Hungry Crustaceans Eat Climate Change Experiment 291
Earlier this month, an expedition fertilized 300 square kilometers of the Atlantic Ocean with six metric tons of dissolved iron. This triggered a bloom of phytoplankton, which doubled their biomass within two weeks by taking in carbon dioxide from the seawater. The dead phytoplankton were then expected to sink to the ocean bed, dragging carbon along with them. Instead, the experiment turned into an example of how the food chain works, as the bloom was eaten by a swarm of hungry copepods. The huge swarm of copepods were in turn eaten by larger crustaceans called amphipods, which are often eaten by squid and whales. "I think we are seeing the last gasps of ocean iron fertilization as a carbon storage strategy," says Ken Caldeira of the Carnegie Institution at Stanford University. While the experiment failed to show ocean fertilization as a viable carbon storage strategy, it has pushed the old "My dog ate my homework" excuse to an unprecedented level.
So... (Score:2, Interesting)
Why is this a problem? (Score:4, Interesting)
The carbon is still being sequestered, just not where they expected it.
Re:Why is this a problem? (Score:3, Interesting)
do squid (and whatever eats squid) and whales sink to the bottom when the die?
Yes. Yes they do. And the carcasses are eaten by bottom-feeding animals, which generally remain at the sea floor. It's a different path through the food chain than they were expecting, but the carbon ends up on the seabed in the end.
Not for carbon sequestration, but how about food? (Score:5, Interesting)
From the results of the experiment, apparently it won't work as a means to sequester carbon.
However, what if we can use this to improve the productivity of the ocean in general? Might the increased amount of biomass serve to improve fisheries? I.e., if there's more food all the way up the food chain, can't we eat more fish? It's a hungry planet and many fisheries have been depleted....
--PeterM
Why Can't This Work... (Score:2, Interesting)
I'm not a biologist or ecologist, but doesn't the ocean food chain start with algae? And don't algae produce oxygen from CO2 instead of sequestering it like phytoplankton?
Can't we fertilize parts of the ocean for plant growth instead?
Re:So... (Score:4, Interesting)
To continue this path, what happens to the dissolved CO2 at those depths:
"Another process, called "the biological pump," transfers CO2 from the ocean's surface to its depths. Warm waters at the surface can hold much less CO2 than can cold waters in the deep. "This is the 'soda bottle on a warm day' effect," says Agassiz professor of biological oceanography James McCarthy, "and is not unique to carbon dioxide; it applies to all gases dissolved in water. There is a higher capacity to hold a gas with a lower temperature than with a higher temperature." This means that when deep ocean waters rise to the surface as part of normal ocean-circulation patterns, the water heats up and actually releases CO2."
from here,
http://harvardmagazine.com/2002/11/the-ocean-carbon-cycle.html [harvardmagazine.com]
So this is a temporary storage solution and the fertilizer might speed up the process but the CO2 is at best dissolved it seems.
I guess CO2 storage could be really helped by dumping CaOH or something like that into the ocean just where this should come from I wonder.
Re:Why Can't This Work... (Score:3, Interesting)
Re:Well it sounds better than (Score:3, Interesting)
No, it prooved that by this method it wont work.
You know the funny thing is, IIRC 10 years ago "they" were proposing iron fertilization as a way to do exactly this: augment fish supply for harvesting (like we needed to pump up the system and stress everything out more). That didn't quite work either because I think they got the result they wanted here, sinking out. Basically, there's a lot of subtleties on when, where, what type of plankton are produced, how it's kept in surface layer, microplankton, jellyfish etc. The issue with large-scale manipulations is N is small and the screwups can stick.
Re:Well it sounds better than (Score:3, Interesting)
Exactly! As long as the damn stuff isn't in the air reflecting infrared back down, who cares if it is floating around as fish, instead of sitting on the bottom?
It seems to have a beneficial effect of creating more food. Since we already overharvest the oceans, it sounds like a good idea to carefully investigate methods for increasing food production in the oceans, IE striking a balance between demand and destruction of ocean environments.
