Evidence Finds BP Gulf Oil Disaster Causing Widespread Deformities in Fish
Crude oil from the 2010 Deepwater Horizon disaster causes severe defects in the developing hearts of bluefin and yellowfin tunas, according to a new study by a team of National Oceanic and Atmospheric Administration (NOAA) and academic scientists.
The findings, published in the Proceedings of the National Academy of Sciences on the 25th anniversary of the Exxon Valdez oil spill, show how the largest marine oil spill in U.S. history may have affected tunas and other species that spawned in oiled offshore habitats in the northern Gulf of Mexico.
Atlantic bluefin tuna, yellowfin tuna and other large predatory fish spawn in the northern Gulf during the spring and summer months, a time that coincided with the Deepwater Horizon spill in 2010. These fish produce buoyant embryos that float near the ocean surface, potentially in harm’s way as crude oil from the damaged wellhead rose from the seafloor to form large surface slicks.
The new study shows that crude oil exposures adversely affect heart development in the two species of tuna and an amberjack species by slowing the heartbeat or causing an uncoordinated rhythm, which can ultimately lead to heart failure.
“We know from the 1989 Exxon Valdez spill in Prince William Sound that recently spawned fish are especially vulnerable to crude oil toxicity,” said Nat Scholz, Ph.D., leader of the ecotoxicology program at NOAA's Northwest Fisheries Science Center in Seattle. “That spill taught us to pay close attention to the formation and function of the heart.”
“The timing and location of the spill raised immediate concerns for bluefin tuna,” said Barbara Block, Ph.D., a study coauthor and professor of biology at Stanford University. “This spill occurred in prime bluefin spawning habitats, and the new evidence indicates a compromising effect of oil on the physiology and morphology of bluefin embryos and larvae.”
Recent studies are increasingly painting a more detailed picture of how oil-derived polycyclic aromatic hydrocarbons (PAHs) act on the heart. Earlier this year, the Stanford-NOAA team showed in a related paper published in Science (Brette et al. 343: 772) that Deepwater Horizon crude oil samples block excitation-contraction coupling—vital processes for normal beat-to-beat contraction and pacing of the heart—in individual heart muscle cells isolated from juvenile bluefin and yellowfin tuna.
“We now have a better understanding why crude oil is toxic, and it doesn’t bode well for bluefin or yellowfin embryos floating in oiled habitats.” said Block. “At the level of a single heart muscle cell, we’ve found that petroleum acts like a pharmacological drug by blocking key processes that are critical for cardiac cell excitability.”
This mechanism explains why the team observed a range of cardiac effects in the developing hearts of intact embryos in the present study. “We directly monitored the beating hearts of living fish embryos exposed to crude oil,” said Dr. John Incardona, NOAA research toxicologist and the study’s lead author. “The tiny offspring of tunas and other Gulf species are translucent, and we can use digital microscopy to watch the heart develop.”
The major difficulty facing the researchers was access to live animals. Tunas are difficult to raise in captivity and few facilities exist worldwide with spawning fish. In the open ocean, fragile fish embryos and larvae are mixed with many other types of plankton, and they usually don’t survive the rough conditions in a net towed near the surface. This made it close to impossible to assess developmental cardiotoxicity in samples collected near the Deepwater Horizon surface oil slicks.
To work around this challenge, the international team brought the oil to the fish. Samples of crude oil were collected from the damaged riser pipe and surface skimmers. The samples were then transported to the only land-based hatcheries in the world capable of spawning tunas in captivity.
This approach allowed the scientists to design environmentally relevant crude oil exposures for bluefin tuna and yellowfin tuna at marine research facilities in Australia and Panama, respectively. Luke Gardner, an Australian native post-doctoral associate from Stanford University and co-author on the PNAS paper, was vital in helping the team investigate the bluefin.
“It is challenging to maintain bluefin in culture and we were privileged to have successfully tested the crude oil in Australian facilities, the only on-land hatchery that has bluefin tuna in culture. This gave us access to tuna embryos and allowed us to study the developmental toxicity of oil,” said Gardner. The pioneering effort to develop new testing methods was also led by Martin Grosell, Ph.D., at the University of Miami.
