Familiar fish find northern seas too warm for comfort

Familiar fish find northern seas too warm for comfort

Fish accustomed to shallow northern waters will search in vain for cooler depths as climate change warms the seas where they thrive.

LONDON, 18 April, 2015 – Some of Northern Europe’s favourite suppers may be about to swim off the menu altogether. Global warming could change the future catch, according to new research.

British scientists report in the journal Nature Climate Change that popular species such as haddock, lemon sole and plaice could become less common as the climate changes and the North Sea warms.

The North Sea is relatively shallow – during the height of the Ice Age, much of the sea bed was dry land – which means that fish that would otherwise find deeper waters to keep cool have nowhere to go.

The North Atlantic is warming fast. The mean annual North Sea surface temperatures have increased by 1.3°C in the past 30 years. This is four times faster than the global average. But fish evolved to make a living in the temperatures that suit them best, and the evidence is that the North Sea is increasingly host to species that were once characteristic of the Mediterranean.

Changing abundance

Fishing is big business: landings in 2007 in the region reached $1.2 billion, and accordingly the ecology of the North Sea has been intensively monitored. Cold-adapted landings have halved in the last 30 years, but landings of warm-adapted species have increased 2.5 times. With a baseline of very detailed data from the past, the researchers were able to use computer models to build up a picture of things to come in northern waters.

And the result is this: the demersal or bottom-feeding fish that were the basis of fish-and-chip suppers from Cornwall in the UK to northern Norway are likely to dwindle over the next 50 years. Many of them cannot move north to get away from the heat, because there is no suitable habitat, and they can’t go deeper, because there isn’t any depth. So the abundance of species will change with time.

“Our study suggests that we will see proportionately less of some of the species we eat most of as they struggle to cope with warming conditions in the North Sea,” said Louise Rutterford of Exeter University, the first author.

Squeezed out

“We provide new insight into how important local depths and associated habitats are to these commercial species. It’s something that is not always captured in existing models that predict future fish distributions.”

Other studies have found that fish in many regions are changing to new latitudes as climates change in response to greenhouse gas emissions from fossil fuel combustion. The same man-made global warming has brought a greater number of sardines, for instance, to northern waters, and in the US fishermen have had to sail ever further north to pursue the black bass. There has even been a warning that the retreat of the Arctic ice means that Atlantic halibut could actually migrate into the North Pacific.

So the latest message is confirmation of an increasingly familiar finding. “We will see a real changing of the guard in the next few decades,” said Steve Simpson, a marine biologist at Exeter, and another of the authors.

“Our models predict cold water species will be squeezed out with warmer water fish likely to take their place. For sustainable UK fisheries, we need to move from haddock and chips and look to southern Europe for our gastronomic inspiration.” – Climate News Network

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Threat to marine life adds to California’s woes

Threat to marine life adds to California’s woes

Unusually high water and air temperatures off the US West Coast as climate patterns shift mean bad news for sea lions, sea birds and the fishing industry.

LONDON, 22 March, 2015 – California, currently in the grip of a devastating drought and facing an increasingly parched future, has just been dealt another blow. Not only is the land less productive, but the state’s fisheries could also be about to feel the heat.

A new report warns that the climate seems to be shifting to warmer, less productive conditions. And that’s bad news for seabirds, salmon, sea lions − and sea fishermen.

At play, according to the National Atmospheric and Oceanic Administration Regional Fisheries Science Centres, is the effect of unusually high coastal water and air temperatures over the last year, and changes in the California Current that washes the West Coast of the US.

The consequence is a dip in what ecologists call “primary productivity” – in this case, the tiny copepods and other microscopic creatures that are the first level of the food chain.

Higher death rates

This means less for salmon and other marine species to eat, and higher death rates among sea lion pups in Southern California, and among sea birds on the Washington and Oregon coasts.

Commercial fisheries so far have been good, but California’s fishermen have begun to specialise, and could see catches fluctuate and revenues fall as their target species start to feel the effects.

Toby Garfield, director of environmental research atthe NOAA Southwest Fisheries Science Centre, says: “We are seeing unprecedented changes in the environment.”

John Stein, who directs the Northwest Fisheries Science Centre, adds: “We’re seeing some major environmental shifts taking place that could affect the ecosystem for years to come. We need to understand and consider their implications across the ecosystem, which includes communities and people.”

The changes are partly cyclic: the sea surface temperatures are at record heights, and these have combined with shifts in meteorological cycles, such as the Pacific Decadal Oscillation, and the North Pacific Gyre Oscillation.

