So even before the horrific April 20 explosion of the Deepwater Horizon oil rig caused the biggest environmental catastrophe in U.S. history, MacAvoy knew there was oil in the gulf’s water—one of his areas of research involves natural oil seepages in the gulf and the ecosystems that coexist with them.

But the millions of gallons of oil that have spewed into the gulf in the past three months were caused by the hand of man, not Mother Nature. The College of Arts and Sciences professor has used the disaster as a teachable moment, opening each session of his undergraduate oceanography class this summer with a discussion of the situation.

“I give them an update, what’s the latest news, how many barrels of oil are being captured, how many are being burnt,” he said. “They’re burning far more than they capture. What’s the next step; how close is the relief well; how likely is that to succeed; what are the challenges. It’s something the students care about. No one likes to see these animals tarred. It makes oceanography a little more real for them.”

Marine science always has been in the forefront of MacAvoy’s mind. He grew up in Connecticut, and during frequent family trips to the beach he’d bring back more than seashells from the shore.

“I would always collect the dead animals and bring them home with me,” he said. “Crabs; fish; jellyfish; the occasional stingray. I’m still doing that. I put them in the freezer and show them to my oceanography class. It’s kind of like a college show-and-tell. I have a Portuguese man-of-war that I pull out. I have a giant isopod from the deep Gulf of Mexico that is really creepy looking. I still use them as a way to engage the students.”

MacAvoy has been capturing environmental science students’ attention at AU for nine years. A biogeochemist, he’s interested in areas where marine and freshwater systems interface

I look at how chemistry affects biology—how the environment shapes organism function

This has led him to the Gulf of Mexico, where natural hydrocarbon seepages are common. MacAvoy studies the exotic animals associated with these areas.

“They’re symbiotic with bacteria that can use gas as an energy source for turning CO2 into sugar,” he said. “You have these deep communities of animals that don’t rely on photosynthesis. They’re using the energy from the petroleum or gas as an energy source. So the question is, could you have a nutrient delivery system from the bottom up as well as from the top down?”

Lest anyone minimize the dire effects of the BP disaster, MacAvoy stresses that natural seepages and a man-made catastrophe are diametrically different.

“The Gulf of Mexico has natural oil slicks—you can actually see them from space,” he said. “But it’s not like oil gushing from a hole. It’s a very thin sheen. When you’re in the middle of the gulf sometimes it will be clear you’re in an oil patch because the waves behave differently when there’s oil on the surface. The water gets very still, but it’s not like any of the animals care. It’s like anything else, the dose makes the poison.”

The BP disaster quickly is proving lethal to life of all kinds in and around the water.

“It’s probably going to kill off plankton and little crustaceans,” he said.

“Plankton and crustaceans form the base of the food web in the ocean. To make one kilogram of tuna, you need 10,000 kilograms of plankton. If you begin to chomp away at the lowest rungs of the food chain, the effects are going to go right up.”

More heart-wrenching to the masses is the sight of dead turtles, fish, and oil-coated birds washing ashore.

“A lot of fish filter feed, so they just keep their mouth open when they go through the water. They’re ingesting this stuff, and they just swallow it,” he said. “If birds get hit with oil, they’ll lose the insulating ability of their feathers, they’ll lose the ability to fly, and in some cases they can suffocate if they ingest the oil. It’s a toxin—just think what would happen if you drank some oil.”

Eventually, the oil will evaporate or be consumed by bacteria, but just how long that will take is anyone’s guess, MacAvoy said.

“I don’t know, and no one really does know, what the environmental ramifications will be, so it’s hard to say how big of a disaster this is,” he said. “There will be effects of this for 20 years. There are still effects from the Exxon Valdez.

“The real interesting thing about environmental science is there are experiments that nature is doing all the time,” he said. “The challenge of environmental science is figuring out what experiments she is doing. Sometimes we alter the experiment by dumping a bunch of pollution in the Anacostia or oil in the Gulf of Mexico. Then I see it as a very important part of my job to help see what nature’s doing. I feel like a detective sometimes.”