Latest news with #marineecology
Yahoo
11-07-2025
- Science
- Yahoo
Expired Cans of Salmon From Decades Ago Contained a Huge Surprise
Canned salmon are the unlikely heroes of an accidental back-of-the-pantry natural history museum – preserving decades of Alaskan marine ecology in brine and tin. Parasites can reveal a lot about an ecosystem, since they tend to get up in the business of multiple species. But unless they cause a major issue for humans, historically we've mostly ignored them. That's a problem for parasite ecologists, like Natalie Mastick and Chelsea Wood from the University of Washington, who had been searching for a way to retroactively track the effects of parasites on Pacific Northwestern marine mammals. So when Wood got a call from Seattle's Seafood Products Association, asking if she'd take boxes of dusty old expired cans of salmon – some dating back to the 1970s – off their hands, her answer was, unequivocally, yes. Related: The cans had been set aside for decades as part of the association's quality control process, but in the hands of the ecologists, they became an archive of excellently preserved specimens; not of salmon, but of worms. While the idea of worms in your canned fish is a bit stomach-turning, these roughly 0.4-inch (1-centimeter) long marine parasites, anisakids, are harmless to humans when killed during the canning process. "Everyone assumes that worms in your salmon is a sign that things have gone awry," said Wood when the research was published last year. "But the anisakid life cycle integrates many components of the food web. I see their presence as a signal that the fish on your plate came from a healthy ecosystem." Anisakids enter the food web when they are eaten by krill, which in turn are eaten by larger species. This is how anisakids end up in the salmon, and eventually, the intestines of marine mammals, where the worms complete their life cycle by reproducing. Their eggs are excreted into the ocean by the mammal, and the cycle begins again. "If a host is not present – marine mammals, for example – anisakids can't complete their life cycle and their numbers will drop," said Wood, the paper's senior author. The 178 tin cans in the 'archive' contained four different salmon species caught in the Gulf of Alaska and Bristol Bay across a 42-year period (1979–2021), including 42 cans of chum (Oncorhynchus keta), 22 coho (Oncorhynchus kisutch), 62 pink (Oncorhynchus gorbuscha), and 52 sockeye (Oncorhynchus nerka). Although the techniques used to preserve the salmon do not, thankfully, keep the worms in pristine condition, the researchers were able to dissect the filets and calculate the number of worms per gram of salmon. They found worms had increased over time in chum and pink salmon, but not in sockeye or coho. "Seeing their numbers rise over time, as we did with pink and chum salmon, indicates that these parasites were able to find all the right hosts and reproduce," said Mastick, the paper's lead author. "That could indicate a stable or recovering ecosystem, with enough of the right hosts for anisakids." But it's harder to explain the stable levels of worms in coho and sockeye, especially since the canning process made it difficult to identify the specific species of anisakid. "Though we are confident in our identification to the family level, we could not identify the [anisakids] we detected at the species level," the authors write. "So it is possible that parasites of an increasing species tend to infect pink and chum salmon, while parasites of a stable species tend to infect coho and sockeye." Mastick and colleagues think this novel approach – dusty old cans turned ecological archive – could fuel many more scientific discoveries. It seems they've opened quite a can of worms. This research was published in Ecology and Evolution. An earlier version of this article was published in April 2024. Melting Glaciers Could Reawaken Hundreds of Earth's Volcanoes Blue Sharks May Be Secret Chameleons, Scientists Discover Scientists Just Debunked 'Earth's Oldest Impact Crater'
Yahoo
08-07-2025
- Climate
- Yahoo
'Toxic to anything with gills': algal bloom spreading
A massive, toxic algal bloom that has killed thousands of fish, sharks and marine animals has spread to a capital city river. The bloom of the microalgae, karenia mikimotoi, was identified off South Australia's Fleurieu Peninsula in March, and grew to more than 4400 sq km, close to the size of Kangaroo Island. It has been breaking up in recent weeks, spreading north into Spencer Gulf, south into the Coorong wetlands and along Adelaide's beaches in Gulf St Vincent. SA Environment Minister Susan Close said the "devastating" bloom had now been detected in Adelaide's Port River. "Karenia mikimotoi has appeared in the Port River and is at reasonably high concentrations around Garden Island and Outer Harbour," she told reporters on Tuesday. "Nothing near like the concentrations that we saw at the beginning of this bloom ... but nonetheless elevated amounts." Ms Close said the algae had killed tens of thousands of marine animals from almost 400 species, and authorities were concerned some may be wiped out in the region. "Although not toxic to humans, it is toxic to anything with gills and anything that seeks to breathe underwater, and we have seen just the beginnings of the extent of the devastation that's occurred under the sea," she said. SA Primary Industries and Regional Development Minister Clare Scriven said the government had started talks with the Commonwealth about recovery assistance. It is not possible for the federal government to declare the incident a national disaster because the definition does not currently include algal blooms, she said. The SA government announced backdated licence fee relief for commercial fishers, aquaculture and charter boat operators impacted by the bloom. About $500,000 worth of fees will be waived to help operators, with a promise that more help will be available if needed. SA Professional Fishers Association chair Ben Barnes said some fishers reported seeing "absolute destruction of the environment" and the industry was yet to see the worst of the disaster. "It will be a recurring thing that we just won't know for the next five to six years," he said. "The extent of the devastation is unknown ... it will have an effect on larvae and eggs and production." Experts believe there are three potential contributing factors causing the bloom. One is a marine heatwave that started in September 2024, with sea temperatures about 2.5C warmer than usual, combined with calm conditions, light winds and small swells. Another is the 2022/23 River Murray flood that washed extra nutrients into the sea. That was followed by an unprecedented cold-water upwelling in summer of 2023/24 that brought nutrient-rich water to the surface.
