Tag Archives: Fish

Warming oceans deter more fish from spawning

When the moment to mate arrives, fish like to play it cool. So warming oceans create special problems for the generation game.

LONDON, 9 July, 2020 – German scientists now know why so many fish are so vulnerable to ever-warming oceans. Global heating imposes a harsh cost at the most critical time of all: the moment of spawning.

“Our findings show that, both as embryos in eggs and as adults ready to mate, fish are far more sensitive to heat than in their larval stage or as sexually mature adults outside the mating season,” said Flemming Dahlke, a marine biologist with the Alfred Wegener Institute at Bremerhaven.

“On the global average, for example, adults outside the mating season can survive in water that’s up to 10°C warmer than adults ready to mate, or fish eggs, can.”

The finding – if it is confirmed by other research – should clear up some of the puzzles associated with fish numbers. There is clear evidence, established repeatedly over the decades, that fish are responding to climate change.

But almost three fourths of the planet is blue ocean, and at depth is responding far more slowly than the land surface to global heating fuelled by fossil fuel exploitation that releases greenhouse gases.

Nearing the brink

Since fish in the temperate zones already experience a wide variation in seasonal water temperatures, it hasn’t been obvious why species such as cod have shifted nearer the Arctic, and sardines have migrated to the North Sea.

But marine creatures are on the move, and although there are other factors at work, including overfishing and the increasingly alarming changes in ocean chemistry, thanks to ever-higher levels of dissolved carbon dioxide, temperature change is part of the problem.

The latest answer, Dr Dahlke and his colleagues report in the journal Science, is that many fish may already be living near the limits of their thermal tolerance.

The temperature safety margins during the moments of spawning and embryo might be very precise, and over hundreds of thousands of years of evolution, marine and freshwater species have worked out just what is best for the next generation. Rapid global warming upsets this equilibrium.

“Adults outside the mating season can survive in water that’s up to 10°C warmer than adults ready to mate, or fish eggs, can”

The Bremerhaven scientists looked at experiments, observations and recorded data for the life cycles of 694 marine and freshwater species, to decide that oxygen supply is the key decider of reproductive success. Warmer waters carry less dissolved oxygen. Embryo fish have no gills: they cannot simply take in deeper breaths.

Fish about to mate are busy producing extra mass in the form of sperm and egg cells: this additional body mass also needs oxygen. Even at lower temperatures, piscine cardiovascular systems are under stress.

So the reasoning follows that, if global heating continues, climate change and rising water temperatures are likely to affect the reproduction of perhaps 60% of all fish species.

“Some species might successfully manage this change,” Dr Dahlke said.
“But if you consider the fact that fish have adapted their mating patterns to specific habitats over extremely long timeframes, and have tailored their mating cycles of specific ocean currents and food sources, it has to be assumed that being forced to abandon their normal spawning areas will mean major problems for them.” – Climate News Network

When the moment to mate arrives, fish like to play it cool. So warming oceans create special problems for the generation game.

LONDON, 9 July, 2020 – German scientists now know why so many fish are so vulnerable to ever-warming oceans. Global heating imposes a harsh cost at the most critical time of all: the moment of spawning.

“Our findings show that, both as embryos in eggs and as adults ready to mate, fish are far more sensitive to heat than in their larval stage or as sexually mature adults outside the mating season,” said Flemming Dahlke, a marine biologist with the Alfred Wegener Institute at Bremerhaven.

“On the global average, for example, adults outside the mating season can survive in water that’s up to 10°C warmer than adults ready to mate, or fish eggs, can.”

The finding – if it is confirmed by other research – should clear up some of the puzzles associated with fish numbers. There is clear evidence, established repeatedly over the decades, that fish are responding to climate change.

But almost three fourths of the planet is blue ocean, and at depth is responding far more slowly than the land surface to global heating fuelled by fossil fuel exploitation that releases greenhouse gases.

Nearing the brink

Since fish in the temperate zones already experience a wide variation in seasonal water temperatures, it hasn’t been obvious why species such as cod have shifted nearer the Arctic, and sardines have migrated to the North Sea.

But marine creatures are on the move, and although there are other factors at work, including overfishing and the increasingly alarming changes in ocean chemistry, thanks to ever-higher levels of dissolved carbon dioxide, temperature change is part of the problem.

The latest answer, Dr Dahlke and his colleagues report in the journal Science, is that many fish may already be living near the limits of their thermal tolerance.

The temperature safety margins during the moments of spawning and embryo might be very precise, and over hundreds of thousands of years of evolution, marine and freshwater species have worked out just what is best for the next generation. Rapid global warming upsets this equilibrium.

“Adults outside the mating season can survive in water that’s up to 10°C warmer than adults ready to mate, or fish eggs, can”

The Bremerhaven scientists looked at experiments, observations and recorded data for the life cycles of 694 marine and freshwater species, to decide that oxygen supply is the key decider of reproductive success. Warmer waters carry less dissolved oxygen. Embryo fish have no gills: they cannot simply take in deeper breaths.

Fish about to mate are busy producing extra mass in the form of sperm and egg cells: this additional body mass also needs oxygen. Even at lower temperatures, piscine cardiovascular systems are under stress.

So the reasoning follows that, if global heating continues, climate change and rising water temperatures are likely to affect the reproduction of perhaps 60% of all fish species.

“Some species might successfully manage this change,” Dr Dahlke said.
“But if you consider the fact that fish have adapted their mating patterns to specific habitats over extremely long timeframes, and have tailored their mating cycles of specific ocean currents and food sources, it has to be assumed that being forced to abandon their normal spawning areas will mean major problems for them.” – Climate News Network

Shrinking Arctic ice slows fish breeding rates

A food source for many species spawns under the Arctic ice. Now fish breeding problems, caused by ice melt, threaten its future.

