Tag Archives: Plankton

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Desert dust feeds deep ocean life

US scientists have found that dust from the Sahara desert provides most of the iron found in the Atlantic ocean. LONDON, 14 July 2014 − Marine scientists have measured levels of iron dissolved in the Atlantic ocean, and at the same time worked out where it came from. In the course of doing so, they have helped explain in more detail why the deep ocean is blue while coastal waters are usually green, and at the same time helped answer more complex questions about the ocean’s role in the great carbon dioxide question. And in the course of settling these points, they have also answered questions about North Africa’s importance to the rest of the world. It keeps the oceans and the Amazon supplied with valuable dust. Tim Conway and Seth John of the University of South Carolina report in Nature that they devised a way to sample large volumes of seawater to identify the content of dissolved iron in the water, and then to distinguish the ratio between different isotopes of that iron. An isotope is a natural variant of an element, and often indicates a different source of origin. Iron is a vital trace element: without it, mammals cannot make haemoglobin to transport oxygen around the bloodstream and plants cannot make chlorophyll to photosynthesize tissue from air and sunlight.

Missing iron

The deep oceans have everything needed for plant growth – sunlight, carbon, nitrogen and water – but they don’t have iron. That is one reason why they tend to be blue while nutrient-rich coastal waters are green. Estuaries and deltas are rich in iron and other nutrients and good for algal growth. Because ocean phytoplankton (microscopic plants which sustain the marine food web) cannot get enough iron, there is a limit to the carbon dioxide they can absorb from the atmosphere. So iron is an element in the great carbon cycle. And it doesn’t need to be available in huge quantities. “I did a calculation once on a ton of sea water. The amount of iron in that ton of water would weigh about as much as a single eyelash,” says Dr John. “The key reason that everybody cares about iron is because it limits the growth of phytoplankton such as algae, in maybe a fifth of the ocean.” The researchers collected 600 samples of sea water during a cruise across the North Atlantic on a research ship, and set to work trying to identify the origin of the few billionths of a gram of iron in every litre of the water collected.

Saharan source

They found that a measurable proportion of oceanic iron seeped up from deep within the crust through hydrothermal vents along the mid-ocean ridge. A fraction came from sediments on the African coast, and more than 10% came from oxygenated muds on the American coast. But they also found that the answer had been blowing in the wind. Somewhere between 71% and 87% was delivered by dust storms from the Sahara desert.  That is, life in the deep ocean depended on an annual delivery of fertiliser from one of the world’s emptiest and most parched regions. The play between dust and life has fascinated scientists for more than a decade. In 2006, Israeli researchers found that more than half the dust needed to fertilise the Brazilian rainforest blew in from just one desiccated valley in Chad. Two years later a team in Liverpool in the UK confirmed the role of Saharan dust as a mineral source for the Atlantic ocean and in 2007 Swiss and German microbiologists analysed dust samples collected by Charles Darwin. They found that wind-blown dust could transport microbes from West Africa all the way to the Caribbean. An estimated 50 million tons of Saharan dust is blown across the Atlantic to the Amazon every year.

Explaining the past

So the South Carolina research is just another example of science in action; a painstaking increment to human knowledge rather than a breakthrough. It adds quantifiable figures to a picture already taking shape. It is a reminder that intercontinental migration is as old as life itself. And it also helps explain a little bit more about the global climate machine. Researchers have already theorised that airborne dust must play a role in cloud formation – and therefore in rainfall and drought – and even that dust storms may play a role in damping down hurricanes. If more dust in the oceans and the forests means more carbon uptake from the atmosphere, then cycles of superstorms of dust could also help tweak the global thermostat. “It could help us understand past climate change, like glacial-interglacial cycles,” Dr John says. “There would have been huge changes in dust fluxes to the ocean in glacial times, and so understanding how much iron comes from dust in the modern day helps us figure out whether that was an important driver of glacial-interglacial cycles.” – Climate News Network

US scientists have found that dust from the Sahara desert provides most of the iron found in the Atlantic ocean. LONDON, 14 July 2014 − Marine scientists have measured levels of iron dissolved in the Atlantic ocean, and at the same time worked out where it came from. In the course of doing so, they have helped explain in more detail why the deep ocean is blue while coastal waters are usually green, and at the same time helped answer more complex questions about the ocean’s role in the great carbon dioxide question. And in the course of settling these points, they have also answered questions about North Africa’s importance to the rest of the world. It keeps the oceans and the Amazon supplied with valuable dust. Tim Conway and Seth John of the University of South Carolina report in Nature that they devised a way to sample large volumes of seawater to identify the content of dissolved iron in the water, and then to distinguish the ratio between different isotopes of that iron. An isotope is a natural variant of an element, and often indicates a different source of origin. Iron is a vital trace element: without it, mammals cannot make haemoglobin to transport oxygen around the bloodstream and plants cannot make chlorophyll to photosynthesize tissue from air and sunlight.

Missing iron

The deep oceans have everything needed for plant growth – sunlight, carbon, nitrogen and water – but they don’t have iron. That is one reason why they tend to be blue while nutrient-rich coastal waters are green. Estuaries and deltas are rich in iron and other nutrients and good for algal growth. Because ocean phytoplankton (microscopic plants which sustain the marine food web) cannot get enough iron, there is a limit to the carbon dioxide they can absorb from the atmosphere. So iron is an element in the great carbon cycle. And it doesn’t need to be available in huge quantities. “I did a calculation once on a ton of sea water. The amount of iron in that ton of water would weigh about as much as a single eyelash,” says Dr John. “The key reason that everybody cares about iron is because it limits the growth of phytoplankton such as algae, in maybe a fifth of the ocean.” The researchers collected 600 samples of sea water during a cruise across the North Atlantic on a research ship, and set to work trying to identify the origin of the few billionths of a gram of iron in every litre of the water collected.

Saharan source

They found that a measurable proportion of oceanic iron seeped up from deep within the crust through hydrothermal vents along the mid-ocean ridge. A fraction came from sediments on the African coast, and more than 10% came from oxygenated muds on the American coast. But they also found that the answer had been blowing in the wind. Somewhere between 71% and 87% was delivered by dust storms from the Sahara desert.  That is, life in the deep ocean depended on an annual delivery of fertiliser from one of the world’s emptiest and most parched regions. The play between dust and life has fascinated scientists for more than a decade. In 2006, Israeli researchers found that more than half the dust needed to fertilise the Brazilian rainforest blew in from just one desiccated valley in Chad. Two years later a team in Liverpool in the UK confirmed the role of Saharan dust as a mineral source for the Atlantic ocean and in 2007 Swiss and German microbiologists analysed dust samples collected by Charles Darwin. They found that wind-blown dust could transport microbes from West Africa all the way to the Caribbean. An estimated 50 million tons of Saharan dust is blown across the Atlantic to the Amazon every year.

