17 Nov 2014: Report

Fast-Warming Gulf of Maine
Offers Hint of Future for Oceans

The waters off the coast of New England are warming more rapidly than almost any other ocean region on earth. Scientists are now studying the resulting ecosystem changes, and their findings could provide a glimpse of the future for many of the world’s coastal communities.

by rebecca kessler

After hauling in the cages at his island oyster farm near Biddeford, Maine, Mark Green's boat is loaded with crusty marine life. Baskets of oysters are there, but so are green crabs — invasive and inedible. "My boat will be full," Green says. "The bottom will just be this undulating mass of green crabs by
green crab
Sandy Richard/Flickr
Green crabs have been proliferating in the waters of the Gulf of Maine recently.
the end of the day. I mean thousands."

A native of Europe, green crabs have been present on the U.S. East Coast for more than a century, but until a couple of years ago they didn't cause much trouble in Maine. Now, thanks to rapidly warming waters, their population has exploded. While they don't bother the tough-shelled oysters, the crabs are laying waste to the region's softshell clams — another important commercial stock — and devastating its seagrass meadows, which Green, an environmental scientist at St. Joseph's College in nearby Standish, calls "the most crucial habitat that exists in an estuary."

"It's crazy," Green says.

The seething, skittering masses of green crabs and mudflats depleted of clams and seagrass are just a few signs of big changes underway in the Gulf of Maine, the pool of Atlantic waters stretching from Cape Cod to southern Nova Scotia. Scientists report that the gulf's waters are warming faster than 99.85 percent of the rest of the world's oceans, and the marine ecosystem is reorganizing itself apace. The changes are so striking — and the fishery they affect is so important to the region's economy and identity — that they are under close watch by the area's many marine scientists. Observers say the gulf has become a "living laboratory" for how climate change could play out in marine ecosystems around the world.

"At minimum what we're seeing now is a window to what we expect our average conditions to be in the middle or towards the end of the century," says Andrew Pershing, chief scientific officer at the Gulf of
Only three other places on earth are heating up as fast as the Gulf of Maine.
Maine Research Institute. "We're kind of seeing a glimpse of the future."

Pershing cautions that it remains unclear how much of the warming trend is driven by climate change and how much is simply a result of the gulf's natural variability, and he suggests that the gulf could cool again somewhat in the short term.

But it is clear, Pershing says, that only three other places on earth are heating up as fast as the Gulf of Maine. Using long-term ocean-temperature data, Pershing and a colleague documented the gulf's rapid warming — including an uptick of roughly three degrees Celsius over the past decade. In 2012, a massive, unprecedented oceanic heat wave descended on the entire northwest Atlantic with the gulf at its epicenter, making it the warmest year on record. Last year proved to be the second warmest ever documented, but Pershing says 2014 may beat that — despite last winter's frigid "polar vortex."

Scientists are also documenting other dramatic environmental transformations in the gulf related to rising greenhouse gas emissions, says Jon Hare, oceanography branch chief for the National Oceanic and Atmospheric Administration's Northeast Fisheries Science Center in Narragansett, Rhode Island. Ocean water is becoming fresher, most likely due to Arctic ice melting into the Labrador Sea, one of the gulf's main water sources. Precipitation is increasing, particularly heavy precipitation during storms. And forthcoming research from NOAA confirms that the gulf is becoming more acidic due to rising atmospheric carbon dioxide levels, Hare says.

All of this is happening against a backdrop of more familiar problems, like overfishing, pollution, and chronic low-oxygen hotspots, which scientists say can combine to stress organisms and make it difficult to pinpoint why they may be struggling.

"Across the physical spectrum there have been a lot of changes," Hare says, and the gulf's marine life is responding fast, starting at the very bottom of the food web. Hare says there is evidence that seasonal blooms of phytoplankton and zooplankton are changing their timing, magnitude, and species composition, and that these shifts could reverberate throughout the ecosystem, although further research is needed to understand how.

Most striking to Hare and other observers are the species from further south that are turning up in waters once too cold for comfort. Strange sightings peaked during the warmest years of 2012 and 2013, although
‘Clearly there’s a big shift going on, which I can’t help but suspect is global warming,’ says one marine scientist.
some reports have continued to roll in this year, they say. Longfin squid, normally found only in the southern gulf and below, rushed north into the gulf's coastal waters in greater numbers than anyone could remember, prompting a squid-fishing spree from the tip of Cape Cod to New Brunswick in Canada. Maine lobstermen hauling their traps found triggerfish, typical of the Carolinas and south, and scientists reportedly even spotted tropical species like filefish and snowy grouper in Maine waters.

One species generating a lot of chatter is the black sea bass, an aggressive, territorial reef fish that used to range mainly from the Gulf of Mexico to Cape Cod. Gulf of Maine lobstermen were surprised when it began showing up regularly in traps a few years ago, says Marissa McMahan, a doctoral student at Northeastern University in Boston. McMahan grew up crewing on her father's lobster boat, but didn't see her first black sea bass until 2012. A dozen appeared in their traps that summer, she says. When fall came, McMahan went off to graduate school and decided to focus her research on the species. The next summer her father sent around 40 black sea bass from his traps for her to examine. She heard similar accounts from other fishermen, whom she relies on for samples and reports of sightings. "It skyrocketed, the amount of fish that they were catching as bycatch. I mean, it went through the roof."

McMahan says many fishermen and scientists are concerned black sea bass, voracious eaters, may be developing a taste for juvenile lobsters as they settle into their new home in the gulf. On the bright side, she says, they are also wondering whether sea bass might turn into a new commodity, since the species generates a good price in its native range, where it's fished commercially.

