Deepwater Horizon Spill Causes Fish Abnormalities

Posted by Eric Haun
Tuesday, March 25, 2014
Oil near the Deepwater Horizon disaster spill source as seen during an aerial overflight on May 20, 2010. (Credit: NOAA)

The National Oceanic and Atmospheric Administration (NOAA) reported that results to a new study conducted by a team of NOAA and academic scientists suggest that crude oil from the 2010 Deepwater Horizon disaster causes severe defects in the developing hearts of bluefin and yellowfin tunas.

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 United States 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.

noaa.gov

  • Yellowfin tuna in a tank at the Achotines Laboratory in Panama. (Image: John Incardona, NOAA)

    Yellowfin tuna in a tank at the Achotines Laboratory in Panama. (Image: John Incardona, NOAA)

  • A normal yellowfin tuna larva not long after hatching (top), and a larva exposed to Deepwater Horizon crude oil during embryonic development (bottom). The oil-exposed larva shows a suite of morphological abnormalities including fluid accumulation from heart failure and poor growth of fins and eyes. (Image: John Incardona, NOAA)

    A normal yellowfin tuna larva not long after hatching (top), and a larva exposed to Deepwater Horizon crude oil during embryonic development (bottom). The oil-exposed larva shows a suite of morphological abnormalities including fluid accumulation from heart failure and poor growth of fins and eyes. (Image: John Incardona, NOAA)

  • Lincoln Marine Science Centre in South Australia. The paper’s authors partnered with the Lincoln Marine Science Centre in South Australia to examine Deepwater Horizon crude oil impacts to bluefin tuna. (Image: John Incardona, NOAA)

    Lincoln Marine Science Centre in South Australia. The paper’s authors partnered with the Lincoln Marine Science Centre in South Australia to examine Deepwater Horizon crude oil impacts to bluefin tuna. (Image: John Incardona, NOAA)

  • The Achotines Laboratory in Panama maintains a broodstock of yellowfin tuna in an in-ground, concrete tank. This specialized facility provides scientists with nearly year-round access to study captive tuna at various life stages, including the fragile embryo stage which was a focus of this study. (Image: John Incardona, NOAA)

    The Achotines Laboratory in Panama maintains a broodstock of yellowfin tuna in an in-ground, concrete tank. This specialized facility provides scientists with nearly year-round access to study captive tuna at various life stages, including the fragile embryo stage which was a focus of this study. (Image: John Incardona, NOAA)

  • Researchers examining tuna embryos at the Achotines Laboratory in Panama. (Image: John Incardona, NOAA)

    Researchers examining tuna embryos at the Achotines Laboratory in Panama. (Image: John Incardona, NOAA)

  • Yellowfin tuna in a tank at the Achotines Laboratory in Panama. (Image: John Incardona, NOAA)
  • A normal yellowfin tuna larva not long after hatching (top), and a larva exposed to Deepwater Horizon crude oil during embryonic development (bottom). The oil-exposed larva shows a suite of morphological abnormalities including fluid accumulation from heart failure and poor growth of fins and eyes. (Image: John Incardona, NOAA)
  • Lincoln Marine Science Centre in South Australia. The paper’s authors partnered with the Lincoln Marine Science Centre in South Australia to examine Deepwater Horizon crude oil impacts to bluefin tuna. (Image: John Incardona, NOAA)
  • The Achotines Laboratory in Panama maintains a broodstock of yellowfin tuna in an in-ground, concrete tank. This specialized facility provides scientists with nearly year-round access to study captive tuna at various life stages, including the fragile embryo stage which was a focus of this study. (Image: John Incardona, NOAA)
  • Researchers examining tuna embryos at the Achotines Laboratory in Panama. (Image: John Incardona, NOAA)
Maritime Reporter May 2015 Digital Edition
FREE Maritime Reporter Subscription
Latest Maritime News    rss feeds

Environmental

Hyde Marine to Present on BWTS at Nor-Shipping

Company to Share Seamless Integration of Ballast Water Treatment System (BWTS); Experience in Retrofits for Small Footprint Installations at Nor-Shipping Maritime

