Lost giant poop disrupts whole planet

http://www.eurekalert.org/pub_releases/2015-10/uov-lgp102315.php

Public Release: 26-Oct-2015
Lost giant poop disrupts whole planet
Study shows declines in whales, fish, seabirds and large animals damages Earth's nutrient cycle
University of Vermont

Giants once roamed the earth. Oceans teemed with ninety-foot-long whales. Huge land animals--like truck-sized sloths and ten-ton mammoths--ate vast quantities of food, and, yes, deposited vast quantities of poop.

A new study shows that these whales and outsized land mammals--as well as seabirds and migrating fish--played a vital role in keeping the planet fertile by transporting nutrients from ocean depths and spreading them across seas, up rivers, and deep inland, even to mountaintops.

However, massive declines and extinctions of many of these animals has deeply damaged this planetary nutrient recycling system, a team of scientists reported October 26 in the Proceedings of the National Academy of Sciences.

"This broken global cycle may weaken ecosystem health, fisheries, and agriculture," says Joe Roman, a biologist at the University of Vermont and co-author on the new study.

On land, the capacity of animals to carry nutrients away from concentrated "hotspots," the team writes, has plummeted to eight percent of what it was in the past--before the extinction of some 150 species of mammal "megafauna" at the end of the last ice age.

And, largely because of human hunting over the last few centuries, the capacity of whales, and other marine mammals, to move one vital nutrient--phosphorous--from deep ocean waters to the surface has been reduced by more than seventy-five percent, the new study shows.

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