The new research adds to a growing list of fish that are affected by crude oil. “This fits the pattern,” said Incardona. “The tunas and the amberjack exposed to Deepwater Horizon crude oil were impacted in much the same way that herring were deformed by the Alaska North Slope crude oil spilled in Prince William Sound during the Exxon Valdez accident.”
Crude oil is a complex mixture of chemicals, some of which are known to be toxic to marine animals. Past research has focused in particular on PAHs, which can also be found in coal tar, creosote, air pollution and stormwater runoff from land. In the aftermath of an oil spill, PAHs can persist for many years in marine habitats and cause a variety of adverse environmental effects.
Developmental abnormalities were evident in bluefin and yellowfin tunas at very low concentrations, in the range of approximately one to 15 parts per billion total PAHs. These levels are below the measured PAH concentrations in many samples collected from the upper water column of the northern Gulf during the active Deepwater Horizon spill phase.
Severely affected fish with heart failure and deformed jaws are likely to have died soon after hatching. However, the NOAA team has shown in previous work that fish surviving transient crude oil exposures with only mild effects on the still-forming heart have permanent changes in heart shape that reduce swimming performance later in life.
“This creates a potential for delayed mortality,” said Incardona. “Swimming is everything for these species.”
The nature of the injury was very similar for all three pelagic predators, and similar also to the response of other marine fish previously exposed to crude oil from other geologic sources. Given this consistency, the authors suggest there may have been cardiac-related impacts on swordfish, marlin, mackerel and other Gulf species. “If they spawned in proximity to oil, we’d expect these types of effects,” said Incardona.
The research was funded by NOAA as part of the on-going Natural Resource Damage Assessment for the Gulf ecosystem following the April 20, 2010 Deepwater Horizon oil spill. Contributing to the findings in addition to NOAA and Stanford University were researchers from the University of Miami’s Rosenstiel School of Marine and Atmospheric Sciences and the University of the Sunshine Coast in Queensland, Australia.
By Gwen Ranniger
Fertility issues are on the rise, and new literature points to ways that your environment may be part of the problem. We've rounded up some changes you can make in your life to promote a healthy reproductive system.
Infertility and Environmental Health: The Facts<ul> <li>Sperm count is declining steeply, significantly, and continuously in Western countries, with no signs of tapering off. Erectile dysfunction is on the rise, and women are facing increasing rates of miscarriage and difficulty conceiving.</li><li>Why? A huge factor is our environmental health. Hormones (particularly testosterone and estrogen) are what make reproductive function possible, and our hormones are increasingly being negatively affected by harmful, endocrine-disrupting chemicals commonplace in the modern world—in our homes, foods, and lifestyles.</li></ul>
What You Can Do About It<p>It should be noted that infertility can be caused by any number of factors, including medical conditions that cannot be solved with a simple change at home.</p><p><em>If you or a loved one are struggling with infertility, our hearts and sympathies are with you. Your pain is validated and we hope you receive answers to your struggles.</em></p><p>Read on to discover our tips to restore or improve reproductive health by removing harmful habits and chemicals from your environment.</p>
Edit Your Health<ul><li>If you smoke, quit! Smoking is toxic, period. If someone in your household smokes, urge them to quit or institute a no-smoking ban in the house. It is just as important to avoid secondhand smoke.</li><li>Maintain a healthy weight. Make sure your caloric intake is right for your body and strive for moderate exercise.</li><li>Eat cleanly! Focus on whole foods and less processed meals and snacks. Studies have found that eating a Mediterranean-style diet is linked to increased fertility.</li><li>Minimize negative/constant stress—or find ways to manage it. Hobbies such as meditation or yoga that encourage practiced breathing are great options to reduce the physical toll of stress.</li></ul>