6,000 Gallons of Diesel Spilt in Alaskan Gulf

Unified Command responding to cleanup aboard vessel in Seldovia, Alaska   A Unified Command consisting of representatives from the U.S. Coast Guard, U.S. Department of the Interior,

US Orders Owner to Clean Up Ruptured Pipeline

Federal order ensures continued action on Santa Barbara County oil spill   The U.S. Environmental Protection Agency and the U.S. Coast Guard issued a joint federal

News

Lifting of US Crude Oil Export Ban Possible within Year

The U.S. Congress could lift the 40-year old ban on domestic crude oil exports within a year as a drop in gasoline prices and the potential return of Iranian

Duke Energy to Help Develop Jeffersonville Port Site

Duke Energy Indiana has selected a 140-acre parcel of land inside the Port of Indiana-Jeffersonville in Clark County for the utility's 2015 Site Readiness Program.

UNOLS Seeks Nominations for Council Positions

The University-National Oceanographic Laboratory System (UNOLS) is an organization of academic oceanographic institutions working in cooperation with agencies of the U.

Marine Science

VIKING’s Top Safety Offerings at Nor-Shipping

Marine safety equipment leader VIKING Life-Saving Equipment will appear in force at Nor-Shipping 2015, displaying both innovative products and services that

US Forecaster Predicts Below-average Atlantic Hurricane Season

The Atlantic Ocean will see a below-average number of hurricanes this season due to cooler seas and a strong El Niño effect, the U.S. government weather forecaster announced on Wednesday.

UNOLS Seeks Fleet Improvement Committee Chair

The University-National Oceanographic Laboratory System (UNOLS) informs it is seeking nominations to fill a Fleet Improvement Committee (FIC) Chair position.   The position,

Government Update

Lifting of US Crude Oil Export Ban Possible within Year

The U.S. Congress could lift the 40-year old ban on domestic crude oil exports within a year as a drop in gasoline prices and the potential return of Iranian

US Orders Owner to Clean Up Ruptured Pipeline

Federal order ensures continued action on Santa Barbara County oil spill   The U.S. Environmental Protection Agency and the U.S. Coast Guard issued a joint federal

Suppression of Random Drug Test Results: A Bad and Unnecessary Decision

Last September, an Administrative Law Judge (ALJ) unsettled much of the U.S. maritime industry when he dismissed with prejudice a U.S. Coast Guard (USCG) action

Offshore Energy

Lamprell to Implement Software for Automated Manufacturing

U.A.E based offshore jackup rig builder Lamprell Energy Ltd., will implement SSI's EnterprisePlatform software solution to allow its engineering team to automate manufacturing processes.

Five Years on from Macondo

An interview with NOIA’s Randall Luthi provides unique perspective on where the offshore energy business has been, where it is now, and where it could be headed next.

Offshore O&G: Weathering the Storm

Vessels are stacked as Gulf oil operators retrench and day rates fall. In the Gulf of Mexico, vessels serving offshore oil-and-gas exploration and production are

Ocean Observation

US Forecaster Predicts Below-average Atlantic Hurricane Season

The Atlantic Ocean will see a below-average number of hurricanes this season due to cooler seas and a strong El Niño effect, the U.S. government weather forecaster announced on Wednesday.

China Builds-up Naval Power

China has outlined a first ever "white paper" on military strategy that outlined a more robust posture for its blue-water navy, and warned of threats to its security

UNOLS Seeks Fleet Improvement Committee Chair

The University-National Oceanographic Laboratory System (UNOLS) informs it is seeking nominations to fill a Fleet Improvement Committee (FIC) Chair position.   The position,

 
 
Maritime Careers / Shipboard Positions Maritime Security Navigation Offshore Oil Pipelines Port Authority Ship Electronics Ship Simulators Shipbuilding / Vessel Construction Winch
rss | archive | history | articles | privacy | contributors | top maritime news | about us | copyright | maritime magazines
maritime security news | shipbuilding news | maritime industry | shipping news | maritime reporting | workboats news | ship design | maritime business

Time taken: 0.2984 sec (3 req/sec)