—————————————————————
“”The final ecological threshold for an aquatic ecosystem is loss of water,”
says Dr. Smol. “These sites have now crossed that threshold.”
“We now think we have been overly optimistic – the speed and magnitude
of environmental changes are worse than even we imagined!”
—————————————————-
Queen’s University
Public release date: 2-Jul-2007
Contact: Nancy Dorrance
nancy.dorrance@queensu.ca
613-533-2869
Some polar sites ‘have already crossed the final ecological
threshold,’ says Queen’s prof
KINGSTON, Ont. — High Arctic ponds — the most common source of
surface water in many polar regions — are now beginning to evaporate
due to recent climate warming, say two of Canada’s leading
environmental scientists.
John Smol (Professor of Biology at Queen’s University and holder of
the Canada Research Chair in Environmental Change) and Marianne
Douglas (Professor of Earth and Atmospheric Sciences and Director of
the Canadian Circumpolar Institute at the University of Alberta) will
publish their startling conclusions next week in the on-line Early
Edition of the prestigious journal, Proceedings of the National
Academy of Sciences (PNAS).
“The final ecological threshold for an aquatic ecosystem is loss of
water,” says Dr. Smol. “These sites have now crossed that threshold.”
Since 1983, Drs. Smol and Douglas have been regularly sampling the
water quality and biota of about 40 ponds on Cape Herschel,
east-central Ellesmere Island, in the Canadian High Arctic. Polar
ecosystems such as these are very sensitive to the effects of
climatic and other environmental changes, they note in their paper.
“In many respects, they are like the ‘miner’s canaries’ of the
planet, showing the first signs of warming.”
But this new discovery by the Canadian researchers has surprised even
them. In the 1990s they were alarmed when they began to recognize a
trend of declining water levels and changes in water chemistry. When
they arrived to begin another field season in July of 2006 (the
warmest year on record for that portion of the Arctic), some of the
ponds were dry, and others had dramatically reduced water levels.
“This study shows the value of long-term monitoring programs,” says
Dr. Douglas. “Had we just arrived at Cape Herschel last year, we
would have surmised that these were naturally temporary ponds. But we
know instead that this was not the case – these had been permanent
water bodies for millennia.”
As well as monitoring the ponds for 24 years, the researchers have
also reconstructed ecological trends over the past several thousand
years in some of the ponds, using paleoecological techniques. In a
controversial 1994 paper published in the journal Science, they
showed that the ponds existed for millennia, but that, beginning in
the 19th century, they underwent marked ecological changes,
consistent with warming.
“We had a bit of a rough ride with that paper for a few years, but
now there is almost universal scientific consensus concerning our
1994 conclusions,” says Dr. Douglas. In 2005, she and Dr. Smol, along
with 24 co-authors, used similar techniques to document widespread
ecological changes, consistent with warming, across the circumpolar
Arctic.
However, the ecological changes recorded in the 1994 study pale in
comparison to those noted in the current paper, where some sites had
completely dried up by July.
While some subarctic lakes have recently disappeared because the
permafrost that formed a largely waterproof barrier has melted, this
is not the case here, say Drs. Smol and Douglas. Instead, the high
Arctic ponds are evaporating due to warming. By measuring changes in
water quality over their 24-year sampling window, they have shown
that the concentration of salts has been steadily increasing.
Using the analogy of a pot of soup simmering on a stove, Dr. Smol
explains: “If you take the lid off, it is similar to what we are
observing in these ponds. The soup will slowly decrease in volume and
it will get saltier and saltier as the water evaporates, leaving the
salts behind.” The same process is happening with the Cape Herschel
ponds, he continues. Water levels are declining and the remaining
water is more concentrated with evaporation due to warming.
Another disturbing finding was the drying-up of neighbouring
wetlands. In the 1980s, portions of their study region were also
characterized by water-saturated wetlands, where the team would need
to don hip waders to sample the surface pools of water persisting
throughout the summer. However, in 2006, the wetlands had dried to
such an extent that they could easily be ignited with a lighter. “The
ecological consequences of shifting wetlands such as these from
carbon sink to potential carbon sources are frightening,” they say.
