Beneath the waves, climate change puts marine life on the move
There was a hefty irony to the announcement by Connecticut’s two U.S. senators earlier this summer that they were joining the sponsorship for a National Lobster Day next month.
The iconic symbol of the state’s fishing industry for years, Long Island Sound was once flush with lobster, traps and people who made their livings from them.
But no more.
Connecticut’s lobster landings topped 3.7 million pounds a year, worth $12 million, in the late 1990s, but by 2014 had diminished to about 127,000 pounds worth a little more than $600,000.
Instead of the picture of fishing success, lobster has become the face of climate change in New England: a sentinel of warming water, ocean acidification and other man-made impacts that have sent them and dozens of other marine animals scurrying in search of a more hospitable environment.
“We’ve found quite dramatic shifts in where species are found,” said Malin Pinsky, an ecologist and evolutionary biologist with the Rutgers University Department of Ecology, Evolution and Natural Resources who researches how climate change affects fish and fisheries. He has used data collected by the National Oceanic and Atmospheric Administration to create OceanAdapt, which includes animations that regionally show how dozens of marine species have moved in the last 50 years. “Especially here in the Northeast you have something like American lobster about 200 miles further north than they used to be, and other species shifting similar amounts.”
These climate-related shifts, on their own and dovetailing with older concerns such as overfishing and pollution, are now upending fishing patterns, threatening to upend fishing management systems and generating political controversy and finger-pointing as policies struggle to keep up with the pace of fish movement, and the Connecticut fishing community struggles to hang on.
But with water now warming and sea levels rising faster than scientists were predicting only a few years ago, how to respond and even what to respond to is, well, a moving target.
“We’re reshuffling the marine ecosystems like a deck of cards,” Pinsky said, echoing almost the exact wording of other scientists and experts. “We don’t entirely know what will happen. We understand the broad outlines of what’s going to happen, but we also know there will be surprises.”
The first surprise may be just how much is at risk.
Rating the risk
A climate-change vulnerability assessment released earlier this year by NOAA’s Northeast Fisheries Science Center looked at 82 marine species in waters off the northeastern U.S. It showed that nearly all are vulnerable to the effects of climate change and that two-thirds had shifted northward.
Jon Hare, the lead author and a fisheries oceanographer in the Science Center’s Narragansett, R.I., office who studies the link between oceanography and fish population dynamics, ranked the climate exposure for the region’s species as very high and high. There was no climate exposure that was low or even moderate.
He plotted that against the species’ biological sensitivity, which ranged from very high to low, for an overall climate vulnerability score that was just about evenly split among the four categories of very high, high, moderate and low.
“This is an area where climate change is happening rapidly. Temperatures are warming; you’ve got this change in storm frequency, changes in storm magnitude, increases in precipitation; the Gulf Stream is moving north; you’ve got increased fresh water coming down from the north,” Hare said. “So the Northeast is an area where the effects of climate change are going to be greater than in many other parts of the world.”
Scientists uniformly say temperature is the biggest factor by far.
“It affects how a fish works – from something as simple as its heart rate to how much oxygen it needs,” Pinsky said. “And eventually for every species, there comes a point where it can’t actually get enough oxygen at very high temperatures to avoid being eaten or to catch enough to eat and survive itself.”
Temperature has driven species generally north and east toward colder and/or deeper water. In places like the Gulf of Maine, however, the movement has been south and west to that body’s colder and deeper areas uniquely carved by glaciers in the last ice age millennia ago.
Either way, species like lobster and winter flounder, once prevalent in the southern limits of the New England region near Connecticut, are heading out. Warmer water species like summer flounder (also known as fluke), black sea bass and scup (also known as porgy), traditionally found much further down the mid-Atlantic, are heading in. While that may seem like a useful swap for fishermen, it isn’t. More on that in Part 2 of this series.
There are other factors at work, not the least of which come from human activities, such as shoreline development, that result in habitat loss for marine species, pollution that can cause oxygen loss in the water – known as hypoxia – as well as changes to the water’s acidity. Just as important – and sometimes considered more important – is the impact of that ancient human activity of fishing.
