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Posted by on October 30, 2010 at 20:53:32:
Whale feces -- should you be forced to consider such matters -- probably conjures images of, well, whale-scale hunks of crud, heavy lumps that sink to the bottom. But most whales actually deposit waste that floats at the surface of the ocean, "very liquidy, a flocculent plume," says University of Vermont whale biologist, Joe Roman. And this liquid fecal matter, rich in nutrients, has a huge positive influence on the productivity of ocean fisheries, Roman and his colleague, James McCarthy from Harvard University, have discovered. Their discovery, published 11 October in the journal PLoS ONE, is what Roman calls a "whale pump." Whales, they found, carry nutrients such as nitrogen from the depths which they feed back to the surface via their feces. This functions as an upward biological pump, reversing the assumption of some scientists that whales accelerate the loss of nutrients to the bottom. "We found that whales increase primary productivity," Roman says, allowing more phytoplankton to grow, which then "pushes up the secondary productivity," he says, of the critters that rely on the plankton. The result: "bigger fisheries and higher abundances throughout regions where whales occur in high densities," Roman says. "In areas where whales were once more numerous than they are today, we suggest that they were more productive," say McCarthy. "Conservative estimates are that large whales have been cut to 25 percent," says Roman, "though the work done on whale genetics shows that we're probably closer to 10 percent," of historical levels. "Anyway you look at it, whales played a much bigger role in ecosystems in the past than they do now," says Roman, a conservation biologist in the University of Vermont's Rubenstein School of Environment and Natural Resources and the author of a book on whales. "And everything that we do to enhance recovery and restoration of the great whales to something like pre-harvest levels works against other deleterious effects that humans are causing in the oceans," says McCarthy, like the decline of overall ocean productivity as climate change drives up water temperatures, which, in turn, causes a decline in nutrients for phytoplankton. “Save the whales, save the fishermen. By restoring populations we have a chance to glimpse how amazingly productive these ecosystems were in the past." To see the full 12 October Science Daily article go to:
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