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Environment / Sustainability

Ecological damage from Gulf oil disaster likely to persist long past our lifetimes

July 1, 2010
By Jayleen Heft

For months, we've watched oil gushing out of a pipe in the Gulf of Mexico and coating beaches, marshes, and wildlife with brownish-orange crude oil. The long nightmare, caused by the explosion of the Deepwater Horizon on April 20 off the Louisiana shore, killed 11 workers and continues affecting the livelihood and well-being of an untold number of coastal dwellers.

Toxic horror

A U.S. Fish and Wildlife Service environmental contaminants coordinator rescues a brown pelican from the Barataria Bay in Grand Isle, La., on June 4. U.S. Coast Guard photo by Petty Officer 3rd Class Ann Marie Gorden.

“Although ecosystems like the Gulf of Mexico are amazingly resilient to many stressors, the Gulf spill is unprecedented,” says William H. Clements, professor in the Department of Fish, Wildlife and Conservation Biology.

Clements research focuses on aquatic ecotoxicology, or the ecological effects of contaminants in water. Much of the research conducted in his lab focuses on factors that determine recovery of ecosystems after contaminants have been removed – making him keenly interested in what is currently happening in the Gulf of Mexico.

Crude oil hydrocarbons

To understand the ecological damage that is underway, it helps to understand the toxins. Hydrocarbons - found naturally in crude oil - can be broadly divided into two major groups of compounds:

  • aliphatics
  • aromatics

Aliphatics are heavier compounds that form the bulk of the oil spill and are generally associated with physical smothering of marshes and seabirds. However, the more ominous threat is occurring underwater and is associated with the aromatic fraction of the hydrocarbons.

Aromatic hydrocarbons can be carcinogenic

Aromatics are more persistent and can be highly toxic (and often carcinogenic).

A clean-up worker finds a blue crab coated in thick oil at Louisiana's Elmer's Island Wildlife Refuge. © BP p.l.c.

“Interestingly, some of these compounds actually become more toxic when exposed to sunlight,” Clements says.

“The direct toxicological effects on fish and invertebrates – and the long-term health of the Gulf coast fisheries – will likely be determined by the aromatic fraction of hydrocarbons.”

Immediate major concern

“The most immediate concern is preventing oil from entering highly sensitive estuaries and marshes along the coastline,” Clements says. “These areas are the most diverse and productive habitats in the Gulf. They also serve as important nurseries for many of the fish and invertebrate species that comprise the Gulf Coast fisheries.”

Oil that washes up on sandy beaches is an eyesore to tourists and a potential hazard to some wildlife (e.g., nesting turtles, shorebirds). However, these oils can be relatively easily removed.

In contrast, oil that penetrates marshes or settles into seagrass meadows will be there for many years. This is why such a tremendous effort is being made to keep the oil from reaching shore.

A northern gannet is cleaned at the Theodore Oiled Wildlife Rehabilitation Center in Theodore, Ala. on June 27. © BP p.l.c.

Never been a spill of this magnitude

“In the long term, the biggest concern is the ecological health of the entire Gulf Coast ecosystem,” Clements says. “There has never been a spill of this magnitude in such a productive habitat. In all honesty, we really don’t know how this will affect the long-term productivity of near-shore or offshore fisheries.”

While a graduate student at Florida State University, Clements conducted research in Apalachee Bay, in Florida’s panhandle. He examined the effects of pulp mill effluents, or waste, on marine seagrass communities – dense, undersea meadows that are extremely diverse and productive habitats for many of the fish and invertebrates native to the region.

Clements familiarity with the area leaves him especially concerned about damage throughout the Gulf ecosystem.

Complete recovery decades away

“I hate to be pessimistic, but given the scale of this spill, and the fact that we’re still uncertain that we can stop the flow of oil, I don’t believe we will see complete recovery of this system in our lifetime,” Clements says.