LONDON, 3 March, 2020 − It’s relatively small, not particularly well-known, but it’s a key indicator of global warming, which is putting some fish breeding rates at risk: enter the polar cod (Boreogadus saida), the smaller cousin of the more familiar north-east Arctic cod.

A recent study by researchers at the Institute of Marine Research (IMR) in Norway has found that declines in winter sea ice cover in the Barents Sea region of the Arctic, plus warmer sea temperatures, are causing declines in polar cod reproduction rates.

This has grave implications − not just for future stocks of polar cod, but for the survival of many other Arctic species as well. The polar cod is a vital part of the Arctic food chain. After spawning under the ice in the early months of the year, the fish – feeding on a diet of zooplankton − grows quickly. It then becomes a food for other larger fish and for sea birds, seals and whales.

“Unfortunately, climate projections suggest that the Barents Sea will become warmer and virtually ice-free as early as in 2030”, says Mats Huserbråten, one of the study’s authors. “The outlook for this cornerstone of the Arctic food chain is therefore bad.”

End of breeding

If trends in ice reduction and the heating of Arctic waters continue, the reproductive cycle of the polar cod could collapse, say the researchers.

The fish is endemic to the polar regions (found nowhere else) and has developed in ways which make it dependent on the presence of ice. Its eggs are spawned under the ice, where they grow, even in sub-freezing temperatures. The larvae then feed on the zooplankton − plentiful in mid-year, when the annual ice melt occurs.

Winter ice cover in the Arctic has been in decline since the 1970s, with a sizeable part of the reduction happening in the Barents Sea.

The polar cod stock there has been monitored annually by a joint Norwegian-Russian survey since 1986. In the IMR study, researchers found that not only were stocks diminishing, but that what are described as spawning assemblages of the polar cod were moving further north.

“Climate projections suggest that the Barents Sea will become warmer and virtually ice-free as early as in 2030. The outlook for this cornerstone of the Arctic food chain is therefore bad”

As climate change warms the planet’s oceans, many fish species have been observed moving away from the equator in search of cooler waters. While such fish movements have resulted in bigger catches in some areas, fish stocks in many more southern regions are in sharp decline.

The reduction in winter ice cover in the Arctic caused by climate change is affecting a wide variety of species – from polar bears to the smallest marine life. It has also made the polar region more accessible – to cruise operators, shipping companies and to the fossil fuel industry.

The Norwegian study says growing human activity in the Arctic is putting further pressure on the polar cod and other vulnerable species.

“Together, these factors mean we need a better understanding of the possible impacts on Arctic ecosystems, to provide a basis for sustainable management of the high north”, say the researchers. “We have excellent tools at our disposal in the shape of models that can help us to understand trends and long-time series of survey data.” − Climate News Network

A food source for many species spawns under the Arctic ice. Now fish breeding problems, caused by ice melt, threaten its future.

LONDON, 3 March, 2020 − It’s relatively small, not particularly well-known, but it’s a key indicator of global warming, which is putting some fish breeding rates at risk: enter the polar cod (Boreogadus saida), the smaller cousin of the more familiar north-east Arctic cod.

A recent study by researchers at the Institute of Marine Research (IMR) in Norway has found that declines in winter sea ice cover in the Barents Sea region of the Arctic, plus warmer sea temperatures, are causing declines in polar cod reproduction rates.

This has grave implications − not just for future stocks of polar cod, but for the survival of many other Arctic species as well. The polar cod is a vital part of the Arctic food chain. After spawning under the ice in the early months of the year, the fish – feeding on a diet of zooplankton − grows quickly. It then becomes a food for other larger fish and for sea birds, seals and whales.

“Unfortunately, climate projections suggest that the Barents Sea will become warmer and virtually ice-free as early as in 2030”, says Mats Huserbråten, one of the study’s authors. “The outlook for this cornerstone of the Arctic food chain is therefore bad.”

End of breeding

If trends in ice reduction and the heating of Arctic waters continue, the reproductive cycle of the polar cod could collapse, say the researchers.

The fish is endemic to the polar regions (found nowhere else) and has developed in ways which make it dependent on the presence of ice. Its eggs are spawned under the ice, where they grow, even in sub-freezing temperatures. The larvae then feed on the zooplankton − plentiful in mid-year, when the annual ice melt occurs.

Winter ice cover in the Arctic has been in decline since the 1970s, with a sizeable part of the reduction happening in the Barents Sea.

The polar cod stock there has been monitored annually by a joint Norwegian-Russian survey since 1986. In the IMR study, researchers found that not only were stocks diminishing, but that what are described as spawning assemblages of the polar cod were moving further north.

“Climate projections suggest that the Barents Sea will become warmer and virtually ice-free as early as in 2030. The outlook for this cornerstone of the Arctic food chain is therefore bad”

As climate change warms the planet’s oceans, many fish species have been observed moving away from the equator in search of cooler waters. While such fish movements have resulted in bigger catches in some areas, fish stocks in many more southern regions are in sharp decline.

The reduction in winter ice cover in the Arctic caused by climate change is affecting a wide variety of species – from polar bears to the smallest marine life. It has also made the polar region more accessible – to cruise operators, shipping companies and to the fossil fuel industry.

The Norwegian study says growing human activity in the Arctic is putting further pressure on the polar cod and other vulnerable species.

