The two-hour drive from New Orleans to Venice, La., is like cutting into a slice of apple pie—it’s as American as it gets. Busy streets and high-rise buildings give way to farms, fields, and wetlands, in the perfect picture of rural, small-town America. With the exception of the occasional oil refinery or church, most buildings in Plaquemines Parish stand no more than a single story high. Driving down Louisiana Highway 23, the sole road in and out of the parish, it is clear to see that fishing is a way of life down here; boats or fishing traps are present in the front yards of most homes. The community here is evidence of the seafood industry being one of the leading sources of income and the highest employers in Louisiana. According to a fisheries economics report from the National Marine Fisheries Service (NMFS), commercial fishermen in the Gulf of Mexico harvested 1.27 billion pounds of finfish and shellfish and earned $659 million in total landings revenue in 2008.

Seafood is more than just catch sizes and dollar signs, though. Go to any restaurant along any beach in the Gulf, and you’ll likely find a menu full of grouper sandwiches and crab legs, shrimp baskets and oysters on the half shell. Seafood isn’t just a source of food or a way to make a living here--it’s a way of life, and an inherent piece of Gulf Coast culture. It is a culture that has been put in jeopardy as a result of the Deepwater Horizon disaster.

After the Deepwater Horizon oil rig exploded on April 20, 2010, more than 200 million gallons of oil flowed out of the Macondo well and into the Gulf of Mexico before the leak was finally plugged. Add to that the nearly two million gallons of the dispersant Corexit subsequently applied to the spill and it’s no wonder that the government, scientists and the public alike are wondering what sort of effects this chemical cocktail will have on the Gulf ecosystem, and especially seafood. While the mainstream media has widely covered the debate over seafood safety, these stories do not delve into the science behind the issue, nor do they highlight the dangers that chemically dispersed oil poses to the marine food web. Not only is there concern about the current safety of Gulf seafood, but there are concerns about the long-term effects dispersed oil may have on fish populations, further jeopardizing Gulf fisheries in the future.

Eric Schwaab, assistant administrator for the National Oceanic and Atmospheric Administration (NOAA) Fisheries Service explains in a press release the joint protocol established by federal and state agencies to ensure seafood safety. "No single agency could adequately ensure the safety of seafood coming from the Gulf following this tragedy," he notes, "but in working together, we can be sure that tainted waters are closed as appropriate, contaminated seafood is not allowed to make it to market, and that closed waters can be reopened to fishing as soon as it is safe."

On April 19, 2011, almost one year to the day of when the Deepwater Horizon disaster first began, NOAA reopened the last section of the Gulf that was once closed to fishing. With all federal waters currently reopened, the question still remains— is the government responding appropriately to ensure not only that the present levels of oil and dispersants are not toxic, but also that those levels won’t build up over time through the accumulation of toxins in the tissues of seafood, contaminating Gulf seafood for generations to come?

Quick to Close, Quick to Open?

Seafood testing, began almost immediately after the spill, and lasted several months and re-testing will occur into the summer. To conduct these tests, government vessels have systematically sampled seafood from across the Gulf by using a grid system.. The samples collected must successfully pass both a sensory test by experts trained in sniffing out trace amounts of oil, and chemical testing in a laboratory.

"Once you’ve opened up the areas, the government has deemed that the product is safe," says Steven Wilson, chief quality officer for NOAA’s Fisheries Seafood Inspection Program.

Some scientists are not as optimistic about the safety of Gulf seafood.

"Any ‘all clear’ should be tempered with caution, because there’s still oil there, it’s still moving around, and so areas that seem clear now could become affected as these plumes drift around in the ocean," says Gina Solomon, a senior scientist for the Natural Resources Defense Council and co-director of the University of California at San Francisco Occupational and Environmental Medicine Residency and Fellowship Program.

"One important thing to note is that the data that have come out so far on seafood haven’t show any elevated contaminants in really any of the commercial seafood from the Gulf," says Solomon. However, she explains there’s a critical need for ongoing testing in the coming months or years to assure that the seafood is not only safe now, but stays safe. "It would be a mistake to do one round of tests, declare the seafood safe, and walk away," Solomon adds.