“We’re seeing some major environmental shifts taking place that could affect the ecosystem for years to come”

The consequence is that the normal upwelling of deep cold waters has weakened in recent years, and so has the supply of nourishing copepods. Sea lion pups and a species of seabird called Cassin’s auklet have been found dying and emaciated, which suggests problems with the food supply.

Since 2014, blobs of warm water have been observed in the Gulf of Alaska and all the way down the coast, and these conditions tend to be accompanied by lower productivity.

In the past, this has meant poorer catches of salmon, anchovy and squid, although better catches of sardines, tuna and marlin. But lately, both anchovy and sardine hauls have been at lower levels.

Double jeopardy

Salmon in particular face double jeopardy in California. Not only is the food supply in the sea threatened, but low snowfalls and greater drought mean that the rivers up which the salmon jump to spawn are less hospitable.

The California drought, the worst in the state’s history, has been tentatively linked to global warming. The changes in the California Current may be a coincidence of natural cycles.

Reports such as these are intended to alert communities to changing conditions. They are not so much prescriptions for doom as practical warnings of potential problems ahead. But the tone may well have become more urgent.

“We are in some ways entering a situation we haven’t seen before,” says Cisco Werner, who directs the Southwest Fisheries Science Centre at La Jolla. “That makes it all the more important to look at how these conditions affect the entire ecosystem.” – Climate News Network

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More Antarctic warmth creates heavier snowfall

More Antarctic warmth creates heavier snowfall

Rising temperatures may result in more snow falling in Antarctica, with the ice that builds up flowing to the ocean and raising sea levels.

LONDON, 16 March, 2015 – It may sound unlikely, but the evidence is mounting that the more the Antarctic warms under the impact of climate change, the more snow will fall on it.

Not only that, says a team of European and US scientists, but as the snow turns to ice it is going to flow downhill, borne by its own weight, and contribute to rising sea levels.

The impact of this paradoxical process is likely to be significant. The team, led by scientists from Germany‘s Potsdam Institute for Climate Impact Research (PIK), says each degree Celsius of warming in the region could increase Antarctic snowfall by about 5%.

Ice-core data

The research, published in Nature Climate Change, builds on high-quality ice-core data and fundamental laws of physics captured in global and regional climate model simulations.

The suggestion that Antarctic snowfall is increasing is not itself new, though not all scientists accept the data without qualification.

What the Potsdam scientists have done is important, not simply because they provide new evidence to support the contention, but because they explore its potential consequences.

Katja Frieler, climate impacts and vulnerabilities researcher at PIK, and lead author of the report, says: “Warmer air transports more moisture, and hence produces more precipitation. In cold Antarctica, this takes the form of snowfall. We have now pulled a number of various lines of evidence together and find a very consistent result: temperature increase means more snowfall on Antarctica.”

To reach a robust estimate, the PIK scientists collaborated with colleagues in the Netherlands and the US.

“Ice-cores drilled in different parts of Antarctica provide data that can help us understand the future,” says co-author Peter U. Clark, professor of geology and geophysics at Oregon State University.

“The Antarctic ice sheet could become a major contributor to future sea-level rise, potentially affecting millions of people in coastal areas” 

“Information about the snowfall spanning the large temperature change during the last deglaciation [the uncovering of land by the melting of glaciers], 21,000 to 10,000 years ago, tells us what we can expect during the next century.”

The researchers combined the ice-core data with simulations of the Earth’s climate history and comprehensive future projections by different climate models, and were able to pin down temperature and accumulation changes in warming Antarctica.

The increasing snowfall on the continent will add to the mass of the ice sheet and increase its height.

But the researchers say it won’t stay there. On the basis of another previous PIK study, they say the extra snow will also increase the amount of ice flowing to the ocean.

Dr Frieler says: “Under global warming, the Antarctic ice sheet, with its huge volume, could become a major contributor to future sea-level rise, potentially affecting millions of people living in coastal areas.”

Additional snowfall

As snow piles up on the ice, its weight presses down – the higher the ice, the greater the pressure. Additional snowfall elevates the grounded ice-sheet on the Antarctic landmass, but has less of an effect on the floating ice shelves at the coast, allowing the inland ice to flow more rapidly into the ocean and raise sea levels, the researchers say.

The 5% increase in Antarctic snowfall that they expect for every 1°C rise in temperature would mean an estimated drop in sea-level of about three centimetres after a century.

But they say other processes will cause an eventual rise in sea-level. For example, relatively slight warming of the ocean could cause coastal ice to break off more easily, allowing more of the continental ice mass to discharge into the ocean.