“Together, these factors mean we need a better understanding of the possible impacts on Arctic ecosystems, to provide a basis for sustainable management of the high north”, say the researchers. “We have excellent tools at our disposal in the shape of models that can help us to understand trends and long-time series of survey data.” − Climate News Network

Food security at risk as web of life unravels

Biodiversity, the web of life, is on the decline. That includes the natural ecosystems that directly and indirectly manage the catering for humanity’s supper table.

LONDON, 1 March, 2019 – The biggest agricultural authority in the world has warned that the web of life is coming apart as the loss of biodiversity increases.

The Food and Agriculture Organisation (FAO) of the United Nations says the wholesale destruction and degradation of natural ecosystems puts human food security at risk, and adds a warning that the same loss could also seriously affect human health and livelihoods.

Although conservationists and biologists have been warning for decades of the increasing threat of mass extinction of species, the FAO study focuses on what its authors call “associated biodiversity for food and agriculture” – that is the networks or ecosystems of living things that underwrite all human food, livestock feed, fuel and fibre, as well as many human medicines.

These ecosystems include all plants, animals and microorganisms – insects, bats, birds, fungi, bacteria, earthworms, mangroves, corals, seagrasses and so on – that create soil fertility, pollinate plants, purify air and water, feed and protect fish, and fight crop and livestock pests and diseases.

Fish in jeopardy

And entirely independently, a team of French scientists has modelled marine biological systems on which humanity’s annual 80 million metric ton haul of fish depends, and warned that climate change could be about to trigger what they call “unprecedented biological shifts” in the world’s oceans.

In a new, 576-page report the FAO concerns itself not just with the remorseless loss everywhere of the natural wilderness and the biological variety fine-tuned by three billion years of evolution, but also with the wild ancestors of crop plants and the myriad breeds, strains and variants selected and bred by generations of farmers and pastoralists during the past 10,000 years of settled agriculture.

There are more than 250,000 flowering plants. Around 6,000 are cultivated for food, but most of the global diet is based on fewer than 200 species, and 66% of all crop production is delivered by just nine crop plants.

All of them are dependent directly and indirectly on associated biodiversity. “Less biodiversity means that plants and animals are more vulnerable to pests and diseases. Compounded by our reliance on fewer and fewer species to feed ourselves, the increasing loss of biodiversity for food and agriculture puts food security and nutrition at risk,” said José Graziano da Silva, director-general of FAO.

Wild food problems

The FAO authors base their study on data from 91 of the 178 countries represented in the organisation. They find that 40 animal species comprise the world’s livestock, but the vast majority of meat, milk and eggs come from just a few species. The global count of breeds of livestock is put at 7,745. Of this huge variety, 26% are at risk of extinction.

Wild foods too – fruits, bulbs, tubers, grains, nuts, kernels, saps and gums, honey and insects and snails – matter hugely to many people in developing countries, but many of these report that 24% of the 4,000 species that provide wild food are in decline.

An estimated 87.5% of all flowering plants are pollinated by animals. Crops pollinated at least partially by animals – bees, but also other insects, birds and bats – account for 35% of all global food but for more than 90% of available vitamin C and more than 70% of available vitamin A.

But the researchers also focus on other services provided by natural ecosystems. Coral reefs, seagrass meadows and kelp forests provide nursery space and food sources for fish, but they also protect coastal communities against floods and storms.

“The increasing loss of biodiversity for food and agriculture puts food security and nutrition at risk”

Wetlands, forests and grassland regulate water flow. Grazing animals reduce the risk of grassland and woodland fire, but overgrazing is a major driver of soil erosion and soil compactions.

The report is a sharp reminder of human dependence on evolution’s generosity, but the warnings about biodiversity loss are hardly new. Researchers have repeatedly warned that the global warming driven by human exploitation of fossil fuels will accelerate the loss of wild things and that once-familiar species are vanishing from many habitats.

Others have already identified the danger of losing the wild ancestors of many crops that could in turn be harmed by climate change, and German scientists warned in 2017 of catastrophic falls in insect populations.

The impact of ever higher carbon dioxide ratios is predicted to harm the kelp forests that provide shelter for many commercial fish species., and warming itself can only impoverish ocean habitats.

Kind of war game

And support for this comes in the journal Nature Climate Change from a team of French researchers with colleagues from other European nations, the US and Japan.

Because monitoring of ocean biological systems is constrained in scale and fragmented in approach, the researchers turned to computer simulation: they designed a large number of pseudo-species of marine creatures, from zooplankton to fish, in 14 eco-regions, all with a range of responses to natural temperature variations, and then conducted a kind of war game of climate change in which local ocean temperature regimes change as the planet warms.

And they warn the world to expect what they call “abrupt community shifts” that could end in long-term change in the global catch, as well as in fish farms and even the ocean’s role in the carbon cycle.

They also point to a recent rise in the number of “climate surprises” that could be attributed to natural ocean warming events such as El Niño, as well as temperature shifts in the Atlantic and Pacific Oceans, and the warming of the Arctic Ocean. – Climate News Network

Biodiversity, the web of life, is on the decline. That includes the natural ecosystems that directly and indirectly manage the catering for humanity’s supper table.

LONDON, 1 March, 2019 – The biggest agricultural authority in the world has warned that the web of life is coming apart as the loss of biodiversity increases.

The Food and Agriculture Organisation (FAO) of the United Nations says the wholesale destruction and degradation of natural ecosystems puts human food security at risk, and adds a warning that the same loss could also seriously affect human health and livelihoods.