Yahoo
05-07-2025
- Science
- Yahoo
Devastating change taking place at Australia's 'best beach': '20 million of them'
It was voted as Australia's Best Beach a few short months ago, but under the surface a dark shift is taking place. An army of invaders is turning the sea bed into a barren wasteland, and experts fear the threat could destroy up to 50 per cent of reefs along the state's coastline if more isn't done to stop it. In February, a stretch of beaches along the famed Bay of Fires on Tasmania's east coast was awarded the title of the best beach in the country. But Dr John Keane, a fisheries research fellow at the Institute for Marine and Antarctic Studies, says underneath the surface it's a different story. Longspined sea urchins, also known as centro from their scientific name centrostephanus rodgersii, have arrived in Tasmania's oceans in droves. Dr Keane estimates the population has grown to more than 20 million. "What makes them so damaging is they've got a very broad spectrum of diet," he said. As well as targeting lush kelp forests, they also eat sessile invertebrates like sponges, corals, anemones and sea squirts. "They basically eat anything on the reefscape and they leave that barren rock that can extend for kilometres." The urchins have been found all the way down the state's east coast, reaching as far south as Port Arthur. Several climate factors are working together to draw the urchin larvae further south than ever before. Tasmania's waters are warming at a rate of twice the global average, according to the CSIRO. The East Australian Current is extending further south, pushing warmer water towards Tasmania. Combined with the general warming of climate change, it's creating a "double effect", Dr Keane said. This creates an environment suitable for the centro to thrive – and take over. Dr Keane believes harvesting urchins is a viable solution, as the buttery golden roe is considered a delicacy and can sell for more than $500 per kg. Up until recently, 500 tonnes of centro were being harvested every year and some sites were seeing a successful decline in numbers alongside the return of kelp. While it was a win for the environment, it was also a win for the Tasmanian economy. The fledgling industry has created jobs in multiple areas, injecting revenue into the state and adding a new taste to Tasmania's already impressive spread of local flavours. Recently, the efforts to manage the urchins have slowed down after the closure of one of the state's major processing facilities. Dr Keane said the company was harvesting around 400 tonnes of centro annually – about 80 per cent of state's collective total – which has left a hole in the market. While smaller businesses are trying to fill that void, they don't have the capacity to handle the same volume of urchins. "There are plenty of divers wanting to go catch these sea urchins. But there's not the market and the processing capacity to be able to do that at the moment," Dr Keane said. Because the catches have declined, data is now showing evidence of the urchin population growing. "The other option is to go out there and kill them without processing, which can be done and it's quite effective, but it's highly expensive," he added. If no control measures were in place, Dr Keane estimates 50 per cent of Tasmania's reefs would barren in 10 years. He's hopeful that change is coming, and the biggest difference could be made through government support. "We need funding to support the industry. That's the solution," Dr Keane said. "Temperate reefs just aren't as sexy as tropical reefs. The Great Southern Reef gets 1 per cent of the funding that the tropical reefs do. "It just doesn't have that iconic image of snorkelling on a coral reef. All the tropical fish. Even though temperate reefs have some amazing biodiversity and kelps and sponge gardens and it's so beautiful, it just doesn't get the light of day, unfortunately." Tasmanians will head to the polls in a matter of weeks for the state election, with Dr Keane reminding residents that change begins with a vote. "If we don't get this fishery up and running, we're just going to continue to lose more reefs, and then that all negatively impacts other commercial fisheries such as rock lobster and abalone, it'll impact tourism, and impact biodiversity and the environment more generally." Do you have a story tip? Email: newsroomau@ You can also follow us on Facebook, Instagram, TikTok, Twitter and YouTube.