Wilson explains that although the state and federal agencies want to continue with some monitoring as the response phase ends and the recovery and restoration phase begins, money may be an issue. "The question is where the funds come from." Wilson says.

In addition to the need for ongoing testing, Solomon believes that "there hasn’t been enough sampling of some of the most potentially risky seafood, and that specifically includes shrimp. We can’t be sure that the sampling is adequate enough to detect a problem if there is a problem out there."

Certain types of seafood are riskier than others. Species at risk include bottom-dwelling species, burrowing crustaceans such as shrimp, and filter-feeding shellfish. Finfish are usually at lower risk of becoming tainted because they are usually not exposed to oil or exposed only briefly and because they rapidly eliminate any oil that winds up in the body. But according to the NOAA Publication Managing Seafood Safety After an Oil Spill, exceptions may occur if a large amount of fresh, light oil is mixed into the water column or if the spill occurs in deep water, conditions which were both met by the Deepwater Horizon oil spill. The oil that flowed from the wellhead was a sweet Louisiana crude, a light oil that is readily dispersed and was aided by dispersants, and the spill occurred at 5,000 feet deep. The circumstances surrounding the Deepwater oil spill created the perfect storm to increase the risk of contamination.

Even if exposure to oil is fleeting, and the concentration of oil is low, there still are dangers. "There is no safe level of exposure to this oil," says Susan Shaw, a marine toxicologist and director at the Marine Environmental Research Institute in Blue Hill, Maine. The oil contains carcinogens and mutagens that can damage DNA and cause cancer and other chronic health problems.

To assess the risk posed by seafood containing polycyclic aromatic hydrocarbons (PAHs), which are known carcinogens, most seafood risk assessments conducted after oil spills in the United States have followed an approach used by the Food and Drug Administration (FDA) in 1990 after the Exxon Valdez oil spill in Prince William Sound, Alaska. The acceptable risk level of cancer from seafood consumption is determined by the quantity of seafood the average individual consumes, the body weight of the average consumer, the average human lifespan, the length of exposure, and the concentration of the PAH benzopyrene. Using this approach, the lifetime cancer risk should be no greater than 1 in 1,000,000.

However, the FDA is now using a less rigorous standard than it did in 1990 – one that tends to underestimate how much seafood Gulf residents actually eat.

"For the Exxon Valdez, there was more awareness of high levels of seafood consumption in local populations," says Solomon. "They used local fish consumption rates to estimate what levels of contaminants were safe or would be excessive. In contrast, with the Gulf oil spill, FDA used national seafood consumption rates that don’t reflect what people on the Gulf Coast are eating."

"The assumption that they’re using […] is not as protective of human health as the one that they used for the Exxon Valdez," says Solomon.

The current FDA risk assessment protocol is based on a 176-pound man eating four shrimp a week. That doesn’t account for women or children, whose body weights are lower, let alone local seafood consumption along the Gulf Coast. "Nobody in the Gulf really eats four shrimp a week, so it’s unrealistic the way they are assessing risk of consumption," says Shaw.

For those who live on the Gulf Coast, seafood is a way of life, and sometimes a daily part of their diet. Louisiana fisherman George Barisich, president of the United Commercial Fisherman’s Association, laughed heartily at the idea of eating only four shrimp a week. Solomon reports that many people she talked to on the Gulf Coast told her, "Four shrimp?! That’s not even one po’ boy!"

Barisich, like many other fishermen, has concerns about going back out into the Gulf. "Some of us have areas that were not much impacted and the product looks good, and some us are still fishing areas that still have oil spills," he says. "They want us to say everything’s okay. Well I don’t know about everything being okay."

According to Barisich, only 18 percent of the fleet is out fishing. The quantity of seafood out there is so small, he says, that if all the fishermen were out, they wouldn’t be bringing much in or making any money. "As consumer confidence grows, then the price may come up. But we took a lick. We took a bad beating in the prices," he laments.