Although conservationists and biologists have been warning for decades of the increasing threat of mass extinction of species, the FAO study focuses on what its authors call “associated biodiversity for food and agriculture” – that is the networks or ecosystems of living things that underwrite all human food, livestock feed, fuel and fibre, as well as many human medicines.

These ecosystems include all plants, animals and microorganisms – insects, bats, birds, fungi, bacteria, earthworms, mangroves, corals, seagrasses and so on – that create soil fertility, pollinate plants, purify air and water, feed and protect fish, and fight crop and livestock pests and diseases.

Fish in jeopardy

And entirely independently, a team of French scientists has modelled marine biological systems on which humanity’s annual 80 million metric ton haul of fish depends, and warned that climate change could be about to trigger what they call “unprecedented biological shifts” in the world’s oceans.

In a new, 576-page report the FAO concerns itself not just with the remorseless loss everywhere of the natural wilderness and the biological variety fine-tuned by three billion years of evolution, but also with the wild ancestors of crop plants and the myriad breeds, strains and variants selected and bred by generations of farmers and pastoralists during the past 10,000 years of settled agriculture.

There are more than 250,000 flowering plants. Around 6,000 are cultivated for food, but most of the global diet is based on fewer than 200 species, and 66% of all crop production is delivered by just nine crop plants.

All of them are dependent directly and indirectly on associated biodiversity. “Less biodiversity means that plants and animals are more vulnerable to pests and diseases. Compounded by our reliance on fewer and fewer species to feed ourselves, the increasing loss of biodiversity for food and agriculture puts food security and nutrition at risk,” said José Graziano da Silva, director-general of FAO.

Wild food problems

The FAO authors base their study on data from 91 of the 178 countries represented in the organisation. They find that 40 animal species comprise the world’s livestock, but the vast majority of meat, milk and eggs come from just a few species. The global count of breeds of livestock is put at 7,745. Of this huge variety, 26% are at risk of extinction.

Wild foods too – fruits, bulbs, tubers, grains, nuts, kernels, saps and gums, honey and insects and snails – matter hugely to many people in developing countries, but many of these report that 24% of the 4,000 species that provide wild food are in decline.

An estimated 87.5% of all flowering plants are pollinated by animals. Crops pollinated at least partially by animals – bees, but also other insects, birds and bats – account for 35% of all global food but for more than 90% of available vitamin C and more than 70% of available vitamin A.

But the researchers also focus on other services provided by natural ecosystems. Coral reefs, seagrass meadows and kelp forests provide nursery space and food sources for fish, but they also protect coastal communities against floods and storms.

“The increasing loss of biodiversity for food and agriculture puts food security and nutrition at risk”

Wetlands, forests and grassland regulate water flow. Grazing animals reduce the risk of grassland and woodland fire, but overgrazing is a major driver of soil erosion and soil compactions.

The report is a sharp reminder of human dependence on evolution’s generosity, but the warnings about biodiversity loss are hardly new. Researchers have repeatedly warned that the global warming driven by human exploitation of fossil fuels will accelerate the loss of wild things and that once-familiar species are vanishing from many habitats.

Others have already identified the danger of losing the wild ancestors of many crops that could in turn be harmed by climate change, and German scientists warned in 2017 of catastrophic falls in insect populations.

The impact of ever higher carbon dioxide ratios is predicted to harm the kelp forests that provide shelter for many commercial fish species., and warming itself can only impoverish ocean habitats.

Kind of war game

And support for this comes in the journal Nature Climate Change from a team of French researchers with colleagues from other European nations, the US and Japan.

Because monitoring of ocean biological systems is constrained in scale and fragmented in approach, the researchers turned to computer simulation: they designed a large number of pseudo-species of marine creatures, from zooplankton to fish, in 14 eco-regions, all with a range of responses to natural temperature variations, and then conducted a kind of war game of climate change in which local ocean temperature regimes change as the planet warms.

And they warn the world to expect what they call “abrupt community shifts” that could end in long-term change in the global catch, as well as in fish farms and even the ocean’s role in the carbon cycle.

They also point to a recent rise in the number of “climate surprises” that could be attributed to natural ocean warming events such as El Niño, as well as temperature shifts in the Atlantic and Pacific Oceans, and the warming of the Arctic Ocean. – Climate News Network

Acid oceans harm more species

FOR IMMEDIATE RELEASE As climate change warms the world’s oceans, they are becoming more acidic. Researchers in Europe and the US have found the rising acidity is bad news for several species. LONDON, 3 December – The chemistry of the oceans is changing. And it isn’t just the corals and the baby oysters that are unhappy. It makes juvenile rockfish really anxious, and it upsets the digestion of sea urchins. The pH (a measure of acidity – the lower the pH, the more acid the water) of the planet’s oceans is dropping rapidly, largely because the carbon dioxide levels in the atmosphere are increasing. Since carbon dioxide dissolves in water to form carbonic acid, the seas are responding to global change. The first and clearest victims are likely to be the corals, which are adapted to a specific value of pH in the oceans, but there have also been problems reported by oyster farmers. Now Martin Tresguerres of the University of California, San Diego reports in the Proceedings of the Royal Society B that at least one species of juvenile fish responds badly to the changes in ocean chemistry. There is a natural aspect to ocean acidification – submarine volcanoes discharge carbon dioxide and turn the deep seas around them to a kind of fizzing champagne, and upwelling ocean currents can occasionally deliver a stressful level of lower pH sea water to blight fishing waters. But Tresguerres reports that he and colleagues subjected young Californian rockfish to the kind of water chemistry predicted as atmospheric carbon levels rise, and then measured their behaviour in response to changes of light in the aquarium, and to an unfamiliar object in the tank.

