June 16, 2010
Whale Poo Helps In Fight Against Global Warming
A study released on Wednesday reveals that Southern Ocean sperm whales' feces are an unexpected ally in the fight against global warming.
The cetaceans have been previously fingered as climate culprits because they breathe out carbon dioxide (CO2), the commonest greenhouse gas.
However, according to the paper published in the British journal Proceedings of the Royal Society B, this is only part of the picture.
Australian biologists estimated that the 12,000 sperm whales left in the Southern Ocean each defecate about 50 tons of iron into the sea each year after digesting the fish and squid they hunt.
The iron is a terrific food for phytoplankton, which are marine plants that suck up CO2 from the atmosphere through photosynthesis.
As a result of fecal fertilization, the whales remove 400,000 tons of carbon each year, twice as much as the 200,000 tons of CO2 that they contribute through respiration.
According to an equation on the website of the U.S. Environmental Protection Agency (EPA), 200,000 tons of CO2 is equal to the emissions of about 40,000 passenger cars.
The paper said the whales' feces are so effective because they are emitted in liquid form and close to the surface, before the mammals dive.
It said that industrialized whaling not only gravely threatens Southern Ocean sperm whales, but also damaged a major carbon "sink."
The paper said that before industrial whaling, the population of this species was about 10 times larger, which meant around two million tons of CO2 were removed annually.
The Southern Ocean is rich in nitrogen but poor in iron, which is essential for phytoplankton.
The scientists say that because sperm whales cluster in specific areas of the Southern Ocean there is a clear link between food availability and cetacean feces.
The researchers believe this could explain the "krill paradox." Scientists have previously discovered that when baleen whales are killed, the amount of krill in that sea area declines, which affects the entire food chain.
The study is lead-authored by Trish Lavery of the School of Biological Sciences at Flinders University in Adelaide.
According to the EPA's website, a passenger car that is driven for 12,000 miles a year yields annual emissions in CO2 or its equivalent of just over five tons.
The future of sperm whales and other species will be debated next week in Agadir, Morocco, where the International Whaling Commission (IWC) discusses a plan to relax a 24-year moratorium on commercial whaling.
On the Net:
- Proceedings of the Royal Society B
- Flinders University
- Whale and Dolphin Conservation Society (WDCS)