Explaining the past

So the South Carolina research is just another example of science in action; a painstaking increment to human knowledge rather than a breakthrough. It adds quantifiable figures to a picture already taking shape. It is a reminder that intercontinental migration is as old as life itself. And it also helps explain a little bit more about the global climate machine. Researchers have already theorised that airborne dust must play a role in cloud formation – and therefore in rainfall and drought – and even that dust storms may play a role in damping down hurricanes. If more dust in the oceans and the forests means more carbon uptake from the atmosphere, then cycles of superstorms of dust could also help tweak the global thermostat. “It could help us understand past climate change, like glacial-interglacial cycles,” Dr John says. “There would have been huge changes in dust fluxes to the ocean in glacial times, and so understanding how much iron comes from dust in the modern day helps us figure out whether that was an important driver of glacial-interglacial cycles.” – Climate News Network

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How nature affects the carbon cycle

FOR IMMEDIATE RELEASE In Australia and the Arctic, scientists say, they have found unexpected ways in which natural processes are helping to compensate for global warming. LONDON, 1 June – The great drylands of the planet – and they cover almost half of the terrestrial surface – may be bigger players in the carbon cycle than anyone had suspected. The world’s semi-arid regions may absorb huge volumes of carbon dioxide from the atmosphere whenever it rains enough. Benjamin Poulter of Montana State University and colleagues report in Nature that they used a mix of computer-driven accounting methods to work out where the carbon goes after fossil fuel burning emits extra carbon dioxide into the atmosphere. Decades of meticulous measurement confirm that, overall, carbon dioxide levels are increasing inexorably, and the world is warming accordingly. But inside this big picture is a lot of seasonal and inter-annual variation. So climate scientists, when they try to work out what all this means for future climates, need to understand the carbon cycle better. The assumption has always been that the most important terrestrial consumers of carbon dioxide were the tropical rainforests. But the match of terrestrial biogeochemical and atmospheric carbon dioxide and global carbon budget accounting models by 13 scientists from the US, Europe and Australia has revealed a different story. In 2011 more than half of the terrestrial world’s carbon uptake was in the southern hemisphere – which is unexpected because most of the planet’s land surface is in the northern hemisphere – and 60% of this was in Australia.

Natural brake

That is, after a procession of unusually rainy years, and catastrophic flooding, the vegetation burst forth and the normally empty arid centre of Australia bloomed. Vegetation cover expanded by 6%. Human activity now puts 10 billion tonnes of carbon into the atmosphere annually, and vegetation in 2011 mopped up 4.1 billion tonnes of that, mostly in Australia. There remains a great deal of uncertainty about the carbon cycle and how the soils and the trees manage the extra carbon. Nobody knows what will happen to this extra carbon now in the hot dry landscapes of Australia: will it be tucked away in the soil? Will it be returned to the atmosphere by subsequent bushfires? As scientists are fond of saying, more research is necessary. But this is an example of negative feedback: as carbon dioxide levels and temperatures rise, the green things respond, and slow the acceleration of both. This is quite different from the positive feedback that follows when Arctic ice – which reflects sunlight – melts and gives way to blue water which absorbs solar energy, thus accelerating the melting. But even the slow disaster of the polar regions could be accompanied by an ameliorating process. British researchers report in Nature Communications that the ice sheet meltwaters may be rich in iron. A boost of iron would stimulate phytoplankton growth, which means more carbon dioxide could accordingly be absorbed from the atmosphere.

Feeding the oceans

The scientists collected meltwater from a Greenland glacier in the summer of 2012, and then tested it to discover significant quantities of what geochemists call “bio-available” iron. So, in another example of those cycles of the elements that make the world go round, ice that scrapes over rock also delivers vital nutrients to the sea, for marine plants to take up yet more carbon dioxide and flourish more vigorously in the oceans and keep the planet a little cooler. The Greenland research gives scientists a chance to estimate more accurately the delivery of this dietary supplement to the oceans: they reckon somewhere between 400,000 and 2.5 million tonnes a year in Greenland and somewhere between 60,000 and 100,000 tonnes in Antarctica. Or, to put it more graphically, it would be like dropping 3,000 fully-laden Boeing 747s into the ocean each year. “The Greenland and Antarctic ice sheets cover around 10% of the global land surface,” said Jon Hawkings, of the University of Bristol, UK. “Our finding that there is also significant iron discharged in runoff from large ice sheet catchments is new. This means that relatively high concentrations are released from the ice sheet all summer, providing a continuous source of iron to the coastal ocean.” – Climate News Network

FOR IMMEDIATE RELEASE In Australia and the Arctic, scientists say, they have found unexpected ways in which natural processes are helping to compensate for global warming. LONDON, 1 June – The great drylands of the planet – and they cover almost half of the terrestrial surface – may be bigger players in the carbon cycle than anyone had suspected. The world’s semi-arid regions may absorb huge volumes of carbon dioxide from the atmosphere whenever it rains enough. Benjamin Poulter of Montana State University and colleagues report in Nature that they used a mix of computer-driven accounting methods to work out where the carbon goes after fossil fuel burning emits extra carbon dioxide into the atmosphere. Decades of meticulous measurement confirm that, overall, carbon dioxide levels are increasing inexorably, and the world is warming accordingly. But inside this big picture is a lot of seasonal and inter-annual variation. So climate scientists, when they try to work out what all this means for future climates, need to understand the carbon cycle better. The assumption has always been that the most important terrestrial consumers of carbon dioxide were the tropical rainforests. But the match of terrestrial biogeochemical and atmospheric carbon dioxide and global carbon budget accounting models by 13 scientists from the US, Europe and Australia has revealed a different story. In 2011 more than half of the terrestrial world’s carbon uptake was in the southern hemisphere – which is unexpected because most of the planet’s land surface is in the northern hemisphere – and 60% of this was in Australia.

Natural brake

That is, after a procession of unusually rainy years, and catastrophic flooding, the vegetation burst forth and the normally empty arid centre of Australia bloomed. Vegetation cover expanded by 6%. Human activity now puts 10 billion tonnes of carbon into the atmosphere annually, and vegetation in 2011 mopped up 4.1 billion tonnes of that, mostly in Australia. There remains a great deal of uncertainty about the carbon cycle and how the soils and the trees manage the extra carbon. Nobody knows what will happen to this extra carbon now in the hot dry landscapes of Australia: will it be tucked away in the soil? Will it be returned to the atmosphere by subsequent bushfires? As scientists are fond of saying, more research is necessary. But this is an example of negative feedback: as carbon dioxide levels and temperatures rise, the green things respond, and slow the acceleration of both. This is quite different from the positive feedback that follows when Arctic ice – which reflects sunlight – melts and gives way to blue water which absorbs solar energy, thus accelerating the melting. But even the slow disaster of the polar regions could be accompanied by an ameliorating process. British researchers report in Nature Communications that the ice sheet meltwaters may be rich in iron. A boost of iron would stimulate phytoplankton growth, which means more carbon dioxide could accordingly be absorbed from the atmosphere.

