Impacts of Oil Spill Found in Marsh Fish Species Important for Ecosystem

Louisiana's Grand Terre Island marshes contaminated with oil;
here, with a minnow trap. Credit: Andrew Whitehead

The restored beaches of the Gulf Coast and the renewed lush green of the Louisiana marshes show little sign of the impacts left behind by the disastrous Deep Horizon oil spill (DWH). Clean up crews removed the black sludge from the surfaces, but the harmful effects on the wildlife tell the rest of the story.

A study conducted by two scientists from Louisiana State University documented the detrimental effects of the oil on a native Louisiana marsh fish vital for the ecosystem.

“The oil disappeared from the surface of the water pretty quickly. But the research demonstrates that the fish are showing biological responses that are highly diagnostic of exposure to those chemicals and the types of effects that they cause,” Andrew Whitehead, assistant professor of Biological Sciences at Louisiana State University said.

Whitehead and his colleague Fernando Galvez discovered the following effects on the fish as a result of oil exposure:

• Physiological and biological responses that could lead to toxicity
• Abnormalities in development and impairment of fish reproduction
• Gill malformation, which impair a fish’s ability to maintain its health through gas exchange – the same purpose human lungs serve, and waste excretion
• Decreased or delayed hatching success of embryos exposed to oiled sediment, and when hatched were malformed and inactive.

"We were blown away by the level of damage to the gills. As a fish physiologist to see this extent of damage on a gill is pretty profound and I was first shocked that the fish we sampled were still alive," Fernando Galvez, assistant professor of Biological Sciences said.

The developmental and reproduction impacts also demonstrate negative effects to the health of the fish.

“Impacts on development and reproduction are of big concern when you think of the long-term integrity of populations. So we found effects of adults in the field and we also found effects when we exposed developing embryos or early life stages to sediments and water collected from the field,” Whitehead said.

Whitehead said this research could be used to make predictions of long-term population effects because there’s 20 years of research of impacts on wildlife from the Exxon Valdez oil spill.

The Exxon Valdez oil spill in 1989 poured more than 10 million gallons into the Gulf of Alaska. The death toll exceeded 100,000 and included seabirds, sea otters, river otters, harbor seals, bald eagles, orcas and billions of salmon and herring eggs. The long-term effects included substantial population decreases to these species and additional species were impacted from remaining toxins rooted in the sediment.

“The responses that we’re seeing now are predictive of long-term population level consequences. It’s not a death sentence for these fish and it’s not certain they’re going to be population-level declines, but if there were to be, these are the responses you’d expect to see,” Whitehead said.

The BP rig spilled more than 172 million gallons of oil into the Gulf. After months of clean up and chemical tests for toxicity, the federal government reported the seafood and the water safe. The long-term effects will take time and possibly several generations before they appear Whitehead said.

Marsh at Belle Fontaine Point, Miss.: the marsh's entrance is boomed in anticipation of oil.

Credit: Andrew Whitehead

A survey conducted by the Louisiana Restaurant Association in April 2011 indicated a decline of seafood available following the spill, which resulted in a loss of revenue for the business members. The survey reported its members experienced shortages in shrimp, crab and finfish since January 2011. But the biggest challenge reported by its members one year later is seafood safety perception.

“Things are getting much better for restaurants, but the perception that Louisiana seafood is unsafe is still a major hurdle we have to conquer,” Erica Papillion, Director of Communications for LRA said.

Despite very low to non-detectable traces of the oil remaining in the water and reports that seafood is safe to eat, Whitehead said studying the biology of the fish is equally important.

“We can only get so far with the chemistry, and just because a fish is officially safe to eat doesn’t mean its growing, reproducing or developing properly. And that’s what we really care about. We care about human health from consumption of seafood on the one hand and we also care about the sustainability of the ecosystem and the integrity of the fisheries and so we need to be doing more than just the chemistry,” Whitehead said.

Just with the Exxon Valdez spill, the oil remains in the sediment.

“The sediment can act as a reservoir of long-term low-level exposures of toxic components of oil to organisms in the ecosystem and that’s what we’re concerned about here, especially with species that are associated with the sediment or spawning in these shallow water habitats where there’s close contact with sediment,”

Whitehead and Galvez plan to follow up on the developmental and multi-generational consequences.

“We want to determine the fitness of the fish to produce future generations and survive in the environment,” Whitehead said.

Galvez presented their research to the House Committee on Natural Resources in Washington, D.C. (oral testimony starts at 45 min in) and Senator Bill Nelson from Florida used portions of the professors' research on the Senate floor in his discussion of the continuing economic, environmental, and ecological consequences of the DWH oil spill. See Nelson presentation to Senate, about 1 hour 50 min in

Galvez and Whitehead said they hope this study will demonstrate the importance of biology research before and following spills.

"We're looking for more funding to follow up on some of the additional data that we've collected to make assessments of long-term damage, which has been difficult to get. We need to get this research to the public and those making legislative decisions so they can be informed," Galvez said.