GUY RAZ, host:
Rising carbon emissions could be good news, but just temporarily for lobster lovers. A new study published in the journal, Geology, shows that if CO2 levels were to soar, the changes in the world's oceans would cripple many species but might result in lobsters 50 percent bigger than normal.
Now, before you make those reservations at Red Lobster or start clarifying (unintelligible) of butter, you should know that those supersized lobsters probably won't last very long. And to explain why, we're joined by the scientist who oversaw that study.
Justin Ries is an assistant professor at the University of North Carolina in Chapel Hill.
Welcome to the program.
Professor JUSTIN RIES (Marine Sciences, University of North Carolina, Chapel Hill): Thanks, Guy. Thanks for having me.
RAZ: Explain how higher CO2 levels in the ocean actually produce bigger, much bigger lobsters.
Prof. RIES: Well, we hypothesize that the lobsters had the ability to control the type of carbon that's adjacent to their shell and, therefore, that they used to build their skeletons. So when you increase CO2 in the atmosphere, you actually increase the amount of carbon in seawater so you increase the amount of material they're using to build their shell. But for most organisms, this is in the wrong form. We hypothesize that the lobsters have the ability to convert that carbon back into a form that they can use in shell building.
RAZ: Justin Ries, that sounds pretty good, I guess, right? I mean, bigger lobsters means better yields for the industry, the seafood industry, maybe better prices for consumers, right?
Prof. RIES: Well, it's a little more complicated than that, and the reason is because this pH control and, therefore, this control of the type of carbon they use may require them to divert energy from other physiological processes like tissue growth and reproduction. So they may be able to maintain elevated levels of calcification under CO2 acidification, but it may come at the expense of other processes. And this could be a very bad thing lobsters.
Another component of this story is that if less CO2 tolerant species within the ecosystem and within the lobster's food web, like clams, for example, one of the main prey of lobsters, they had a very negative response. And if their shells become thinner and they become exploited by lobsters and crustaceans that are not able to prey on them more effectively, they're prey could ultimately - populations could decline. And even though the lobsters are building stronger shells, their populations would probably be sure to follow.
RAZ: How did you do this research? I understand that you did this in a controlled environment. Obviously, you didn't do this in the ocean. Describe what you actually did.
Prof. RIES: We took seawater and we bubbled it with mixed gases that were formulated at the CO2 levels that are predicted for the future. And we grew the organisms for 60 days under these future high CO2 scenarios. And then we measured how the organism's rate of calcification changed over that 60-day period. And the way we did this is we actually measure their buoyant weight, which is the standard method for measuring just the weight of the shell.
RAZ: So you build these tanks and you have these each tank sort of predicts what the carbon levels will be in the ocean 100 years from now, 200 years from now and beyond. The lobsters did well; some of the other crustaceans did well. Which organisms didn't do well?
Prof. RIES: That's a great question. The organisms that didn't do well generally were the coral we looked at and the mollusk clams, quahogs, the clam that you use in clam chowder, bay scallop, the American oyster and a soft clam. And actually, six of these species began to dissolve under the highest CO2 level. That means over the 60-day period, their shell weighed less at the end than at the beginning. And this suggests that given sufficient time, these organisms could lose their shell completely.
Now, in general, the marine sea floor is a very tough place to live. It's rife with intense predation. And in order for you to survive on the sea floor, you need to be able to protect yourself from predation. And one of the main ways organisms do that is to build their shells. If they lose these shells, they're not going to be able to protect themselves from the highly predatory marine sea floor.
RAZ: Justin Ries is a marine geologist at the University of North Carolina, Chapel Hill. His new study on how rising carbon levels affect marine organisms is in the latest issue of the journal, Geology.
Justin Ries, thanks.
Prof. RIES: Thank you very much, Guy.
RAZ: And you can get a look at the supersized lobsters that Justin Ries grew at our Web site. That's npr.org.