Ponds, the dominant source of surface waters in many Arctic regions,
are “hot spots” of biodiversity, as well as habitat for many birds,
insects, and other organisms, the researchers point out. The
resulting ecological changes will likely cascade throughout the
ecosystem.
“In the past, researchers like us have sometimes been accused of
being alarmist when we discussed climate warming,” says Dr. Smol,
winner of the 2004 NSERC Herzberg Gold Medal as Canada’s top
scientist or engineer. “We now think we have been overly optimistic –
the speed and magnitude of environmental changes are worse than even
we imagined!”
###
The research was funded primarily by the Natural Sciences and
Engineering Research Council of Canada and the Polar Continental
Shelf Project. Contacts:
Nancy Dorrance, Queen’s News & Media Services, 613.533.2869 Lorinda
Peterson, Queen’s News & Media Services, 613.533.3234
Attention broadcasters: Queen’s has facilities to provide broadcast
quality audio and video feeds. For television interviews, we can
provide a live, real-time double ender from Kingston fibre optic
cable. Please call for details.
—
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“So far this year, scientists haven’t seen a
decline in numbers, and they are not sure what’s
causing the whales to be so thin. But they
suspect it may be the same thing that triggered
the die-off eight years ago: rapid warming of
Arctic waters where the whales feed. Whales
depend on cocktail-shrimp-size crustaceans to
bulk up for their long southerly migration. As
Arctic ice recedes, fat-rich crustaceans that
flourished on the Bering Sea floor are becoming
scarce.”
—————
Los Angeles Times
July 6, 2007
A giant of the sea finds slimmer pickings
Gray whales are skinnier, and scientists suspect
Arctic warming is the reason why
<http://www.latimes.com/news/local/la-me-skinnywhale6jul06,0,2979215.story?coll=la-home-local>
By Kenneth R. Weiss
Times Staff Writer
SAN SIMEON, CALIF. – A female gray whale labored
up the coast, the bony ridge of a shoulder blade
protruding from what should be the smooth, plump
roundness of healthy blubber.
“That female looks a little skinny,” said federal
biologist Wayne Perryman, peering through his
binoculars. “You can see her scapula sticking
out. Yeah, she’s a skinny girl.”
Scientists from Mexico to the Pacific Northwest
are reporting an unusually high number of scrawny
whales this year for the first time since
malnourishment and disease claimed a third of the
gray whale population in 1999 and 2000.
So far this year, scientists haven’t seen a
decline in numbers, and they are not sure what’s
causing the whales to be so thin. But they
suspect it may be the same thing that triggered
the die-off eight years ago: rapid warming of
Arctic waters where the whales feed. Whales
depend on cocktail-shrimp-size crustaceans to
bulk up for their long southerly migration. As
Arctic ice recedes, fat-rich crustaceans that
flourished on the Bering Sea floor are becoming
scarce.
Skinny whales were first spotted this year in the
protected waters of San Ignacio Lagoon in Baja
California, where gray whales spend the winter
breeding and nursing their calves before
returning every summer to the Arctic.
That’s where a team led by Steven Swartz of the
National Marine Fisheries Service in Silver
Spring, Md., and Jorge Urban of the Autonomous
University of Baja California Sur noticed that
about 10% looked more bony than blubbery, a
telltale sign of malnutrition.
Instead of making steady progress during their
long migrations, the whales have been stopping
often to eat along the way.
They have been seen straining mysid shrimp from
kelp beds off California and British Columbia,
sucking up mouthfuls of sand in Santa Barbara
Harbor and skimming surface waters for krill-like
crustaceans all along the West Coast.
Such opportunistic feeding has its risks.
Switching to new food can expose the whales to
harmful parasites as well as other hazards. There
have been at least two fatal accidents this
spring near San Francisco’s Golden Gate Bridge.
Gray whales, surfacing to breathe after dining on
seafloor snacks, have been ripped apart by
propellers on cargo vessels.
To find food, some gray whales have been
expending more energy by extending their
5,000-mile northerly migration beyond the Bering
Strait into the Chukchi and Beaufort seas north
of Alaska.