Stomach problems

What the researchers found was that the lower pH had a pronounced effect on one of the fish neuroreceptors linked to anxiety, and this effect lasted for at least seven days after the little creatures were returned to normal sea water. The change was not permanent: normal responses seemed to return after 12 days. Meanwhile, across the Atlantic, Meike Stumpp of the University of Gothenburg in Sweden has been looking at how sea urchin larvae respond to altered pH in the seas. She and colleagues report in Nature Climate Change that they too tweaked the seawater chemistry, to discover that digestion took longer and was less effective, a bit of a problem for any young creature – especially one hardly a fifth of a millimeter in length – in the competitive world of the oceans. “My measurements demonstrated a very strong pH dependency”, she said. “The enzymes in the sea urchins’ stomachs are optimised to function at very high pH – which is different from the situation in mammals, where stomach pH is acidic and enzymes work best at low pH.” The implications are that as pH levels fall, life will become a great deal more problematic for at least some key marine species. And the likelihood of change is increasing. Scientists of the International Geosphere-Biosphere Programme  recently allotted a “very high” confidence level to a set of simple findings. One was that humans were indeed making the seas more acidic, another was that the capacity of the oceans to absorb carbon dioxide would fall with increasing acidity, and a third was that the impact of this change in water chemistry would be felt for centuries. They also had “high confidence” that cold water corals and mollusc communities would be affected. – Climate News Network

FOR IMMEDIATE RELEASE As climate change warms the world’s oceans, they are becoming more acidic. Researchers in Europe and the US have found the rising acidity is bad news for several species. LONDON, 3 December – The chemistry of the oceans is changing. And it isn’t just the corals and the baby oysters that are unhappy. It makes juvenile rockfish really anxious, and it upsets the digestion of sea urchins. The pH (a measure of acidity – the lower the pH, the more acid the water) of the planet’s oceans is dropping rapidly, largely because the carbon dioxide levels in the atmosphere are increasing. Since carbon dioxide dissolves in water to form carbonic acid, the seas are responding to global change. The first and clearest victims are likely to be the corals, which are adapted to a specific value of pH in the oceans, but there have also been problems reported by oyster farmers. Now Martin Tresguerres of the University of California, San Diego reports in the Proceedings of the Royal Society B that at least one species of juvenile fish responds badly to the changes in ocean chemistry. There is a natural aspect to ocean acidification – submarine volcanoes discharge carbon dioxide and turn the deep seas around them to a kind of fizzing champagne, and upwelling ocean currents can occasionally deliver a stressful level of lower pH sea water to blight fishing waters. But Tresguerres reports that he and colleagues subjected young Californian rockfish to the kind of water chemistry predicted as atmospheric carbon levels rise, and then measured their behaviour in response to changes of light in the aquarium, and to an unfamiliar object in the tank.

Stomach problems

What the researchers found was that the lower pH had a pronounced effect on one of the fish neuroreceptors linked to anxiety, and this effect lasted for at least seven days after the little creatures were returned to normal sea water. The change was not permanent: normal responses seemed to return after 12 days. Meanwhile, across the Atlantic, Meike Stumpp of the University of Gothenburg in Sweden has been looking at how sea urchin larvae respond to altered pH in the seas. She and colleagues report in Nature Climate Change that they too tweaked the seawater chemistry, to discover that digestion took longer and was less effective, a bit of a problem for any young creature – especially one hardly a fifth of a millimeter in length – in the competitive world of the oceans. “My measurements demonstrated a very strong pH dependency”, she said. “The enzymes in the sea urchins’ stomachs are optimised to function at very high pH – which is different from the situation in mammals, where stomach pH is acidic and enzymes work best at low pH.” The implications are that as pH levels fall, life will become a great deal more problematic for at least some key marine species. And the likelihood of change is increasing. Scientists of the International Geosphere-Biosphere Programme  recently allotted a “very high” confidence level to a set of simple findings. One was that humans were indeed making the seas more acidic, another was that the capacity of the oceans to absorb carbon dioxide would fall with increasing acidity, and a third was that the impact of this change in water chemistry would be felt for centuries. They also had “high confidence” that cold water corals and mollusc communities would be affected. – Climate News Network

UK waters grow cooler – and more acid

EMBARGOED until 0001 GMT on Thursday 28 November A comprehensive report on the state of the seas around the United Kingdom says ocean acidification is probably increasing faster than for the last 300 million years. LONDON, 28 November – Dipping your toes in the waters around Britain has grown marginally less inviting: in the last few years the seas have grown slightly colder. Against the background of a continued warming trend, this blip is explained by scientists as an example of the climate’s tendency sometimes to go “off trend”, and to show clear variations from the norm. UK researchers say the average UK coastal sea surface temperature in the last decade was lower in 2008-2012 than in 2003-2007, an example of short-term variability which they say is at odds with temperature records which “continue to show an overall upward trend“. The finding – perhaps not surprising, given the slower pace of atmospheric warming in recent years – is reported by the Marine Climate Change Impacts Partnership (MCCIP) and is published in its latest Report Card, which assesses how climate change is affecting UK waters. MCCIP, launched in 2005, is a partnership between scientists, the UK Government and its agencies, non-governmental organisations and industry.