Yahoo
04-07-2025
- Climate
- Yahoo
Algal bloom turns coast into a 'marine graveyard'
A massive, unstoppable, toxic algal bloom that has turned beaches into "marine graveyards" has prompted calls for a federal investigation. The microalgae, karenia mikimotoi, was identified off South Australia's Fleurieu Peninsula in March. The bloom grew to an unprecedented scale, close to the size of Kangaroo Island, at more than 4400 sq km, and as deep as 25m. It's now breaking up and has spread into most of Gulf St Vincent, including along Adelaide's beaches and south into the Coorong wetlands. There have been hundreds of reports of marine deaths, ranging from sharks and penguins to popular fishing species such as flathead, squid, crabs, and rock lobsters. Greens senator Sarah Hanson-Young said the bloom was a horrific and heartbreaking "environmental catastrophe". "When parliament resumes in two weeks time in Canberra, I will be moving for a federal parliamentary inquiry," she told reporters on Friday. "We need proper investigation and proper federal support." Beaches have become "graveyards" for marine species, and the fishing and tourism industries have been significantly impacted, she said. Ms Hanson-Young claimed the federal government ignored warnings about the algae before it took hold. "It is very concerning that the country's leading marine scientists have been ignored and dismissed," she said. Experts believe there are three potential plausible contributing factors causing the bloom, the SA government said. One is a marine heatwave that started in September 2024, with sea temperatures about 2.5°C warmer than usual, combined with calm conditions, light winds and small swells. Another is the 2022-23 River Murray flood washing extra nutrients into the sea and an unprecedented cold-water upwelling in summer 2023-24 that brought nutrient-rich water to the surface. SA Environment Minister Susan Close said the bloom had lasted longer than experts thought it would. "Now that it's here, it's going to be hard to get rid of," she said. "It's easy to feel helpless, because the bloom itself is something that we can't stop." The SA government met with impacted commercial fishers, tourism operators and local councils about support packages. "It's been very, very distressing for people, and it's affected people's livelihoods," Ms Close said. The state government is also starting work on a recovery plan. This could include creating artificial reefs to help build up marine life, restocking fish into the ocean and increasing the number of marine sanctuary zones along the coast. "Although we're looking forward to the end of this experience, we cannot assume it's the last time we've had it," Ms Close said. Karenia mikimotoi is in SA's waterways and waiting to come back to life when conditions are right, she said. "This is what climate change means." OzFish previously said more than 200 species of fish, sharks and other marine creatures had been killed by the algae bloom. This includes rarely encountered deepwater sharks and leafy sea dragons, and recreational fishing species like flathead, squid, crabs, and rock lobsters. Karenia mikimotoi is toxic to fish and invertebrates but does not cause long-term harmful effects in humans. But, exposure to discoloured or foamy water can cause short-term skin or eye irritation and respiratory symptoms, including coughing or shortness of breath. The last large event of this type of algae recorded in SA was at Coffin Bay in 2014.
Yahoo
03-07-2025
- Science
- Yahoo
This was the best place on Earth to see great white sharks—then they vanished
Built like a torpedo with rows of terrifying 2.5-inch teeth, the world's largest predatory shark is an intimidating sight. So intimidating that some might think an ocean without great white sharks (Carcharodon carcharias) would be a good thing. But their loss causes a ripple effect that transforms the entire ecosystem. A new study in Frontiers in Marine Science shows what happens when sharks vanish. Seal Island, off South Africa's False Bay was once a great white hotspot—one of the few places on Earth where the sharks could be seen surging out of the water to capture prey. 'It was air Jaws,' says marine ecologist Neil Hammerschlag, executive director of the Shark Research Foundation Inc. and a coauthor on the new study. 'I don't think there's anything more remarkable in nature than seeing a 2,000-pound great white flying out of the air with a seal in its mouth.' When the predators disappeared, researchers and conservationists pointed fingers at both encroaching orcas and humans as the culprit. But Hammerschlag and his colleagues, who began studying the ecosystem around the island in 2000 long before the vanishing, saw some surprising changes. Twenty years ago, Seal Island was 'the greatest place on earth to see great whites,' recalls Hammerschlag, who also serves as president of Atlantic Shark Expeditions. Around 2010, white shark numbers around False Bay started dropping off, and the decline got steeper from 2015 on. By 2018, the great whites were gone. Exactly why the sharks vanished remains a mystery. 'The departure of the white shark is really open to discussion,' says Greg Skomal, a shark biologist with Massachusetts Division of Marine Fisheries who wasn't involved in the study. Some suggest the animals fled because killer whales moved in. Orcas can kill a shark in minutes by precisely carving out its nutrient-rich liver. Hammerschlag thinks humans could also be to blame, as nearby shark nets kill 'somewhere between 25 and 30 great whites a year.' Even a small loss can drive the population into decline, he says, because great whites become sexually mature late in life—males in their 20s and females in their 30s—and have small litters of up to 12 pups. (A baby great white shark led scientists to a huge nursery near NYC.) Sharks are thought to keep marine habitats healthy by removing weak and sick animals from the food chain and keeping things in balance. But proving these impacts in a real-world habitat this is challenging. 