A recent paper published online in the Proceedings of the Royal Society B (I have no idea what the B means, but maybe one of you can clarify with a comment) draws an enticing connection between whale excrement and climate change.  Because this study involved whale poop, it even made the mainstream news.  The folks at MSN were even nice enough to provide an areal photo of what it looks like when a whale goes to the bathroom.  I have been lucky enough to experience this first hand on a whale watch when a whale shared the contents of its bowels with those of us aboard the ship, so this study had a little bit of a personal connection for me!  Hat tip to Chrissy at Working Through the Blue for pointing me towards this article.

The paper (entitled “Iron defecation by sperm whales stimulates carbon export in the Southern Ocean”) can be found here, and seems to be available for download without subscription.  You might be wondering whether this study draws a connection to the microbial world, or if I am just excited to write about whale poop… I assure you there is a connection.  In most environments certain nutrients are limiting, and therefore control the rate of primary production.  This means that no matter how much energy (food, sunlight, or chemical energy) is available, the microbes that form the base of the food pyramid can only convert that energy into biomass (storing carbon in the process) when that limiting nutrient is present.  In the case of the Southern Ocean, iron is the limiting nutrient.  The microscopic phytoplankton floating at the surface take CO2 out of the atmosphere and convert it to biomass that eventually falls through the water column and acts as food for other organisms.  However, they are restricted in how fast they do this because there is not much iron dissolved in these surface waters.

This is where the Sperm Whales come in.  These giants descend into the cold dark depths to feed (mostly on squid), and come up to the surface to breathe and relieve themselves.  It turns out that their waste is iron-rich.  By depositing this lovely substance in the photic zone, they apparently stimulate primary productivity.  This means that the photosynthetic plankton absorb CO2, grow, reproduce, are eaten, and so on, and eventually organic material sinks down and provides energy to life in the darker regions.  But wait you say (being the savvy reader that you are), don’t the whales exhale a lot of CO2 back into the atmosphere?  Yes, they do, but according to the modeling of these researchers, the plankton take up much more CO2 as a result of the iron released by the whale than the whale releases.  “By enhancing new primary production, the populations of 12,000 sperm whales in the Southern Ocean act as a carbon sunk, remivong 2 x 105 tonnes more carbon from the atmosphere than they add during respiration”.  They go on to suggest that the reduction of whale populations due to whaling is likely to have diminished this carbon sink.

How did the scientists calculate all of this?  They first assume that these whales eat only cephalopods (mostly squid).  I do not study whales, so I don’t really know how accurate of an assumption this is, but it seems to be true for this region (in other areas sperm whales eat more fish).  Then, they used published reports of the amount of iron in cephalopods, and then calculated the amount of prey consumed by the whales by averaging previous studies that had estimated how much these animals eat.  From what is known about iron retention in marine mammals (maybe as low as 10%, they used 15% as their estimate), they were then able to estimate how much iron must be released by the whales during defecation.  They then had to figure out how much of that iron stays in the photic zone long enough to initiate primary production.  They did this by assuming (based on observations) that undigested squid beaks sink almost immediately, but that the liquid material stays around for a long time (this is admittedly non-quantitative).  Finally, they know the form that iron is generally found in the gut (ferrous salts), and they know that that form  can be expected to dissolve quickly and therefore would hang around in the photic zone.  Their estimate was that 75% of the defecated iron would stay around in the photic zone.

I explain this because while headlines like “whale poop may help offset CO2 emissions” are certainly catchy, to gauge the accuracy of this claim it is important to know how the numbers were crunched.  Flashy findings like this can trickle into the mainstream news, but people generally don’t get an explanation of why they should believe this.  [SoapBoxAlert] I think this is part of why it can be so hard for non-scientists to determine which bits of “science” to “believe” and which to be critical of, especially when it comes to climate change [now back to the regularly scheduled science].

In this case the researchers have made some very interesting calculations (they also provide estimates of the losses in carbon sequestration that historical whaling may have caused).  I think it is important to know that their numbers are based on a model rather than actual measurements of the iron concentration of whale feces or what happens to that iron over time.  Models are only as good as the data that go into making them, and in this case it seems (to me, admittedly knowing very little about whales) that they have done a pretty good job.  Whales are very difficult animals to study, and something as simple as sampling their feces would take much more time, energy, and money than you might thing, so I am certainly not faulting the authors for this.  Similar calculations were done to estimate the rate of carbon withdrawn from the atmosphere, and then sunk, but since this is already getting long, I will spare you those details.

In summary, this study provided me the opportunity to write about whales, poo, microbes, the carbon cycle, and scientific methods at once… what better way to spend a Sunday morning!


An editorial from the Chicago Tribune on Monday gives me an opportunity to discuss something I’ve been meaning to talk about for a while: the retraction (pdf) of the scientific paper in The Lancet that originally proposed a link between MMR vaccinations and autism.

