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Mysterious foam on South Australian beaches caused by bloom of tiny but toxic algae

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Tuesday, March 25, 2025

Confronting images of dead seadragons, fish and octopuses washed up on South Australian beaches – and disturbing reports of “more than 100” surfers and beachgoers experiencing flu-like symptoms after swimming or merely breathing in sea spray – attracted international concern last week.Speculation about the likely cause ranged from pollution and algae to unusual bacterial infections or viruses. We can reveal the culprit was a tiny – but harmful – type of planktonic algae called Karenia mikimotoi.The South Australian government sent us water samples from Waitpinga beach, Petrel Cove beach, Encounter Bay boat ramp and Parsons Headland on Tuesday. We studied the water under the microscope and extracted DNA for genetic analysis.Our results revealed high numbers of the tiny harmful algal species – each just 20 microns in diameter (where one micron is one thousandth of a millimetre). While relatively common in Australian coastal waters, blooms of K. mikimotoi occur only sporadically. But similar harmful algal blooms and fish kills due to K. mikimotoi have happened in the past, such as the 2014 bloom in Coffin Bay, South Australia. And this latest one won’t be the last.Harmful algal bloomsSingle-celled, microbial algae occur naturally in seawater all over the world.They are also called phytoplankton because they float in the water column and photosynthesise like plants. “Phyto” comes from the Greek word for plant and “plankton” comes from the Greek word for wanderer, which relates to their floating movement with ocean currents and tides.Like plants on land, the microalgae or phytoplankton in the ocean capture sunlight and produce up to half the oxygen in our atmosphere. There are more than 100,000 different species of microalgae. Every litre of seawater will normally contain a mixed group of these different microalgae species.But under certain conditions, just a single species of microalgae can accumulate in one area and dominate over the others. If we are unlucky, the dominant species may be one that produces a toxin or has a harmful effect.This so-called “harmful algal bloom” can cause problems for people and for marine life such as fish, invertebrates such as crabs, and even marine mammals such as whales and seals.K. mikimotoi causes harmful deadly algal blooms in Asia, Europe, South Africa and South America, as well as Australia and New Zealand. Photograph: Anthony RowlandThere are hundreds of different species of harmful algae. Each produces its own type of toxin with a particular toxic effect.Most of these toxic chemical compounds produced by harmful algae are quite well known, including neurotoxins that affect the brain. But others are more complicated, and the mechanisms of toxicity are poorly understood. This can make it more difficult to understand the factors leading to the deaths of fish and other marine life. Unfortunately, the toxins from K. mikimotoi fall into this latter category.Introducing Karenia mikimotoiThe species responsible for recent events in South Australia, K. mikimotoi, causes harmful algal blooms in Asia, Europe, South Africa and South America, as well as Australia and New Zealand. These blooms all caused fish deaths, and some also caused breathing difficulties for some beachgoers.The most drastic of these K. mikimotoi blooms have occurred in China over the past two decades. In 2012, more than 300 sq km of abalone farms were affected, causing about A$525m in lost production.Explaining the toxic effectsMicroalgae can damage the gills of fish and shellfish, preventing them from breathing. This is the main cause of death. But some studies have also found damage to the gastrointestinal tracts and livers of fish.Tests using fish gill cells clearly show the dramatic toxic effect of K. mikimotoi. When the fish gill cells were exposed to intact K. mikimotoi cells, after 3.5 hours more than 80% of the fish cells had died.Leafy seadragons were among the dead sea creatures that washed up on South Australian beaches. Photograph: Anthony RowlandFortunately, the toxin does not persist in the environment after the K. mikimotoi cells are dead. So once the bloom is over, the marine environment can recover relatively quickly.Its toxicity is partly due to the algae’s production of “reactive oxygen species”, reactive forms of oxygen molecules which can cause the deaths of cells in high doses. K. mikimotoi cells may also produce lipid (fat) molecules that cause some toxic effects.Finally, a very dense bloom of microalgae can sometimes reduce the amount of dissolved oxygen in the water column, which means there is less oxygen for other marine life.The human health effects are not very well known but probably relate to the reactive oxygen species being an irritant.K. mikimotoi cells can also produce “mucilage”, a type of thick, gluey substance made of complex sugars, which can accumulate bacteria inside it. This can cause “sea foam”, which was evident on beaches last week.Unanswered questions remainA question for many people is whether increasing water temperatures make blooms of K. mikimotoi more likely.Another concern is whether nutrient runoff from farms, cities and aquaculture could cause more harmful algal blooms.Unfortunately, for Australia at least, the answer to these questions is we don’t know yet. While we know some harmful algal blooms do increase when nutrient runoff is higher, others actually prefer fewer nutrients or colder temperatures.We do know warmer water species seem to be moving farther south along the Australian coastline, changing phytoplankton species abundance and distribution.While some microalgal blooms can cause bioluminescence that is beautiful to watch, others such as K. mikimotoi can cause skin and respiratory irritations.If you notice discoloured water, fish deaths or excessive sea foam along the coast or in an estuary, avoid fishing or swimming in the area and notify local primary industry or environmental authorities in your state.

