by Kaea Latronic – While surfers spend their time reading the waves and riding the lineup, the ocean’s largest mammals are running a massive operation directly beneath the board. What they are doing down there keeps the ocean alive and florid.
Most people paddling out never think about the ocean’s basic supply problem: in the open ocean, nutrients needed for flourishing marine life are constantly falling out of reach. Crucial building blocks like iron and nitrogen succumb to gravity, drifting down into the deep. This would leave the sunlit surface waters devoid of microfauna — but Nature has Her ways: the largest megafauna, whales. These gargantuan mammals act as the ocean’s heavy machinery, crucial to a global nutrient recycling system called the “whale pump.” This biological plumbing system is also one of the planet’s most potent natural defenses against climate change.
To understand this built-in solution, one need only to look at the physical distance between where whales feed and where they breathe. Whales forage in the darkest depths, diving hundreds of feet down to feast on nutrient-dense prey: from tiny krill to squid of all sizes. As any mammal must, they surface to air- and water pressure changes trigger their bodies to excrete waste – right in the sunlit surface waters. These waste plumes act as a highly concentrated fertilizer packed with the elements surface waters desperately lack. After depositing these nutrients right where the light hits, massive blooms of phytoplankton grow exponentially. These microscopic algae act as the ocean’s lungs, pulling carbon from the atmosphere and generating half the world’s oxygen. Algae and phytoplankton capture carbon dioxide amounts equivalent to four Amazon rainforests every single year.
This natural plumbing system also drives nutrients horizontally across the globe by what is complementarily called “the whale conveyor belt.” Species like baleen whales migrate up to 12,000 miles seasonally, moving between freezing feeding grounds and warm, nutrient poor tropical zones, where they birth calves. Along these vast corridors, they redistribute organic matter through waste, sloughed skin, and placentas, providing a vital nutrient supply to areas of the ocean. Over its lifetime, a single whale functions as a vault, storing an average of 33 tons of carbon dioxide within its tissue. That’s more carbon than a massive live oak tree, which only locks up about 12 tons of carbon dioxide over a 500-year lifespan.
The carbon dioxide management doesn’t end when a whale’s life does. When a whale’s time has come, its carcass yields to gravity a final time, sinking to the deep abyssal plain of the ocean floor. This “whale fall” buries tons of accumulated carbon into deep sea mud, locking it away from the atmosphere for centuries. On the barren seafloor the whale’s remains create a hyper productive feeding oasis, a localized ecosystem that fuels specialized scavengers, crabs, and zombie worms for decades.
This entire self-sustaining cycle drives home the importance of a close look at how human activity has altered the ocean. Historically, whaling was a major industry: lamps and lights burned whale fat. Humans now have other fuel to replace whale oil. In 1986, the International Whaling Commission implemented a global ban on commercial whaling, putting up a legal shield to give the depleted populations appropriate time and space needed to rebuild and reproduce.
Wonderfully, the results are visible today. Southwestern Atlantic humpback whales have rebounded from only a few hundred individuals to over 25,000, nearly returning to historical numbers. Blue whale populations off the U.S. West Coast has also recovered to almost 97 percent of their original population! The modern story of the return of whales is one of remarkable recovery and environmental repair. Ultimately, the ocean’s role in a healthy Earth isn’t stagnant, but a dynamic ecosystem engineered, nourished and provisioned by its largest and gentlest inhabitants.