It used to be a rare occurrence to see gray
whales off Barrow, Alaska, said Craig George, a
North Slope Borough wildlife biologist since the
1970s. In recent years they have become
summertime regulars, churning up mud plumes along
the shoreline in search of food.
Their arrival has become an annoyance and even a
navigational hazard for local Inupiat (Eskimo)
subsistence hunters, who have permits to hunt
bowhead whales but not grays. “A few people have
been running skiffs along the coast and have hit
them,” George said. “During fall bowhead whale
hunting season, they see a blow and divert off
course – only to find it’s a gray whale.”
Historically, the eastern Pacific gray whales
congregated every summer in the shallows of the
Chirikov Basin, a place in the north Bering Sea
known for its vast seafloor carpets of
crustaceans called amphipods. The whales sucked
in great mouthfuls, straining out the sand and
mud, packing on the pounds in the few months
before their long annual journey to Baja and back.
“You could practically walk across the gray
whales in the Chirikov Basin in the 1980s,” said
Sue Moore, a former director of the National
Marine Mammal Laboratory in Seattle who has
conducted aerial surveys. “They were stacked up
to the horizon. In 2002, I went back and
everything had changed.”
The carpets of crustaceans were frayed – and, in some places, gone.
Scientists first thought that the gray whale
population, which had been hunted nearly to
extinction in the 1930s, had simply grown too
large for its primary food source and eaten more
than nature could provide. Such overgrazing was
thought to have been responsible for the mass
die-off in 1999 and 2000 that saw the population
drop from 26,600 to about 17,400.
Now scientists suspect that the climatic changes
in the Bering Sea played a role in the population
plunge by reducing the whale’s primary food:
amphipods that appear to be affected by warming
temperatures and vanishing sea ice.
These amphipods grow in tubes on sandy or muddy
seafloors and cannot move around like many sea
creatures. They count on bits of algae to come to
them, or at least close enough so they can use
their antennae to pull the food into their mouths.
One source is a confetti that rains down from
shaggy mats of algae that grow on the underside
of ice sheets at the ocean’s surface. Another is
brought by ocean currents, carrying a soupy mix
of algae or plankton.
Both sources have diminished or been cut off as
the northern Bering Sea has undergone a shift
from a seasonally ice-dominated region to more of
an open ocean dotted with thin ice that is
quickly broken up by storms. And the basin’s
waters have warmed enough to allow new types of
fish to migrate north, gobbling up the amphipods
or competing with them for food.
Whales are not the only animals struggling to
adapt to these rapid changes. Researchers have
also noticed dramatic declines in other species
that feed on the bottom, such as walruses and sea
ducks.
Federal scientists believe the gray whale
population is holding steady at 18,000, although
they are working on an updated estimate.
The population had been growing steadily until
1998, the year of a warm El Niño now seen as a
turning point for the Bering Sea’s amphipod beds.
Since then, the annual tally of calves has
fluctuated. This year’s was one of the lowest
since the federal government began keeping track
in 1994.
“The gray whales don’t seem as robust as they
once were,” said Perryman, a National Marine
Fisheries Service scientist in charge of the
annual count of gray whale cows and calves.
He and his crew keep watch 12 hours a day from
March to June tallying each gray whale that
passes by the Piedras Blancas Lighthouse near San
Simeon’s Hearst Castle on California’s Central
Coast. Perryman believes that the number of
calves plunges when whales do not get enough to
eat.
The loss of Bering Sea feeding grounds is
responsible for another trend: An increasing
number of whales don’t bother heading that far
north. Some stop at Alaska’s Kodiak Island.
Others don’t get even that far and spend summers
near British Columbia’s Vancouver Island or off
the Oregon coast. Smaller groups remain off
California, feeding on shrimp in kelp beds or
anything else they can scrounge.
“These animals are feeding on things that
scientists haven’t observed in modern times,”
said Bruce Mate, director of the Marine Mammal
Institute at Oregon State University. “They are
beginning to become more diverse in their diet
because they have to.”
But switching food could expose them to parasites
that contribute to their emaciated condition,
scientists say.
