Tag Archives: Algal blooms

Fish supplies face rising threat from algal blooms

Fish farms, and the protein supply of over three billion people, are at increasing risk from algal blooms.

LONDON, 10 June, 2021 – Toxic algal blooms that can kill fish and sometimes humans cause severe economic losses and are an increasing danger to food supplies.

The threat has increased dramatically, not because the quantity of algae is necessarily increasing, but because humankind is relying more and more on aquaculture to provide fish. There has been a 16-fold increase in fish farming since 1985.

Around 3.3 billion people rely on seafood for a fifth of their animal protein, and it is an increasingly important source as land-based agriculture faces great strains because of climate change.

An international team of scientists who carried out a statistical analysis of three sources, notably HAEDAT, the Harmful Algal Event Database, covering the years from 1985 to 2018, report their findings in the journal Nature Communications: Earth & Environment.

Their analysis, the first of its kind, was undertaken because of a widespread belief that the problem is worsening. They say it may only appear to be more acute because wild fish, unlike those in fish farms, can swim safely away from algal blooms. So it is possible the blooms have simply not been reported as often because fish have managed to avoid them.

Climate heating implicated

They write: “Global trends in the occurrence, toxicity and risk posed by harmful algal blooms to natural systems, human health and coastal economies are poorly constrained, but are widely thought to be increasing due to climate change and nutrient pollution. . .

“We find no uniform global trend in the number of harmful algal events and their distribution over time, once data were adjusted for regional variations in monitoring effort.”

However, a new factor that may be increasing the danger of algae to aquaculture is climate change. This is because harmful blooms have occurred in temperature increase hotspots in the Asia Pacific region and off the coasts of Chile and south-east Australia. Other climatic factors such as ocean acidification, nutrient alterations and lower oxygen levels are also playing a role.

The researchers did though discover wide variations across the world in the incidence of harmful blooms, with some areas having reduced human poisoning and fish kills and others increasing occurrences. The reason is not known.

The use of coastal waters for aquaculture has been the key driver for the reporting of blooms, because the mass fish mortality has led occasionally to disastrous long-lasting economic impacts. This in turn has driven awareness of new harmful algal species and new toxin types.

“Global trends in the risk posed by harmful algal blooms are widely thought to be increasing”

There are about 5,000 species of marine phytoplankton, of which 200 can harm humans through the production of toxins that either make them ill or kill the fish or shellfish they would otherwise eat. Some toxins also kill marine mammals, particularly their calves.

By December 2019 a total of 9,503 events of harmful algae had been recorded from across the world. Nearly half were of toxins in seafood; 43% of blooms caused water discolouration or surface scum, producing other impacts, for example on tourism. Around 70 incidents caused mass animal or plant mortality.

The researchers say shellfish toxin outbreaks are now well-managed in developed countries and economies can recover swiftly, although  aquaculture industries can take many years to rebuild after mass mortality. The problem is becoming more acute because of the increasing reliance of an ever-larger human population on fish protein for survival.

Examples of severe economic losses from fish farms are a US$71 million loss in Japan in 1972, with $70m in Korea in 1995, $290m in China in 2012 and $100m in Norway in 2019. The worst was the 2016 Chilean salmon farm mortality that created a record $800m loss and caused major social unrest.

The scientists conclude that algal blooms are an increasing threat to the world’s food supply because of humans’ ever-growing reliance on aquaculture for protein. They recommend a worldwide sharing of knowledge and data in order to keep a check on the problem and how to control it. – Climate News Network

Fish farms, and the protein supply of over three billion people, are at increasing risk from algal blooms.

LONDON, 10 June, 2021 – Toxic algal blooms that can kill fish and sometimes humans cause severe economic losses and are an increasing danger to food supplies.

The threat has increased dramatically, not because the quantity of algae is necessarily increasing, but because humankind is relying more and more on aquaculture to provide fish. There has been a 16-fold increase in fish farming since 1985.