Local consequences

For the first time the report looks at Arctic sea-ice coverage, and agrees that a long-term decline is clearly apparent, with sea-ice extent retreating and the ice becoming thinner as temperatures rise. It says the overall warming trend of recent decades is expected to continue. It emphasises the importance of local-scale impacts, describing the movement of fish species and how non-native species are expanding their range. It says: “International commercial landings from the north-east Atlantic of species identified as warm-adapted (e.g. grey gurnard, red mullet, hake) have increased 250% in the last 30 years, while landings of cold-adapted species (e.g. cod, haddock, whiting) have halved.” The report also identifies a possible trend to smaller fish: “”Evidence is emerging that fish body-size is affected by climate change. For example, warm, lower-oxygen conditions favour smaller individuals, and by 2050 the average fish weight could be reduced by 14-24%.

Accelerating acidity

“However, there are multiple drivers of changes in size distributions including the known effects of fishing.” One cause of change the report identifies with high confidence is growing ocean acidification. It says: “The current rate of increase in acidity… is probably more rapid now than any time in the last 300 million years.” The researchers say changes to primary fish production are expected throughout the UK, with southern regions (for instance the Celtic Sea and English Channel) becoming up to 10% more productive and northern regions (like the central and northern North Sea) up to 20% less so. But they acknowledge “some challenges” in identifying the impacts of climate change. These challenges are caused by difficulties in distinguishing both between short-term variability and long-term trends, and between climate influences and other pressures. Over 150 scientists from 55 UK science organisations contributed to the report, which covers a range of 30 marine and coastal topics. The detailed peer-reviewed briefings on all the topics covered in the summary series are available online.  The 2013 Report Card and the 33 topic reports will be available online shortly after publication. – Climate News Network

EMBARGOED until 0001 GMT on Thursday 28 November A comprehensive report on the state of the seas around the United Kingdom says ocean acidification is probably increasing faster than for the last 300 million years. LONDON, 28 November – Dipping your toes in the waters around Britain has grown marginally less inviting: in the last few years the seas have grown slightly colder. Against the background of a continued warming trend, this blip is explained by scientists as an example of the climate’s tendency sometimes to go “off trend”, and to show clear variations from the norm. UK researchers say the average UK coastal sea surface temperature in the last decade was lower in 2008-2012 than in 2003-2007, an example of short-term variability which they say is at odds with temperature records which “continue to show an overall upward trend“. The finding – perhaps not surprising, given the slower pace of atmospheric warming in recent years – is reported by the Marine Climate Change Impacts Partnership (MCCIP) and is published in its latest Report Card, which assesses how climate change is affecting UK waters. MCCIP, launched in 2005, is a partnership between scientists, the UK Government and its agencies, non-governmental organisations and industry.

Local consequences

For the first time the report looks at Arctic sea-ice coverage, and agrees that a long-term decline is clearly apparent, with sea-ice extent retreating and the ice becoming thinner as temperatures rise. It says the overall warming trend of recent decades is expected to continue. It emphasises the importance of local-scale impacts, describing the movement of fish species and how non-native species are expanding their range. It says: “International commercial landings from the north-east Atlantic of species identified as warm-adapted (e.g. grey gurnard, red mullet, hake) have increased 250% in the last 30 years, while landings of cold-adapted species (e.g. cod, haddock, whiting) have halved.” The report also identifies a possible trend to smaller fish: “”Evidence is emerging that fish body-size is affected by climate change. For example, warm, lower-oxygen conditions favour smaller individuals, and by 2050 the average fish weight could be reduced by 14-24%.

Accelerating acidity

“However, there are multiple drivers of changes in size distributions including the known effects of fishing.” One cause of change the report identifies with high confidence is growing ocean acidification. It says: “The current rate of increase in acidity… is probably more rapid now than any time in the last 300 million years.” The researchers say changes to primary fish production are expected throughout the UK, with southern regions (for instance the Celtic Sea and English Channel) becoming up to 10% more productive and northern regions (like the central and northern North Sea) up to 20% less so. But they acknowledge “some challenges” in identifying the impacts of climate change. These challenges are caused by difficulties in distinguishing both between short-term variability and long-term trends, and between climate influences and other pressures. Over 150 scientists from 55 UK science organisations contributed to the report, which covers a range of 30 marine and coastal topics. The detailed peer-reviewed briefings on all the topics covered in the summary series are available online.  The 2013 Report Card and the 33 topic reports will be available online shortly after publication. – Climate News Network

Salmon and hydropower can both thrive

FOR IMMEDIATE RELEASE Scientists produce handbook that shows how better river management can mean more breeding success for migratory fish and more electricity from a vital source of renewable energy LONDON, 13 October – Hydropower can dramatically alter rivers and destroy the habitat of migratory species such as salmon, but now scientists have shown that it is perfectly possible for rivers to produce more fish and more electricity at the same time. After years of experience with hydro schemes in their own country, Norwegian scientists have produced a handbook to assist river engineers and to explain how to protect vulnerable species while exploiting rivers for renewable energy. The Centre for Environmental Design of Renewable Energy (CEDREN) believes that by understanding the needs of migratory fish and controlling the flow of the river to accommodate their lifestyle, the breeding success can be improved. At the same time, by adapting and improving the turbine capacity and making it more flexible, more energy can be produced. While the handbook is based on experience in Norway, the same principles can be applied to many rivers in mountainous areas that have salmon or other migratory fish. Some of the ideas might also apply to fast-flowing rivers in places such as the Himalayas, the European Alps, the Rockies in North America, and the Andes in South America. There is resistance in many of these places to hydropower because it can cause drastic alteration to natural rivers and destroy their wildlife. As a result, there is still a large untapped potential for hydropower schemes in some regions.