Feeding the oceans

The scientists collected meltwater from a Greenland glacier in the summer of 2012, and then tested it to discover significant quantities of what geochemists call “bio-available” iron. So, in another example of those cycles of the elements that make the world go round, ice that scrapes over rock also delivers vital nutrients to the sea, for marine plants to take up yet more carbon dioxide and flourish more vigorously in the oceans and keep the planet a little cooler. The Greenland research gives scientists a chance to estimate more accurately the delivery of this dietary supplement to the oceans: they reckon somewhere between 400,000 and 2.5 million tonnes a year in Greenland and somewhere between 60,000 and 100,000 tonnes in Antarctica. Or, to put it more graphically, it would be like dropping 3,000 fully-laden Boeing 747s into the ocean each year. “The Greenland and Antarctic ice sheets cover around 10% of the global land surface,” said Jon Hawkings, of the University of Bristol, UK. “Our finding that there is also significant iron discharged in runoff from large ice sheet catchments is new. This means that relatively high concentrations are released from the ice sheet all summer, providing a continuous source of iron to the coastal ocean.” – Climate News Network

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Plankton loss threatens marine food web

FOR IMMEDIATE RELEASE Researchers warn that marine life could be dramatically affected as climate change threatens to cause severe reduction of plankton – the key source of nutrients − in some ocean regions by the end of the century LONDON, 12 May − There are plenty more fish in the sea − but not for too much longer in some parts of the world, researchers say. And the reason is very simple: the food on which they all depend faces a marked decline. Researchers from AZTI-Tecnalia, a Spanish-based technology centre specialising in marine and food research, report in the journal Global Change Biology that the warming of the oceans will cause phytoplankton biomass to decrease by 6% by the end of this century. Phytoplankton are the single-celled plants that are the basic building blocks of most marine life. In particular, they sustain zooplankton − tiny animals that are eaten in turn by fish. The study found evidence that, by 2100, zooplankton biomass will be 11% less than it is today, with obvious implications for the fish that feed on them. The report says that sea surface temperature is predicted to increase by 2ºC on average globally by 2080-2100. The consequences of this increase will include changes in ocean circulation and higher water column stratification, where water of different densities forms distinct layers instead of mixing, affecting the availability of nutrients.

Biomass reduction

The depletion expected in the amount of plankton in the marine food web could reduce fish biomass in 47% of the total global ocean area, especially in tropical oceans. But phytoplankton and zooplankton reduction will affect different regions in different ways. In the North Sea and temperate north-east Atlantic, higher stratification and lower nutrient levels will reduce phytoplankton growth. In the Baltic, Barents and Black Seas, it is expected to increase. Guillem Chust, an Azti-Tecnalia researcher and the lead author of the paper, said: “In the ocean regions that lose more phytoplankton and zooplankton biomass, fish biomass may also decrease dramatically.” He said this would especially affect pelagic species − deep-sea fish that are not bottom dwellers. He said the oceans’ role in moderating climate change would also be damaged: “As there will be less phytoplankton, absorption of CO2 from the atmosphere by the oceans will be lower, as plankton is responsible for half of the planet’s photosynthetic activity. This in turn will reduce the ocean’s capacity to regulate the climate.” The research was undertaken as part of Marine Ecosystem Evolution in a Changing Environment (MEECE), a European Union project to explore the impact of climate and human activities on marine ecosystems. One of the project’s concerns is the growing evidence of damage from ocean acidification, the process by which emissions of carbon dioxide are making the seas increasingly acid and hostile to some forms of marine life.

Emission limits

A group which works to protect seafood supplies and marine ecosystems, Global Ocean Health, has welcomed a move by the US Environmental Protection Agency  intended to lead to the introduction of performance-based emission limits for new power plants, which would help to reduce the threat of acidification. “The rule would help protect productive fisheries and oceans,” GOH says. “Although it cannot single-handedly staunch the flow of carbon emissions that drive ocean acidification, the rule would make a good start.” Capping CO2 emissions per unit of power produced would, GOH says, effectively block any new coal plants in the US, ensuring a continued shift towards natural gas, which is cheaper than coal. In the last six months, it says, more than 80% of the new electricity capacity added to the US grid was renewable energy. It also believes the rule would dampen global investors’ appetite for coal projects by demonstrating that the US is no longer willing to tolerate unlimited CO2 emissions from coal. “With this policy, the world’s most influential economic superpower would signal to global capital markets that coal is no longer a safe investment,” GOH says. This would add to the growing argument that fossil fuel reserves risk becoming unusable “frozen assets” because of their climate impact. − Climate News Network

FOR IMMEDIATE RELEASE Researchers warn that marine life could be dramatically affected as climate change threatens to cause severe reduction of plankton – the key source of nutrients − in some ocean regions by the end of the century LONDON, 12 May − There are plenty more fish in the sea − but not for too much longer in some parts of the world, researchers say. And the reason is very simple: the food on which they all depend faces a marked decline. Researchers from AZTI-Tecnalia, a Spanish-based technology centre specialising in marine and food research, report in the journal Global Change Biology that the warming of the oceans will cause phytoplankton biomass to decrease by 6% by the end of this century. Phytoplankton are the single-celled plants that are the basic building blocks of most marine life. In particular, they sustain zooplankton − tiny animals that are eaten in turn by fish. The study found evidence that, by 2100, zooplankton biomass will be 11% less than it is today, with obvious implications for the fish that feed on them. The report says that sea surface temperature is predicted to increase by 2ºC on average globally by 2080-2100. The consequences of this increase will include changes in ocean circulation and higher water column stratification, where water of different densities forms distinct layers instead of mixing, affecting the availability of nutrients.