Another co-author is Anders Levermann, PIK professor of dynamics of the climate system, and also a lead author of the sea-level rise chapter in the latest report by Intergovernmental Panel on Climate Change.

He says: “If we look at the big picture, these new findings don’t change the fact that Antarctica will lose more ice than it will gain, and that it will contribute to future sea-level change.” – Climate News Network

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Satellite link puts sharper focus on ocean acidity rise

Satellite link puts sharper focus on ocean acidity rise

Global data network could provide scientists with an easy and cheaper way of finding answers to crucial questions on the oceans’ changing chemistry.

LONDON, 25 February, 2015 − Climate scientists are looking for a new perspective on the increasingly acidic oceans through a suite of satellites 700 km out in space, watching over parts of the seas that research ships cannot reach.

They report in the journal Environmental Science and Technology that thermal cameras could measure ocean temperatures, while microwave sensors could measure ocean salinity. Together, the two sets of data could help answer, cheaply and easily, questions about the chemistry of the oceans – and in particular changes in pH, the index of acidity.

Until now, researchers have depended on specialist instruments or shipboard samples to provide answers to huge questions about the oceans’ increasing uptake of carbon dioxide. Such research is costly and limited.

But ocean science has become ever more important. Each year, 36 billion tonnes of CO2 are released into the atmosphere, and about a quarter of this gets into the oceans.

Greenhouse gas

That’s a good thing: if it did not, global warming would accelerate at an even greater rate. But the same global transfer of greenhouse gas also delivers a stronger solution of carbonic acid to the oceans, and ocean acidity levels have risen by 26% over the last 200 years.

The consequences for all those sea creatures that evolved to exploit ocean chemistry to build shells or skeletons are uncertain, but the evidence so far is that changes can affect fish behaviour, shellfish reproduction, and coral growth.

The changes could almost certainly affect fisheries in the short term, and in the long term could possibly alter the continuous and vital exchanges between atmosphere and ocean that controls the climates of continents.

So marine scientists launched a Global Ocean Acidification Observing Network to assemble worldwide expertise and find new ways to monitor change.

“We are pioneering these techniques so that we can monitor large areas of the Earth’s oceans”

“Satellites are likely to become increasingly important for the monitoring of ocean acidification especially in remote and dangerous waters like the Arctic,” says one of the report’s authors, Jamie Shutler, an oceanographer at the University of Exeter. UK.

“It can be difficult and expensive to take year-round direct measurements in such inaccessible locations. We are pioneering these techniques so that we can monitor large areas of the Earth’s oceans, allowing us to quickly and easily identify those areas most at risk from the increasing acidification.”

The European Space Agency’s SMOS satellite in orbit. Image: ESA

The European Space Agency’s SMOS satellite in orbit.
Image: ESA

The new approach will exploit a number of existing satellites, along with the European Space Agency’s Soil Moisture and Ocean Salinity sensor (SMOS), launched in 2009, and the US space agency NASA’s Aquarius satellite, launched in 2011.

The satellites cannot, of course, directly measure ocean pH values, but the capacity of CO2 to dissolve in water is controlled by ocean temperatures.

Salinity levels

On the other hand, salinity levels play into the capacity to form carbonates. Chlorophyll levels in the oceans also indicate the rates at which biology can exploit any of the dissolved carbon dioxide.

If the scientists have temperature and air pressure data as well, they have enough to begin to calculate the rates at which any stretch of sea might be acidifying.

Although such measurements are indirect, and involve complex mathematical calculation, the results can be checked in some places against real-time data from a network of autonomous instruments called Argo, and by shipboard laboratory studies.

But satellites are about the only way of making consistent measurements of the desolate and hostile Arctic and Indian Oceans. They could also help researchers understand the changes taking place in complex stretches of sea such as the Bay of Bengal and the Greater Caribbean.

The research is in its infancy. But the authors say that satellite studies − supported by good measurements taken directly at sea − could become a key element in understanding and assessing the acidification of the oceans. – Climate News Network

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Sardines swim into northern waters to keep cool

Sardines swim into northern waters to keep cool

Fish species in subtropical European waters are migrating north to escape warming seas − leaving fishermen who rely on them for a living with empty nets.

LONDON, 20 February, 2015 − Several important fish species that for centuries have been part of the staple diet of people in the Mediterranean region are abandoning sub-tropical seas because the water is too warm and are heading north.