Algae blooms can be a problem for marine life and people but it’s not yet clear if warmer oceans and nutrient runoff are causing more of themConfronting images of dead seadragons, fish and octopuses washed up on South Australian beaches – and disturbing reports of “more than 100” surfers and beachgoers experiencing flu-like symptoms after swimming or merely breathing in sea spray – attracted international concern last week.Speculation about the likely cause ranged from pollution and algae to unusual bacterial infections or viruses. We can reveal the culprit was a tiny – but harmful – type of planktonic algae called Karenia mikimotoi. Continue reading...

Confronting images of dead seadragons, fish and octopuses washed up on South Australian beaches – and disturbing reports of “more than 100” surfers and beachgoers experiencing flu-like symptoms after swimming or merely breathing in sea spray – attracted international concern last week.

Speculation about the likely cause ranged from pollution and algae to unusual bacterial infections or viruses. We can reveal the culprit was a tiny – but harmful – type of planktonic algae called Karenia mikimotoi.

The South Australian government sent us water samples from Waitpinga beach, Petrel Cove beach, Encounter Bay boat ramp and Parsons Headland on Tuesday. We studied the water under the microscope and extracted DNA for genetic analysis.

Our results revealed high numbers of the tiny harmful algal species – each just 20 microns in diameter (where one micron is one thousandth of a millimetre). While relatively common in Australian coastal waters, blooms of K. mikimotoi occur only sporadically. But similar harmful algal blooms and fish kills due to K. mikimotoi have happened in the past, such as the 2014 bloom in Coffin Bay, South Australia. And this latest one won’t be the last.

Harmful algal blooms

Single-celled, microbial algae occur naturally in seawater all over the world.

They are also called phytoplankton because they float in the water column and photosynthesise like plants. “Phyto” comes from the Greek word for plant and “plankton” comes from the Greek word for wanderer, which relates to their floating movement with ocean currents and tides.

Like plants on land, the microalgae or phytoplankton in the ocean capture sunlight and produce up to half the oxygen in our atmosphere. There are more than 100,000 different species of microalgae. Every litre of seawater will normally contain a mixed group of these different microalgae species.

But under certain conditions, just a single species of microalgae can accumulate in one area and dominate over the others. If we are unlucky, the dominant species may be one that produces a toxin or has a harmful effect.

This so-called “harmful algal bloom” can cause problems for people and for marine life such as fish, invertebrates such as crabs, and even marine mammals such as whales and seals.

K. mikimotoi causes harmful deadly algal blooms in Asia, Europe, South Africa and South America, as well as Australia and New Zealand. Photograph: Anthony Rowland

There are hundreds of different species of harmful algae. Each produces its own type of toxin with a particular toxic effect.

Most of these toxic chemical compounds produced by harmful algae are quite well known, including neurotoxins that affect the brain. But others are more complicated, and the mechanisms of toxicity are poorly understood. This can make it more difficult to understand the factors leading to the deaths of fish and other marine life. Unfortunately, the toxins from K. mikimotoi fall into this latter category.

Introducing Karenia mikimotoi

The species responsible for recent events in South Australia, K. mikimotoi, causes harmful algal blooms in Asia, Europe, South Africa and South America, as well as Australia and New Zealand. These blooms all caused fish deaths, and some also caused breathing difficulties for some beachgoers.

The most drastic of these K. mikimotoi blooms have occurred in China over the past two decades. In 2012, more than 300 sq km of abalone farms were affected, causing about A$525m in lost production.

Explaining the toxic effects

Microalgae can damage the gills of fish and shellfish, preventing them from breathing. This is the main cause of death. But some studies have also found damage to the gastrointestinal tracts and livers of fish.

Tests using fish gill cells clearly show the dramatic toxic effect of K. mikimotoi. When the fish gill cells were exposed to intact K. mikimotoi cells, after 3.5 hours more than 80% of the fish cells had died.