Biomass reduction

The depletion expected in the amount of plankton in the marine food web could reduce fish biomass in 47% of the total global ocean area, especially in tropical oceans. But phytoplankton and zooplankton reduction will affect different regions in different ways. In the North Sea and temperate north-east Atlantic, higher stratification and lower nutrient levels will reduce phytoplankton growth. In the Baltic, Barents and Black Seas, it is expected to increase. Guillem Chust, an Azti-Tecnalia researcher and the lead author of the paper, said: “In the ocean regions that lose more phytoplankton and zooplankton biomass, fish biomass may also decrease dramatically.” He said this would especially affect pelagic species − deep-sea fish that are not bottom dwellers. He said the oceans’ role in moderating climate change would also be damaged: “As there will be less phytoplankton, absorption of CO2 from the atmosphere by the oceans will be lower, as plankton is responsible for half of the planet’s photosynthetic activity. This in turn will reduce the ocean’s capacity to regulate the climate.” The research was undertaken as part of Marine Ecosystem Evolution in a Changing Environment (MEECE), a European Union project to explore the impact of climate and human activities on marine ecosystems. One of the project’s concerns is the growing evidence of damage from ocean acidification, the process by which emissions of carbon dioxide are making the seas increasingly acid and hostile to some forms of marine life.

Emission limits

A group which works to protect seafood supplies and marine ecosystems, Global Ocean Health, has welcomed a move by the US Environmental Protection Agency  intended to lead to the introduction of performance-based emission limits for new power plants, which would help to reduce the threat of acidification. “The rule would help protect productive fisheries and oceans,” GOH says. “Although it cannot single-handedly staunch the flow of carbon emissions that drive ocean acidification, the rule would make a good start.” Capping CO2 emissions per unit of power produced would, GOH says, effectively block any new coal plants in the US, ensuring a continued shift towards natural gas, which is cheaper than coal. In the last six months, it says, more than 80% of the new electricity capacity added to the US grid was renewable energy. It also believes the rule would dampen global investors’ appetite for coal projects by demonstrating that the US is no longer willing to tolerate unlimited CO2 emissions from coal. “With this policy, the world’s most influential economic superpower would signal to global capital markets that coal is no longer a safe investment,” GOH says. This would add to the growing argument that fossil fuel reserves risk becoming unusable “frozen assets” because of their climate impact. − Climate News Network

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Right whales go wrong way

FOR IMMEDIATE RELEASE One of the world’s rarest whale species seems to have deserted its habitual feeding grounds during 2012 – and scientists think climate change may be a factor. LONDON, 9 December – A mystery is unfolding in the waters of the North Atlantic. Every summer and autumn, numbers of North Atlantic right whales gather in the waters between the eastern Canadian provinces of New Brunswick and Nova Scotia to feed on massive amounts of zooplankton. But this year the right whales – one of the rarest and most endangered animals on earth – have not turned up in a stretch of water called the Bay of Fundy. While no-one is sure what is causing the change in the whales’ behaviour, a report in the Yale environment360 online magazine says alterations in the whales’ feeding patterns are taking place against a backdrop of major climate-related ecosystem shifts throughout the north-west Atlantic Ocean. The right whale – Eubalaena glacialis – came by its name because it was considered by whalers as “the right whale” to hunt, due to its large concentrations of valuable blubber.  It was also easy prey: adult right whales average between 12 and 16 metres in length and can weigh up to 70 tons. They move relatively slowly through the water and float when killed, making them easy to handle.

Record year

At one stage the North Atlantic right whale was hunted to the point of extinction: in recent years numbers have grown to more than 500 individuals. Marine scientists are now investigating whether changes in water temperature are responsible for shifting the whales’ food supplies and so causing their migratory pattern to alter. The main ingredient in the whales’ diet is the zooplankton Calanus finmarchicus. Researchers say there’s been a scarcity of the zooplankton in waters around the Bay of Fundy recently: marine scientists say warming waters in the Gulf of Maine, south of the Bay of Fundy, are one likely cause of the decline. In 2012 waters in the Gulf of Maine and elsewhere in the north-western Atlantic underwent a sharp rise in temperature due, say scientists, both to long-term climate change and to an unusually warm year in the area. In the continental US, 2012 was the hottest summer ever recorded.

Fleeing the heat

Various marine species, including cod and red hake, have been moving more to the north in recent years. A study by the US National Oceanic and Atmospheric Administration found that of 36 fish stocks examined, more than half were shifting northwards or to greater depths to compensate for warming water temperatures. Lobster and shrimp – vital to the Gulf of Maine’s fishing industry – are also believed to be moving to cooler waters further north. Shifts in stocks of species at the base of the food chain – phytoplankton and zooplankton – are thought to be due both to warming waters in the north-west Atlantic and to changes in ocean currents.  Scientists have shown that the melt of Arctic sea ice, together with more melting of ice sheets in Greenland and Canada, is likely to mean more freshwater being poured into the north-west Atlantic, leading to increased stratification of ocean waters and alterations in plankton stocks. But the disappearance of right whales from their usual autumn feeding ground in the Bay of Fundy remains a mystery.  Some have been reported in waters well to the north. In winter, large numbers have been sighted further south, in Cape Cod Bay, off the US coast. In winter right whales usually move more than 1,000 miles south to breeding grounds off the coasts of the states of Georgia and Florida. Now, with waters staying relatively warm further north, they might be changing their migratory behaviour, deciding not to make the long journey south in the winter months. – Climate News Network

FOR IMMEDIATE RELEASE One of the world’s rarest whale species seems to have deserted its habitual feeding grounds during 2012 – and scientists think climate change may be a factor. LONDON, 9 December – A mystery is unfolding in the waters of the North Atlantic. Every summer and autumn, numbers of North Atlantic right whales gather in the waters between the eastern Canadian provinces of New Brunswick and Nova Scotia to feed on massive amounts of zooplankton. But this year the right whales – one of the rarest and most endangered animals on earth – have not turned up in a stretch of water called the Bay of Fundy. While no-one is sure what is causing the change in the whales’ behaviour, a report in the Yale environment360 online magazine says alterations in the whales’ feeding patterns are taking place against a backdrop of major climate-related ecosystem shifts throughout the north-west Atlantic Ocean. The right whale – Eubalaena glacialis – came by its name because it was considered by whalers as “the right whale” to hunt, due to its large concentrations of valuable blubber.  It was also easy prey: adult right whales average between 12 and 16 metres in length and can weigh up to 70 tons. They move relatively slowly through the water and float when killed, making them easy to handle.

Record year

At one stage the North Atlantic right whale was hunted to the point of extinction: in recent years numbers have grown to more than 500 individuals. Marine scientists are now investigating whether changes in water temperature are responsible for shifting the whales’ food supplies and so causing their migratory pattern to alter. The main ingredient in the whales’ diet is the zooplankton Calanus finmarchicus. Researchers say there’s been a scarcity of the zooplankton in waters around the Bay of Fundy recently: marine scientists say warming waters in the Gulf of Maine, south of the Bay of Fundy, are one likely cause of the decline. In 2012 waters in the Gulf of Maine and elsewhere in the north-western Atlantic underwent a sharp rise in temperature due, say scientists, both to long-term climate change and to an unusually warm year in the area. In the continental US, 2012 was the hottest summer ever recorded.