Cheap and reliable

The handbook is intended as a blueprint to help engineers and environmentalists to work together to improve the habitat for wildlife, while extracting much-needed electricity from water power to help combat climate change. Hydropower is one of the cheapest and most reliable of renewables. As far as salmon rivers are concerned, the handbook says the first task is to identify current problems that limit salmon production in rivers. These include lack of spawning grounds or shelter, low water periods, or periods of disadvantageous water temperature. Looking at the existing or potential hydropower, engineers need to work out operating strategies for the power stations to avoid interfering with the salmon. These could include ideas such as transferring water from neighbouring rivers to improve flow at critical times, and increasing the capacity of turbines and waterways to make operation more flexible. How the available water in the river is used is critical. Water flow to ensure environmental quality and water releases at different times of the year need to be closely regulated. To achieve this, a flexible “water bank” will be required to ensure a good supply of water when needed. There also needs to be a smooth transition between high and low water flows, with some water being saved for critical periods. Physical measures in the river might be needed, such as creating favourable gravel for spawning, restoring rapids and pool sequences in the river, creating shelter in the river bed as hiding-places for fish, and removing fine sediment that inhibits spawning. Atle Harby, a senior research scientist, said that the new handbook – a world first of its type – can counter the current belief held by many that salmon inevitably suffer as a result of electric power generation in regulated rivers. Harby heads the CEDREN research centre – one of Norway’s “national teams” in environmentally-friendly energy, and which is manned by scientists from SINTEF Energy Research, the Norwegian University of Science and Technology (NTNU) and the Norwegian Institute for Nature Research (NINA).

No contradiction

He said: “Increased hydropower generation and larger salmon stocks are not necessarily a contradiction in terms. We can use new knowledge and new methods to increase salmon production without compromising power production in many of the regulated rivers. And this can be done using measures that don’t necessarily require major investments. “It won’t be possible everywhere, and in some rivers we have still to choose between salmon and power. But it is quite possible in many important salmon rivers to produce more salmon while maintaining existing power generation. We believe that our conclusions will be valid for a good number of important highly-regulated rivers. “We hope that the handbook will be used to identify what will be possible in each individual river.” Torbjørn Forseth, a senior scientist at NINA, said that salmon is an important indicator species in rivers. If salmon are doing well, and reproduce and thrive as they should, then other aspects of the river’s ecological system are also probably functioning well. Many of the handbook’s recommendations do not cost money. Much can be achieved by concentrating releases of water down the river during periods that are important for the salmon’s living conditions. Water temperature, riverbed structures and habitat conditions are important for the salmon and vary from year to year, but can be monitored and improved by river management. Forseth added that while transfer of water from neighbouring rivers can be costly, it is another possible option to ensure that hydropower companies and salmon have more water to share. – Climate News Network.

FOR IMMEDIATE RELEASE Scientists produce handbook that shows how better river management can mean more breeding success for migratory fish and more electricity from a vital source of renewable energy LONDON, 13 October – Hydropower can dramatically alter rivers and destroy the habitat of migratory species such as salmon, but now scientists have shown that it is perfectly possible for rivers to produce more fish and more electricity at the same time. After years of experience with hydro schemes in their own country, Norwegian scientists have produced a handbook to assist river engineers and to explain how to protect vulnerable species while exploiting rivers for renewable energy. The Centre for Environmental Design of Renewable Energy (CEDREN) believes that by understanding the needs of migratory fish and controlling the flow of the river to accommodate their lifestyle, the breeding success can be improved. At the same time, by adapting and improving the turbine capacity and making it more flexible, more energy can be produced. While the handbook is based on experience in Norway, the same principles can be applied to many rivers in mountainous areas that have salmon or other migratory fish. Some of the ideas might also apply to fast-flowing rivers in places such as the Himalayas, the European Alps, the Rockies in North America, and the Andes in South America. There is resistance in many of these places to hydropower because it can cause drastic alteration to natural rivers and destroy their wildlife. As a result, there is still a large untapped potential for hydropower schemes in some regions.

Cheap and reliable

The handbook is intended as a blueprint to help engineers and environmentalists to work together to improve the habitat for wildlife, while extracting much-needed electricity from water power to help combat climate change. Hydropower is one of the cheapest and most reliable of renewables. As far as salmon rivers are concerned, the handbook says the first task is to identify current problems that limit salmon production in rivers. These include lack of spawning grounds or shelter, low water periods, or periods of disadvantageous water temperature. Looking at the existing or potential hydropower, engineers need to work out operating strategies for the power stations to avoid interfering with the salmon. These could include ideas such as transferring water from neighbouring rivers to improve flow at critical times, and increasing the capacity of turbines and waterways to make operation more flexible. How the available water in the river is used is critical. Water flow to ensure environmental quality and water releases at different times of the year need to be closely regulated. To achieve this, a flexible “water bank” will be required to ensure a good supply of water when needed. There also needs to be a smooth transition between high and low water flows, with some water being saved for critical periods. Physical measures in the river might be needed, such as creating favourable gravel for spawning, restoring rapids and pool sequences in the river, creating shelter in the river bed as hiding-places for fish, and removing fine sediment that inhibits spawning. Atle Harby, a senior research scientist, said that the new handbook – a world first of its type – can counter the current belief held by many that salmon inevitably suffer as a result of electric power generation in regulated rivers. Harby heads the CEDREN research centre – one of Norway’s “national teams” in environmentally-friendly energy, and which is manned by scientists from SINTEF Energy Research, the Norwegian University of Science and Technology (NTNU) and the Norwegian Institute for Nature Research (NINA).

