Latest news with #OzFish
Indian Express
14-05-2025
- Science
- Indian Express
Sharks, octopuses among 200 species killed by toxic algae in Australia
A toxic algae bloom off the coast of South Australia, which has been affecting the coastline since March, led to the killing of more than 200 marine species, including sharks and octopuses. The toxic algal bloom has now spread to about 150km on the coastline and nearly half (47%) of the dead species belonged to ray-finned fish while another 26% were sharks and rays, according to an analysis by OzFish, The Guardian reported. The algae responsible is called Karenia mikimotoi and it is reported to be like a toxic blanket which has smothered marine life, the OzFish South Australia project manager Brad Martin said. The algae produces poison which acts like a blanket above the water body and suffocates marine life, including fish, rays and sharks to death. 'It's an unprecedented event, because the bloom has continued to build and build,' wildlife scientist Vanessa Pirotta said, BBC reported. More than 200 marine species off the coast of South Australia (SA) have been killed by a weeks-long toxic algae explosion, in what conservationists have described as 'a horror movie for fish'. The algal bloom – a rapid increase in the population of algae in water systems -… — Rita Rosenfeld (@rheytah) May 13, 2025 Martin further explained that toxic algae can suffocate fish from their gills, cause haemorrhaging by attacking their red blood cells, and act as a neurotoxin which could attack the water creature's nervous system and cause unusual behaviour. 'This is why some fish and sharks are acting so strangely and why many of the dead have a red tinge, it is like a horror movie for fish,' Martin said. One of the causes of algal bloom identified by the state's environmental department is the ongoing marine heatwave, which has led to a rise in water temperature by 2.5 degree celsius. Since the density of algal bloom is large in nature, it effectively means that oxygen is being taken out of the water and hence the fishes are suffocating to death. This serious event has been documented with people sending and uploading pictures and videos of dead wildlife washed up on beaches. According to South Australia's environment minister, the outbreak has grown to an unprecedented magnitude. (with inputs from BBC, The Guardian)
The Independent
13-05-2025
- Health
- The Independent
Toxic algae bloom kills hundreds of marine species in Australia
A toxic algal bloom in South Australia has killed over 200 marine species, including deepwater sharks, octopuses and leafy sea dragons, in what conservationists have called one of the worst marine die-offs the region has ever seen. The algae, Karenia mikimotoi, has spread across more than 150km of coastline since it was first detected in March, nearly the size of the Kangaroo Island. Since the algae appeared, local people and scientists have observed mass deaths of fish, shellfish, sharks, sea dragons, rays, cuttlefish, and deepwater species along the southern coastline. South Australia 's environment minister said the outbreak had grown to an unprecedented scale. "It is a larger bloom than we have ever seen before," Susan Close said. Scientists say that it is being fuelled by an ongoing marine heatwave, with sea temperatures 2.5C above average, and calm conditions that allow it to thrive. Described as a 'toxic blanket', the bloom suffocates fish by damaging their gills and attacking red blood cells and the nervous system. It can lead to haemorrhaging and erratic behaviour in affected animals. 'It is like a horror movie for fish,' Brad Martin of OzFish told The Guardian. Ms Close said there was not much the government could do. "The only thing that is going to break this bloom up is a change in the weather and starting to get strong westerly winds," she said. An analysis of over 1,400 citizen science reports found around half of the dead species were ray-finned fish and more than a quarter were sharks and rays. Cephalopods like squid and cuttlefish and crustaceans such as crabs and lobsters were among the affected species as well. Though not toxic to humans, the algae has caused skin irritation and respiratory symptoms in some beachgoers. Authorities have temporarily closed several oyster farms and banned pipi harvesting in parts of South Australia. An alarm about the bloom was first sounded by beachgoers back in March after thick foam and dead marine animals washed up on Waitpinga and Parsons beach on the Fleurieu Peninsula. Professor Shauna Murray, a marine biologist at the University of Technology Sydney, identified the algae under a microscope and through DNA analysis. She told The Guardian that K mikimotoi was known to produce reactive oxygen that could suffocate marine life. South Australia's government said winds needed to disperse the algal bloom were being delayed by persistent high-pressure systems – another symptom of shifting climate patterns. Authorities say the full ecological and economic impact of the bloom is yet to be understood but environmental groups urge improved monitoring and stronger action on marine heatwaves, which are growing much more frequent as oceans continue to warm. Alongside the marine heatwave, southern Australia is suffering through one of the worst droughts on record. Ms Close sounded the alarm on how climate change was making the crisis worse. The minister said ocean monitoring showed 'a full-scale climate emergency in our coastal waters', with the bloom extending across an area roughly the size of Kangaroo Island and up to 20m deep. 'These extreme marine heat waves are not just anomalies, they are the new reality. And our marine ecosystems are the first casualties.'