In some species, Hare said, “Fishing had a greater impact than climate change. We are a very effective predator.”
Overall, he said, two general patterns jumped out from the study. One was that species that need both fresh and salt water – known as diadromous species – are in a very high vulnerability category because they are exposed to climate change from ocean and land.
Fish like salmon, American shad and hickory shad feel pressure from earlier snow melts and high spring stream flows as well as from development that causes loss of their critical marsh and wetland spawning areas.
The other pattern was that a number of shellfish species, including Atlantic scallops, surf clams, Eastern oysters and hard clams like quahogs, were highly vulnerable because of higher water acidity, known as ocean acidification, which prevents those species from developing shells properly.
Acidification is caused by increased carbon dioxide – one of the factors in climate change – being absorbed by the water along with the nutrient runoff from fertilizers, pesticides and other sources that has plagued the Sound for decades.
“Those multiple stressors,” Hare said. “Would make a system like Long Island Sound, like Narragansett Bay vulnerable to change.”
Long Island Sound has definitely felt it.
Long Island Sound
There is clear evidence of warming water in the Sound, documented since 1976 by the operators of the Millstone Nuclear Power Station, which sits on the shore of Niantic Bay. The plants are required to take multiple readings many times a day, making it one of the most consistent measures of the Sound’s water temperature.
Last year’s annual mean temperature was more than 3 Fahrenheit degrees warmer than the annual mean in 1976. The exceptionally warm 2012 was more than 5.5 Fahrenheit degrees warmer. And the mean temperature in August 2012 was 6 Fahrenheit degrees warmer than August 1976. It was the warmest monthly mean temperature ever recorded at Millstone, and there are expectations that this year’s warm winter followed by a so-far exceptionally warm summer could track closer to 2012.
After early allegations that the precipitous lobster die-off in the Sound that began in the late 1990s might have been caused by pesticide runoff, it is now widely thought to be the result of the warmer water. Lobster is highly sensitive to temperature, and Long Island Sound, always at the southern edge of their range, is now thought to be too warm.
Despite their near-disappearance from the Sound, the climate risk to American lobster is not extreme on Hare’s color-coded grid. That’s because the crustaceans have generally relocated to the north, especially the Gulf of Maine, where their population is strong.
Among the species in jeopardy considered most important to Connecticut-area fishermen are winter flounder, already known to be moving north. Data collected by the Department of Energy and Environmental Protection showed winter flounder landings vastly diminished in recent years. Economic data from NOAA show a drop in all flounder landings and their value.
Among the bi-valve shellfish thought to face acidification stress, Atlantic scallops could be of greatest concern. They are now a mainstay of the fishing industry in Connecticut as well as nationally, fetching very high prices. NOAA’s data show a drop in both scallop landings and value in Connecticut.
The problem, scientists say, is that acidification may not be recognized in shellfish until it’s too late.
It’s only in the last year that the Connecticut Department of Agriculture’s Aquaculture Division has added acidification and how to handle it to its ongoing concern with the warming water temperature from climate change and its effects.
The warmer water is believed to be the cause of outbreaks of the bacteria vibrio in shellfish during the extreme warm spell of 2012 and 2013. “We did not have an issue for a very long time, and now all of a sudden we do,” said Kristin Derosia-Banick, an environmental analyst in the bureau. “Vibrio for sure is linked to climate issues.
“Global sea-surface temperatures are the primary driver on vibrio.”
And that does not bode well for the remainder of the summer, given its heat following the warm winter. “My full-time job now is pretty much managing vibrio,” Derosia-Banick said.
But with acidification now also a worry, she attended her first workshop through the Northeast Coastal Acidification Network this past winter after hearing reports from Maine that acidification was becoming a problem. “We’re talking to experts and trying to figure out what we’re supposed to be monitoring,” she said.
The biggest concerns for Connecticut are the natural shellfish seeding beds, which account for about 95 percent of the shellfish seeding operations in the state. They are located at the mouths of rivers, which catch the brunt of the runoff from storms, now made more extreme by climate change and therefore more laden with pollution.