Sardines, which for generations have been the most abundant commercial fish species in Portugal, are moving away. They are now established in the North Sea, and are being caught in the Baltic – a sea that until recently was normally frozen over in the winter.

Sardines, anchovies and mackerel − three fish species that are important in the diet of many southern European and North African countries − have been studied by scientists trying to discover how climate change and warming seas are affecting their distribution.

Fishing industry

As well as the affect on the fishing industry, the abundance or disappearance of these species is crucial for many other marine species that rely on them for food.

A pioneering study, published in Global Change Biology, analysed 57,000 fish censuses conducted over 40 years, and has tracked the movement of these fish during this period.

It confirms that the continued increase in water temperature has altered the structure and functioning of marine ecosystems across the world. But it also shows that the effect has been greater in the North Atlantic, with increases of up to 1.3 ºC in the average temperature over the last 30 years.

This variation in temperature directly affects the frequency and range of pelagic fish, which live in the middle of the water column and are directly influenced by temperature, rather than habitat. It includes the sardine (Sardina pilchardus), anchovy (Engraulis encrasicolus), horse mackerel (Trachurus trachurus) and mackerel (Scomber scombrus), among others.

Sardines and other fish represent “an exceptional bioindicator to measure the direction and speed of climate change expected in the near future”

They feed off phytoplankton and zooplankton, and are themselves the staple diet of large predators, such as cetaceans, large fish and marine birds. These fish occur off the shores of many coastal countries in the world and are important sources of protein.

Scientists have known that fish were moving to new areas, but did not know whether it was in response to their main food supply plankton moving first or whether it was a simple response to changing temperatures.

The new study has developed statistical models for the North Sea area, and confirms the great importance of sea temperatures.

“Time series of zooplankton and sea surface temperature data have been included to determine the factor causing these patterns,” Ignasi Montero-Serra, lead author of the study and researcher in the department of Ecology at the University of Barcelona, explains to the Scientific Information and News Service.

To demonstrate the consequences of the warming of the seas, the research team analysed fish censuses from commercial fishing performed independently along the European continental shelf between 1965 and 2012, extracted from data provided by the International Council for the Exploration of the Sea.

The study, which is the first to be carried out on such a large timescale and area, allows for the dynamics of this species to be understood in relation to the rapid warming of the oceans that has been happening since the 1980s.

The results reveal that sardines and other fish with fast life cycles, planktonic larval stage and low habitat dependence are highly vulnerable to changes in ocean temperature, and therefore represent, Montero-Serra says, “an exceptional bioindicator to measure the direction and speed of climate change expected in the near future”.

Accelerated increase

Montero-Serra says that accelerated increase in temperature of the continental seas has resulted in sardines and anchovies − with a typically subtropical distribution − increasing their presence in the North Sea and “even venturing into the Baltic Sea”. And the presence of species with a more northern distribution, such as the herring and the sprat, has decreased.

The analysis is therefore a clear sign that species in the North Sea and Baltic Sea are “becoming subtropical”.

This is due to the pelagic fish being highly dependent on environmental temperatures at different stages of their life cycle − from reproductive migrations and egg-laying, to development and survival of larvae.

According to the researchers, the changes in such an important ecological group “will have an effect on the structure and functioning of the whole ecosystem”, although they still do not know the scale of the socio-economic and ecological repercussions. – Climate News Network

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Climate change triggers threats to marine ecosystems

Climate change triggers threats to marine ecosystems

A two-way migration of fish species between the northern Pacific and Atlantic as oceans warm could have drastic ecological and commercial impacts.

LONDON, 7 February, 2015 − The Atlantic halibut is about to go where no Atlantic halibut has gone before – into the Pacific. And it could meet the Alaska pollock coming in the other direction.

Just as marine commerce could soon exploit the opening of the fabled north-west or north-east passages between the two great oceans, so could at least 80 species of fish.

Mary Wisz, an ecologist now with the Danish DHI group, but formerly at the Arctic Research Centre of Aarhus University in Denmark, reports with colleagues in Nature Climate Change that as sea temperatures increase, and food sources begin to flourish at the highest latitudes, shoals of fish from the Atlantic could reach the Pacific along once almost impassable seaways north of Arctic Canada and Siberia.

Northerly species

The last such large-scale transfer was nearly three million years ago, with the opening of the Bering Strait. But climate conditions that were once harsh have begun to open migration opportunities for the northerly species in both oceans, the researchers say.

Such changes have happened before. Since the opening of the Suez Canal in 1869, the Mediterranean has been invaded by 55 Red Sea species, with a “drastic impact” on commercial fisheries.