No contradiction

He said: “Increased hydropower generation and larger salmon stocks are not necessarily a contradiction in terms. We can use new knowledge and new methods to increase salmon production without compromising power production in many of the regulated rivers. And this can be done using measures that don’t necessarily require major investments. “It won’t be possible everywhere, and in some rivers we have still to choose between salmon and power. But it is quite possible in many important salmon rivers to produce more salmon while maintaining existing power generation. We believe that our conclusions will be valid for a good number of important highly-regulated rivers. “We hope that the handbook will be used to identify what will be possible in each individual river.” Torbjørn Forseth, a senior scientist at NINA, said that salmon is an important indicator species in rivers. If salmon are doing well, and reproduce and thrive as they should, then other aspects of the river’s ecological system are also probably functioning well. Many of the handbook’s recommendations do not cost money. Much can be achieved by concentrating releases of water down the river during periods that are important for the salmon’s living conditions. Water temperature, riverbed structures and habitat conditions are important for the salmon and vary from year to year, but can be monitored and improved by river management. Forseth added that while transfer of water from neighbouring rivers can be costly, it is another possible option to ensure that hydropower companies and salmon have more water to share. – Climate News Network.

Warming bad for life in freshwater lakes and rivers

For immediate release On both sides of the Atlantic scientists studying lakes have discovered they are warming – and this is bad news both for water quality and the fish. London, 14 June – The Alpine lakes of Austria are warming up. By 2050, their surface waters could be up to 3°C warmer, according to new research in the journal Hydrobiologia. Martin Dokulil of the Institute for Limnology at the University of Innsbruck studied data from nine lakes larger than 10km2. The largest, Bodensee or Lake Constance, touches Austria’s border with Germany and Switzerland to the west; 800 kms to the east, Neusiedler See borders Germany and Hungary. The nine lakes range from 254 to 1.8 metres maximum depth and they are vital to Austria’s tourist industry: they play powerful roles in the Alpine ecosystem and they are of course reservoirs of water. But the Alpine valleys are warming: between 1980 and 1999 the region warmed at three times the global average and by 2050 the median temperatures for the region could have risen by 3.5°C. The challenge has been to anticipate the impact of global warming on the lakes. “The predicted changes in surface water temperatures will affect the thermal characteristics of the lakes,” says Dr Dokulil. “Warmer water temperatures could lead to enhanced nutrient loads and affect water quality by promoting algal blooms and impairing the biological functions of aquatic organisms. “Significant increases in summer temperatures will affect the carbon cycling in the lakes, with potential consequences on atmospheric carbon dioxide levels and the Earth’s climate.”  Next, the fish The Austrian research so far is concerned only with freshwater temperatures. Peter Moyle, a biologist at the University of California Davis, has been more concerned with the freshwater fish that make their homes in, or migrate to, California’s rivers and lakes. He and colleagues report in the journal PLOS One – the Public Library of Science – that if current climate trends continue, then 82 per cent of California’s native fish could be extinct, and their native homes colonized by invasive species. The scientists looked at 121 native species and found that four fifths of them were likely to be driven to extinction or at least to very low numbers. These include prized sporting fish such as the Klamath River summer steelhead and other trout, the Central Valley Chinook salmon, the Central Coast coho salmon and many others that depend on cold water. “These fish are part of the endemic flora and fauna that makes California such a special place,” said Prof Moyle. “As we lose these fishes, we lose their environments and are much poorer for it.” – Climate News Network        

For immediate release On both sides of the Atlantic scientists studying lakes have discovered they are warming – and this is bad news both for water quality and the fish. London, 14 June – The Alpine lakes of Austria are warming up. By 2050, their surface waters could be up to 3°C warmer, according to new research in the journal Hydrobiologia. Martin Dokulil of the Institute for Limnology at the University of Innsbruck studied data from nine lakes larger than 10km2. The largest, Bodensee or Lake Constance, touches Austria’s border with Germany and Switzerland to the west; 800 kms to the east, Neusiedler See borders Germany and Hungary. The nine lakes range from 254 to 1.8 metres maximum depth and they are vital to Austria’s tourist industry: they play powerful roles in the Alpine ecosystem and they are of course reservoirs of water. But the Alpine valleys are warming: between 1980 and 1999 the region warmed at three times the global average and by 2050 the median temperatures for the region could have risen by 3.5°C. The challenge has been to anticipate the impact of global warming on the lakes. “The predicted changes in surface water temperatures will affect the thermal characteristics of the lakes,” says Dr Dokulil. “Warmer water temperatures could lead to enhanced nutrient loads and affect water quality by promoting algal blooms and impairing the biological functions of aquatic organisms. “Significant increases in summer temperatures will affect the carbon cycling in the lakes, with potential consequences on atmospheric carbon dioxide levels and the Earth’s climate.”  Next, the fish The Austrian research so far is concerned only with freshwater temperatures. Peter Moyle, a biologist at the University of California Davis, has been more concerned with the freshwater fish that make their homes in, or migrate to, California’s rivers and lakes. He and colleagues report in the journal PLOS One – the Public Library of Science – that if current climate trends continue, then 82 per cent of California’s native fish could be extinct, and their native homes colonized by invasive species. The scientists looked at 121 native species and found that four fifths of them were likely to be driven to extinction or at least to very low numbers. These include prized sporting fish such as the Klamath River summer steelhead and other trout, the Central Valley Chinook salmon, the Central Coast coho salmon and many others that depend on cold water. “These fish are part of the endemic flora and fauna that makes California such a special place,” said Prof Moyle. “As we lose these fishes, we lose their environments and are much poorer for it.” – Climate News Network