It’s possible, Swartz and other researchers said,
that their scrawniness is merely a temporary
condition as the whales learn to adapt to a
rapidly changing Arctic.
“Gray whales are good at switching prey,” Swartz
said. “They need to find new places to feed,
because the ocean is changing on them. I hope we
are watching a transition rather than a serious
problem.”
Copyright 2007 Los Angeles Times
—
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“… warmer New England waters could mean less cod and more
summer flounder, while greater ocean acidity could threaten
scallops and other shell-producing sea creatures.”
“Temperature is such a vital part of virtually every aspect of
the biology of cold-blooded marine animals that there is
potential for tremendous impact on all of them.”
“As oceans become more acidic, they lose calcium carbonate
that some marine animals such as corals and scallops need
to produce shells or exoskeletons.”
—————————————-
South Coast Today (Massachusetts, US)
July 6, 2007
Uncertain catch: Global warming brings a change in fishing climate
By BECKY W. EVANS
Northeast fish and shellfish stocks targeted by
local fishermen will face a new marine
environment as global warming raises coastal
water temperatures, reduces the saltiness of the
water and alters ocean currents and circulation.
Fisheries scientists are unsure how successful
stocks will be at adapting to the changing
environment, but they agree there will be winners
and losers. For example, warmer New England
waters could mean less cod and more summer
flounder, while greater ocean acidity could
threaten scallops and other shell-producing sea
creatures.
“The environmental change due to global warming
will affect all Northeast species, commercial and
non-commercial,” National Marine Fisheries
Service (NMFS) fisheries biologist Jon Brodziak
wrote in an e-mail to The Standard-Times.
Increases in atmospheric carbon dioxide and other
greenhouse gases – largely due to emissions from
fossil fuel-burning power plants, cars and other
man-made sources – are heating the Earth and
causing the climate to change more rapidly than
in the past.
Scientists believe global warming is driving
changes in the ocean that are affecting where
fish live and how big they grow.
A recent report published by the
Intergovernmental Panel on Climate Change
concluded that “observed changes in marine and
freshwater biological systems are associated with
rising water temperatures, as well as related
changes in ice cover, salinity, oxygen levels and
circulation.”
The ocean, which interacts with the atmosphere,
exchanging heat, water and momentum, has a large
influence on the global climate system. As
greenhouse gases trap more of the sun’s heat in
the atmosphere, both air and ocean temperatures
are projected to rise significantly.
Sea surface temperatures in the waters off the
Northeast coast have already increased by 1
degree Fahrenheit over the last century,
according to a 2006 report published by the Union
of Concerned Scientists.
The report predicts that by the end of this
century, the temperature of those waters will
increase between 5 to 8 degrees Fahrenheit
depending on the amount of greenhouse gas
emissions.
Kenneth Sherman, a NMFS fisheries scientist and
adjunct professor at the University of Rhode
Island’s Graduate School of Oceanography, said he
believes currents carrying cold, fresh water from
melting ice in Greenland and Labrador will
“dampen any persistent increase in water
temperature” off the Northeast coast.
If global warming does heat up New England
waters, the change will affect fish and
shellfish, whose life cycles are intricately
linked to water temperature, said NMFS fisheries
scientist Michael Fogarty, who is also an adjunct
scientist at Woods Hole Oceanographic Institution.
Changes in ocean temperature can affect fish,
whose body temperatures, growth rates,
respiration and geographic range are dependent on
water temperature.
“Temperature is such a vital part of virtually
every aspect of the biology of cold-blooded
marine animals that there is potential for
tremendous impact on all of them,” Dr. Fogarty
said.
Fish stocks already under stress from overfishing
or other factors are especially vulnerable to
changes in ocean temperature, he said.
Shifting stocks
As water temperatures increase from global
warming, they could alter the size, abundance and
distribution of marine species that are staples
of New Bedford’s seafood industry.
“In this area, as things warm, conditions may
become more favorable for some fish,” said
fisheries scientist Brian Rothschild, a professor
and former dean of the UMass Dartmouth School for
Marine Science and Technology.