Around 3.3 billion people rely on seafood for a fifth of their animal protein, and it is an increasingly important source as land-based agriculture faces great strains because of climate change.

An international team of scientists who carried out a statistical analysis of three sources, notably HAEDAT, the Harmful Algal Event Database, covering the years from 1985 to 2018, report their findings in the journal Nature Communications: Earth & Environment.

Their analysis, the first of its kind, was undertaken because of a widespread belief that the problem is worsening. They say it may only appear to be more acute because wild fish, unlike those in fish farms, can swim safely away from algal blooms. So it is possible the blooms have simply not been reported as often because fish have managed to avoid them.

Climate heating implicated

They write: “Global trends in the occurrence, toxicity and risk posed by harmful algal blooms to natural systems, human health and coastal economies are poorly constrained, but are widely thought to be increasing due to climate change and nutrient pollution. . .

“We find no uniform global trend in the number of harmful algal events and their distribution over time, once data were adjusted for regional variations in monitoring effort.”

However, a new factor that may be increasing the danger of algae to aquaculture is climate change. This is because harmful blooms have occurred in temperature increase hotspots in the Asia Pacific region and off the coasts of Chile and south-east Australia. Other climatic factors such as ocean acidification, nutrient alterations and lower oxygen levels are also playing a role.

The researchers did though discover wide variations across the world in the incidence of harmful blooms, with some areas having reduced human poisoning and fish kills and others increasing occurrences. The reason is not known.

The use of coastal waters for aquaculture has been the key driver for the reporting of blooms, because the mass fish mortality has led occasionally to disastrous long-lasting economic impacts. This in turn has driven awareness of new harmful algal species and new toxin types.

“Global trends in the risk posed by harmful algal blooms are widely thought to be increasing”

There are about 5,000 species of marine phytoplankton, of which 200 can harm humans through the production of toxins that either make them ill or kill the fish or shellfish they would otherwise eat. Some toxins also kill marine mammals, particularly their calves.

By December 2019 a total of 9,503 events of harmful algae had been recorded from across the world. Nearly half were of toxins in seafood; 43% of blooms caused water discolouration or surface scum, producing other impacts, for example on tourism. Around 70 incidents caused mass animal or plant mortality.

The researchers say shellfish toxin outbreaks are now well-managed in developed countries and economies can recover swiftly, although  aquaculture industries can take many years to rebuild after mass mortality. The problem is becoming more acute because of the increasing reliance of an ever-larger human population on fish protein for survival.

Examples of severe economic losses from fish farms are a US$71 million loss in Japan in 1972, with $70m in Korea in 1995, $290m in China in 2012 and $100m in Norway in 2019. The worst was the 2016 Chilean salmon farm mortality that created a record $800m loss and caused major social unrest.

The scientists conclude that algal blooms are an increasing threat to the world’s food supply because of humans’ ever-growing reliance on aquaculture for protein. They recommend a worldwide sharing of knowledge and data in order to keep a check on the problem and how to control it. – 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        

Warming climate can drive algal blooms

FOR IMMEDIATE RELEASE  A warming climate is expected to encourage the development of suitable conditions for more algal blooms to form on one of the Great Lakes of the North American continent. LONDON, 3 April – Devastating algal blooms on one of the Great Lakes on the Canada-US border could become a much more frequent event, according to scientists from the Carnegie Institution and the University of Michigan. They report in the Proceedings of the National Academy of Sciences that conditions in 2011 were just right for a perfect storm of algal growth that turned Lake Erie an ugly blue-green, killed fish, fouled harbours, clogged marine engines, created oxygen-free dead zones and released unwholesome quantities of a liver toxin poisonous to mammals. And although the bloom was a consequence of the unhappy combination of agricultural management and unusual weather conditions, global warming could make such episodes more frequent. In 2010 conditions were fine for both the planting and harvesting of corn, wheat and soya in Ohio’s Maumee River basin. The Maumee drains into western Lake Erie. The following spring, record rains fell in May, dumping 75% more water than the average for that month, and washing large quantities of phosphorus fertiliser applied to the soil that spring down the water course and into the lake. The spring storms were followed by a fine summer, with calm winds and warm water temperatures. These conditions were ideal for the explosive growth of the toxic blue-green algae Microcystis, and the poison it produced was, at its highest, 224 times the World Health Organisation guidelines for safe levels.

