SCIENCE: Can fish poop limit climate-related ocean acidity? (01/16/2009) Lauren Morello, E&E reporter
Fish waste appears to play an important role in regulating the oceans' delicate chemistry, helping to balance acid levels that can harm sea life, according to research published today in Science. The news comes at a time of increasing concern about the effects that humans' carbon dioxide emissions are having on the world's oceans. Since the beginning of the Industrial Revolution, the oceans have absorbed about a third of human-caused CO2 emissions. That has resulted in water 30 percent more acidic than it was before factories, cars, planes and other fossil-fuel burning machines became widespread. And that's a problem for shellfish, corals and marine animals that grow hard shells made of a chalky, alkaline mineral called calcium carbonate. If ocean water becomes too acidic, it can begin dissolving those shells, sometimes faster than the creatures can rebuild them. And that, according to the new research led by University of Exeter scientist Rod Wilson, is where fish poop becomes a crucial part of the equation. Bony fish -- more than 90 percent of all species -- take in seawater as they swim. Dissolved calcium in that water combines with carbon dioxide from the fishes' bodies to form calcium carbonate, which they excrete. Those fish feces may contribute between 3 and 15 percent of the total carbonate concentration in the top 1,000 meters of the ocean, the new study found. All told, the approximately 812 million to 2,050 million tons of bony fish in the world's oceans could produce up to 100 million tons of calcium carbonate per year, helping to regulate the ocean's acid balance. The hypothesis attempts to answer an enduring question for ocean scientists, who believed plankton produced most of the carbonate in the ocean -- but their activity couldn't fully account for the concentrations researchers observed. "These findings may help answer a long-standing puzzle facing marine chemists," Wilson said. "But they also reveal limitations to our current understanding of the marine carbon cycle." --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en -~----------~----~----~----~------~----~------~--~---
