Giant baleen whales eat (and defecate) three times more than previously believed
A new study, led by the Stanford University and published in Nature, reveals that bearded whales, like blue whales, fin whales or humpbacks, they consume an average of three times more food per year than had been calculated so far.
By underestimating the amount of food these cetaceans consume, scientists have also underestimated the significance of these marine giants for the global health and productivity of the oceans.
Large nutrient recyclers
The importance of this discovery lies in the excrement from whales, a crucial source of nutrients in the open ocean. By consuming more food than previously thought, whales also produce more feces, and therefore generate more nutrients.
As the authors explain, when they go out to breathe, cetaceans keep the nutrients that feed the blooms of phytoplankton, microalgae that absorb carbon and form the basis of food webs in the ocean.
The Stanford team tracked 321 baleen whales of seven different species via GPS across the Atlantic, Pacific and Antarctic oceans.
Without whales, those nutrients sink more easily to the seafloor, reducing productivity in certain parts of the ocean and, in turn, limiting the ability of ocean ecosystems to absorb the carbon dioxide that is warming the planet.
The team of Matthew Savoca of the American university followed 321 baleen whales of seven different species through GPS along the Atlantic, Pacific and Antarctic oceans, and estimated their eating patterns by means of aerial photographs of their feeding areas, and acoustic measurements of the density of prey in these areas.
Regain lost ocean productivity
Many species of baleen whales have not recovered from the industrial hunting of cetaceans that was practiced during the twentieth century, and their populations are still very small. Between 1910 and 1970 alone, this hunt killed more than 1.5 million whales in Antarctic waters, and their population has not recovered since.
The Stanford team claims that an increase in the whale population could restore productivity lost marine life and, as a result, increase the amount of carbon dioxide absorbed by phytoplankton, the main food of krill, which is, in turn, a source of food for whales.
Our results suggest that [en el pasado] whales’ contribution to global productivity and carbon removal was on a par with forest ecosystems on entire continents, in terms of scale
Nicholas Pyenson, study co-author
“If the whale population could be restored to pre-hunting levels in the early 20th century, ocean ecosystems would regain a large number of lost functions,” he says. Nicholas Pyenson, conservator of fossil marine mammals from the Smithsonian National Museum of Natural History, and co-author of the study.
Pyenson notes that “it may take a few decades to see the benefits, but it is the clearest reading yet on the enormous role that great whales have on our planet.”
“Our results suggest that [en el pasado] the contribution of whales to global productivity and carbon removal was on par with the forest ecosystems of entire continents, in terms of scale ”, comments the researcher.
The scientist emphasizes that “this system is still there, and helping the whales to recover could restore the lost functioning of the ecosystem and contribute to naturally mitigate the climate crisis.”
Rights: Creative Commons.