In her day job, Jane Lubchenco is a professor of marine biology at Oregon State University, an expert on coastal environments. In the rest of her life, she's an advocate for the world's oceans, one of the best-known American voices for marine conservation. Lubchenco is a former president of the American Association for the Advancement of Science and a member of the Pew Oceans Commission, which issued the influential 2003 report America's Living Oceans: Charting a Course for Sea Change. Fourteen years ago, she founded the Aldo Leopold Leadership Program, which trains scientists in media skills. "I thought it was high time that scientists learned how to be better communicators of their knowledge, so that they could share it more broadly," the 59-year-old biologist explained recently to Claudia Dreifus, author of Scientific Conversations (Holt/Times Books), while sitting in the living room of her Corvallis home.

You are outspoken about the befouled state of the world's oceans. What are the main reasons?
Climate change is one reason. Coastal development is another. But there's also overfishing. And pollution, especially from nitrogen-based fertilizers. They trigger an explosion of microscopic plants that can lead to dead zones and red tides in coastal waters.

With overfishing, I think this is happening because many people assume that since the oceans are so vast, they are infinitely bountiful. One of the hardest things for people to understand is that there are so many more of us than ever before. When we do the same things we always did, the consequences are infinitely greater. The North Atlantic cod was once a bountiful fishery, but it was so exploited that it has collapsed and may never recover. Many species of West Coast rockfish have been overfished. The bottom line is, we're just dumping too many things into the ocean and we're taking too much out.

What kinds of changes have you seen in the oceans since you began studying them in the l970s?
Well, let me talk about one type of marine ecosystem, coral reefs. When I was a young professor at Harvard, I taught a class at the marine laboratory at Discovery Bay on the north coast of Jamaica. The reef there was among the most spectacular in the world: crystalline waters, immense corals the size of huge rock formations, and the most astounding diversity of fishes and glorious invertebrates. The fish and the shrimp had the most remarkable colors and sounds -- a lot of snapping and crackling.

Recently I went back to Discovery Bay and snorkeled in the same places I'd studied. I was appalled to see this former Garden of Eden transformed into a wasteland. I was so stunned, I broke into tears, crying into my mask. Most of the corals were dead. Weedy algae covered every surface. The reef had been assaulted by sewage dumping, fertilizer pollution, massive overfishing, a disease that had wiped out sea urchins, and finally a hurricane. I wish this were an isolated story. However, nearly every coral reef in the world is suffering from similar degradation. All are threatened, though some are in worse shape than others.

How is climate change impacting the oceans?
It is having a very dramatic effect. With coral reefs, the water keeps getting warmer and it's causing coral bleaching, which can kill the reef. Throughout all the oceans the water is warmer, and that is causing a lot of dislocation of animal life, especially in the Arctic and the Antarctic. The creatures keep moving, but a lot of them don't have anywhere to move to. Sea levels are rising, and the intensity and frequency of storms are changing our coasts.

Elizabeth Kolbert recently reported in the New Yorker that seawater is becoming more acidic. What's your opinion?
Yes, it is. And the reason is that oceans have absorbed about half the carbon dioxide that people have put into the atmosphere since the Industrial Revolution. We don't know how much more they can absorb. The change in acidity is likely to have insidious long-term consequences for a lot of marine life -- anything that has a shell or a skeleton such as mussels, oysters, sea stars, and corals, and even microscopic plants, the food source for bigger animals. This is a newly discovered and worrisome threat.

There are scientists who've suggested that atmospheric warming might be slowed by pumping CO2 emissions into shafts under the ocean. Do you think carbon sequestration beneath the sea is a sound idea?
The evidence suggests that it might be safe and effective to bury carbon dioxide under land. But burying it in mines under the sea is likely to be much more problematic, because it is harder to monitor there. Another proposal involves pumping carbon dioxide into the deep sea and letting it just sit on the seafloor. We don't know enough about how long carbon dioxide would last there or whether it would just come to the surface and be released. Frankly, I have doubts about most of these tech-fix solutions. They are just more of the "out of sight, out of mind" attitude about the oceans that has gotten us into trouble in the past. That's part of the mind-set that has caused us to use the sea as a dumping ground and a sewer. It's full of life that we depend on.

In policy circles, one hears that oceans may become the next big environmental issue to attract public attention. Do you see it happening?
I sure hope so. The factors that turned the climate change debate around were a combination of good scientific evidence, strong environmental advocacy, a change of heart among key leaders in the business community, and evidence of the problem in people's daily lives. We need some of the same confluence to jump-start awareness of oceans. It's beginning to happen. When people notice that their local beach has been closed down because of pollution or that there's a warning about mercury or PCBs in some fish, they become aware of the problem.

Perhaps you need an Al Gore?
We do! Individuals like Sylvia Earle or Jean-Michel Cousteau have been champions, but no, there's no Inconvenient Truth for the oceans yet.

Does the borderless quality of the world's oceans make them difficult to protect?
Some say this is the case. But I think it's a myth that we can't solve some of the problems of the oceans without international treaties. You certainly do need international agreements to protect those creatures that crisscross the oceans, like sharks, whales, and tuna. But they aren't typical. Most coastal ocean ecosystems are relatively self-contained. If we protect and restore those, we'll be doing a lot -- even if countries continue to overfish the high seas. Truth be told, we need both strong national and international action.

You are a great supporter of marine reserves as one strategy for restoring oceanic environments. Why?
Because they work. Networks of no-take reserves, where fishing, drilling, and mining are banned, have been shown to restore marine habitats and some fisheries. In reserves, everything gets much bigger -- the fishes, the scallops, the urchins, the crabs. And those larger, longer-living individuals have many, many more young than the smaller, shorter-living ones. A 14-inch vermilion rockfish will make about 150,000 young. Let it grow to 24 inches and it will make 1.7 million babies!

One of the first reserves ever was on the north coast of New Zealand. It's been closely monitored since the 1970s. Inside, life is now bountiful. The fish there live longer and breed for many more years and thus have far more offspring. Alas, many other nations have been far ahead of the United States in adapting this smart conservation tool. The Australians have turned a third of the Great Barrier Reef into a reserve network. South Africa has decided to set aside a quarter of its coastline in reserves. Far less than 1 percent of our coastal waters have reserves.

Is that because American fishermen oppose the concept?
Some do. Everywhere marine reserves have been created, most fishermen fought the idea. They saw it as losing someplace where they've traditionally fished or as yet another onerous regulation. But once the reserves were in place for a few years, they were impressed. At that New Zealand reserve, the fisherman now place their lobster pots all along the borders, catching the lobsters that spill from the reserve.

One of the most exciting developments I've seen is the recent collaboration between the environmental and fishing communities. In some parts of the West Coast and New England, for instance, new catch/share programs are taking hold: There are firm limits on the total amount of a catch that can be taken, but individuals are guaranteed a set fraction of the total. This has been very successful with Alaska halibut. With catch/share, you create incentives to leave breeding fish in the oceans for another time. It's a little like having stocks and dividends.

In the last budget, federal monies for oceanic exploration and monitoring were slashed. At the same time, appropriations for a manned mission to Mars were increased. What does that say to you?
I find it incredible. Our oceans are as much of a frontier as space. Plus, the more we understand about how the oceans work, the more that will help us understand how the entire planet works. Our future depends on it.