Record-breaking spread

  The bloom began in mid-July over a 600 square-kilometre patch of water and then – because the conditions were perfect –  began to spread. Because there were no currents, the potential nutrients stayed in the lake and because temperatures were mellow the algal bloom went on spreading. At its peak in October, a thick scum of the bloom covered 5,000 square kilometres. Blooms had happened before: this one was seven times greater than the average of the last nine years, and more than three times bigger than the last record bloom in 2008. The researchers took a long cool look at past and projected future climates, and came to a conclusion that – once again because of the continued release of greenhouse gases and consequent planetary warming – there would be an increase in “extreme spring precipitation events”. Stronger storms could be twice as frequent. Sluggish circulation of the lake water is also expected in future, because wind speeds across the US on average seem to be decreasing. So the conditions for devastating blooms will continue. “Lacking the implementation of a scientifically guided management plan designed to mitigate these impacts”, the paper’s 29 authors conclude, “we can therefore expect this bloom to indeed be a harbinger of future blooms in Lake Erie.” – Climate News Network

FOR IMMEDIATE RELEASE  A warming climate is expected to encourage the development of suitable conditions for more algal blooms to form on one of the Great Lakes of the North American continent. LONDON, 3 April – Devastating algal blooms on one of the Great Lakes on the Canada-US border could become a much more frequent event, according to scientists from the Carnegie Institution and the University of Michigan. They report in the Proceedings of the National Academy of Sciences that conditions in 2011 were just right for a perfect storm of algal growth that turned Lake Erie an ugly blue-green, killed fish, fouled harbours, clogged marine engines, created oxygen-free dead zones and released unwholesome quantities of a liver toxin poisonous to mammals. And although the bloom was a consequence of the unhappy combination of agricultural management and unusual weather conditions, global warming could make such episodes more frequent. In 2010 conditions were fine for both the planting and harvesting of corn, wheat and soya in Ohio’s Maumee River basin. The Maumee drains into western Lake Erie. The following spring, record rains fell in May, dumping 75% more water than the average for that month, and washing large quantities of phosphorus fertiliser applied to the soil that spring down the water course and into the lake. The spring storms were followed by a fine summer, with calm winds and warm water temperatures. These conditions were ideal for the explosive growth of the toxic blue-green algae Microcystis, and the poison it produced was, at its highest, 224 times the World Health Organisation guidelines for safe levels.

Record-breaking spread

  The bloom began in mid-July over a 600 square-kilometre patch of water and then – because the conditions were perfect –  began to spread. Because there were no currents, the potential nutrients stayed in the lake and because temperatures were mellow the algal bloom went on spreading. At its peak in October, a thick scum of the bloom covered 5,000 square kilometres. Blooms had happened before: this one was seven times greater than the average of the last nine years, and more than three times bigger than the last record bloom in 2008. The researchers took a long cool look at past and projected future climates, and came to a conclusion that – once again because of the continued release of greenhouse gases and consequent planetary warming – there would be an increase in “extreme spring precipitation events”. Stronger storms could be twice as frequent. Sluggish circulation of the lake water is also expected in future, because wind speeds across the US on average seem to be decreasing. So the conditions for devastating blooms will continue. “Lacking the implementation of a scientifically guided management plan designed to mitigate these impacts”, the paper’s 29 authors conclude, “we can therefore expect this bloom to indeed be a harbinger of future blooms in Lake Erie.” – Climate News Network