For other fish, conditions will become less favorable.
“It’ll be a struggle of which animal wins,” Dr. Rothschild said.
Warmer waters off the Northeast coast could drive
cod, haddock, American plaice and other
cold-water species further north or further
offshore to colder waters.
“We’ve already seen a pretty large decrease in
cod in areas in southern New England,” Dr.
Fogarty said.
Southern New England waters are near the
southernmost boundary of the geographic range for
cod and other cold-water fish.
As those waters get warmer, that boundary could shift further north.
The survival of cod and other fish stocks that
head north in search of colder water will depend
on a variety of factors including bottom habitat,
said NMFS oceanographer David Mountain, who works
at the agency’s Northeast Fisheries Science
Center in Woods Hole.
Juvenile cod survive best on a gravel bottom,
where they can hide from predators.
“If they move north, they may not find that” kind
of habitat, Dr. Mountain said.
The gap left by cod and other fish will likely be
filled by species that prefer warmer waters.
“If somebody leaves, someone else could come,” Dr. Mountain said.
Bluefish are already moving north to Georges Bank
and the Gulf of Maine, Dr. Fogarty said.
Scientists list mackerel, herring, silver hake
(whiting), spiny dogfish, blue crabs, summer
flounder (fluke) and certain types of squid among
the species that might appear in Northeast waters
more frequently and in greater abundance if water
temperatures increase as predicted.
New predators and problems
Warmer waters could introduce new predators and
invasive species to New England waters with
unknown consequences, said Vincent Malkoski, a
biologist with the Massachusetts Division of
Marine Fisheries.
Lionfish– tropical, venomous fish that prey on
other fish and crustaceans and have no predators
of their own– have appeared as far north as
Jamestown, Rhode Island after hitching a ride in
the Gulf Stream from the Caribbean. These
lionfish typically die in the late fall when the
water gets too cold, but the population could
begin to thrive in New England waters if
temperatures get hot enough to support them, Mr.
Malkoski said.
Other scientists report that warm-water jellyfish
are becoming more common on Georges Bank.
Jellyfish, which feed on larval fish, could pose
a threat to existing fish stocks.
Global warming could “change the pattern” of red
tides, which form under the right mix of weather
and ocean conditions, Mr. Malkoski said. Changes
in salinity and water temperature could bring new
species that cause red tides to the region, he
said.
Red tides are harmful algal blooms which
contaminate shellfish with toxins that can be
lethal to humans who eat them and damaging to
fishermen who harvest them. The toxic blooms can
have harmful effects on fish, marine mammals and
birds as well as humans.
The development of harmful algal blooms in
Georges Bank could “drastically change” the
marine food web, said NMFS research fishery
biologist Jason Link, who works at the science
center in Woods Hole.
If water temperatures increase in shallow,
coastal waters, the change could alter vital fish
habitat that serves as feeding and nursery
grounds for a variety of species, including
flounder, scup, sea bass, snapper and juvenile
bass, Mr. Malkoski said.
Eelgrass and other vegetation that provides
protection and shelter for young fish will die if
the water gets too warm, he said.
Fish kills are also possible when temperatures
rise too high, robbing shallow coastal waters of
oxygen. Warm waters create large blooms of
microscopic plants and animals, known as
plankton. When plankton dies, it sinks to the
bottom and decays, sucking up oxygen from the
water that fish need to breathe.
Lobster losses
Global warming could stress out local lobster
stocks as Northeast waters heat up.
“Their whole life is dictated by water
temperature,” said Robert Glenn, an aquatic
biologist with the state Division of Marine
Fisheries.
It determines how much lobsters grow, when they
will shed their shells (molt), when they will
reproduce, and when females will release their
eggs, he said.
Each spring lobsters move inshore, where the
water is warmer and shallower, to molt, mate and
lay eggs.
If coastal waters exceed the temperature
threshold for lobsters, they may decide to remain
in deeper waters, making it difficult for inshore
lobstermen to catch them, Dr. Glenn said.
Higher water temperatures make lobsters more
prone to disease, stress and mortality, he said.