But consumer confidence in Gulf seafood is low, very low. In a recent study by the University of Minnesota, 44 percent of respondents said they would only eat seafood if they knew it didn’t come from the Gulf of Mexico. "Much more data is needed to restore public confidence," says Shaw. "There’s an urgency to reopen the fishing areas but I think it’s likely that we’re going to find oil in the food chain."

The public is not only worried about seafood contamination from oil, but also from the dispersant Corexit.

"What we do see, or expect to see, is that consumers are very wary of buying fish from the Gulf, in part because of the issue of the dispersant," says Jennifer Jacquet, a post-doctoral researcher at the University of British Columbia. "We’re seeing consumers saying ‘We don’t want Corexit fish.’"

With the public and independent scientists crying out for testing of dispersants in seafood, in late October NOAA and FDA began testing seafood for the presence of dioctyl sodium sulfosuccinate, better known as DOSS. When asked why DOSS was chosen for the dispersant tests out of hundreds of chemicals in Corexit, NOAA’s Wilson says, "This was the best was obvious to all the agencies that this was the ingredient that should be looked at."

Shaw disagrees with the validity of the DOSS tests.

"The DOSS testing is rather unimportant because it does not address the toxicity of the oil-dispersant mixture," says Shaw. "It only measures one of hundreds of compounds in Corexit, as a tracer, but the toxicological significance is minor. In reality, the DOSS testing does not ‘strengthen public confidence’ in the safety of seafood, as claimed."

In July, Shaw authored a consensus statement opposing the use of chemical dispersants in the Gulf of Mexico. Some of the initial signatories of the consensus statement include high-profile marine scientists such as Sylvia Earle, Ocean Explorer-in-Residence for the National Geographic Society; Carl Safina, president of Blue Ocean Institute; David Guggenheim, president of 1planet1ocean; and Wallace J. Nichols, research associate at the California Academy of Scientists. One of the recommendations called for the full disclosure of all the chemical ingredients in the two Corexit formulations used by BP and full data on the toxicity of these chemicals when combined with oil.

"We still do not have disclosure on hundreds of chemical ingredients present in Corexit products because these are protected under US law as trade secrets," explains Shaw. "This makes it difficult, if not impossible, to predict with certainty the extent of toxicity of this dispersant or how the dispersant ingredients interact with oil in the water column."

The Issue of Dispersants

In early October, a staff working paper from the National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling became publicly available. The paper, "The Use of Surface and Subsurface Dispersants During the BP Deepwater Horizon Oil Spill", points out that the use of dispersants during the aftermath of the Macondo deepwater well explosion was controversial for three reasons. First, the total amount of dispersants used was unprecedented: nearly two million gallons. Second, 771,000 of those gallons were applied directly at the wellhead, with little to no prior testing on the effectiveness and potential adverse environmental consequences of using dispersants at that depth, let alone at those volumes. Third, the existing federal regulatory system pre-authorized dispersant use in the Gulf of Mexico without any limits or guidelines as to amount or duration.

"We allowed BP to disperse the oil so now it’s more persistent and toxic. Deepwater Horizon oil is in the food chain, and will be there for decades," says Shaw. "The motivation was economics, not health or the environment." BP is economically liable for every barrel spilled; dispersing the oil so that it cannot be collected by skimmers and accounted for, could result in the amount spilled to be underestimated, and smaller payouts by BP.

After the US Environmental Protection Agency (EPA) conducted a round of dispersant tests back in July, it announced that Corexit 9500 "is generally no more or less toxic than mixtures with the other available alternatives" and "the dispersant-oil mixtures are generally no more toxic to the aquatic test species than oil alone." The tests failed to test Corexit 9527, the more toxic of the two. Additionally, the tests were conducted in a laboratory setting on only two aquatic species— mysid shrimp and small estuarine fish – although more than 15,000 marine species inhabit the Gulf, and only measured the concentrations that cause 50 percent of the test organisms to die within 48 or 96 hours of exposure.

Most important, perhaps, EPA tests failed to measure sub-lethal effects of oil dispersants, such as the potential impact on the growth or reproduction of various seafood species.