Leafy seadragons were among the dead sea creatures that washed up on South Australian beaches. Photograph: Anthony Rowland

Fortunately, the toxin does not persist in the environment after the K. mikimotoi cells are dead. So once the bloom is over, the marine environment can recover relatively quickly.

Its toxicity is partly due to the algae’s production of “reactive oxygen species”, reactive forms of oxygen molecules which can cause the deaths of cells in high doses. K. mikimotoi cells may also produce lipid (fat) molecules that cause some toxic effects.

Finally, a very dense bloom of microalgae can sometimes reduce the amount of dissolved oxygen in the water column, which means there is less oxygen for other marine life.

The human health effects are not very well known but probably relate to the reactive oxygen species being an irritant.

K. mikimotoi cells can also produce “mucilage”, a type of thick, gluey substance made of complex sugars, which can accumulate bacteria inside it. This can cause “sea foam”, which was evident on beaches last week.

Unanswered questions remain

A question for many people is whether increasing water temperatures make blooms of K. mikimotoi more likely.

Another concern is whether nutrient runoff from farms, cities and aquaculture could cause more harmful algal blooms.

Unfortunately, for Australia at least, the answer to these questions is we don’t know yet. While we know some harmful algal blooms do increase when nutrient runoff is higher, others actually prefer fewer nutrients or colder temperatures.

We do know warmer water species seem to be moving farther south along the Australian coastline, changing phytoplankton species abundance and distribution.

While some microalgal blooms can cause bioluminescence that is beautiful to watch, others such as K. mikimotoi can cause skin and respiratory irritations.

If you notice discoloured water, fish deaths or excessive sea foam along the coast or in an estuary, avoid fishing or swimming in the area and notify local primary industry or environmental authorities in your state.

Read the full story here.
Photos courtesy of

In “Cancer Alley,” Black Communities Get All the pollution, But Few of the Jobs

This story was originally published by Grist and is reproduced here as part of the Climate Desk collaboration. Residents of the mostly Black communities sandwiched between chemical plants along the lower Mississippi River have long said they get most of the pollution but few of the jobs produced by the region’s vast petrochemical industry.  A new study led by Tulane University […]

This story was originally published by Grist and is reproduced here as part of the Climate Desk collaboration. Residents of the mostly Black communities sandwiched between chemical plants along the lower Mississippi River have long said they get most of the pollution but few of the jobs produced by the region’s vast petrochemical industry. A new study led by Tulane University backs up that view, revealing stark racial disparities across the US’s petrochemical workforce. Inequity was especially pronounced in Louisiana, where people of color were underrepresented in both high- and low-paying jobs at chemical plants and refineries.  “It was really surprising how consistently people of color didn’t get their fair share of jobs in the petrochemical industry,” said Kimberly Terrell, a research scientist with the Tulane Environmental Law Clinic. “No matter how you slice or dice the data by states, metro areas or parishes, the data’s consistent.” Toxic air pollution in Louisiana’s petrochemical corridor, an area often referred to as “Cancer Alley,” has risen in recent years. The burdens of pollution have been borne mostly by the state’s Black and poor communities, according to the US Environmental Protection Agency.  The Tulane study’s findings match what Cancer Alley residents have suspected for decades, said Joy Banner, co-founder of the Descendants Project, a nonprofit that advocates for Black communities in the parishes between New Orleans and Baton Rouge. “You hear it a lot—that Black people are not getting the jobs,” she said. “But to have the numbers so well documented, and to see just how glaring they are—that was surprising.” People of color were underrepresented in all of the highest-paying jobs among the 30 states with a large petrochemical industry presence, but Louisiana and Texas had “the most extreme disparities,” according to the study, which was published in the journal Ecological Economics.  While several states had poor representation on the upper pay scale, people of color were typically overrepresented in the lower earnings tiers.  In Texas, nearly 60 percent of the working-age population is nonwhite, but people of color hold 39 percent of higher-paying positions and 57 percent of lower-paying jobs in the chemical industry.  Louisiana was the only state in which people of color are underrepresented in both pay categories. People who aren’t white make up 41 percent of the working-age population but occupy just 21 percent of higher-paying jobs and about 33 percent of lower-paid jobs.  The study relied on data from the US Census Bureau, the Equal Employment Opportunity Commission, the Bureau of Labor Statistics and Louisiana Economic Development. The chemical industry disputed the study’s findings. “We recognize the importance of examining equity in employment, however, this study offers an incomplete and misleading portrayal of our industry and its contributions,” David Cresson, president and CEO of the Louisiana Chemical Association, said in a statement.  Cresson pointed to several industry-supported workforce development programs, scholarships and science camps aimed at “closing the training gap in Louisiana.” But the study indicates education and training levels aren’t at the root of underrepresentation among states or metro areas. Louisiana’s education gap was modest, with college attainment at 30 percent for white residents and 20 percent for people of color. In places like Lake Charles and St. John the Baptist Parish, where petrochemical jobs are common, the gap was minimal—five percentage points or less. The industry’s investments in education are “just public relations spin,” Banner said.  “The amount of money they’re investing in schools and various programs pales in comparison to how much they’re profiting in our communities,” she said. “We sacrifice so much and get so little in return.” Louisiana is also getting little from generous tax breaks aimed at boosting employment, the study found.  The state’s Industrial Tax Exemption Program has granted 80 percent to 100 percent property tax exemptions to companies that promise to create new jobs. For each job created in Cameron Parish, where large natural gas ports have been built in recent years, companies were exempted from almost $590,000 in local taxes. In St. John, each job equated to about $1 million in uncollected tax revenue. “This tradeoff of pollution in exchange for jobs was never an equal trade,” said Gianna St. Julien, one of the study’s authors. “But this deal is even worse when the overwhelming majority of these companies’ property taxes are not being poured back into these struggling communities.”   This coverage was made possible through a partnership between Grist and Verite News, a nonprofit news organization producing in-depth journalism in underserved communities in the New Orleans area.