Re:Well it sounds better than (Score:5, Interesting)
I don't even see how this yielded negative results. What did they expect would happen? I mean the summary says they expected the dead phytoplankton to sink to the bottom of the ocean. Ok, so instead it was eaten, how is that negative? Isn't the carbon still sequestered away inside the crustaceans? If so, how is this negative or a failure again?
There has to be something missing here like that the crustaceans suddenly started flying and farting...or something. Otherwise, it looks like it was a win and nobody has recognized it as such.
Anyone?
Re:Why is this a problem? (Score:3, Interesting)
If we assume that an animal stores in its body all of the CO2 from plants it eats throughout its lifetime, then I suppose so...
And that's the rub. A good rule of thumb is that for every step in the food chain, 90% of material (carbon) is lost as respiration (C02 back to the environment). So zooplankton eating phytoplankton and sinking is 10% as efficient as phytoplankton sinking. Fish eating zooplankton is 1%. Whales 0.1%. Etc.
Re:Well it sounds better than (Score:3, Interesting)
Dead phytoplankton sinking to the bottom = capturing carbon
Creating a chain reaction in the food-chain = destabilizing the ecosystem
This isn't good because you're directly increasing the number of predators without increasing their pray. As a result, these hungry predators will create a collapse of pray since the experiment was a one-off. Look at it like this (simplistic, I know): the number of lions and zebras in Africa are in a dynamic balance. One day a group of researchers comes in and add a shitload of Wildebeests. Number of lions increase as their diet became richer. The extra Wildebeests are removed by the lions, the next season there are too many lions per zebra. Bye bye zebras.
Re:Well it sounds better than (Score:5, Interesting)
According to a recent study that I'm too lazy to google for (and is only a single study, so it's not proof of anything), fish excrement contains a significant amount of calcium carbonate.
If this CaCO3 sinks to the bottom before it dissolves, it would sequester the carbon. If, however, it dissolves before it sinks, it releases the carbon right back into the water. The fate of the fish excrement was beyond the scope of the study.
So a significant amount of carbon may or may not be sequestered by the fish that prey on the plankton that capture the carbon, while a significant amount is caught up in the biomass of the fish.
However, with rampant overfishing, including use of illegal catch-em-all nets in "protected" areas, which is just about impossible to police, all of the carbon that becomes part of fish biomass will end up back in the atmosphere after passing through someone's digestive system.
But, if somehow fishermen around the world can be convinced to use iron fertilization as part of a comprehensive aquaculture system, and actually increase the global fish biomass...
Nah, you'll never get enough people cooperating to make that happen.
Re:Well it sounds better than (Score:3, Interesting)
Do whales evaporate when they die? I am failing to identify why a whale dying and a plankton dying would yield a different result regarding their sequestered carbon...?
Re:Well it sounds better than (Score:3, Interesting)
It's less than clear that carbon on the ocean's floor is just removed from the system. We know crabs eat sunk dead whales, and we know we have a lot of knowledge gaps about deep ocean-floor ecology (heck, we only found out about thermal vent ecologies twenty years ago.)
So, we try the next experiment: seed iron and fine silica - maybe that works in getting the diatoms crunchy enough that they survive the sink to the floor.
Re:This experiment was NOT a failure! (Score:2, Interesting)
Honest question here:
How does the amount carbon sequestered by this process compare to the carbon released by mining/processing the iron and by the ships travelling across the ocean spreading the iron? That seems like a problem.
Wrong! (Score:3, Interesting)
"This experiment has proved that iron fertilization is not going to work as a carbon storage strategy."
It did no such thing.
If this was done in the middle of the ocean, in deep water, then it might not be such a hot idea.
But what if you do it in CORAL RICH areas? Can the phytoplankton be eaten by corals? If so, then the bulk of the carbon absorbed would be deposited in the form of coral skeletons(calcium carbonate) that persist for millions of years. Sounds like a handy place to store carbon to me.
The idea just needed to be focused in a different way, maybe...
How about feeding captive mollusk beds(clams, mussels, oysters...) with phytoplankton? Eat the good part, then bury the shells. Food AND carbon sequestration.