The EPA claims that dispersant-oil mixtures are generally no more toxic than oil alone. But in a review of literature related to oil spill dispersants from 1997 to 2008, the Prince William Sound Regional Citizens’ Advisory council found that, in the recent toxicity studies, about 75 percent of researchers found that chemically-dispersed oil was more toxic than physically dispersed oil. The main concern is not so much the dispersants themselves, but rather how the dispersants change the oil. Dispersants function like detergents to break up the oil into small droplets that mix easily into the water column, where they may be more easily picked up by the bodies of fish and shellfish. "The dispersed oil ends up small enough that it can get in through the gills or be more easily eaten by fish or shrimp, and that could mean that the oil could accumulate more in seafood," says Solomon.

According to Shaw, there is already evidence that crabs and crab larvae have oil in their bodies, and recent studies by two separate laboratories show that Gulf shrimp contain oil and hydrocarbons.

Scientists aren’t the only ones concerned.

"You’re scared to death to put a product on the market that may or may not be tainted, even though the overwhelming testing on the tissue…is conclusive that there’s no level of toxicity that can hurt anybody," says third-generation shrimper Barisich, in his typical, southern Louisiana accent. "But there’s also the argument that the bioaccumulation over time, we’re gonna get screwed."

Over time these toxins have the potential to accumulate within organisms, and then be passed further up the food chain. One species of concern is the lowly menhaden. Aaron Adams, manager of the Fisheries Habitat Ecology Program at Mote Marine Laboratory in Sarasota, Florida explains, "With menhaden, they can actually accumulate toxins that are in the plankton after the oil spill, and then fish that eat them could magnify concentrations of those and that can actually be passed up the food chain."

These effects won’t be seen right away, as levels of toxins build gradually up over time.

"We have decades of toxicity in the Gulf water column that will not be seen," says Shaw. "It will take decades to understand the full extent of impacts of this oil on niches in the food web."

Scientists are not only concerned about the accumulation of toxins in organisms, but also the effects that the dispersed oil may have in the long-run on the growth, reproduction, fertilization success and embryo development of marine life in the Gulf.

"It’s so easy to take pictures of oiled birds, but the real impacts and the real work are under the surface," says Adams. He compares the unseen oil in the Gulf to cancer in a human, saying, "You don’t see it. The cancer isn’t evident until it’s way too late to do anything about it, but it’s still probably going to kill the person anyway or at least cause issues. You don’t have to see it for it to have an effect."

The Fate of Fisheries

Some species may be hit harder than others, such as the Atlantic bluefin tuna, which spawn at the exact same time and location that the oil spill occurred. Already considered critically endangered by the International Union for the Conservation of Nature (IUCN) due to an 80 percent decline in the past 30 years, new satellite data from the European Space Agency shows that one-fifth of juvenile Atlantic bluefin tuna were killed as a result of the Deepwater Horizon oil spill. Other species may be hit hard too, as many of the reef-associated species in the Gulf spawn around that time of year as well.

It would not be the first time that a large-scale event had ecological repercussions; the impacts of which will not be seen for some time. In 2005, there was a very extensive red tide that lasted for many months along the west coast of Florida. When a fisheries stock assessment was completed last year, the models didn’t quite fit until they were modified to include factors related to a large population die-off due to the red tide. "It would appear that the 2005-year class of many of the reef-associated species was in fact impacted by this red tide," concludes Stephen Bortone, executive director of the Gulf of Mexico Fishery Management Council, which makes fisheries recommendations to the National Marine Fisheries Service .

"Big events like [the red tide or oil spill] can have impacts on whole year classes of species in significant portions of the Gulf," says Bortone. These impacts wouldn’t be seen until many years later, when the species reaches sexual maturity and joins the fishery part of a population. Adams explains that continued monitoring is going to be important, especially for the long-lived species, the effects of the spill will be reflect in trends.

"One of the biggest challenges that we face with this event is that we really are in a data-poor situation when it comes to marine resources in the Gulf of Mexico," says Adams. "Rather than have the resource managers caught with their pants down again, it would be quite a reasonable investment to do the monitoring now that they weren’t doing before, so they can actually be able to make those predictions and have much better answers."

