All things environmental

Musings about the environment and all it touches, from education to city planning

The poo blog: whale poo could save us

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Nietzsche supposedly remarked that as long as we retain an alimentary tract and need to defecate, we, humanity, will never mistake ourselves for gods.

Thank you mister Nietzsche; I suppose I needed that reminder.

Turns out Nietzsche has got it backwards, though.  If there is life on Earth, at least as we know it, it is because of our ability to defecate.  No shit. If there’s a god somewhere, he or she has a sense of humour.

marine snow in the Gulf of Mexico

It gets even more bizarre when you learn that the solution to most of our problems – global warming, ocean acidification, you name it – lies in making sure there’s enough poo around; whale poo, to be specific.

I’m not making this up.  Follow me, it’s an interesting ride.

About half a billion years ago, there we no animals or land plants because planet Earth, all of it, was covered by a giant ice sheet.  (This really has little to do with the story, but it’s a cool factoid.)

Then the ice melted (blame volcanoes) and the oceans filled up with microscopic algae.  And algae live like all plants do: they grow by converting carbon dioxide into oxygen.  A good thing, obviously, since we all breathe oxygen, and pass out if there’s too much carbon dioxide in the air.  And, of course, the planet starts cooking if there’s a lot of carbon dioxide in the air.

The problem is, all these algae end up dying, and whatever carbon they had accumulated in their bodies turns back into carbon dioxide.  And in doing so, they use up all the oxygen they had previously released.  So if algae is the only thing around, there’s no chance for oxygen to accumulate to levels that we need.  This is where shit comes in.

If anything eats the algae, and is larger than, say, bacteria, it poops.  That’s a law of nature. And – here’s the key point – since we’re in the ocean, the poop falls to the bottom of it.  And stays there.  Little happens to it, it doesn’t turn back into carbon dioxide, it doesn’t use up oxygen.  It just accumulates.  And so does the oxygen left behind: it also accumulates, and we now have enough of it to breathe.  All thanks to little critters’ shit.  (Use the words “faecal pellets” when explaining this, and you’ll sound very scholarly.)   In the words of Nick Lane (from his 2002 book Oxygen):

In a clever paper published in Nature in 1995, Graham Logan and his colleagues contradicted Nietzsche, arguing, in effect, that we owe our most god-like qualities, indeed our very existence, to the primal need for defecation.  Faecal pellets from the first large animals, they say, cleansed the oceans, paving the way for the Cambrian explosion.  Few theories of environmental change in the terminal Precambrian are quite so down to earth (or at least, seafloor).

This phenomenon continues to this day, and has been given the poetic name of “marine snow”.  (Maybe as in “yellow snow”, the kind your mom told you not to eat.)  What happens to it is more complicated than I let on; for instance, it is the main source of food for the strange creatures that live in the very deep ocean.  But the principle of a carbon sink, in the form of a marine snow of faecal pellets, is now well established.  It was even possible to measure how much of it there is, and how fast it sinks, after the Chernobyl explosion; scientists were able to track the progress of the radioactive poop that sank. (That’s what happens when fish eat radioactive food – few develop three eyes, a la The Simpsons; most just poop the radioactivity out.  And, yes, that’s what ocean scientists love to do: follow the trail of radioactive poop.)

If you’ve followed so far, you may be wondering where the whales fit in all this, and why their poo, in particular, matters with all that “marine snow”.  Well, in part, whale poo matters because it’s very liquid, like bad human diarrhoea.  Sorry for the graphic details, but it’s important: whale poo is very dilute, and it floats.  No marine snow from these giants.

It matters because whales get their food from the depths, where there are a lot of micronutrients, like iron.  And this iron can then fertilize the algae via whale poop – because whales poop near the surface.  These micronutrients are precisely what algae need to grow, and they are rare at the surface, where algae live.  Think of pooping whales as fertilizer pumps.

What happens next, you know: the algae get eaten by pooping critters, marine snow is produced, and lots of carbon drop to the bottom of the ocean for good.

sperm whale posing for diver

And the amounts are huge (a shitload orf carbon, if I may).  Just for the sperm whales of southern ocean, Trish Lavery and her co-workers estimate that twenty thousand tonnes of carbon dioxide are removed per year.  To put this in perspective, this is equivalent to the greenhouse gases produced by about 150,000 cars – all gone thanks to little old poop!  Imagine the results if there were many more whales, no longer in danger.  Similar findings apply to humpbacks in the Gulf of Maine.

But whales have to protected.  To recap: no whales, no whale poo.  No whale poo, no fertilizer, no algae.  No algae, no food for small critter, no faecal pellets, no marine snow, no carbon buried at depth. No carbon burial leaves more in the atmosphere, causing climate change.  Just like that, we could lose one of nature’s way to control the climate.

In Star Trek IV, planet Earth is in mortal danger in the 23rd century because whales went extinct.  Trekkies were on to something.

So save the whales, I say, if only for their poo.  In whale poo is salvation (I think that’s a catchy slogan – you?).


Written by enviropaul

February 22, 2012 at 6:12 pm

4 Responses

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  1. […] yet, the importance of predators for climate should not be minimized.  I already mentioned the importance of whales: their excrement doesn’t sink, and the fertilizing effect it has is important for carbon […]

  2. […] the way to more salmon. But the excess algae also contribute to carbon sequestration; that makes whales one of the ocean’s main defence against climate change. Who […]

  3. […] about this topic before, including a few book reviews (here and here), a paean to whale shit here, or a look at how the costs of sewers in a sprawling city can be enough to bankrupt it […]

  4. […] marine snow, as it’s called, is a key regulator; indeed, without the appearance of pooping zooplankton, there […]

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