No one seems to know yet exactly how the oil spill in the Gulf of Mexico is affecting wildlife. But it’s going to have some effect, obviously. Look no further than the fallout in Prince William Sound for proof.

The situation is summed up best perhaps by Andre Landry, Jr., a turtle expert at Texas A&M, who told OnEarth’s Osha Gray Davidson, "At this point, I can't say if any turtles have died due to oil from the rig explosion. That doesn't mean they haven't. And it certainly does not mean that they won't."

The animals at risk include lots and lots of fish, from shellfish like shrimp and crabs to finfish like red snapper and bull sharks; birds like the brown pelican and royal tern; marine mammals like sperm whales and bottlenose dolphins; and the aforementioned turtles, like Kemp’s Ridleys and hawksbills.



Much of the final damage is predicated on where the oil goes and what exactly type of oil it is, and both of those questions are still unanswered. The prevailing opinion is that the oil is of the lighter type, not the really heavy stuff like what leaked from the Valdez in Alaska, which would be a relatively good thing, as the U.S. Fish and Wildlife Service (pdf) describes it, saying, “Light oils contain moderate concentrations of soluble toxic compounds. Light oils leave a film or layer on intertidal resources with the potential of longterm contamination. Cleanup can be very effective on spills of light oil.”

As far as where the spill is headed, that’s up to the current and winds. National Oceanic and Atmospheric Administration tracks have the spill staying offshore for a while, which is, as with the type of oil, a relatively good thing. So things would seem to be shaping up, at this early point in what will be the overall life history of spill, to be kind of a best-case scenario. But things could certainly change very quickly.

One of the worst-case scenarios is if the spill gets caught in the right current and heads to Florida, home to very sensitive coral reefs and coastal areas. In fact, a Unified Command was just set up in case the oil does hit Florida. In a bid to pin down more details on just what kind of damage we might see to ecosystems and wildlife, I spoke via e-mail with several experts on various topics.

Coral Reefs, Mangroves, and Seagrass Beds
Dr. Richard E. Dodge, Professor and Dean at Nova Southeastern University Oceanographic Center and Executive Director of the National Coral Reef Institute, says, “Oil entrained in the loop current could be delivered to the coral reefs of South Florida and Southeast Florida, from the Dry Tortugas in the south, throughout the Florida Keys, to Palm Beach in the north. A long duration spill could have toxic substances entering the water column and affecting corals anywhere from mucous production to damaging their reproductive system, to bleaching and mortality.” Dodge says dispersants, now being used to help break up the spill, “should NOT be used in proximity to coral reefs because this will make the oil more toxic and available to corals and the plants and animals that live in coral reefs.”

And if it takes a while before the oil reaches Florida? Could be even worse news, Dr. Dodge says. “If oil arrives during the spawning times of coral in August, this could be highly detrimental to the reproductive success of corals, threatening the next generation on the reef.”

Dr. Dodge is also quick to point out the economic impact loss of such unique habitats would have. “Florida has 84% of the nation's coral reef ecosystems,” Dodge says, “hence it is important to recognize that vital national resources are at stake. It has been estimated in a 2000 study by NOAA that reefs represent an annual economy of over $6 billion for South Florida, as well as over 71,000 jobs.”

Massive amounts of oil could also be disastrous for Florida’s sensitive mangrove forests, home to thousands of animals, from alligators to bobcats. “Mangrove forests serve as nursery grounds for many species of fish and shellfish. They also bind sediment. Loss of these forests would result in the collapse of this type of ecosystem,” Dr. Dodge says.

And if the currents and tides really conspire just right, the oil could infest Florida’s seagrass beds. “If this slick made it up on to the southwest Florida Shelf and was transported in the prevailing current direction to the south, it could end up at the mouth of Florida Bay,” according to Dr. Jim Fourqurean, professor at Florida International University. “This worst-case scenario is not particularly likely – but if it occurs, it will be devastating,” Fourqurean warns.

Due to the complex properties of the bay, the oil “would likely be there for an extended period – maybe even years. Florida Bay averages only 3 feet deep over the 2,000 km2 of the bay, and most of that area is within the boundaries of Everglades National Park. Florida Bay is carpeted with seagrass beds,” Fourqurean explains. “One small piece of good news is that seagrasses themselves are quite resistant to the effects of oil spills, so we would expect loss of seagrasses only in places that oil were pushed in to intertidal areas and stranded for extended periods at low tide.” So the seagrass might be fine, but what about the animals that frequent these beds?



“Oil contains many toxic compounds that could kill most of the important animals that reside in the seagrass beds, including commercially import pink shrimp; valuable game fish like tarpon, bonefish, redfish and seatrout; juvenile spiny lobsters; juvenile fish that use the bay as a nursery; and the wading birds that feed on these animals. Air-breathing manatees and sea turtles would be poisoned and covered with oil, wading birds would be covered ...” and Fourqurean leaves it at that, the implication clear.

Fish
Though I’ve said thus far it’s kind of a best-case scenario with the spill, some variables don’t bode well for the survival of fish, according to Dr. David W. Kerstetter, a research scientist at Nova Southeastern University Oceanographic Center. “Many of the fish species in the Gulf have pelagic (open-water) eggs that float at the surface, where the oil layer congregates,” Kerstetter says. And he points out it doesn’t take much oil to start causing trouble, saying, “Studies have suggested that concentrations of 1 part-per-billion have toxic effects to fish eggs.”

It’s also just plain bad timing, with now “the time of the year in which the western Atlantic population of bluefin tuna congregate in the northen Gulf to spawn, a population which is already at extremely low levels,” Kerstetter points out. “Should the sheen spread and persist, a loss of a whole year's larval fish production in some species is possible.”

“The spill will likely impact sensitive coastal saltmarsh estuary and barrier lagoon systems in the northern Gulf – some reports are that the oil already is there – systems which are important nursery grounds for shrimp, sharks, and many other species of fishes, as well as adult habitat for species such as oysters, redfish (red drum), and sea trout,” Kerstetter says.

And the top-of-the-food-chain fish, the ones targeted by both commercial and recreational fishermen, will also be affected, according to Dr. Kerstetter. “As these pollutants (including the oil dispersant chemicals) are released into the water, they’re likely to be absorbed into the prey species' tissues and then re-absorbed into the tissues of predator species, like tunas and sailfish. We know very little about how some of these substances affect growth, reproduction, and even basic survival for most of these fish species.”

We’re waiting to hear back from experts on how the spill might affect birds, too, and will update soon.