Fleeing the heat

Various marine species, including cod and red hake, have been moving more to the north in recent years. A study by the US National Oceanic and Atmospheric Administration found that of 36 fish stocks examined, more than half were shifting northwards or to greater depths to compensate for warming water temperatures. Lobster and shrimp – vital to the Gulf of Maine’s fishing industry – are also believed to be moving to cooler waters further north. Shifts in stocks of species at the base of the food chain – phytoplankton and zooplankton – are thought to be due both to warming waters in the north-west Atlantic and to changes in ocean currents.  Scientists have shown that the melt of Arctic sea ice, together with more melting of ice sheets in Greenland and Canada, is likely to mean more freshwater being poured into the north-west Atlantic, leading to increased stratification of ocean waters and alterations in plankton stocks. But the disappearance of right whales from their usual autumn feeding ground in the Bay of Fundy remains a mystery.  Some have been reported in waters well to the north. In winter, large numbers have been sighted further south, in Cape Cod Bay, off the US coast. In winter right whales usually move more than 1,000 miles south to breeding grounds off the coasts of the states of Georgia and Florida. Now, with waters staying relatively warm further north, they might be changing their migratory behaviour, deciding not to make the long journey south in the winter months. – Climate News Network

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Tiny plankton may have big impact

FOR IMMEDIATE RELEASE As the oceans become more acidic because of rising carbon dioxide levels, smaller plankton will thrive at the expense of larger species, with potentially serious effects. LONDON, 23 September – Some of the most minute forms of marine life may have a significant effect both on more developed creatures and on the oceans’ ability to absorb carbon dioxide. An international team of scientists has found that the smallest species of plankton thrive when levels of CO2, the main greenhouse gas from human sources, rise and increase the acidity of the oceans. Writing in Biogeosciences, a journal of the European Geosciences Union, they say this could knock the marine food web off balance and also lessen the oceans’ uptake of CO2, a mechanism which helps to regulate the global climate by absorbing gas which would otherwise heat the atmosphere. The study took place off the coast of Svalbard, the Norwegian high Arctic archipelago, and was led by Ulf Riebesell, a professor of biological oceanography at the GEOMAR Helmholtz Centre for Ocean Researct Kiel in Germany. “If the tiny plankton blooms, it consumes the nutrients that are normally also available to larger plankton species,” he says. But the bigger plankton play an important role in transferring carbon down to the ocean depths. So in a system dominated by the minute pico- and nanoplankton, less carbon will leave surface waters and the oceans could in future absorb less CO2, says Riebesell. The potential imbalance in the food web may have an even bigger impact. Large plankton are also important as producers of a climate-cooling gas called dimethyl sulphide, which stimulates cloud formation over the oceans. Less dimethyl sulphide will mean more sunlight reaches the Earth’s surface, adding to the greenhouse effect. The root of the problem is the growing acidity of the Arctic. This, coupled with the availability of nutrients, allows the very smallest plankton to thrive at the expense of their larger cousins.

Natural laboratory

The Arctic seas are among those most vulnerable to acidification, because the cold allows them to absorb more CO2. This increasing acidity is already known to affect some Arctic creatures which use calcium to build their shells, including some sea snails, mussels and other molluscs. But scientists had not known unil now how acidification alters both the base of the marine food web and oceanic carbon transport. The five week-long field study, conducted in the Kongsfjord in Svalbard, sought to close this knowledge gap. For the experiment the scientists deployed nine large “mesocosms” – eight-metre long flotation frames carrying plastic bags with a capacity of 50 cubic metres. These bags let researchers study plankton communities in their natural environment under controlled conditions, rather than in a laboratory. The scientists gradually added CO2 to the mesocosm water so that it reached the acidity levels expected in 20, 40, 60, 80 and 100 years, with two bags left as controls. They also added nutrients to simulate a natural plankton bloom. They found that, with higher CO2, pico- and, to a lesser extent, nanoplankton grew, consuming nutrients and leaving fewer for larger plankton. “The different responses we observed made it clear that the communities’ sensitivity to acidification depends strongly on whether or not nutrients are available,” Riebesell says. “…the tiniest plankton benefit from the surplus CO2, they produce more biomass and more organic carbon, and dimethyl sulphide production and carbon export decrease.” Researchers at two UK universities reported earlier this month that they had found that rising temperatures in the oceans would affect plankton development, upsetting the natural cycles of carbon dioxide, nitrogen and phosphorous.  – Climate News Network

FOR IMMEDIATE RELEASE As the oceans become more acidic because of rising carbon dioxide levels, smaller plankton will thrive at the expense of larger species, with potentially serious effects. LONDON, 23 September – Some of the most minute forms of marine life may have a significant effect both on more developed creatures and on the oceans’ ability to absorb carbon dioxide. An international team of scientists has found that the smallest species of plankton thrive when levels of CO2, the main greenhouse gas from human sources, rise and increase the acidity of the oceans. Writing in Biogeosciences, a journal of the European Geosciences Union, they say this could knock the marine food web off balance and also lessen the oceans’ uptake of CO2, a mechanism which helps to regulate the global climate by absorbing gas which would otherwise heat the atmosphere. The study took place off the coast of Svalbard, the Norwegian high Arctic archipelago, and was led by Ulf Riebesell, a professor of biological oceanography at the GEOMAR Helmholtz Centre for Ocean Researct Kiel in Germany. “If the tiny plankton blooms, it consumes the nutrients that are normally also available to larger plankton species,” he says. But the bigger plankton play an important role in transferring carbon down to the ocean depths. So in a system dominated by the minute pico- and nanoplankton, less carbon will leave surface waters and the oceans could in future absorb less CO2, says Riebesell. The potential imbalance in the food web may have an even bigger impact. Large plankton are also important as producers of a climate-cooling gas called dimethyl sulphide, which stimulates cloud formation over the oceans. Less dimethyl sulphide will mean more sunlight reaches the Earth’s surface, adding to the greenhouse effect. The root of the problem is the growing acidity of the Arctic. This, coupled with the availability of nutrients, allows the very smallest plankton to thrive at the expense of their larger cousins.

