Opinion

Kaderka: Deepwater Horizon disaster continues to harm environment Deepwater Horizon disaster continues to harm environment

Fire boats battle a fire at the off shore oil rig Deepwater Horizon April 21, 2010 in the Gulf of Mexico off the coast of Louisiana. Multiple Coast Guard helicopters, planes and cutters responded to rescue the Deepwater Horizons 126 person crew after an explosion and fire caused the crew to evacuate. (Photo by U.S. Coast Guard via Getty Images) for Lise Olsen story on Oil Patch Deaths -- Day 1 less Fire boats battle a fire at the off shore oil rig Deepwater Horizon April 21, 2010 in the Gulf of Mexico off the coast of Louisiana. Multiple Coast Guard helicopters, planes and cutters responded to rescue the ... more Photo: U.S. Coast Guard, Handout Photo: U.S. Coast Guard, Handout Image 1 of / 1 Caption Close Kaderka: Deepwater Horizon disaster continues to harm environment 1 / 1 Back to Gallery

This week, as we mark the fourth anniversary of the April 2010 Deepwater Horizon oil spill, evidence of that catastrophe's effects on wildlife continues to emerge.

Despite sunny assurances from BP, the largest oil spill in U.S. history is leaving its mark on everything from marine mammals to mollusks.

Bottlenose dolphins have been particularly hard-hit.

Some 900 of these graceful creatures have been found stranded, most of them dead, in the northern Gulf between April 2010 and March 2014, and the National Oceanic and Atmospheric Administration recently published a study linking the ill health of dolphins in Louisiana's Barataria Bay - anemia, adrenal problems and lung disease - to oil exposure.

Birds that migrate through the Gulf Coast or winter here are likewise showing signs of oil exposure.

White pelicans were far away in their northern breeding grounds at the time of the spill. But these birds winter along the Pacific and Gulf coasts, and in 2012, scientists examining eggs from the largest colony of American white pelicans in Northern America found petroleum compounds and residues of the chemical dispersant widely used during the Deepwater Horizon spill.

Minnesota Department of Natural Resources scientists are still studying the impacts of this exposure, but these compounds have been shown to cause cancer and disrupt embryo development in other species.

Exposure to oil and dispersants also appears to have affected oysters across the Gulf for several years running.

By-products of these compounds are toxic to oysters at all stages of development and can greatly impair reproduction.

Scientists have found low "spat recruitment" (the stage when larval oysters settle onto a hard surface) from the fall of 2010 through the fall of 2012 in large areas of oyster habitat along the northern Gulf coast. They are still evaluating the effects of the 2010 oiling, but for a species that was already down to 20 percent of its historic size and distribution in some areas, the Deepwater Horizon event was a major blow.

These studies and other troubling evidence of damage to wildlife point to a need for continued and long-term monitoring of the impacts of this disaster. It may be decades before we know the full extent of the harm it caused to the Gulf ecosystem.

BP, not surprisingly, seems bent on putting the whole thing behind it.

On April 16, the company announced that cleanup operations along the Gulf Coast were complete - a claim immediately disputed by the Coast Guard. They also attacked as politically motivated a boat tour of Barataria Bay the National Wildlife Federation sponsored recently to enable reporters to see first-hand some of the spill's lasting damage, including, most dramatically, Cat Island, a former pelican rookery whose oil-decimated mangroves no longer support any birds.

At the same time that BP is putting a happy face on Gulf recovery, its lawyers are dragging out the litigation over the company's civil liability for as long as possible.

Despite a massive public relations campaign promising to "make it right," BP's real strategy seems to be "make them wait."

Maybe people will forget. Maybe coastal communities will get preoccupied by other problems. Maybe impaired and declining populations of Gulf fish and wildlife will become the new normal.

The citizens of the Gulf Coast should not let this happen. We should continue to insist that the Justice Department and our national leaders hold BP fully accountable for its actions.

And we should make sure our state leaders are committed to using the fines already paid by others and the fines BP will eventually owe to protect and restore the Gulf of Mexico.

This glorious, productive ecosystem supports our economy and sustains our people.

It is part of who we are, and its health and vitality should not be sacrificed as a cost of doing business.

Susan Kaderka is regional executive director for the nonprofit National Wildlife Federation.