Meanwhile, the gulf's native species are shifting fast, too. Populations of cod and northern shrimp, once fishing industry pillars, have plummeted. This month officials announced historic emergency measures to protect cod that effectively shut down the gulf's iconic fishery, at least until spring, after survey results showed stocks around 3 percent of what would constitute sustainable levels. This follows the closing of the northern shrimp season altogether for a second year in a row due to dwindling stocks across the entire North Atlantic. What remains of the cod and the shrimp populations appear to be moving north into cooler waters, leaving devastated fishing families in their wake.

By contrast, the lobster fishery is flourishing. It now dominates the region's post-cod fishing economy, and it's probably no coincidence that cod was
Scientists are starting to think of the region as a case study for other parts of the world.
once a major lobster predator, scientists say. But even the lobsters' abundance may be precarious. They've been shedding their shells earlier and earlier in the spring, and during the 2012 heat wave they molted a full month earlier than usual. A staggering early catch flooded the market that year and caused prices to plunge. Though the catch has stabilized and lobstermen are making money again, there is some uneasiness about the future.

Green points out that only two studies have explored how lobsters might respond to ocean acidification, with contradictory results. And a disease that rots their shells seems to be creeping slowly northward, he notes, after quickly wiping out lobster industries to the south within a year or two.

Many observers see an ecosystem-wide pattern that extends beyond commercial stocks and will require a great deal more research to fully understand.

"There's this big change happening in the Gulf of Maine in general, for whales and turtles and dolphins and gulls and fish and lobsters and just everything," says Kathleen Hunt, a research scientist at the New England Aquarium in Boston who studies whales and sea turtles. "Every population I know of is changing its distribution. It's either appearing where it didn't used to be or it's disappearing from where it did used to be, or it's starving, or it's getting a new disease.

"Clearly there's a big shift going on, which I can't help but suspect is global warming," she adds. "But as scientists we're not allowed to say that yet till


A North Atlantic Mystery:
Case of the Missing Whales

right whale
Endangered North Atlantic right whales are disappearing from customary feeding grounds off the U.S. and Canadian coasts and appearing in large numbers in other locations, leaving scientists to wonder if shifts in climate may be behind the changes.
we see if it's a 20-year trend or not."

No one wants to wait that long for answers. New research initiatives are looking directly at how climate change is playing out in the Gulf of Maine, with the goal of helping fishermen and managers adapt to what may be one of the fastest-changing ecosystems in the world. NOAA, for instance, has developed new methodology for quickly assessing how vulnerable marine species are to climate change, starting with 79 species from the northeastern U.S. and southeastern Canada, including the gulf. Hare, the project lead, says he expects the techniques will be applied elsewhere.

Scientists are starting to think of the region as a case study for other parts of the world that remain relatively stable for now, Pershing says. "What we've seen is something that everybody around the world is going to be seeing at one level or another, maybe at a more gradual rate, maybe at a faster rate," Pershing says. "But we've seen it here, and I think we have a real duty to learn from it."

POSTED ON 17 Nov 2014 IN Biodiversity Climate Climate Energy Oceans Policy & Politics North America North America 


It is misleading to draw conclusions from reports
that the Gulf of Maine waters are warming faster
than 99.85 percent of the rest of the world's oceans.
The Gulf of Maine is separated from the Atlantic
Ocean by Georges Bank and Browns Bank. Atlantic
Ocean water salinity is 36 parts per thousand. The
Gulf of Maine salinity is 34 parts per thousands due
to contributions from the St. Johns, Kennebec,
Merrimack and other rivers.
Cold Labrador current water flows into the Gulf of
Maine through about a 30 mile wide deep water
channel between the Banks. Cold salty ocean water
flows in beneath outgoing fresher water.

Scientists refer to the annual input of Labrador
Current water into the Gulf of Maine as “barn door
open,” “barn door closed,” and “barn door ajar.”
Ocean wildlife within the Gulf of Maine responds to
these changing conditions with shifts in where they
dwell and in fertility rates.

I suspect the faster than the rest of the world’s
ocean is based on a very limited number of years of
water temperatures. In recent years there was little
cooling in the Gulf of Maine by the Labrador
Current. Scientists have yet to find a pattern in the
annual sequencing of barn door open, closed or
ajar. It is as chaotic as mapping the cooling rates
of liquid coffee portions within a cup. You know the
surface will cool first but how that cooler water
sinks into and exchanges heat with the rest of the
fluids is random.

For the cod’s perspective Georges Bank is warming
faster than is the Gulf of Maine because Georges
Bank is never cooled by the Labrador Current. Even
with no fishing, expect to see the fish stock of cod
on Georges Bank decline faster than the fish stock
of cod in the Gulf of Maine. For the latter cod stock
it is likely that one year soon the barn door will be
open giving long-lived fish a good year.

Posted by Rob Moir on 21 Nov 2014

In the presence of the warming acidic water and lack of prey, crabs, lobster, and jelly fish will abound. It's not a good sign.
Posted by Green on 29 Nov 2014

What a great article! I just started my Ocean Blog Magazine oceanamp.org! Since I live in Germany I am a bit lonely with environmental ocean news. There are not many people talking about this subject here.
Posted by Anja Medau on 06 Jan 2015

Gulf of Maine water temps were below long term
averages in 2015
Posted by Jeff on 18 Jan 2016


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rebecca kesslerABOUT THE AUTHOR
Rebecca Kessler is a freelance science and environmental journalist based in Providence, Rhode Island. A former senior editor at Natural History, her work has been published by Climate Central, Conservation, Discover, ScienceNOW, ScienceInsider, and Environmental Health Perspectives. She has previously written for Yale Environment 360 about the endangered North Atlantic right whale and efforts to help fish migrate around dams.



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