Air, Light Pollution Increase Risk Of Thyroid Cancer In Children

By Dennis Thompson HealthDay ReporterFRIDAY, April 18, 2025 (HealthDay News) -- Babies exposed to air and light pollution have a higher risk of...

By Dennis Thompson HealthDay ReporterFRIDAY, April 18, 2025 (HealthDay News) -- Babies exposed to air and light pollution have a higher risk of developing childhood thyroid cancer, a new study says.Airborne particle pollution and outdoor artificial light both increased babies’ risk of developing thyroid cancer before they turned 20, researchers recently reported in the journal Environmental Health Perspectives.“These results are concerning, especially given how widespread both of these exposures are,” lead researcher Nicole Deziel, an environmental epidemiologist at the Yale School of Public Health, said in a news release.“Fine particulate matter is found in urban air pollution due to automobile traffic and industrial activity, and artificial light at night is common, particularly in densely populated urban areas,” she added.Both fine particle pollution and light pollution are considered environmental carcinogens that disrupt the body’s endocrine system, including thyroid function, researchers said in background notes.Particle pollution pose a threat because they’re small enough to enter the bloodstream. The airborne particles can be smaller than 2.5 micrometers, while a human hair is 50 to 70 micrometers wide, according to the U.S. Environmental Protection Agency (EPA).And outdoor artificial light can suppress melatonin and alter a person’s sleep/wake rhythm, which also influences hormone-regulated cancers, researchers said.For the study, researchers compared data from 736 young people diagnosed with thyroid cancer before age 20 with that from 36,800 healthy kids, all of whom hail from California.The team assessed the cancer patients’ exposure to air and light pollution based on their families’ home address when they were born.Results showed that for every 10 micrograms per cubic meter increase in particle pollution, a child’s odds of developing thyroid cancer rose by 7% overall.The strongest associations between air pollution and thyroid cancer were found among 15- to 19-year-olds (8% increased risk) and Hispanic children (13% increased risk), researchers said.Likewise, children born in areas with high levels of outdoor artificial light were as much as 25% more likely to develop thyroid cancer."Thyroid cancer is among the fastest growing cancers among children and adolescents, yet we know very little about what causes it in this population," Deziel said."Our study is the first large-scale investigation to suggest that these exposures early in life — specifically to PM2.5 and outdoor light at night — may play a role in this concerning trend,” she added.Compared to adults, children are often diagnosed with thyroid cancer at more advanced stages, with larger and harder-to-treat tumors, researchers said.Even if kids survive thyroid cancer, they can suffer aftereffects like headaches, physical disabilities and mental fatigue that will haunt them throughout their lives, researchers said.Researchers emphasized that more work is needed to replicate and validate their findings.“In the meantime,” Deziel noted, “our results point to the critical importance of addressing environmental factors in childhood cancer research. Reducing exposures to air pollution and managing light pollution could be important steps in protecting children's health.”SOURCE: Yale School of Public Health, news release, April 15, 2025Copyright © 2025 HealthDay. All rights reserved.