The story got plenty of press, touched off a raging debate about the safety of vaccines, and scared many parents away from inoculating their kids.

There was just one problem. Researchers hadn’t actually proved a link between the vaccine and autism. They were pushing a theory, one that lead researcher Andrew Wakefield was paid nearly half a million pounds to pursue. He was paid by lawyers who were trying to prove that the MMR vaccine caused autism.

As this article notes, the original paper got tons of press, and a movement started that has convinced millions of parents not to vaccinate their kids. In the 12 years since the original paper was published, many other, more thorough investigations have found no link.

A dozen epidemiological studies have not found a link between the MMR vaccine and autism. But the fear of a link remains. And some parents complain that kids receive too many vaccines. In 1960, young children were routinely vaccinated against five diseases: diphtheria, pertussis, tetanus, polio and smallpox. The CDC now recommends vaccination by age 2 against 13 diseases.

But negative results don’t generate the same kinds of screaming headlines, and the “controversy” continued. Dr. Richard Horton, the current editor of The Lancet, put it well in a recent interview on NPR’s On the Media:

This was a system failure. We failed, I think the media failed, I think government failed, I think the scientific community failed. And we all have to very critically examine what part we played in this. I think the media certainly did sustain the story over a decade. It became a political story, with did Tony Blair have his son vaccinated with MMR or not, suddenly a huge media furor around that.

Andrew Wakefield would make many statements during the course of those ten years, each of which was dutifully reported as if it was the gospel truth. Profiles of him were written as this charismatic doctor saving the lives of children. I mean, I think we all have to look very carefully at ourselves and say, we really messed up here[…]

We used to think that we could publish speculative research which advanced interesting new ideas which may be wrong, but which were important to provoke debate and discussion. We don’t think that now.

This is a basic problem with scientific outreach – journalists often report sensationalist stories based on major advances, but major advances are rare. Furthermore, the implications for the major breakthroughs often aren’t understood for years, after a great deal of follow-up – certainly long after the “newsworthieness” has gone away. As any grad student will tell you, science is long, plodding work. Victories are small and far between, but there’s an inexorable march towards understanding. Unfortunately, you’ll never see that on the front page.

Much has been made in recent years of the decline of newspapers in general and the slashing of science reporting budgets in particular. Earlier this year, our own Boston Globe eliminated it’s popular Health/science section, and other newspapers, even cable TV are fairing no better. Some scientists may not be unhappy with this turn of events, as attitudes ranging from ambivalent to downright hostile emerge over science reporters and newspapers misrepresenting, over playing or downright botching coverage of their research. Here’s a representative  attitude from the hostile camp:

How does this crap get published? How does it have a market in ‘journalism’? Its not just non-information. And its not just stupid. Its harmful.

So whats my point? Hmm. I guess that more scientists should open blogs and take a moment to write about cutting edge research, and the profession of pop-science/newspaper/magazine ‘science’ writer should either shape up, cut the fat from their ranks, or disappear.

I clearly like the idea of scientists themselves reporting on science (hence, this blog), but I’m not sure I buy the argument that this can replace traditional science journalism whole-sale. Enter Futurity.org, a site that presents “News from leading research universities.” This site seems like the best of both worlds – science reporting, but direct from the scientists themselves, right?

Not so fast: these “articles” are actually press-releases from the representative universities represented as unbiased reporting. Bob Garfield of NPR’s “On the Media” lays out the problem succinctly:

When we lose the journalism part of the reporting cycle on science, don’t we lose the skepticism and the arms-length relationship that we need to trust that which we are reading?

On the other hand, Garfield is revleived that

at a very minimum, Futurity does not fall prey to the temptations for oversimplification and overhype that so riddles the mainstream media’s coverage of health and science issues, and has for such a long time. These things are quite straightforward and very few of the “Cancer Cure?” question mark kind of headlines that we’ve come to expect.

But I’m not so sure. Within one week of watching the headlines from futurity, I saw “Wonder Drug May Treat Cancer, Addiction.” The research is straightforward and seems to show potential (in mice) to treat addiction, but can we trust unbiased reporting from an institution that heralds some preliminary data of a mouse model as a “Wonder drug?”

In addition to the roll of journalists providing context, part of the appeal of main-stream science coverage is that it brings the information to a wider audience. People reading a blog like this are likely to already be interested in science, but what about those whose only exposure might be while flipping over to the sports page?

the decline of science journalism is decried because it is declining in precisely those places where it has the most reach.

To be fair, bad science journalists would just copy press releases to avoid doing the work of understanding, so maybe it’s reasonable to go straight to the source without the illusion of a mediator. Hopefully, scientist bloggers will see when abuses occur and work to correct the record, but will anyone be paying attention?