Edit Your Home<p>We spend a lot of time in our homes—and care that what we bring into them will not harm us. You may not be aware that many commonly found household items are sources of harmful, endocrine-disrupting compounds. Read on to find steps you can take—and replacements you should make—in your home.</p><p><strong>In the Kitchen</strong></p><ul> <li>Buy organic, fresh, unprocessed foods whenever possible. <a href="https://www.ehn.org/clean-grocery-shopping-guide-2648563801.html" target="_blank">Read our grocery shopping guide for more tips about food.</a></li><li>Switch to glass, ceramics, or stainless steel for food storage: plastics often contain endocrine-disrupting chemicals that affect fertility. <a href="https://www.ehn.org/bpa-pollution-2645493129.html" target="_blank" rel="noopener noreferrer">Learn more about the dangers of plastic here.</a></li><li>Ban plastic from the microwave. If you have a plastic splatter cover, use paper towel, parchment paper, or an upside-down plate instead.</li><li>Upgrade your cookware: non-stick may make life easier, but it is made with unsafe chemical compounds that seep into your food. Cast-iron and stainless steel are great alternatives.</li><li>Filter tap water. Glass filter pitchers are an inexpensive solution; if you want to invest you may opt for an under-the-sink filter.</li><li>Check your cleaning products—many mainstream products are full of unsafe chemicals. <a href="https://www.ehn.org/how-to-shop-for-cleaning-products-while-avoiding-toxics-2648130273.html" target="_blank" rel="noopener noreferrer">Check out our guide to safe cleaning products for more info</a>.</li></ul><p><strong>In the Bathroom </strong></p><ul> <li>Check the labels on your bathroom products: <em>fragrance-free, paraben-free, phthalate-free</em> and organic labels are all great signs. You can also scan the ingredients lists for red-flag chemicals such as: triclosan, parabens, and dibutyl phthalate. Use the <a href="https://www.ewg.org/skindeep/" target="_blank">EWG Skin Deep database</a> to vet your personal products.</li><li>Ditch the vinyl shower curtain—that new shower curtain smell is chemical-off gassing. Choose a cotton or linen based curtain instead.</li><li>Banish air fresheners—use natural fresheners (an open window, baking soda, essential oils) instead.</li></ul><p><strong>Everywhere Else</strong></p><ul><li>Remove wall-to-wall carpet. If you've been considering wood or tile, here's your sign: many synthetic carpets can emit harmful chemicals for years. If you want a rug, choose wool or plant materials such as jute or sisal.</li><li>Prevent dust build-up. Dust can absorb chemicals in the air and keep them lingering in your home. Vacuum rugs and wipe furniture, trim, windowsills, fans, TVs, etc. Make sure to have a window open while you're cleaning!</li><li>Leave shoes at the door! When you wear your shoes throughout the house, you're tracking in all kinds of chemicals. If you like wearing shoes inside, consider a dedicated pair of "indoor shoes" or slippers.</li><li>Clean out your closet—use cedar chips or lavender sachets instead of mothballs, and use "green" dry-cleaning services over traditional methods. If that isn't possible, let the clothes air out outside or in your garage for a day before putting them back in your closet.</li><li>Say no to plastic bags!</li><li>We asked 22 endocrinologists what products they use - and steer clear of—in their homes. <a href="https://www.ehn.org/nontoxic-products-2648564261.html" target="_blank">Check out their responses here</a>.</li></ul>
Learn More<ul><li>For more information and action steps, be sure to check out <em>Count Down: How Our Modern World Is Threatening Sperm Counts, Altering Male and Female Reproductive Development, and Imperiling the Future of the Human Race</em> by EHS adjunct scientist Shanna Swan, PhD: <a href="https://www.shannaswan.com/" target="_blank" rel="noopener noreferrer">available for purchase here.</a></li><li><a href="https://www.ehn.org/st/Subscribe_to_Above_The_Fold" target="_blank" rel="noopener noreferrer">Sign up for our Above the Fold Newsletter </a>to stay up to date about impacts on the environment and your health.</li></ul>
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