Natural laboratory

The Arctic seas are among those most vulnerable to acidification, because the cold allows them to absorb more CO2. This increasing acidity is already known to affect some Arctic creatures which use calcium to build their shells, including some sea snails, mussels and other molluscs. But scientists had not known unil now how acidification alters both the base of the marine food web and oceanic carbon transport. The five week-long field study, conducted in the Kongsfjord in Svalbard, sought to close this knowledge gap. For the experiment the scientists deployed nine large “mesocosms” – eight-metre long flotation frames carrying plastic bags with a capacity of 50 cubic metres. These bags let researchers study plankton communities in their natural environment under controlled conditions, rather than in a laboratory. The scientists gradually added CO2 to the mesocosm water so that it reached the acidity levels expected in 20, 40, 60, 80 and 100 years, with two bags left as controls. They also added nutrients to simulate a natural plankton bloom. They found that, with higher CO2, pico- and, to a lesser extent, nanoplankton grew, consuming nutrients and leaving fewer for larger plankton. “The different responses we observed made it clear that the communities’ sensitivity to acidification depends strongly on whether or not nutrients are available,” Riebesell says. “…the tiniest plankton benefit from the surplus CO2, they produce more biomass and more organic carbon, and dimethyl sulphide production and carbon export decrease.” Researchers at two UK universities reported earlier this month that they had found that rising temperatures in the oceans would affect plankton development, upsetting the natural cycles of carbon dioxide, nitrogen and phosphorous.  – Climate News Network

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Plankton will suffer as oceans warm

EMBARGOED until 1800 GMT on Sunday 8 September One effect of the warming of the oceans will be to depress the growth of plankton, with consequences for fish and other species that depend on it. LONDON, 8 September – Researchers at two UK universities have found that rising temperatures in the world’s oceans will affect the development of the plankton on which most marine life feeds. The research team, from the universities of East Anglia and Exeter, has demonstrated that the increasing warmth caused by a changing climate will upset the natural cycles of carbon dioxide, nitrogen and phosphorous. This will affect the plankton, making it scarcer and so causing problems for fish and other species higher up the food chain. There are also likely to be implications for climate change, but just what they will be, the team leader says, is far from clear. Plankton play an important role in the oceanic carbon cycle by removing half of all CO2 from the atmosphere during photosynthesis – the process during which plants and other organisms convert light, usually from the Sun, into energy. The carbon then falls deep into the ocean and ends up on the sea bed, where it remains safely isolated from the atmosphere for centuries. But the novel point about the team’s work, published in Nature Climate Change, is their discovery that water temperature has a direct impact on maintaining the plankton’s delicate ecosystem. This means the effects of oceanic warming will affect plankton and drive “a vicious cycle of climate change”. Researchers from UEA’s School of Environmental Sciences and the School of Computing Sciences investigated phytoplankton – microscopic plant-like organisms which rely on photosynthesis to reproduce and grow. The lead researcher, Dr Thomas Mock, says: “Phytoplankton, including micro-algae, is responsible for half of the carbon dioxide that is naturally removed from the atmosphere. “As well as being vital to climate control, it also creates enough oxygen for every other breath we take, and forms the base of the food chain for fisheries, so it is incredibly important for food security. “Previous studies have shown that phytoplankton communities respond to global warming by changes in diversity and productivity. But with our study we show that warmer temperatures directly impact the chemical cycles in plankton, which has not been shown before.

Higher nitrogen ratio

“We found that temperature plays a critical role in driving the cycling of chemicals in marine micro-algae. It affects these reactions as much as nutrients and light, which was not known before.” Team members from Exeter developed computer-generated models to create a global ecosystem model which took into account world ocean temperatures, 1.5 million plankton DNA sequences taken from samples, and biochemical data. As temperatures warm, marine micro-algae appear not to produce as many ribosomes as they do in cooler water (ribosomes join up the building blocks of proteins in cells and are rich in phosphorous). If their numbers fall this will produce higher ratios of nitrogen compared with phosphorous. The result, says Dr Mock, would be lower plankton productivity, with implications for the marine carbon cycle. He told the Climate News Network: “There will be consequences both for climate change and for marine food webs. “The oceans may retain less CO2, though other factors, like the stratification of the water layers under the influence of temperature and salinity, may counteract that. “But warming the oceans and increasing the amount of nitrogen they contain could equally well mean that they can store more CO2 than they do now. “So there’ll certainly be an effect on climate change, but the ultimate outcome is really difficult to predict. With food webs it’s much easier: we know there will simply be less plankton available for higher species.” – Climate News Network

EMBARGOED until 1800 GMT on Sunday 8 September One effect of the warming of the oceans will be to depress the growth of plankton, with consequences for fish and other species that depend on it. LONDON, 8 September – Researchers at two UK universities have found that rising temperatures in the world’s oceans will affect the development of the plankton on which most marine life feeds. The research team, from the universities of East Anglia and Exeter, has demonstrated that the increasing warmth caused by a changing climate will upset the natural cycles of carbon dioxide, nitrogen and phosphorous. This will affect the plankton, making it scarcer and so causing problems for fish and other species higher up the food chain. There are also likely to be implications for climate change, but just what they will be, the team leader says, is far from clear. Plankton play an important role in the oceanic carbon cycle by removing half of all CO2 from the atmosphere during photosynthesis – the process during which plants and other organisms convert light, usually from the Sun, into energy. The carbon then falls deep into the ocean and ends up on the sea bed, where it remains safely isolated from the atmosphere for centuries. But the novel point about the team’s work, published in Nature Climate Change, is their discovery that water temperature has a direct impact on maintaining the plankton’s delicate ecosystem. This means the effects of oceanic warming will affect plankton and drive “a vicious cycle of climate change”. Researchers from UEA’s School of Environmental Sciences and the School of Computing Sciences investigated phytoplankton – microscopic plant-like organisms which rely on photosynthesis to reproduce and grow. The lead researcher, Dr Thomas Mock, says: “Phytoplankton, including micro-algae, is responsible for half of the carbon dioxide that is naturally removed from the atmosphere. “As well as being vital to climate control, it also creates enough oxygen for every other breath we take, and forms the base of the food chain for fisheries, so it is incredibly important for food security. “Previous studies have shown that phytoplankton communities respond to global warming by changes in diversity and productivity. But with our study we show that warmer temperatures directly impact the chemical cycles in plankton, which has not been shown before.

Higher nitrogen ratio

“We found that temperature plays a critical role in driving the cycling of chemicals in marine micro-algae. It affects these reactions as much as nutrients and light, which was not known before.” Team members from Exeter developed computer-generated models to create a global ecosystem model which took into account world ocean temperatures, 1.5 million plankton DNA sequences taken from samples, and biochemical data. As temperatures warm, marine micro-algae appear not to produce as many ribosomes as they do in cooler water (ribosomes join up the building blocks of proteins in cells and are rich in phosphorous). If their numbers fall this will produce higher ratios of nitrogen compared with phosphorous. The result, says Dr Mock, would be lower plankton productivity, with implications for the marine carbon cycle. He told the Climate News Network: “There will be consequences both for climate change and for marine food webs. “The oceans may retain less CO2, though other factors, like the stratification of the water layers under the influence of temperature and salinity, may counteract that. “But warming the oceans and increasing the amount of nitrogen they contain could equally well mean that they can store more CO2 than they do now. “So there’ll certainly be an effect on climate change, but the ultimate outcome is really difficult to predict. With food webs it’s much easier: we know there will simply be less plankton available for higher species.” – Climate News Network

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Volcano 'did little to lower CO2'

FOR IMMEDIATE RELEASE
The eruption almost three years ago of an Icelandic volcano added iron to the seas south of the island. But it disappointed hopes that it would help a natural process to remove much carbon dioxide from the atmosphere.