Fish are already moving north in response to climate change, and Dr Wisz and her colleagues modelled what would happen to 515 species of fish under predicted conditions of global warming later this century.

By 2050, the scientists believe, trans-Arctic traffic will accelerate, and by 2100, 41 Atlantic species − among them cod and herring − could reach the Pacific, while 44 species could get into the Atlantic.

They warn: “This exchange of fish species may trigger changes in the North Atlantic and the North Pacific, with ecological and economic consequences to ecosystems that at present contribute 39% to global marine fish landings.”

Changes to marine chemistry also threaten the balance of power in the oceans

The Danish-led team was essentially modelling temperature, currents and spawning strategies to see which species were most likely to find new grounds. But changes to marine chemistry also threaten the balance of power in the oceans.

The seas are predicted to become more acidic as more carbon dioxide gets into the atmosphere, and this change in water chemistry is likely to affect not just fish and shellfish but also entire communities of creatures.

Scientists have tested the fauna that foul ships’ hulls. These are the tiny barnacles and squirts that attach themselves to hard surfaces wherever they can in the oceans.

Lloyd Peck, a biologist with the British Antarctic Survey, and colleagues report in Global Change Biology that they tested creatures from a lagoon off the Algarve in Portugal, in aquarium tanks.

One set of tanks was filled with normal sea water; in the other set, the sea water was set at levels of acidity predicted to be normal within the next 50 years. Within 100 days, in the more acid tanks, the make-up of the community that colonised the hard surfaces had begun to change.

Worms with hard shells in the more acidic tanks were reduced to a fifth of their normal levels, but sponges and sea squirts multiplied twofold and even fourfold.

“Our experiment shows the response of one biofouling community to a very rapid change in acidity,” said Professor Peck. “What’s interesting is that the increased acidity at the levels we studied destroys not only the building blocks in the outer shell of the worms itself, but the binding that holds it together.

“Many individuals perish, but we also showed their larvae and juveniles are also unable to establish and create their hard exoskeletons.”

Altered behaviour

Climate change could also alter the behaviour of the green sea turtle, Chelonia mydas, according to an international team led by Professor Kyle Van Houtan, of the Nicholas School of the Environment and Earth Sciences at Duke University, US.

The researchers studied six years of turtle observations off Oahu, Hawaii, and 24 years of satellite data for sea surface temperatures in regions that are home to 11 populations of the turtle.

They report in Biology Letters that they know why the turtles crawl up onto the beach to bask. Not all populations bask, but the ones that do tend to sprawl in the sand do so to regulate body temperatures, and were least likely to bask when local winter sea temperatures stayed above 23°C. When the seas stayed warm, the turtles stayed in the water.

Given the predicted ocean temperature rises over the next century, the scientists calculate that green turtles may stop basking altogether by 2100. – Climate News Network

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Trapped methane escapes as Pacific depths warm up

Trapped methane escapes as Pacific depths warm up

Oceanographers in the US warn that volumes of methane equivalent to a major oil spill are rising to the surface each year as warmer waters heat the frozen ocean bed.

LONDON, 11 January, 2015 – Researchers studying methane trapped in frozen layers below the Pacific Ocean seafloor predict that more and more of the potent greenhouse gas could bubble towards the surface as the deep water begins to warm.

“We calculate that methane equivalent in volume to the Deepwater Horizon oil spill [in 2010] is released every year off the Washington coast,” says Evan Solomon, assistant professor at the University of Washington School of Oceanography in the US.

Methane hydrates are the natural gas methane in solid form. Volume for volume, methane is at least 20 times more potent a greenhouse gas than carbon dioxide, although it is released in smaller quantities and has a much shorter lifespan in the atmosphere.

Vast quantities of the stuff are known to be trapped in sedimentary rocks and in the sea bed, in “frozen” form − held by a combination of temperature and pressure.

Fastest warming

Until now, most of the focus has been on the methane hydrates in the Arctic, the fastest warming region on the planet.

But Dr Solomon, oceanographer and lead author Susan Hautala and colleagues report in Geophysical Research Letters their calculations that between 1970 and 2013, some 4 million tonnes of methane have been released from the sea floor off the coast of Washington state.

This is about the equivalent of the natural gas released in 2010 when the Deepwater Horizon oil well blew out off the coast of Louisiana, and 500 times the rate of natural release from the sea floor.