A recent study, co-authored by Dr. Glenn and
Tracy L. Pugh, suggests that the onset of shell
disease among lobsters in Buzzards Bay could be
linked to warmer surface water temperatures.
Shell disease is a mysterious sickness that
disfigures and weakens lobsters, causing some to
die prematurely.
While it is difficult to predict the long-term
effects of increasing water temperatures, Dr.
Glenn said they could lead to a “contraction in
the range of the North American lobster,” which
currently spans from Maine to New Jersey.
Acidic oceans
For Dr. Brodziak – who recently moved from the
Woods Hole science center to NMFS Pacific Islands
Fisheries Science Center in Honolulu, Hawaii –
global warming’s greatest threat to fisheries is
increasing ocean acidity.
Oceans are estimated to absorb about one-quarter
of man-made carbon dioxide emissions.
When carbon dioxide dissolves in the ocean,
carbonic acid is produced through a chemical
reaction. Carbonic acid lowers the pH balance of
sea water, making it more acidic.
Since the beginning of the industrial revolution,
ocean acidity has increased by about 30 percent,
Dr. Brodziak wrote in an e-mail.
“There is no precedent for this kind of long-term
change in ocean chemistry in human history,” he
wrote. “It will alter marine food webs in unknown
ways.”
As oceans become more acidic, they lose calcium
carbonate that some marine animals such as corals
and scallops need to produce shells or
exoskeletons.
Scientists are just beginning to discover what
less calcium carbonate means to these and other
shell-making animals, but it is “possible that it
could affect them in different parts of their
lifecycle,” Dr. Fogarty said.
Atlantic sea scallops, which have made New
Bedford the most valuable fishing port in the
nation, could suffer from reduced growth,
decalcification of their shells, and increased
risk to infection and predation, Dr. Brodziak
wrote. He noted that planktonic scallops, called
spat, and juvenile scallops would be most
susceptible to the effects of more acidic oceans.
“Reduced juvenile survival rates would directly
impact abundance and distribution of the
resource,” he wrote.
Salinity slump
Another impact of global warming on oceans is a
reduction in salinity, or the amount of salt in
sea water.
As global warming melts ice and increases
precipitation and runoff from land, more
freshwater will flow into the ocean, reducing its
saltiness. Since freshwater is less dense than
saltwater, it sits on top, increasing
stratification or layering within the water
column.
Warmer surface water temperatures can further
increase stratification and prevent the mixing of
nutrient-rich bottom water throughout the water
column.
“When you have a blanket of freshwater sitting on
top of saltwater it prevents the ocean from
turning over” nutrients and phytoplankton, Dr.
Rothschild said.
These conditions can alter the marine food web,
leaving cod and other fish without enough food to
eat, he said.
Strong stratification can deplete ocean waters of
oxygen, killing bottom-dwelling fish, shellfish
and other marine animals.
Winds affect the mixing of the water column and
drive ocean surface currents. Changes in winds,
salinity and water temperature can combine to
alter ocean currents that carry phytoplankton,
nutrients and fish larvae through the ocean.
As global warming modifies ocean circulation
patterns there will be major impacts in the
distribution of marine animals and the
environment where they live.
Fishermen’s fate
Scientists say local fishermen should be aware
that global warming will alter the contents of
fishing nets hauled in by their children and
grandchildren.
“We have a pretty strong sense that the species
they target are going to change and they need to
adapt to that,” Dr. Link said.
“With the system likely to change, don’t
anticipate that it’s going to change in a way
that’s favorable to you,” Dr. Mountain added.
How fishermen will fare depends in part on
whether a market develops for the new species
they catch, Dr. Link said.
It comes down to economics and sociology, he said.
With global warming likely to affect fish
productivity, growth and distribution,
sustainable fisheries management is as important
as ever, scientists say.
Fishing on stocks that are already experiencing
stress from global warming could increase their
risk of depletion.
“We need to think of the interplay with what we
do when we’re harvesting stocks and what a change
in climate might bring,” Dr. Fogarty said. “We
have to change the exploitation strategies we use
so we don’t overstress a stock.”
Copyright © 2007 The South Coast Media Group.
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