Alarmingly warm water in Gulf of Maine bringing changes

Posted Dec. 17, 2012, at 12:24 p.m.
Last modified Dec. 18, 2012, at 11:26 a.m.

Poll Question

Ed Monat, a seasonal tour boat operator and scallop fisherman from Bar Harbor, has seen a lot in his more than two decades of scuba diving below the waves of Frenchman Bay.

He focuses on finding scallops during winter dives. In the summer, he takes tourists and an underwater video camera with him so they can watch on a large flat-screen monitor as Monat dives and then holds up lobster, starfish, sea cucumbers and other creatures for them to see. Each spring, Monat also leads a cleanup of the harbor and has recovered, among more mundane items, submerged electronics, appliances and even a bronze bust of Procter & Gamble founder William Procter.

One thing Monat never saw underwater prior to this past summer, however, was a 60-plus degree thermometer reading at the bottom of the bay. For much of the year, coastal waters in the Gulf of Maine generally are expected to waver between the mid-30s and mid-50s Fahrenheit, including at depths of 40-50 feet, where Monat often descends. On a late-August dive this summer near the breakwater that helps protect Bar Harbor from the open ocean, he said, his dive thermometer registered 63 degrees.

“That’s crazy, crazy warm,” Monat said recently. “This was a really warm summer in the water.”

He said that, in the past year, the amount of lobster in the bay has been “out of control” while starfish seem to be staying in deeper water. He added that there was poor visibility in the bay in August, which he attributed to a prolonged algae bloom, and that dogfish in the bay this summer were unusually scarce.

“I’m worried about any changes that might happen,” Monat said. “It’s definitely different on the bottom, that’s for sure.”

Monat is not the only one who has noticed. Extreme examples of climate change that have happened elsewhere — rapidly melting glaciers, catastrophic damage from increasingly violent storms, deadly heat spikes — have not been replicated in Maine, but there are signs that ocean temperatures in the Gulf of Maine are on the rise.

Officials have suggested that higher temperatures in the gulf have been a factor in bacterial outbreaks in bivalves and in sea lice infestations in Cobscook and Passamaquoddy bays. Some have put partial blame on the gulf’s warmer waters for a northeasterly shift of cod in the gulf into colder waters, for declining shrimp catches and for the glut of soft-shell lobsters this past summer that plummeted prices lobstermen were receiving for their catch.

Patrice McCarron, executive director of Maine Lobstermen’s Association, said this month that rising temperatures in the gulf are “a huge concern” for the organization, the membership of which includes approximately 1,200 of the state’s 5,300 or so licensed commercial lobstermen. She said she has heard from some association members that water temperatures in the mouth of Penobscot Bay still, as of December, are unusually and consistently warm, from depths of a few feet to more than 150 feet.

“It’s 50 degrees throughout the water column,” McCarron said. “That’s crazy.”

According to data recorded by the Northeast Regional Association of Coastal and Ocean Observing Systems, temperatures close to shore remain about 10 degrees warmer than they were last winter.

McCarron said one big concern among fishermen is that, if water in the gulf does not get cold enough this winter, the lobsters won’t go through their usual relatively dormant winter state, which could continue to throw off their molting schedule. Large catches of lobster in the spring, when market demand for Maine lobster is fairly low, likely would continue to have a depressing effect on the price.

McCarron said that, though it is not far-fetched to anticipate a repeat of this year’s soft-shell lobster glut, one year of highly unusual conditions in the fishery does not constitute a trend, so it’s not known what may happen next spring. Fishermen are paying a lot more attention to water temperature readings than they did a few years ago, she said, but still are unsure what to make of the thermometer readings.

“People are expecting to expect the unexpected,” McCarron said.

Scientific research

Water temperatures in the gulf, which draws cold water from the Labrador current and is largely separated from warmer Gulf Stream water by Georges Bank, generally are colder than in other places along the East Coast. The cold water and the rich level of nutrients it supports in the Gulf of Maine and along Georges Bank have been cited as a major reason why, historically, commercial marine species such as groundfish, scallops and lobsters have been abundant in the region.