LONDON, 21 March – Plankton, tiny marine organisms, are a good way of cleansing the atmosphere of one of the main greenhouse gases, carbon dioxide. To do this they need dissolved iron to help them to grow, and if they lack iron then they cannot do much to reduce CO2 levels.

So the eruption in 2010 of an Icelandic volcano gave scientists a perfect opportunity to see how much the cataclysm helped the plankton by showering them with unexpected clouds of iron.

Their verdict, published in the journal Geophysical Research Letters – the volcano certainly helped, but not for long enough to make much difference.

This is a blow to some supporters of geo-engineering, who have suggested that one way to tackle climate change is large-scale seeding of the oceans with iron to stimulate plankton to absorb more carbon dioxide (see our 14 March story, Who will regulate the researchers?).

The volcano’s impact was assessed by a team led by scientists from the UK’s National Oceanography Centre, Southampton, who were on a shipboard research expedition in the area at the time.

When it erupted in April 2010 the volcano, Eyjafjallajökull, hurled clouds of ash several kilometres into the atmosphere, bringing air travel to a standstill across Europe and, in a less noticeable effect, seeding the seas south of Iceland with ash.

In many parts of the ocean the productivity of phytoplankton – microscopic plants at the base of the marine food chain – is limited by the availability of dissolved iron.

In 2007 the team had shown that, after a large spring bloom, phytoplankton in the Iceland Basin failed to grow much because it lacked iron. The scientists wanted to see whether the ash from Eyjafjallajökull supplied enough iron to sustain the spring blooms for longer than usual.

More iron, less nitrogen

 

The team – from Southampton, the University of Cape Town and the Norwegian Institute for Air Research – conducted three research voyages in 2010 investigating ocean productivity in the area affected by ash from Eyjafjallajökull.

They took samples of ash and dust in the atmosphere, and of nutrients in the ocean, and also measured the activity of the phytoplankton.

The chief scientist for the summer research cruise and lead author of the Geophysical Research Letters paper, Professor Eric Achterberg, said: “The high latitude North Atlantic ocean is a globally important ocean region, as it is a sink for atmospheric carbon dioxide, and an area where deep water formation takes place.

“A limit to the availability of iron in this region means that the ocean is less efficient in its uptake of atmospheric carbon dioxide.”

The team found that the five-week eruption supplied dissolved iron to a region of the North Atlantic of up 570,000 square kilometres, increasing the number of phytoplankton cells.

Biological experiments showed that the ash did release the iron which the phytoplankton needed to stimulate their growth. But the effect was short-lived as the extra iron resulted in the rapid removal of biological nitrate, depriving the phytoplankton of the nitrogen which they also needed, a caveat to proponents of this form of geo-engineering.

Professor Achterberg said: “The additional removal of carbon by the ash-stimulated phytoplankton was therefore only 15 to 20% higher than in other years, making for a significant but short-lived change to the biogeochemistry of the Iceland Basin.”

The National Oceanography Centre develops technology for coastal and deep ocean research. It is based in Southampton and Liverpool. – Climate News Network

FOR IMMEDIATE RELEASE
The eruption almost three years ago of an Icelandic volcano added iron to the seas south of the island. But it disappointed hopes that it would help a natural process to remove much carbon dioxide from the atmosphere.

LONDON, 21 March – Plankton, tiny marine organisms, are a good way of cleansing the atmosphere of one of the main greenhouse gases, carbon dioxide. To do this they need dissolved iron to help them to grow, and if they lack iron then they cannot do much to reduce CO2 levels.

So the eruption in 2010 of an Icelandic volcano gave scientists a perfect opportunity to see how much the cataclysm helped the plankton by showering them with unexpected clouds of iron.

Their verdict, published in the journal Geophysical Research Letters – the volcano certainly helped, but not for long enough to make much difference.

This is a blow to some supporters of geo-engineering, who have suggested that one way to tackle climate change is large-scale seeding of the oceans with iron to stimulate plankton to absorb more carbon dioxide (see our 14 March story, Who will regulate the researchers?).

The volcano’s impact was assessed by a team led by scientists from the UK’s National Oceanography Centre, Southampton, who were on a shipboard research expedition in the area at the time.

When it erupted in April 2010 the volcano, Eyjafjallajökull, hurled clouds of ash several kilometres into the atmosphere, bringing air travel to a standstill across Europe and, in a less noticeable effect, seeding the seas south of Iceland with ash.

In many parts of the ocean the productivity of phytoplankton – microscopic plants at the base of the marine food chain – is limited by the availability of dissolved iron.

In 2007 the team had shown that, after a large spring bloom, phytoplankton in the Iceland Basin failed to grow much because it lacked iron. The scientists wanted to see whether the ash from Eyjafjallajökull supplied enough iron to sustain the spring blooms for longer than usual.

More iron, less nitrogen

 

The team – from Southampton, the University of Cape Town and the Norwegian Institute for Air Research – conducted three research voyages in 2010 investigating ocean productivity in the area affected by ash from Eyjafjallajökull.

They took samples of ash and dust in the atmosphere, and of nutrients in the ocean, and also measured the activity of the phytoplankton.

The chief scientist for the summer research cruise and lead author of the Geophysical Research Letters paper, Professor Eric Achterberg, said: “The high latitude North Atlantic ocean is a globally important ocean region, as it is a sink for atmospheric carbon dioxide, and an area where deep water formation takes place.

“A limit to the availability of iron in this region means that the ocean is less efficient in its uptake of atmospheric carbon dioxide.”

The team found that the five-week eruption supplied dissolved iron to a region of the North Atlantic of up 570,000 square kilometres, increasing the number of phytoplankton cells.

Biological experiments showed that the ash did release the iron which the phytoplankton needed to stimulate their growth. But the effect was short-lived as the extra iron resulted in the rapid removal of biological nitrate, depriving the phytoplankton of the nitrogen which they also needed, a caveat to proponents of this form of geo-engineering.