The young clams and oysters feel the impact of acidification more acutely. Big storms have been known to cause dramatic drops in the pH level of the water – essentially reflecting higher acidity.
“A lot of runoff in a very short amount of time and that’s where you get your big issue,” Derosia-Banick said.
But not all climate-related impacts are bad for all marine animals.
Hare’s survey showed about one-third of the species he examined will feel positive impacts from climate change, with a number of warm-water species able to expand their ranges and migratory patterns. Showing up around Connecticut along with the black sea bass, summer flounder and scup documented by DEEP’S trawl survey are hogchoker, northern sea robin, striped sea robin, puffer, smooth flounder and northern kingfish.
“Northern kingfish and smooth flounder are the new ones that are just flying up,” said Penny Howell, a senior fisheries biologist for the marine fisheries division of DEEP’s Bureau of Natural Resources.
She said the warm-water species are pulsing in. “When there’s a warm year they’re coming in like gangbusters. The cold guys are like, ‘This is okay; it’s not too warm for me in the spring yet.’ But the competition between them is probably increasing quite a bit.”
Winter survival is key for the newcomers, she said. The problem is, while the general direction of fish movement is toward warmer water, the rate of the movement isn’t clear. There are factors like the long-term climate cycles that have occurred regularly for centuries. It’s unknown, for instance, whether they might buffer climate change, or perhaps intensify it. It’s also unknown how permanent or temporary some of the species movement is.
“We know the direction; we know which ones are more sensitive; we can kind of take educated guesses on what’s going to effect growth or whatever,” Howell said. “It’s an uncontrolled experiment with 82 species.
“It’s a free for all.”
Hare offered a similar caution. “One of the weaknesses of our study and much of this work is that we don’t understand the true adaptive capacity of marine species,” he said. “Basically you’re asking – how fast can they evolve?”
That remains a huge unknown because the cascade of effects throughout the marine ecosystem is unpredictable, rife with unexpected consequences, and in many respects, unknowable ones.
Shuffling the deck
Take one simple known possibility – black sea bass eat lobster. But unknown is what that will do, if anything, to the lobster population in Maine – if it’s not too far north for black sea bass. Will it make it harder for the bass to survive in waters around Connecticut with so much less lobster than there used to be? Is there another food here the sea bass can eat, or adapt to eat? And if there is, what will that do to the fish that normally eat that food? And will any of those fish now be too diminished for fishermen to make a living from?
The cascade of effects could be enormous, said Mike Fogarty, a senior scientist at the Northeast Fisheries Science Center who has worked on climate issues since the mid-1990s. He is especially trying to understand potential impacts of climate change on marine ecosystems and has studied several specific ones, including Georges Bank.
“We’re seeing changes and are likely to see more changes right at the very base of the food web all the way through it,” he said.
He’s talking about the microscopic stuff like plankton that starts the cascade of who eats what. A change in any one part will have effects on other parts.
“It’s becoming increasingly clear that in the ocean, and also in terrestrial ecosystems, that the way they operate is such that you can get very large effects from small changes under certain circumstances,” he said.
And because it’s the ocean, you can’t really do a controlled experiment to figure out what might happen. You have to tease things out after the fact – what happened, why and what it means. “It’s a detective story,” Fogarty said.
As for understanding the full cascade effect: “You have to have a fair bit of humility about making predictions on this,” he said. “We’re really moving into uncharted waters.”
And that is what’s causing headaches for fishing management in the age of climate change and moving species. If you don’t really know what’s going to happen, how do you figure out policy?
Jan Ellen Spiegel is the Mirror’s environmental reporter. Contact her at firstname.lastname@example.org
Sign up for CT Mirror's free daily news summary.
Free to Read. Not Free to Produce.
The Connecticut Mirror is a nonprofit newsroom. 90% of our revenue comes from people like you. If you value our reporting please consider making a donation. You'll enjoy reading CT Mirror even more knowing you helped make it happen.YES, I'LL DONATE TODAY