During recent interviews, several scientists in Maine have said that scientific data leave no room for doubt that the gulf is getting warmer.

Jeffrey Runge, a biological oceanographer for University of Maine and Gulf of Maine Research Institute, said recently that temperatures in the gulf in the past few years have increased “dramatically higher” than the historical rate of 1 degree every 100 years. Evidence suggests that the average sea surface temperature in the gulf has risen 1.5 degrees from 2011 to 2012, he said, and that in the past four years it has risen between 2 and 3.5 degrees, depending on how one looks at the data.

“It’s pretty striking,” Runge said. “We can’t explain it.”

Runge said there are multiple species in the gulf that scientists suspect could be significantly affected by increased water temperatures. However, what those changes might be cannot be predicted.

Lobster, shrimp, cod and calanus finmarchicus — a type of copepod, or small crustacean, that is the dominant form of plankton in the gulf — all stand to be displaced or to have their normal reproductive and growth cycles disrupted as the gulf gets warmer, he said.

“At some point, [the gulf] is going to be inhospitable to cod,” Runge said. “We’re getting close to that now.”

And with the calanus copepod in the mix of affected species, there could be a domino effect on others that feed on the minuscule creature, Runge wrote in a scientific study he co-authored with three other scientists. Results of the study have yet to be published in a scientific journal but were presented this fall at an oceanography conference Virginia, he said.

The study projects that the copepod will disappear from the gulf by 2050, based on sea surface temperature predictions.

“Since the lipid-rich Calanus is a key prey for forage species such as herring, sand lance, mackerel, as well as the northern right whale, regional shifts in feeding distributions and abundance of these planktivorous predators may be anticipated,” the study said.

Robert Steneck, a marine ecologist at UMaine’s Darling Marine Center in South Bristol, said Thursday that the Gulf of Maine is a complex, dynamic ecosystem, which makes it hard to predict what may happen from one year to the next, or how any species might be affected by a constantly changing array of factors.

What’s not so hard to predict is that marine species will seek out the water temperature that’s best for them to live in, he said. Higher temperatures certainly caused the sooner-then-expected molt this past spring, Steneck said, and over recent years may have actually helped boost the success rate of larval lobsters, which tend to fare better in slightly warmer water than adult lobsters.

A higher survival rate of larval lobsters and the relative lack of cod, which feed heavily on lobsters, are believed to be part of why annual lobster landings in Maine have shot up from less than 22 million pounds in 1988 to more than 100 million pounds in 2011.

But, Steneck added, if water in the gulf gets too warm, near 70 degrees, the lobster population may suffer severely, as it has south of Cape Cod. Factors for the population collapse in southern New England include increased susceptibility to shell disease, which might be a symptom of temperature-weakened immune systems, and increased runoff from shore, he said. And the higher the lobster density in the gulf is, the more devastating a disease could be throughout the population.

No experts are suggesting the dropoff in lobster numbers in southern New England will happen in the Gulf of Maine, but no one is saying it can’t happen, either. And, according to Steneck, there are other indicators of climate change that should cause concern.

Last summer, an estimated 1,400 terns on Metinic Island abandoned their nesting sites after four days of hard rain, he said. Squid appeared in high numbers for several months, an unusually long time, along the coast this past summer. And the size and power of Hurricane Sandy, which caused widespread damage in New Jersey and New York, is a direct result of warmer ocean temperatures along the East Coast.

“The world seems to be getting warmer faster than we would like,” Steneck said. “It’s a real problem.”

Other changes

Increased storm activity, which climatologists have said is a result of global climate change, could affect the Gulf of Maine in other ways. Even without storms, warmer temperatures are expected to cause sea levels to rise worldwide, which in turn is expected to affect coastal habitats such as marshes.

Changes in weather patterns could affect seasonal outbreaks of red tide. Nicole DeLisle, a scientist with DMR’s biotoxin monitoring program, said this month that higher temperatures by themselves aren’t expected to make seasonal blooms of red tide worse. The biotoxin blooms — which can cause paralytic shellfish poisoning in people who eat shellfish with high concentrations of the harmful algae — may happen earlier in the year with temperature increases, she said, but they would not necessarily happen more frequently or be more severe.