Coring machine used to gather sediment samples from the Pacific. Image: Robert Cannata/University of Washington

Coring machine used to gather sediment samples from deep in the Pacific Ocean.
Image: Robert Cannata/University of Washington

The Pacific Northwest has high rates of biological activity, and methane is a natural biological product. At high ocean pressures and low sea temperatures, it “freezes” or crystallises in a solid state. And because the waters of the Pacific Northwest have been so rich in life, the seabed below is rich in methane hydrates.

But ocean waters have started to warm, at depth, and currents have carried the warming water across the ocean to the North American shelf.

Atmospheric warming

As water warms, the submarine methane “ice line” retreats further offshore − rather in the way that a snowline moves up hill, or a glacier retreats, in response to atmospheric warming.

The Washington scientists calculate that, since 1970, the boundary at which methane stays frozen has retreated by about a kilometre. By 2100, it will have moved perhaps another three kilometres off shore.

Their calculations suggest that, by the century’s end, 400,000 metric tonnes a year will escape. And the puzzle now is where the released methane will end up.

Some could be consumed by methane-eating bacteria in the seafloor ooze. But fishermen have also observed the stuff bubbling to the surface, to add to the burden of atmospheric greenhouse gases.

The finding, the researchers say, has “worldwide implications” for other oceanic reservoirs of the stuff, close to continental shelves and therefore vulnerable to large-scale melting. – Climate News Network

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Scientists track natural responses to climate change

Scientists track natural responses to climate change

Researchers in the US have identified a wide range of impacts – human and natural – that global warming has on fish, forests, birds and wildflowers.

LONDON, 31 December, 2014 − Lumberjacks are selecting different trees, US fishermen are sailing further north to catch black sea bass, desert birds are nesting later in California and Arizona, and one kind of wildflower is changing shape in the Rocky Mountains − and all in response to climate change, according to new research.

None of these responses is simple, or necessarily ominous, and global warming is not the only factor at work. But all are nevertheless examples of adaptation to − so far – very modest changes in temperature.

Adena Rissman and Chad Rittenhouse, of the University of Wisconsin-Madison, report in the Journal of Environmental Management that they looked at weather records and logging data and found that, since 1948, the winter interval during which ground is firmly frozen has declined by an average of two to three weeks.

Hard winters are the logger’s friend as the ground can support heavy machinery, whereas muddy soils can make tracks impassable. So, over the decades, foresters have harvested more and more red pine and jack pine − species that flourish in sandy, well-drained soil more accessible to trucks, tractors and chainsaws.

Significant decline

“We wanted to know how weather affects our ability to support sustainable working forests,” says Dr Rissman, assistant professor of human dimensions of ecosystem management. “We found a significant decline in the duration of frozen ground over the past 65 years and, at the same time, a significant shift in the species being harvested.”

Such changes in selection tend to affect ecosystems – on land or at sea.

Scientists at the Northeast Fisheries Science Centre in the US report in the ICES Journal of Marine Science that they looked at trawl survey data collected between 1972 and 2008 to analyse variations in abundance of black sea bass, scup, and summer and winter flounder. All had shown “significant poleward shifts” in at least one season.

“We demonstrated how a combination of fishing and climate can influence the distribution of marine fish”

The bass and scup were responding to changes in temperature. The summer flounder were more likely to be responding to a decrease in fishing pressure − that is, the species could recolonise former habitat. There was no change in the distribution in the southern New England/Mid Atlantic Bight stock of winter flounder.

“Using these data, we demonstrated how a combination of fishing and climate can influence the distribution of marine fish,” said lead author Richard Bell, research associate at the US National Oceanic and Atmospheric Administration fisheries service laboratory at Narrangansett.“It is not one or the other.”

Meanwhile, in the arid American southwest’s Sonora Desert, all 13 desert bird species have tended to delay nesting by two weeks or more, as a response to severe drought.

Delays in nesting

This makes survival a problem for the birds as their young are more vulnerable to nest predators and parasites. Some species forego breeding entirely during an extreme drought. Even without global warming, droughts are an enduring fact of life in the region. But ecologists point out that climate models predict a greater frequency of droughts, which could lead to even more delays in nesting.

“These responses are predicted to become more frequent and extreme, due to climate change, causing us to question how desert birds will persist in the long term,” Chris McCreedy, a desert ecologist at Point Blue Conservation Science, reports in The Auk, the American Ornithologists’ Union journal.

The hardy Rocky Mountain mustard plant Image: USDA via Wikimedia Commons

The hardy Rocky Mountain mustard plant
Image: USDA via Wikimedia Commonse

At least one species has responded to climate change by altering not just its life cycle but its shape.