Express Tribune
13-05-2025
- Health
- Express Tribune
South Australia hit by mass deaths of fish, sharks and octopuses due to toxic algae: Research says
Photo: Algal bloom become the reason for marine life death in South Australia Listen to article A toxic algal bloom stretching along South Australia's coastline since March has killed more than 200 marine species, including sharks, leafy sea dragons and octopuses, researchers said. The bloom, caused by the harmful algae "Karenia mikimotoi", has acted like a 'toxic blanket', suffocating marine life, said Brad Martin, South Australian project manager at OzFish, a conservation group. Analysis of more than 1,400 citizen scientist reports by OzFish found that 47% of the species killed were ray-finned fish, while 26% were sharks and rays. Cephalopods such as squid, cuttlefish and octopuses accounted for 7% of the casualties, while decapods – including crabs, lobsters and prawns – made up a further 6%. 'This type of bloom creates a low-oxygen environment, and marine animals simply cannot escape it,' Martin said. Karenia blooms are rare but deadly, releasing toxins and depleting oxygen levels in affected waters. Scientists say changing ocean conditions may be fuelling more frequent and severe outbreaks. Coastal communities and fisheries have reported widespread beach strandings, with some species never before seen in such numbers in die-offs. Local environmental groups have called for increased monitoring and long-term marine health strategies as ocean temperatures rise. 'It can choke fish by blocking their gills, trigger internal bleeding by damaging red blood cells, and act as a neurotoxin that disrupts the brain and nervous system, leading to erratic behaviour,' he said. 'That's why some fish and sharks have been behaving abnormally, and why many of the dead animals appear reddish – it's like a horror scene beneath the waves.' South Australia's environment department said the algal bloom is being fuelled by a prolonged marine heatwave, with sea temperatures around 2.5 degrees Celsius above average, combined with calm seas, low wind, and minimal swell. Though not harmful to humans, the algae can trigger skin irritation and respiratory issues, and has led to widespread marine deaths. First detected in mid-March off the Fleurieu Peninsula, the bloom has since spread to coastal areas across the state's south-east, including the Gulf St Vincent, Yorke Peninsula and Kangaroo Island, according to OzFish's Brad Martin. OzFish, a group focused on restoring aquatic ecosystems, expressed concern over the long-term consequences for fisheries, as the bloom has affected fish of all life stages – from juveniles to mature, breeding adults – along with their natural prey. South Australia's environment minister, Susan Close, said several oyster farms and commercial pipi harvesting operations had been suspended due to the outbreak, calling it an unprecedented event for the state. 'This is a major algal bloom with serious effects on marine species,' she said, adding that in some areas, the bloom has penetrated as deep as 20 metres. Professor Shauna Murray, a marine biologist at the University of Technology Sydney who identified the algae using microscopy and DNA analysis, said around 100 species of harmful algae are known globally, each with distinct toxic impact. Although not yet fully understood, Karenia mikimotoi is believed to release a reactive form of oxygen that damages fish gill cells, effectively suffocating them, said Professor Shauna Murray. The current bloom spans more than 150 kilometres along the coast, but it is not the largest recorded in Australia. In 2013, a different algal species, Alexandrium catenella, covered Tasmania's entire east coast, halting aquaculture and seafood operations for nearly four months, Murray added. Large-scale algal blooms can also reduce oxygen levels in the water, said Professor Martina Doblin, an oceanographer at the University of Technology Sydney who specialises in harmful algal events. Karenia mikimotoi is unusual, Doblin explained, in that it can draw energy from both sunlight and feeding on other organisms. This dual capability, combined with abnormally warm and stable ocean temperatures, has allowed the bloom to expand and persist over time. 'At low levels, it forms part of the natural food chain. But when it grows in large concentrations, it becomes a serious threat,' she said. Though rare, such blooms can have serious consequences for local economies. Doblin said better early warning and response systems could help minimise the impact of future outbreaks. A spokesperson for South Australia's environment department said strong westerly winds are needed to disperse the algae. However, the presence of ongoing high-pressure systems across southern Australia has delayed the arrival of those wind.