However, more severe storms, which have been attributed to global climate change, could affect the intensity of the blooms, DeLisle said. Recent years in which there have been more severe red tides, such as 2003 and 2009, have been aggravated by storms that have churned up the water column in the gulf, she said. Tropical Storm Danny affected the gulf in late summer of 2003, while Hurricane Juan did the same six years later.

“If there’s a bloom going on and a hurricane hits Maine, it’s just going to spread everywhere,” DeLisle said.

Increased storm activity in the region is affecting ocean conditions off Maine in other ways, too, according to William “Barney” Balch of Bigelow Laboratory for Ocean Sciences in Boothbay.

Balch said Wednesday that studies he has conducted across the gulf, and data collected over recent decades by other scientists, show that the gulf’s salt content has been falling. The melting of the polar ice cap is diluting the salinity level of the Labrador Current, he said, and more freshwater has been flowing from rivers into the gulf.

Balch said that, since 1895, each of the top eight years with the most precipitation in Maine have had dumped more than 4.6 feet of rain on the state. Of those eight rainiest years, four have occurred since 2005 — as many as in the previous 110 years, according to Balch.

“That’s a lot of rain,” he said.

With the rain has come a greater flow of dissolved organic matter that competes with phytoplankton in the gulf for sunlight. This is significant, Balch said, because phytoplankton, like plants, needs sunlight to grow and is the main food source for creatures at the bottom of the food chain. Phytoplankton in the world’s oceans also generates half of all oxygen in Earth’s atmosphere.

“You can thank the phytoplankton for every other breath you take,” Balch said.

In 2007, during the recent wet period, phytoplankton production in the gulf “fell off a cliff,” he added. Data collected this past summer, however, indicate that rainfall has decreased in the watershed this year and phytoplankton production has come back up.

It’s unclear whether heavy rainfall returns in the next few years, or how the years of low plankton production might have affected the growth of fish or shellfish that still haven’t reached harvestable size, he said.

“These are big, gigantic processes manifested over huge areas,” Balch said. “[But] clearly, [the gulf] is getting warmer.”


Patrick Keliher, commissioner of Maine Department of Marine Resources, said Thursday that there’s nothing within the department’s purview that it can do to prevent temperatures in the gulf from rising. He said that it has happened before — in the 1950s, when a four-year spike in water temperatures caused a temporary collapse in the gulf’s northern shrimp population — but that the trend inexplicably reversed itself and cooler water returned.

“We’re definitely seeing a warming trend,” Keliher said. “Obviously, what we’re hoping now is that it will reverse itself again.”

Scientists interviewed for this article said the 1950s temperature anomaly in the gulf was isolated and may not be comparable to what’s going on today, given the global scope of observed climate changes.

But whether it reverses or not, ocean temperatures are something DMR pays attention to, Keliher said. Every stock assessment of every regulated commercial marine species includes data on how habitat conditions are changing, he said.

The state’s $334 million lobster industry is a good example of what changes in water temperature can do and how serious the issue is, he said. The mild winter caused the lobsters’ normal molting and landings schedules to be be pushed up months earlier than expected, which in turn caused the price to bottom out and a high degree of mortality among the stockpiled lobsters. Warm water may have helped boost scallop growth in some areas and elver abundance in general, he said, but it likely is the reason why the level of shrimp in the gulf appears to be so low.

The key from a management standpoint, he said, is to monitor how conditions are changing in the gulf and to learn how to anticipate how they will affect habitat and the abundance of species. If conditions are becoming less predictable, he said, it is important that the department be able to react to them in a timely manner, to try to keep the affected species and fisheries viable over the long run.

“They’re extremely variable,” Keliher said of DMR’s readings of water surface temperatures. “Our science staff already is keeping a close eye on it.”

Follow BDN reporter Bill Trotter on Twitter at @billtrotter.