Further research is needed to determine the impacts that the oil spill will have on fisheries in the Gulf of Mexico. Bortone reports that the Gulf of Mexico Fishery Management Council is increasing its assessments directly related to oil spill associated features. In addition, the organization wrote a fairly extensive letter of advisement to the National Marine Fisheries Service calling for additional research in areas that they anticipate were impacted. Bortone said, "There was new impetus to reinforce the increase of much more environmental data and fisheries data relative to the spill."

The other component to all this new data is that scientists and managers need a way to share this information. In mid-November, Mote Marine Laboratory co-sponsored a symposium with the National Wildlife Federation and the University of South Florida College of Marine Science. One of the aims of the workshop was to develop a regional research and management body that would serve as a central point for gathering all the data for the Gulf of Mexico. This new body would not only include state and federal management agencies, but research biologists at academic institutions and non-governmental organizations as well, and all the partners would be included in the process. "I think that if the Gulf is ever going to have any kind of comprehensive resource management plan, it’s going to need some kind of entity like that," says Adams. "To some extent, it’s kind of fortunate that the spill occurred, if it’s used as a wake-up call to fix a system that’s obviously very broken."

"We should definitely take a look at using a variety of management techniques," says Joshua Drew, a National Science Foundation post-doctoral research fellow working at the Biodiversity Synthesis Center in the Field Museum of Natural History in Chicago, Illinois, who advocates that rather than just listing fishing quotas, fisheries managers should take a more holistic approach and look at the entire ecosystem instead of just a single species. "If we muck this up, this really special aspect of American culture— the sort of southeastern fisherman, I can see that disappearing just because we’ve trashed the resource."

A Slice of Americana

Scientists are only beginning to understand the effects that the oil spill will have on seafood and fisheries, but the issue hits closest to home for the numerous Gulf fishermen whose lives and livelihoods depend on those outcomes. The proper handling of the Gulf’s marine resources will allow them to continue cultural traditions that have existed for generations.

"I think fishing, more than a lot of other industries, has this romance about it, and has this very American feel to it," says Drew. "It’s kind of like baseball— it’s just kind of one of those things that’s characteristic of being an American, and people are very, very willing to see that there is a lot of pride in being a fisherman."

Barisich, a pillar in the fishing community, has that sense of pride.

"You’re in this situation -- you can’t walk away from it," says Barisich. "I can’t leave people. I got all these fishermen depending on me ‘cause the boys around here started an association about 20 years ago, standing up for people, standing up for myself, and now we’re the ones who need support."

NOAA reports that both actual and potential contamination of seafood can substantially affect commercial and recreational fishing, and that loss of confidence in seafood safety and quality can impact seafood markets long after any actual risk to seafood from the spill has subsided, resulting in serious economic consequences. If seafood safety testing isn’t handled properly, it will be a long, hard journey to earn back the trust of the American public and restore confidence in seafood— and that’s a hit that Gulf fishermen can’t take.

"It’s like after Katrina. They don’t know it’s killing you from the inside," says Barisich. He recounts an interview he did with BBC, where when asked where he sees himself in ten years, he said he’d probably be dead. "Five years ago I lost everything in Katrina. I had a full head of black hair, a six pack, and I had some forty-five guns in my arms, ok? Five years, I said I got a one pack- that’s how big my belly is- I’ve lost half my hair, and it’s all gray and I got little twenty-twos now for guns now in my arms. That’s what five years has done. You figure ten years will kill me."

Image Credits: 1) USCG, Petty Officer 3rd Class Nathan Bradshaw, 2) NOAA, Monica Allen, 3) Allison Wilkinson, 4) U.S. Coast Guard, Stephen Lehmann/Marine Photobank, 5) USCG, Petty Officer 1st class Mike Lutz, 6) USCG, Petty Officer 3rd class Erik Swanson, 7) USCG, Petty Officer 3rd class Nathan Bradshaw

About the Author: Allie Wilkinson is a freelance science writer and multimedia specialist with a background in environmental studies and conservation biology, especially interested in issues dealing with human dimensions of natural resources, human-wildlife conflict, and environmental pollutants. You can follow her on her blog Oh, For the Love of Science! and Twitter.

The views expressed are those of the author and are not necessarily those of Scientific American.