FRISCO — Whales may play a much bigger role in ocean ecosystems than previously thought, according to a University of Vermont researcher who studied how the great cetaceans recycle and move nutrients from one region to another.
“For a long time, whales have been considered too rare to make much of a difference in the oceans,” notes University of Vermont conservation biologist Joe Roman.
That was a mistake, he said, explaining how his research shows that whales have a powerful and positive influence on the function of oceans, global carbon storage, and the health of commercial fisheries.
“The decline in great whale numbers, estimated to be at least 66 percent and perhaps as high as 90 percent, has likely altered the structure and function of the oceans,” Roman and his colleagues wrote in the July 3, 2014, online edition of Frontiers in Ecology and the Environment, ” but recovery is possible and in many cases is already underway.”
“The continued recovery of great whales may help to buffer marine ecosystems from destabilizing stresses,” the team of scientists wrote. This recovered role may be especially important as climate change threatens ocean ecosystems with rising temperatures and acidification. “As long-lived species, they enhance the predictability and stability of marine ecosystems,” Roman said.
Baleen and sperm whales, known collectively as the “great whales,” include the largest animals to have ever lived on Earth. With huge metabolic demands — and large populations before humans started hunting them — great whales are the ocean’s ecosystem engineers. They eat many fish and invertebrates, are themselves prey to other predators like killer whales, and distribute nutrients through the water. Even their carcasses, dropping to the seafloor, provide habitat for many species that only exist on these “whale falls.” Commercial whaling dramatically reduced the biomass and abundance of great whales.
“As humpbacks, gray whales, sperm whales and other cetaceans recover from centuries of overhunting, we are beginning to see that they also play an important role in the ocean,” Roman said. “Among their many ecological roles, whales recycle nutrients and enhance primary productivity in areas where they feed.” They do this by feeding at depth and releasing fecal plumes near the surface—which supports plankton growth—a remarkable process described as a “whale pump.” Whales also move nutrients thousands of miles from productive feeding areas at high latitudes to calving areas at lower latitudes.
Sometimes, commercial fishermen have seen whales as competition. But this new paper summarizes a strong body of evidence that indicates the opposite can be true: whale recovery “could lead to higher rates of productivity in locations where whales aggregate to feed and give birth,” supporting more robust fisheries.
As whales recover, there may be increased whale predation on aquaculture stocks and increased competition—real or perceived—with some commercial fisheries. But the new paper notes ” a recent investigation of four coastal ecosystems has demonstrated the potential for large increases in whale abundance without major changes to existing food-web structures or substantial impacts on fishery production.”
In death, whale carcasses store a remarkable amount of carbon in the deep sea and provide habitat and food for an amazing assortment of creatures that only live on these carcasses. “Dozens, possibly hundreds, of species depend on these whale falls in the deep sea,” Roman notes.
“Our models show that the earliest human-caused extinctions in the sea may have been whale fall invertebrates, species that evolved and adapted to whale falls,” Roman said, “These species would have disappeared before we had a chance to discover them.”
Until recently, ocean scientists have lacked the ability to study and observe directly the functional roles of whales in marine ecosystems. Now with radio tagging and other technologies they can better understand these roles.
“The focus of much marine ecological research has been on smaller organisms, such as algae and planktonic animals. These small organisms are essential to life in the sea, but they are not the whole story,” Roman said.
New observations of whales will provide a more accurate understanding of historical population dynamics and “are likely to provide evidence of undervalued whale ecosystem services,” note the ten scientists who co-authored this new paper, “this area of research will improve estimates of the benefits—some of which, no doubt, remain to be discovered—of an ocean repopulated by the great whales.”
Why whale poo could be the secret to reversing the effects of climate change
I have been at the wrong end of a defecating sperm whale: it smells, it’s nutrient rich, and could just save the world
theguardian.com, Tuesday 8 July 2014 12.00 EDT
The first success of the environmental movements of the 1960s was to save the whale. Now, with deep irony, whales may be about to save us with their poo. A new scientific report from the University of Vermont, which gathers together several decades of research, shows that the great whales which nearly became extinct in the 20th century – and are now recovering in number due to the 1983 ban on whaling – may be the enablers of massive carbon sinks via their prodigious production of faeces.
Not only do the nutrients in whale poo feed other organisms, from phytoplankton upwards – and thereby absorb the carbon we humans are pumping into the atmosphere – even in death the sinking bodies of these massive animals create new resources on the sea bed, where entire species exist solely to graze on rotting whale. There’s an additional and direct benefit for humans, too. Contrary to the suspicions of fishermen that whales take their catch, cetacean recovery could “lead to higher rates of productivity in locations where whales aggregate to feed and give birth”. Their fertilizing faeces here, too, would encourage phytoplankton which in turn would encourage healthier fisheries.
Such propositions speak to our own species’ arrogance. As demonstrated in the fantastical geoengineering projects dreamed up to address climate change, the human race’s belief that the world revolves around it knows no bounds. What if whales were nature’s ultimate geoengineers? The new report only underlines what has been suspected for some time: that cetaceans, both living and dead, are ecosystems in their own right. But it also raises a hitherto unexplored prospect, that climate change may have been accelerated by the terrible whale culls of the 20th century, which removed hundreds of thousands of these ultimate facilitators of CO2 absorption. As Greg Gatenby, the acclaimed Canadian writer on whales told me in response to the Vermont report, “about 300,000 blue whales were taken in the 20th century. If you average each whale at 100 tons, that makes for the removal from the ocean of approximately 30m tons of biomass. And that’s just for one species”.
There’s another irony here, too. American whaling, as celebrated in Herman Melville’s Moby-Dick (1851), declined in part because of the discovery of mineral oil wells in the second half of the 19th century. One unsustainable resource – the whale oil which lit and lubricated the industrial revolution – was replaced by another. By killing so many whales, then turning to carbon-emitting mineral oil, humans created a double-whammy for climate change. (Conversely, and perhaps perversely, some US commentators have claimed that capitalism saved the whales rather than environmentalists. They contend that our use of mineral oil actually alleviated the pressure on whale populations – proof, they say, that human ingenuity has the ultimate power to solve the planet’s problems).
The 10 scientists who jointly contributed to the new paper note the benefits of “an ocean repopulated by the great whales”. Working on a whalewatching boat off Cape Cod last month, I witnessed astonishing numbers of fin whales, humpbacks and minkes feeding on vast schools of sand eels. I watched dozens of whales at a time, co-operatively hoovering up the bait – and producing plentiful clouds of poo in the process. (Having been at the receiving end of a defecating sperm whale, I can testify to its richly odiferous qualities.)
Observers in the Azores have reported similarly remarkable concentrations of cetaceans this summer. And with a 10% increase in humpback calves returning to Australian waters each year, and blue whales being seen in the Irish Sea, a burgeoning global population of cetaceans might not just be good for the whalewatching industry, they may play a significant role in the planet’s rearguard action against climate change.
It would certainly be a generous return on their part, given what we’ve inflicted on them. Indeed, as Melville imagined in his prophetic chapter in Moby-Dick, Does the Whale’s Magnitude Diminish?, the whale might yet have the last laugh, regaining its reign in a flooded world of the future to “spout his frothed defiance to the skies”.