Students at Dartmouth College in New Hampshire and the University of South Carolina report in Global Change Biology that the Rocky Mountain mustard plant (Boechera stricta) offers an example of what biologists call “phenotypic plasticity”.

This means that it doesn’t evolve to meet climate change − it just looks different under different conditions. It changes according to whether the conditions are hot and dry, or cold and wet. In experiments that simulated future climate change, it also flowered seven days earlier.

This little ready-for-anything brassica plant seemed able to respond differently according to whether or not there was snow around it. Or, as the researchers put it: “Extensive plasticity could buffer against immediate fitness declines due to changing climates.” – Climate News Network

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Sea urchins refine survival instincts as oceans change

Sea urchins refine survival instincts as oceans change

As climate change adds to the threat of extinction faced by many species, new research shows how sea urchins can adapt to the increasing temperature and levels of acidity in Antarctic waters.

LONDON, 17 December, 2014 − The sea urchins of the Southern Ocean could be safe from the threat of extinction. They may not enjoy global warming and the increasingly acid oceans, but new research indicates that they can adapt to climate change.

Researchers from the British Antarctic Survey and Bangor University in Wales − in what they describe as the largest study of its kind − collected 288 urchins of the species Sterechinus neumayeri from waters off the Antarctic Peninsula, carried them to Cambridge in the UK, and tested them in aquarium tanks over a two-year span, covering two full reproductive cycles.

During this time, they report in the Journal of Animal Ecology, they changed the water chemistry and turned up the temperature. The environment was made less alkaline and the thermometer notched up another 2°C − which are the conditions sea creatures could expect by 2100 if the world goes on burning fossil fuels and pumping greenhouse gases under the notorious business-as-usual scenario.

Intricate network

Research like this matters because it helps scientists to better understand the intricate network of environmental conditions that underwrite life on the planet, and because it provides answers to one of the big questions of climate change: how will it affect the estimated seven million species with whom humans share the planet?

According to the journal Nature, the lowest estimate is that 10 species become extinct every week, and the number could be as high as 690 a week. The uncertainty is an indicator of how little is known about the diversity of life on the planet.

The oceans, in particular, have been hard hit by human action. Other marine survival studies have not been encouraging: ocean acidification promises to be very bad news for corals, and therefore for the rich and diverse communities that depend on coral reefs. It also offers a survival threat to bivalves that exploit ocean chemistry to build protective shells.

Other experiments have shown that it can affect the survival behaviour of fish, and can even affect the lugworms that anglers favour as bait for fish.

But the news from the laboratory aquarium in Cambridge is encouraging. It took the sea urchins six to eight months to acclimatise and adjust to the new acidity levels and temperature − but they survived.

Artificial insemination experiments suggested that the urchins could spawn successfully under the new conditions, but to be sure of this, the researchers need more time. Antarctic invertebrates mature very slowly and sea urchins could live for 40 years or more.

“With predictions of warmer, more acidic waters in the future, this work shows how resilient these animals are to climate change,” said Melody Clark, project leader for the Adaptations and Physiology Group at the British Antarctic Survey.

“It also emphasises the importance of conducting long-term experiments in making accurate predictions. These animals live a long time, and so they do everything really slowly. They take around eight months to get used to new conditions, and two years to produce gonads (sexual organs). If we had stopped this experiment at three or even six months, we would have got very different results.”

Change habitat

Sea urchins cannot easily change their habitat: they must adapt or perish. But four-legged, warm-blooded terrestrial creatures have another option. In another instance of long-term research, scientists have established that small mountain mammals are prepared to move uphill as the climate warms.

Karen Rowe, biodiversity research fellow at Museum Victoria in Melbourne, Australia, and colleagues report in Proceedings of the Royal Society that they looked at records of observations of small mammals, made between 1911 and 1934 at 166 sites in the Californian mountains. Then, between 2003 and 2010, they surveyed the same species in the same locations.

Warmer winters are bad for hibernating mammals such as the chipmunk. Image: Vlad Lazarenko via Wikimedia Commons

Warmer winters are bad for hibernating mammals such as the chipmunk.
Image: Vlad Lazarenko via Wikimedia Commons

Altogether, they looked at 30,000 observations that recorded the foraging and breeding ranges of 34 species of chipmunk, gopher, pika, shrew, deer mouse, woodrat and squirrel at altitudes that varied from sea level to about 4,000 metres.

Moving uphill

Since the first, historic set of systematic measurements, the average temperatures in the region have climbed by 0.6°C, and many mammals have shifted their range accordingly – by moving uphill.