Professor Achterberg said: “The additional removal of carbon by the ash-stimulated phytoplankton was therefore only 15 to 20% higher than in other years, making for a significant but short-lived change to the biogeochemistry of the Iceland Basin.”

The National Oceanography Centre develops technology for coastal and deep ocean research. It is based in Southampton and Liverpool. – Climate News Network

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Volcano ‘did little to lower CO2’

FOR IMMEDIATE RELEASE The eruption almost three years ago of an Icelandic volcano added iron to the seas south of the island. But it disappointed hopes that it would help a natural process to remove much carbon dioxide from the atmosphere. LONDON, 21 March – Plankton, tiny marine organisms, are a good way of cleansing the atmosphere of one of the main greenhouse gases, carbon dioxide. To do this they need dissolved iron to help them to grow, and if they lack iron then they cannot do much to reduce CO2 levels. So the eruption in 2010 of an Icelandic volcano gave scientists a perfect opportunity to see how much the cataclysm helped the plankton by showering them with unexpected clouds of iron. Their verdict, published in the journal Geophysical Research Letters – the volcano certainly helped, but not for long enough to make much difference. This is a blow to some supporters of geo-engineering, who have suggested that one way to tackle climate change is large-scale seeding of the oceans with iron to stimulate plankton to absorb more carbon dioxide (see our 14 March story, Who will regulate the researchers?). The volcano’s impact was assessed by a team led by scientists from the UK’s National Oceanography Centre, Southampton, who were on a shipboard research expedition in the area at the time. When it erupted in April 2010 the volcano, Eyjafjallajökull, hurled clouds of ash several kilometres into the atmosphere, bringing air travel to a standstill across Europe and, in a less noticeable effect, seeding the seas south of Iceland with ash. In many parts of the ocean the productivity of phytoplankton – microscopic plants at the base of the marine food chain – is limited by the availability of dissolved iron. In 2007 the team had shown that, after a large spring bloom, phytoplankton in the Iceland Basin failed to grow much because it lacked iron. The scientists wanted to see whether the ash from Eyjafjallajökull supplied enough iron to sustain the spring blooms for longer than usual.

More iron, less nitrogen

  The team – from Southampton, the University of Cape Town and the Norwegian Institute for Air Research – conducted three research voyages in 2010 investigating ocean productivity in the area affected by ash from Eyjafjallajökull. They took samples of ash and dust in the atmosphere, and of nutrients in the ocean, and also measured the activity of the phytoplankton. The chief scientist for the summer research cruise and lead author of the Geophysical Research Letters paper, Professor Eric Achterberg, said: “The high latitude North Atlantic ocean is a globally important ocean region, as it is a sink for atmospheric carbon dioxide, and an area where deep water formation takes place. “A limit to the availability of iron in this region means that the ocean is less efficient in its uptake of atmospheric carbon dioxide.” The team found that the five-week eruption supplied dissolved iron to a region of the North Atlantic of up 570,000 square kilometres, increasing the number of phytoplankton cells. Biological experiments showed that the ash did release the iron which the phytoplankton needed to stimulate their growth. But the effect was short-lived as the extra iron resulted in the rapid removal of biological nitrate, depriving the phytoplankton of the nitrogen which they also needed, a caveat to proponents of this form of geo-engineering. Professor Achterberg said: “The additional removal of carbon by the ash-stimulated phytoplankton was therefore only 15 to 20% higher than in other years, making for a significant but short-lived change to the biogeochemistry of the Iceland Basin.” The National Oceanography Centre develops technology for coastal and deep ocean research. It is based in Southampton and Liverpool. – Climate News Network

FOR IMMEDIATE RELEASE The eruption almost three years ago of an Icelandic volcano added iron to the seas south of the island. But it disappointed hopes that it would help a natural process to remove much carbon dioxide from the atmosphere. LONDON, 21 March – Plankton, tiny marine organisms, are a good way of cleansing the atmosphere of one of the main greenhouse gases, carbon dioxide. To do this they need dissolved iron to help them to grow, and if they lack iron then they cannot do much to reduce CO2 levels. So the eruption in 2010 of an Icelandic volcano gave scientists a perfect opportunity to see how much the cataclysm helped the plankton by showering them with unexpected clouds of iron. Their verdict, published in the journal Geophysical Research Letters – the volcano certainly helped, but not for long enough to make much difference. This is a blow to some supporters of geo-engineering, who have suggested that one way to tackle climate change is large-scale seeding of the oceans with iron to stimulate plankton to absorb more carbon dioxide (see our 14 March story, Who will regulate the researchers?). The volcano’s impact was assessed by a team led by scientists from the UK’s National Oceanography Centre, Southampton, who were on a shipboard research expedition in the area at the time. When it erupted in April 2010 the volcano, Eyjafjallajökull, hurled clouds of ash several kilometres into the atmosphere, bringing air travel to a standstill across Europe and, in a less noticeable effect, seeding the seas south of Iceland with ash. In many parts of the ocean the productivity of phytoplankton – microscopic plants at the base of the marine food chain – is limited by the availability of dissolved iron. In 2007 the team had shown that, after a large spring bloom, phytoplankton in the Iceland Basin failed to grow much because it lacked iron. The scientists wanted to see whether the ash from Eyjafjallajökull supplied enough iron to sustain the spring blooms for longer than usual.

More iron, less nitrogen

  The team – from Southampton, the University of Cape Town and the Norwegian Institute for Air Research – conducted three research voyages in 2010 investigating ocean productivity in the area affected by ash from Eyjafjallajökull. They took samples of ash and dust in the atmosphere, and of nutrients in the ocean, and also measured the activity of the phytoplankton. The chief scientist for the summer research cruise and lead author of the Geophysical Research Letters paper, Professor Eric Achterberg, said: “The high latitude North Atlantic ocean is a globally important ocean region, as it is a sink for atmospheric carbon dioxide, and an area where deep water formation takes place. “A limit to the availability of iron in this region means that the ocean is less efficient in its uptake of atmospheric carbon dioxide.” The team found that the five-week eruption supplied dissolved iron to a region of the North Atlantic of up 570,000 square kilometres, increasing the number of phytoplankton cells. Biological experiments showed that the ash did release the iron which the phytoplankton needed to stimulate their growth. But the effect was short-lived as the extra iron resulted in the rapid removal of biological nitrate, depriving the phytoplankton of the nitrogen which they also needed, a caveat to proponents of this form of geo-engineering. Professor Achterberg said: “The additional removal of carbon by the ash-stimulated phytoplankton was therefore only 15 to 20% higher than in other years, making for a significant but short-lived change to the biogeochemistry of the Iceland Basin.” The National Oceanography Centre develops technology for coastal and deep ocean research. It is based in Southampton and Liverpool. – Climate News Network