UofSC professor: Human-driven climate change devastating ocean ecosystems
Erin Meyer-Gutbrod researches the movement of right whales, reef fish in response to climate change
Posted on: September 28, 2021; Updated on: September 28, 2021
By Rose Cisneros and Bryan Gentry, cisneror@mailbox.sc.edu, 803-576-7239
Warming oceans are driving some marine populations out of their habitats and into peril, according to new research by University of South Carolina professor Erin Meyer-Gutbrod.
The temperature change is affecting creatures large and small, from the critically endangered North Atlantic right whale to more common fish whose habitats are losing oxygen. Meyer-Gutbrod published two research articles this month that examine the oceans’ changes over the past 15 years and provide a cautionary tale for those who manage waterways and fisheries.
By understanding how ocean dwellers will move with the warming waters, we can more effectively preserve species that are important to the ecosystem and the economy.
The preservation of our ecosystems and the maintenance of biodiversity impact everyone. Human well-being is intricately connected with the environment.
— Erin Meyer-Gutbrod
Right whales move to find food
At 140,000 pounds and 52 feet long, the North Atlantic right whale weighs in among the world’s largest creatures. It is twice the size of a humpback whale, but just under half the size of the blue whale.
But the species has long faced dangers from human activity. In fact, it got its name from being the “right” whales to hunt, according to the National Oceanic and Atmospheric Administration Fisheries.
Meyer-Gutbrod, an assistant professor in the School of the Earth, Ocean and Environment, started studying the effects of climate change on right whales in the North Atlantic as a doctoral student at Cornell University. It’s an attractive species to study because long-term monitoring provides plenty of historical data to compare and its endangered status means people pay more attention to her findings.
“The US and Canada maintain protective policies to reduce anthropogenic [human-caused] impacts on the species,” she says. “This means that my research can have a direct impact on conservation and management.”
And that guidance couldn’t come at a better time. In the summer of 2017, the U.S. National Marine Fisheries Service discovered 17 dead right whales, most of which had died from being hit by ships or tangled in fishing gear. Twelve were found in the Gulf of St. Lawrence, hundreds of miles north from the whales’ normal summer feeding area in the Gulf of Maine.
Meyer-Gutbrod set out to find out why the whales were moving. Her findings, published in the journal Oceanography, trace the move to a “regime shift,” a prolonged change caused by elevated water temperatures.
What we are seeing is right whales responding to a climate-driven change in their prey environment.
— Erin Meyer-Gutbrod
Meyer-Gutbrod's findings paint a grim picture for the right whale. She says a northward shift in the Gulf Stream warmed the Gulf of Maine from below, causing a decline in the zooplankton that right whales eat.
As the whales left their traditional foraging grounds in search of food, they left protected waters, causing more deadly ship strikes and fishing gear entanglements.
“What we are seeing is right whales responding to a climate-driven change in their prey environment," Meyer-Gutbrod said. “As they moved north to feed in the Gulf of St. Lawrence, many individuals were killed by ship strikes or entanglement in fishing gear, largely because there were no protective policies in place in this unexpected habitat.”
Compounding the problem, the lower food availability and disruption of foraging environments leads to lower calving rates. The calves that are born are more likely to die earlier and more often from malnutrition.
Estimates indicate that there are fewer than 360 right whales left. The population decrease is so severe that right whales were elevated to the critically endangered list in 2020.
But there is good news. Meyer-Gutbrod’s research identifies ways the United States and Canada can help protect right whales, such as monitoring ocean conditions and whale sightings to eventually predict changes in new right whale habitats. As the whales move, protective regulations should move with them, she says.
Meyer-Gutbrod urges quick action to to adapt regulations to the whales’ movement.
“Canada and the U.S. will need to adopt more dynamic management plans,” Meyer-Gutbrod
says. “Failure to adopt such measures and significantly reduce anthropogenic mortality
sources could commit the right whale population to extinction before the end of the
century.”
Fish move to find oxygen
Meyer-Gutbrod's research also explores how the warming ocean affects underwater oxygen and the fish who depend on it.
Her recent research published in Global Change Biology, co-authored with a team of researchers at the University of California, Santa Barbara, reveals that oceanic oxygen concentrations are dropping. Lower oxygen levels are pushing some fish species into shallower waters while driving others deeper, which has ecological and economic ramifications.
When fish move out of their normal foraging areas, it disrupts every other population that depends on those fish — and that includes us.
Their research is the first to track changes in fish distribution in the same location while also tracking the decline in oxygen over a period of 15 years.
Fish can drown if there is not enough oxygen in the water. So, they either move to more oxygenated areas or they risk dying from low oxygen. For some species, this means finding shallower water, where atmospheric oxygen mixes with surface water.
However, other research indicates that fish may need to move to deeper, cooler waters to avoid anthropogenic warming at the surface. When fish move up to avoid low oxygen and move down to avoid warm waters, this results in a compression of usable habitat.
“The depth band that they can occupy is getting narrower and narrower through time,” Meyer- Gutbrod says.
This shrinking habitat causes overcrowding, and it could affect fishing practices.
“If you throw your net in the water,” Meyer-Gutbrod says, “and you get a ton of fish — more than you’re used to getting — you may think, ‘Oh, it’s a good year for the fish. Maybe the population is recovering.’ But instead, it could be that all the fish are just squished into a tighter area. You could have fishery regulations changing to increase fish allowances because of this increase in landings.”
Scientists don’t yet know the consequences of this narrowing band. What they do know
is that fish are being forced out of their optimal habitats. And they’re not the only
ones.
The local impacts of climate change
Meyer-Gutbrod's research is more than an esoteric look at changes deep under water and 1,500 miles away. It has impacts close to home.
For example, whale watchers often gather on the South Carolina coast to spot the right whale during breeding and calving season, meaning the species’s decline would be felt right here in the Palmetto State.
As for fish, if the compressed habitat leads to over-fishing, then it could affect human food supplies and the fishing economy. Despite different environments, humans, whales and fish inhabit an interconnected, global ecosystem.
But there are ways you can help.
“Find ways to reduce the carbon footprint in your life and in your community. Communicate with your politicians about protecting our vulnerable ecosystems and reducing human impacts.
“The preservation of our ecosystems and the maintenance of biodiversity impact everyone,” Meyer-Gutbrod says. “Earth's biosphere provides services that humans rely on, including producing oxygen and food. Human well-being is intricately connected with the environment.”
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