The pattern wasn’t consistent, but the researchers identified a problem for those animals that normally hibernate: warmer winters could be very bad news for creatures adapted to the chillier mountain slopes. And those animals that live at the highest altitudes might soon have nowhere to go.

“While mammals can avoid heat stress by behavioural means (such as shifting daily activity), warming winters lead to increased energy expenditures for hibernators and reduce the snow layer, which acts as insulation for non-hibernators,” they conclude.

“Global climate projections suggest that disappearing climates will be an increasing challenge for predicting future species’ responses.” – Climate News Network

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Deep concern over invisible threat to Antarctic glaciers

Deep concern over invisible threat to Antarctic glaciers

As ocean temperatures rise, warmer currents are attacking the Antarctic ice sheet from below and adding to the threats posed by a melting rate that has trebled in the last two decades.

LONDON, 13 December, 2014 − The Antarctic ice shelf is under threat from a silent, invisible agency – and the rate of melting of glaciers has trebled in the last two decades.

The ocean waters of the deep circumpolar current that swirl around the continent have been getting measurably warmer and nearer the ocean surface over the last 40 years, and now they could be accelerating glacier flow by melting the ice from underneath, according to new research.

And a separate study reports that the melting of the West Antarctic glaciers has accelerated threefold in the last 21 years.

Calamitous consequences

If the West Antarctic ice sheet were to melt altogether – something that is not likely to happen this century – the world’s sea levels would rise by 4.8 metres, with calamitous consequences for seaboard cities and communities everywhere.

Researchers from Germany, Britain, Japan and the US report in Science journal that they base their research on long-term studies of seawater temperature and salinity sampled from the Antarctic continental shelf.

This continued intrusion of warmer waters has accelerated the melting of glaciers in West Antarctica, and there is no indication that the trend is likely to reverse.

Other parts of the continent so far are stable – but they could start melting for the first time.

“The Antarctic ice sheet is a giant water reservoir,” said Karen Heywood, professor of environmental sciences at the University of East Anglia, UK. “The ice cap on the southern continent is on average 2,100 metres thick and contains 70% of the world’s fresh water. If this ice mass were to melt completely, it could raise global sea level by 60 metres. That is not going to happen, but it gives you an idea of how much water is stored there.”

“These waters have warmed . . . and  are significantly shallower than 50 years ago”

Temperatures in the warmest waters in the Bellinghausen Sea in West Antarctica have risen from 0.8°C in the 1970s to about 1.2°C in the last few years.

“This might not sound much, but it is a large amount of extra heat available to melt the ice,” said Sunke Schmidtko, an oceanographer at the Geomar Helmholtz Centre for Ocean Research in Kiel, Germany, who led the study. “These waters have warmed in West Antarctica over 50 years. And they are significantly shallower than 50 years ago.”

The apparent rise of warm water, and the observed melting of the West Antarctic ice shelf, could be linked to long-term changes in wind patterns in the southern ocean. Although melting has not yet been observed in other parts of the continent, there could be serious consequences for other ice shelves.

The shelf areas are where the Antarctic krill – the little shrimp that plays a vital role in the Antarctic ocean food chain – are getting warmer, with unpredictable consequences for spawning cycles, and then for ocean biodiversity.

Meanwhile, according to US scientists writing in Geophysical Research Letters, the glaciers of the Amundsen Sea in West Antarctica are shedding ice faster than any other part of the region.

Tyler Sutterley, a climate researcher at the University of California Irvine, and NASA space agency colleagues used four sets of observations to confirm the threefold acceleration.

They took their data from NASA’s Gravity Recovery and Climate Experiment (GRACE) satellites, from a NASA airborne project called Operation IceBridge, from an earlier satellite called ICESat, and from readings by the European Space Agency’s Envisat satellite.

Loss calculated

The observations spanned the period 1992 to 2013 and enabled the researchers to calculate the total loss of ice, and also the rate of change of that loss.

In all, during that period the continent lost 83 gigatonnes, or 83 billion metric tonnes, of ice per year on average. Since Mount Everest weighs an estimated 161 billion tonnes, this is as if the ice cap lost an Everest’s worth of ice every two years.

After 1992, the rate of loss accelerated by 6.1 billion tonnes a year, and between 2003 and 2009 the melt rate increased by 16.3 gigatonnes a year on average. So the increasing rate of loss is now nearly three times the original figure.

“The mass loss of these glaciers is increasing at an amazing rate,” said Isabella Velicogna, Earth system scientist at both UC Irvine and the NASA Jet Propulsion Laboratory. – Climate News Network

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