Scientists have been studying the effects of carbon dioxide on climate for decades. More recently, however, an additional carbon dioxide problem has come to light. The oceans have absorbed about a third of the carbon dioxide emitted into the atmosphere. Carbon dioxide alters ocean chemistry, making seawater more acidic. The term researchers use for this phenomenon is ‘Ocean Acidification’ and it threatens not only the ecological health of the oceans, but also the economic well-being of the people and industries that depend on a healthy and productive marine environment.

Dr. Shallin Busch co-leads a team of scientists at NOAA’s Northwest Fisheries Science Center studying ocean acidification, and she is in Washington, DC, this week to brief Congress on its ecological and economic impacts. She stopped in to NOAA headquarters while in town, and we had a chance to ask Dr. Busch a few questions.

 

NOAA Fisheries: Shallin, thanks for taking the time to talk with us. You’re here in DC to brief Congress on ocean acidification. What is ocean acidification and why is it important?

Shallin Busch: Ocean acidification is a change in the ocean’s chemistry caused by carbon dioxide. When carbon dioxide dissolves into water it forms an acid—carbon dioxide is what we call an acid gas. As we increase the levels of carbon dioxide in the atmosphere, more carbon dioxide moves into the seawater and forms carbonic acid.  So ocean acidification is a change in ocean chemistry that results in a drop in pH and an increase in acidity.

NF: What is the single most important thing for people to know about ocean acidification?

SB: That ocean acidification is a problem for today, not just for the future. We know from earth’s history and from experiments that we’re doing in the lab that many marine species are sensitive to changes in ocean chemistry. So, acidification is a problem for marine ecosystems. We can take that a step further and say, well, why should we care about marine ecosystems? First of all, many societies value biodiversity.  Furthermore, acidification’s potential effects on marine ecosystems are an economic concern. Acidification may impact fisheries and the jobs and revenue that depend on fisheries. This may raise food security issues. Ocean acidification is an environmental problem, it’s a potential economic issue, and it’s a potential food security issue. And it’s all those things today, not some distant day in the future.

NF: What species are threatened by ocean acidification?

SB: What we can see right now is that commercial shellfish, species like oysters, are showing potential impacts of acidification. These potential impacts are not necessarily occurring in advance of those on other species, but rather we may see them first because we’re looking at these species very closely. On the west coast, the shellfish industry is having trouble producing larval shellfish in hatcheries and rearing them successfully. There’s also been a reduced natural set [of juvenile oysters] in some of the estuaries where the commercial shellfish industry relies on natural reproduction of oysters. So, that causes a big alarm. It could be that the same thing is happening with other species, but that we just don’t know about it yet. We see oysters as the canary in the coal mine.

NF: What is the main question that you and your colleagues at the Northwest Fisheries Science Center are trying to answer?

SB: What we’re interested in is how marine communities will change under ocean acidification. We look at that from the point of view of biodiversity and protected species, but we also look at it from the point of view of fisheries management. We have specific questions that we answer when we do experiments in the laboratory or fieldwork or modeling work, but all of it joins together to address that larger question: How will marine communities change under ocean acidification?

NF: And how will marine communities change under ocean acidification?

SB: The effects of acidification on individual species will have ripple effects throughout the ecosystem. So species that might not be directly affected by acidification may still be influenced by it if their predators or their prey are affected by acidification.  These food web interactions are difficult to predict, and may play out in unexpected ways.

Typically, when there’s a stressor in the marine environment, you have species that turn out to be losers, and species that turn out to be winners. And we expect acidification to be the same. We shouldn’t expect that all species will suffer under acidification. Some of them will do well. And that’s important to emphasize. If you say that all species are going to suffer, and then some species end up doing well, people will doubt the science. Marine life is not coming to an end. Rather, the marine community is changing. We’re trying to figure out what these changes are going to be, and how we can manage our fisheries differently and manage our resources differently so that we can adapt to these coming changes.

NF: How did you get into studying ocean acidification?

SB: My Ph.D. focused on physiological ecology, which is, in part, the study of how species physiology changes as their environment changes. I studied birds, mostly tropical birds, and I measured their response to environmental changes by measuring their hormones.  Hormones are the body’s internal communications system, and we tapped into that to understand how organisms deal with stress.

My main research interests are how do human-caused environmental changes effect populations, and how can we understand these changes by studying species physiology? Much of ocean acidification research focuses on these questions. Ocean acidification is a human-caused change to the environment which effects populations through physiological mechanisms.

When the scientific community realized that ocean acidification was going to be an issue and that it needed to be studied, I was already working at the Northwest Fisheries Science Center. I was doing my postdoc on salmon population demographics. My postdoc advisor, Paul McElhany, and I started working on ocean acidification together, and we built a lab to study it.

NF: Is there something I should have asked you about ocean acidification but didn’t?

SB: Most people, when they think about ocean acidification and its effects on marine organisms, think about the problems that shell-producing organisms might have. That’s because many calcifying organisms have a difficult time creating and maintaining their shells in acidified conditions. But it turns out that other physiological processes, and organisms that don’t produce shells, are also sensitive to changes in pH. For our research program at the Northwest Fisheries Science Center, we study things like how growing fish might be affected by pH. For example, fish use their gills to regulate pH balance. It turns out that the early stages of larval fish don’t have gills. There are developmental processes that can be compromised across all kinds of species, not just shell-producing species.

NF: Shallin, you’re preparing to brief the members of Congress. Are you nervous?

SB: I’m sure I will be! I’ve never done a Congressional briefing before. But what’s cool about being a biologist is that, most of the time, people are very interested in what you have to say.

NOAA Fisheries Service, 26 September 2012. Article.