 A Chicago law could shift where heavy industry operates — and who bears the burden of pollution

As Trump dismantles protections, the ordinance is a test case for environmental justice.

This coverage is made possible through a partnership between Grist and WBEZ, a public radio station serving the Chicago metropolitan region. Chicago city leaders are set to consider a major overhaul in how and where polluting businesses are allowed to open, nearly two years after the city settled a civil rights complaint that alleged a pattern of discrimination threatening the health of low-income communities of color. The measure, expected to be introduced Wednesday, would transform how heavy industry is located and operated in the country’s third largest city. If passed into law, it would require city officials to assess the cumulative pollution burden on communities before approving new industrial projects. As the Trump administration dismantles protections for poor communities facing lopsided levels of pollution, Chicago’s ordinance is a test case for local action under a federal government hostile toward environmental justice. Over the past three months, the Trump administration has already undone long-standing orders to address uneven environmental burdens at the federal level and challenged government programs monitoring environmental justice issues across the country.  Now, advocates are hoping the local legislation becomes a blueprint for how state and local governments can leverage zoning and permitting to protect vulnerable communities from becoming sacrifice zones.  “The Trump administration is trying to erase history,” said Gina Ramirez, the Natural Resources Defense Council’s Midwest director of environmental health. “You can’t erase our industrial past — it’s literally haunting us.” Chicago’s industrial history is especially pronounced in low-income communities on the city’s South and West sides. The proposed ordinance would give these communities a voice in the permitting process via a new environmental justice advisory board, Ramirez said.  “Nobody wants to be sick,” said Cheryl Johnson, an environmental activist on the Far South Side who has been advocating for pollution protections for almost 40 years. Read Next Why a tree-planting nonprofit in Chicago is suing the Trump administration Juanpablo Ramirez-Franco The Chicago ordinance is named after Johnson’s mother, Hazel Johnson, who started fighting in the 1970s for the health of her neighbors at a public housing community surrounded by a “toxic doughnut” of polluters. Cheryl Johnson runs People for Community Recovery, an organization started by her mother, with the same mission to protect human health. “The most important thing — and the only thing that we get — is good health or bad health,” Johnson said. “That’s what my mother fought for.” In 2020, Johnson’s group, along with several other local environmental justice organizations, launched a civil rights complaint over the city’s role in the relocation of a metal-shredding operation from its longtime home on the North Side to a majority Black and Latino neighborhood on the far South Side of the city. An investigation by the U.S. Department of Housing and Urban Development concluded in 2022 that Chicago had long placed polluters in low-income areas, while sparing majority-white affluent neighborhoods.  In a binding agreement with former President Joe Biden’s administration, the city promised to offer a legal fix. Former mayor Lori Lightfoot signed the agreement with HUD hours before she left office in 2023. Her successor, Mayor Brandon Johnson, vowed to follow the agreement and said that September that an ordinance proposal would be offered in short order. But weeks and months turned into years, and community, health, and environmental advocates complained that the mayor was slow-walking his promises. Nearly two years later, the city is finally set to deliver.  Not all community groups are happy with the proposal. Theresa McNamara, an activist with the Southwest Environmental Alliance, said at a recent public meeting she didn’t think the measure would go far enough. She called it a “weak piece of crap” based on her understanding of the main points. Read Next The odds are Illinois won’t hit its 2030 climate goals Juanpablo Ramirez-Franco Experts said the law’s success would depend on the city’s will to execute and enforce it. “There’s a lot of states and even cities that have assessment tools, but the question is, what do you do with those?” said Ana Baptisa, an environmental policy professor at The New School in New York. In New Jersey, Baptista helped pass a similar ordinance — then the first of its kind — through the Newark City Council in 2016. Since then, local and state governments across the country have followed suit. At least eight states have passed this type of legislation, including California, Minnesota, New York, and Delaware.  Still, Baptista said Newark’s bill has failed to rein in polluting industries. “It proved to be what we feared: a sort of formality that oftentimes doesn’t even get completed,” she said.  Even without power to deny or constrain new pollution sources, the advisory board itself marks progress, according to Oscar Sanchez, whose Southeast Environmental Task Force helped file the original civil rights complaint,.  Sanchez added that as the federal government retreats from its commitments to environmental justice, state and local entities are on the front line of buffering communities from greater pollution burdens. “We are pushing the needle of what people can try to achieve in their own communities,” he said. This story was originally published by Grist with the headline  A Chicago law could shift where heavy industry operates — and who bears the burden of pollution on Apr 16, 2025.

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