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Whales are not only large, they are also important to the health of the oceans. The whale poop carries tons of nutrients from deep water to the surface.
Now, new research shows that whales also carry large amounts of nitrogen thousands of miles in their urine, a process that scientists have dubbed "the great funnel of whale urine."
These tons of nitrogen contribute to the health of tropical ecosystems and fish, especially in areas where nitrogen supply is limited. In some places, such as Hawaii, the nutrients of whales are greater than that of local sources.
In 2010, scientists revealed that whales, by feeding deep and pooping on the surface, provide a fundamental resource for plankton growth and ocean productivity. A new study led by the University of Vermont shows that whales also carry huge amounts of nutrients horizontally, through entire ocean basins, from the rich and cold waters where they feed to the warm axis near the equator where they mate and give birth.
Most are transported in the form of urine, although they also contribute to detached skin, whale corpses, rug stools and placentas. "These coastal areas tend to have clear waters, a sign of a low nitrogen level, and many have coral reef ecosystems," explains Joe Roman, a biologist at the University of Vermont, who co-led the new research.
"The movement of nitrogen and other nutrients can be important for the growth of phytoplankton, or microscopic algae, and provide food to sharks and other fish and many invertebrates." The study, published in March in the journal Nature Communications, estimates that, in oceans around the world, large whales, including candies, gray and humpbacks, transport about 4,000 tons of nitrogen to coastal areas with few nutrients in the tropics and subtropics each year.
They also provide more than 45,000 tons of biomass. Before whale hunting decimated populations, scientists believe these long-distance inputs could have been three or more times higher.
An important example of this process can be seen in the thousands of humpback whales traveling from a vast power zone in the Gulf of Alaska to a more restricted area in Hawaii, where they breed each year. There, in the national sea sanctuary of humpback whales on the Hawaiian islands, the supply of nutrients, tons of pee, skin, corpses and poop, of the whales is approximately twice as much as the local sources carry, the team of scientists calculates.
"We call it the great conveyor belt of whales," says Roman, "or you can think of it as a funnel because whales feed in large areas, but they need to be in a relatively confined space to find a partner, reproduce and give birth." This means that nutrients scattered across the vast ocean are concentrated in much smaller coastal and coral ecosystems, "as if we picked leaves to make compost for our garden."
In summer, adult whales feed on high latitudes (such as Alaska, Iceland and Antarctica), accumulating tons of fat. According to recent research, North Pacific humpback whales fatten about 14 kilos a day in spring, summer and autumn.
They need this energy for their epic ocean voyages. Grey whales travel more than 11,000 kilometers between feeding areas off Russia and breeding areas along Baja California. The humpback whales in the southern hemisphere travel more than 8,000 kilometers from the feeding areas near Antarctica to mating sites off to Costa Rica.
Once in their breeding places, the whales urinate large amounts of nitrogen-rich urea. A study in Iceland suggests that rorcuales produce almost 1,000 litres of urine a day when feeding. By comparison, humans produce less than two litres of urine a day.
"Because of their size, whales can do things that no other animal does. They live life on a different scale," says Andrew Pershing, one of ten co-authors of the new study and oceanographer of the nonprofit Climate Central. "The nutrients come from outside, not from a river, but through these migratory animals," he adds. 'We don't think other animals, apart from humans, have an impact on a planetary scale, but whales really have it.'
Before industrial whaling began in the 19th century, the nutrient intakes "would have been much higher and this effect would have been much greater," Pershing says. In the Antarctic Ocean, blue whale populations remain very small after the intense 20th century hunt.
The study underscores the importance of boosting conservation efforts to increase populations across the globe. "Animals form the circulatory system of the planet," Roman says, "and whales are the extreme example." (Source: Euronews)