BBC News
13-05-2025
- Science
- BBC News
South Australia fish kill: Toxic algae poisons 200 marine species
More than 200 marine species off the coast of South Australia (SA) have been killed by a weeks-long toxic algae explosion, in what conservationists have described as "a horror movie for fish".The algal bloom - a rapid increase in the population of algae in water systems - has been spreading since March, growing to about 4,500 sq km (3,400 sq miles), or roughly the size of nearby Kangaroo Island."It's an unprecedented event, because the bloom has continued to build and build," said Vanessa Pirotta, a wildlife scientists say the algae produces poisons which "act like a toxic blanket that suffocates" a wide range of marine life, including fish, rays and sharks. Brad Martin, SA project manager for OzFish, a non-profit organisation that protects fishing habitats, said that while algal blooms are not uncommon, the "massive" scale of the current event has had a dramatic impact on marine produced by the algae can cause "gill and tissue damage" by attacking the red blood cells, Mr Martin told the large density of the bloom also means that oxygen is being taken out of the water, "so we know that the fish are suffocating"."It is like a horror movie for fish," he event has been widely documented by people sending in pictures of dead wildlife washed up on beaches. The effect on sharks and rays has been particularly graphic, with large numbers washing up on beaches "bright red", showing indications of haemorrhaging.A three-metre great white shark was among those found dead in recent weeks. Among the more than 200 species that have been killed, which range from the smallest of baby fish to great whites, some are more vulnerable than others. Reef species like crabs and pufferfishes have been the worst hit, as they are less mobile and can't swim away from the toxic the algae isn't harmful to humans, those exposed to high doses can experience skin irritation and respiratory symptoms such as coughing or breathing SA government has advised people to avoid swimming at beaches where there is discoloured water and blooms occur during sunny and warm conditions, and SA has had a marine heatwave since last September, with temperatures about 2.5 degrees warmer than has also been experiencing unseasonably warm conditions since March, which has further driven the size and duration of the current algal last time SA recorded a large event of this type of toxic algae was in 2014, according to the state's environment and water spread has also affected some commercial fisheries, which have pre-emptively closed harvest coastal businesses have also seen a dip in visitors due to the sheer number of dead marine life washing up on shore. Meanwhile, researchers and the SA government are continuing to monitor the bloom as it moves west.
The Guardian
12-05-2025
- Health
- The Guardian
‘A horror movie': sharks and octopuses among 200 species killed by toxic algae off South Australia
More than 200 marine species, including deepwater sharks, leafy sea dragons and octopuses, have been killed by a toxic algal bloom that has been affecting South Australia's coastline since March. Nearly half (47%) of the dead species were ray-finned fish and a quarter (26%) were sharks and rays, according to OzFish analysis of 1,400 citizen scientist reports. Cephalopods – like squid, cuttlefish and octopuses – accounted for 7%, while decapods – like crabs, lobsters and prawns – made up 6% of species reported dead or washed up on beaches. The OzFish South Australian project manager, Brad Martin, said the harmful bloom – of Karenia mikimotoi algae – was like a toxic blanket that smothered marine life. Get Guardian Australia environment editor Adam Morton's Clear Air column as an email 'It can suffocate fish from their gills, cause haemorrhaging by attacking their red blood cells, and act as a neurotoxin and attack the fish's nervous system and brain, causing unusual behaviour,' he said. 'This is why some fish and sharks are acting so strangely and why many of the dead have a red tinge – it is like a horror movie for fish.' According to the state's environment department, the algal bloom was being driven by an ongoing marine heatwave – with water temperatures 2.5C hotter than usual – as well as relatively calm marine conditions with little wind and small swells. While not toxic to humans, the algae could cause skin irritations and respiratory symptoms, and caused mass mortalities in marine life. The algae was first identified in mid March on the state's Fleurieu Peninsula and had since expanded to coastlines across the south-east, the Gulf St Vincent, the Yorke Peninsula and Kangaroo Island, Martin said. OzFish, an organisation dedicated to restoring waterways and fish habitats, was concerned about the long-term impact on fisheries, given the bloom had killed fish at all ages – from fingerlings, or baby fish, up to full-grown breeding fish – as well as their food sources. Several oyster farms and the commercial harvesting of pipis have been temporarily closed due to the outbreak, which has been unprecedented for South Australia, its environment minister, Susan Close, said. 'We're talking about a very large algal bloom with a significant impact on marine life,' she said, with some parts of the outbreak going 20 metres deep. Marine biologist Prof Shauna Murray from the University of Technology Sydney – who identified the algae under the microscope and by analysing its DNA – said there were about 100 species of harmful algae, each with a different toxic effect. Sign up to Clear Air Australia Adam Morton brings you incisive analysis about the politics and impact of the climate crisis after newsletter promotion While still not well understood, Karenia mikimotoi was thought to produce a reactive oxygen that caused gill cell damage in fish – which meant they could not breathe, Murray said. While the current bloom stretched over 150km, it was not the worst in Australia's history. In 2013, a bloom of a different species, Alexandrium catenella, had 'basically covered the entire east coast of Tasmania and shut down their aquaculture and seafood industries for about four months', she said. Large blooms could also reduce the amount of oxygen in the water, said Prof Martina Doblin, a UTS oceanographer who specialises in algal blooms. Karenia mikimotoi is an unusual algae that was capable of feeding on sunlight as well as other organisms, she said. And it is these characteristics, combined with unusually high and stable water temperatures, that enabled the algal bloom to become so large and sustained. 'In low abundance, it is part of the natural food web. But in high abundance, it can become very problematic,' Doblin said. While such events were rare, they can be devastating for local economies, she said. Improved early warning systems and management had the potential to limit the damage. Strong westerly winds were ultimately needed to dissipate the algae, according to a spokesperson for SA's environment department. 'However, persistent high-pressure systems affecting southern Australia have delayed these winds,' they said.
