Climate Change Pushing Sea Turtles, Crabs, Sharks Toward the Poles

By: Terrell Johnson

Published: August 15,2013

 

 

 

 

 

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Sharks

A great white shark jumps out of the water as it hunts Cape fur seals near False Bay, South Africa. The world's changing climate is forcing ocean species like sharks to migrate to cooler places at a pace nearly 10 times faster than is happening with species on land. (Carl de Souza/AFP/Getty Images)

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The sight of sea turtle tracks along the beach may one day be a thing of the past across much of the U.S. coastline, as warming ocean temperatures are forcing sea turtles and many other ocean creatures to find new homes in cooler waters, according to a study published this month in the journal Nature Climate Change.
More than 80 percent of the world's marine life is responding to warming waters and the changing chemistry of the oceans by migrating to different places and by changing their breeding and feeding patterns, the study reports.
Some species have migrated as much as 600 miles from where they were once abundant just a few decades ago, the study also found, noting that ocean life is responding to climate change by moving to new places as much as 10 times faster than species that live on land.
“Marine species are responding much, much faster than [land] species," said Ben Halpern, a research biologist at the University of California-Santa Barbara and one of the study's co-authors. "Which is both surprising and worrisome because it has consequences – some of which we know about, and some of which will only unfold in the near future."
Already, some of the smallest and most important life in the oceans have experienced perhaps its biggest shifts. Phytoplankton, the tiny single-celled plants that make up the base of the food chain for all life in the oceans, have moved as much as 1,000 miles away from their previous locations.
Why is this important? Because phytoplankton blooms – bursts of explosive growth in their populations along the world's coastlines -- serve as a kind of ocean buffet, the food source upon which all larger marine life depends. "These images you see in National Geographic of these massive concentrations of animals in the oceans is driven by these blooms in phytoplankton," Halpern says.
"So this (climate change) is moving the food source, the base of the food web, a thousand miles across the ocean" he adds. "If you’re lucky, if you’re a bigger fish, you can track that, but maybe you can’t and then you’re out of luck."
Not only are these blooms occurring in different places, they're also happening earlier than in the past, notes Carrie Kappel, a marine conservation biologist at UCSB and a study co-author. "Spring is coming earlier, summer is coming earlier," she said. "And so all those ocean events are starting to happen earlier too, like the way things are happening earlier on land."
These changes may have major impacts on where and whether we'll continue to find the kinds of fish people love to eat, especially in the U.S., says Frank Schwing, an oceanographer with NOAA’s National Marine Fishery Service and another of the study's co-authors, noting that ocean animals are "much more sensitive" to changes like these than land animals.
Over the last several decades, he notes, some species have moved up when they reproduce by as much as a month. "So if the timing of the spring bloom is a month earlier, species who have evolved to take advantage of [it] may no longer find it there," he adds. "Animals hatch out and the food is not there anymore."
(MORE: This Is What Global Warming Looks Like)
That's what's driving the fast migration of species, Schwing said. "Everything from salmon to grouper to the things we catch recreationally as anglers, as well as the fish for our dinner tables and restaurants -- those are the ones that seem to be most responsive, they move the most rapidly."
This is leading to a "scrambling" of ecosystems throughout the oceans, Kappel said, in which some species keep pace and others get left behind, particularly those trapped in land-locked inland seas. Species that can move quickly will invade waters where they've never lived before, while others will be lost forever.
“It’s an uncontrolled experiment that we don’t know how it’s all going to play out," she adds. "It’s never been seen at this scale or at this pace on our planet before."
The world's changing ocean habitats will also have a big impact on the millions of people living in the small coastal villages and towns that depend on the ocean for their survival, Halpern said, adding that "even though humans are very adaptable, they learn quickly, there are some things that are very slow to change."
"You can't just pick up an entire fishing village and move it 200 miles north and plop it down again," he noted. "People have embedded their infrastructure, their heritage, their culture, their generational knowledge in a particular place – and that can't be moved very easily.