrimp, oyster and other fisheries—tainting the reputation of the fish may be as economically damaging as any chemical taint.
“As for wildlife, the Delta is some 40% of U.S. wetlands, a very rich and biodiverse region. Potential impact: huge.”
Q: There were several chemicals used during the Exxon Valdez cleanup. How were they used and did they work? Were there any long term ecological effects from the chemicals?
A (Josh Schimel): At sea, they used dispersants. Those are likely relatively short-lived in the environment, and given the flow patterns of the Sound, would be flushed out to the south-west with the prevailing currents to be diluted into the North Pacific Ocean. Their characteristics might also make them somewhat biodegradable or photodegradable themselves.
On shore, the main chemicals used in bioremediation were fertilizers—two mixes were used widely: Customblen, a slow release mix of nutrients in polymerized vegetable oil, and inopol which sticks to oil. If I remember correctly, it’s essentially urea in oleic acid (olive oil). The fertilizers did somewhat accelerate oil breakdown. Their direct long-term impact would have been limited because of tidal flushing. But would they need to fertilize the Delta? This is a region that is home to the largest marine Dead Zone going, almost entirely too excessive nutrient input from agricultural chemicals up the Mississippi. Would they need to (or want to) add more?
I think any amount they might add would be small relative to what comes down the river. However, it seems likely that the prime obstacle to biodegradation won’t be nutrients but oxygen and physical access. The Delta is made up of fine sediments that have come down river—sediments that are likely organic matter rich and are flooded. Organic-rich fine sediments are a great matrix for binding oil and making it unavailable for bacteria, while their flooded state makes for anaerobiosis—and hydrocarbon degrading bacteria do badly under anaerobic conditions. So the sediments are a perfect place to block biodegradation and a difficult one to try to stimulate it. Pumping oxygen might be more useful than fertilizer but more difficult than just spreading pellets.
Q: This area is known for its fisheries and seafood industry, how do you think these will fare and how long do you suspect it will take for them to recover?
A (Felicia Coleman): It’s hard to hazard a guess as to the scale of the impact. That will depend on the weather, oceanic current structure and the ability of BP and all government entities involved to contain the damage. But the effect will be greatest on foundation species—saltmarshes, seagrass beds and oyster reefs—and the communities they support by providing the structural integrity, the nursery grounds for many fisheries species and essential ecosystem services.
“If the Exxon Valdez spill is the best example—and there is every indication that this one could be far worse—it could take decades for recovery to occur in these areas.”
Q: Is there any particular significance of this time of the year for fish?
A (Felicia Coleman): There isn’t a ‘good’ time of year ecologically for a spill. Spawning of one suite of reef fish just finished (including a number of reef fish species important to the economy of the eastern Gulf) while others are just starting. Any pelagic larvae are likely not to survive immersion in oil. Those that have completed spawning weeks ago may have escaped a pelagic effect because they’ve reached their inshore nursery grounds, but they could still be affected weeks from now as oil moves into these inshore areas. Bound to be at greatest risk are those species that remain attached to the bottom and can’t escape the effects of prolonged exposure to oil pollution, including oysters, mussels and clams.
Q: How long do you estimate the wildlife and ecosystem recovery to take, given past experience with Exxon Valdez?
A (Josh Schimel): I think that is still very hard to predict. With the Valdez, we knew quickly how much oil went into the water and we knew where it went. With this spill, we still have no idea whatsoever how much oil is going to end up in the sea, or how much will ground. We do know that wetlands are the worst possible environment for a spill, and that of course, is what the Mississippi Delta is.
“If a significant amount of oil gets into the wetlands of the Delta, I would guess that major, visible impacts will last for somewhere between 3 and 10 years with measurable impacts potentially lasting for decades, slowly tapering off.”
One issue I would watch for would be toxicity to plants that help hold the sediments of the Delta in place. If there is significant toxicity to plants, we could see significant physical degradation of the system.
Q: What, if anything, can be done to prevent further or future damage?
A (Felicia Coleman): That’s a tough question because this is an extraordinary situation and likely to be the most environmentally damaging event we’ve ever witnessed. One of the things falling into place now is the set up of staging areas all along the coast to try to keep oil away from the shore where it can destroy sensitive habitats.
“The best thing any of us can do is contact the relevant Department of Environmental Protection in our states and find out ways to become part of state-coordinated efforts.”
There will be a series of sites going up in Florida soon that will provide the details, list-serves and updates. [Continue to check EcoTone for updates.]
And future damage? Ah, well, herein lies the rub. You can look at this from a number of different perspectives. Overall, it’s all about tradeoffs. If we, the citizens of this country, want to use non-renewable resources like oil, gas and coal, then we have to understand the risks (e.g., oil spills, increased CO2 in the atmosphere, climate change, sea-level rise, subsidence) and be willing to make that trade.
If we aren’t willing to trade, then we’ll invest in reducing our individual ecological footprints by either changing our habits or changing the energy sources we use. And if we’re really interested, we’ll let our government representatives know how we feel and that can affect some change.
Felicia Coleman is the director of Florida State University’s Coastal and Marine Lab, Alan Covich is professor and former director of the Institute of Ecology at the University of Georgia and Josh Schimel is chair of the Environmental Studies Program and professor at the University of California, Santa Barbara.
For more information on the status of the spill, the coordinated efforts by BP, NOAA, the Environmental Protection Agency and others are being tracked on the Deep Horizon Incident site. Florida’s Department of Environmental Protection has been designated the lead state agency for responding to potential impacts of the Deepwater Horizon oil spill along Florida’s shoreline; visit to help. Visit the Louisiana Department of Environmental Quality to help in that state.