'These kinds of ecosystem effects are very difficult for us to tease out because they require long-term data sets,' says Skomal. In False Bay, Hammerschlag's and his colleagues partnered with an ecotourism company, allowing them to spend 'full days on the water, 200 days a year.' The team collected over 20 years of data, from before, during and after the great whites' disappearance. 'We saw things happen that we'd never expect,' Hammerschlag says. Broadnose sevengill sharks (Notorynchus cepedianus) suddenly appeared—sometimes as many as 15 in one day. These animals usually hang out several kilometers away in kelp beds, which offer protection from great white attacks. 'From nothing to double digits. It's just mind blowing,' he says. The Cape fur seal (Arctocephalus pusillus pusillus) population also increased. Safe from the threat of sharks, seals were rafting—floating in groups, like a living raft—and going after the cage divers' bait. 'That would have been suicide just a few years earlier,' he says. Both seals and sevengills were on the menu for great whites, so it made sense to see their numbers rise. But Hammerschlag and his colleagues also wanted to find out if the populations of animals that seals and sevengills eat had changed, too. Luckily, scientist Lauren De Vos had installed cameras in 2012 to get a snapshot of fish populations at the time for another study. Hammerschlag's team followed the same method—even down to borrowing the same equipment. As expected, the new data showed a decline in seal prey like anchovies and Cape horse mackerel and sevengill prey, such as smoothhound sharks and pyjama catsharks. This zigzag of impacts—white sharks vanish, their prey increases and, in turn, the animals they eat declines—suggests this isn't caused by problems like pollution or development. 'If habitat destruction was occurring, you would think everything would go down,' rather than some species declining and some increasing, Hammerschlag says. But the study numbers don't reflect that. The small area of False Bay, with relatively few species, made figuring out some of these food chain impacts easier. 'Hammerschlag has that connectivity mapped out because he knows what eats what,' says Skomal. The more species in an ecosystem, the more difficult it is to map the food chain and track the impacts when an animal is lost. Establishing the relationships between animals in a broader area, like the Gulf of Maine, which has hundreds of species, would be much harder, he says. (Cape Cod may have the highest density of great white sharks in the world.) Scientists in South Africa have noticed great white shark population changes in other ecosystems, too, and researchers believe the factors driving these changes are similar to the ones cited in False Bay. Shark behavioral ecologist Lacey Williams has seen 'pretty significant changes' in Mossel Bay and Plettenberg Bay, or 'Plett.' In Plett, shark appearances used to be 'random,' she says. Then around 2022, locals started noticing the sharks 'in a very predictable spot' around Robberg Peninsula. Before long, the sharks started arriving later in the season and then sightings dwindled. In Mossel Bay, great white sightings stayed relative steady until around 2021 but have declined since then. In May 2022, drone footage emerged of two orcas killing a white shark. 'That was really the beginning of the significant changes of white sharks in Mossel Bay,' she says. Last year, the cage diving company that Williams works with saw 'less than one handful' of sightings between April and December, she says. South Africa's white shark population had already been declining 'prior to the arrival of these two very famous, sexy scapegoats,' Williams says. 'The orcas are like pouring kerosene on an already burning bonfire.' Human have driven the broader declines too, she says. Long line fisheries have targeted demersal sharks—that live just above the seabed, like critically endangered soupfin sharks (Galeorhinus galeus) and smooth-hound sharks—for decades. These species are a key food source for white sharks so removing them has a ripple effect. As in False Bay, shark nets are another concern. Many people mistakenly believe that these form a barrier to protect swimmers from sharks. 'It doesn't really protect people from anything,' says Williams. 'The only thing it really does is kill wildlife indiscriminately.' Although there's no silver bullet, potential solutions include Shark Spotters, drones, and SharkSafe BarrierTM technology. This magnetic device, which imitates kelp forests, seems to deter white sharks. These systems are expensive, but the investment is worth it, says Williams. 'If we don't have an ecosystem, we're going to lose tourism.' It currently seems too early to tell how the decline in white sharks in Mossel Bay and Plettenberg might impact the wider ecosystem. 'It's worth looking into, though,' Williams says. 'I think it's safe to say we'll see changes.' Back in False Bay, one possible outcome of all of these shifts is that seals and sevengills might run out of animals to eat. Could the ecosystem collapse? It's too early to know. 'That would be the next question,' says Skomal. 'Is it too many seals?' Today, great whites' incredible aerial displays are a thing of the past at Seal Island. 'You'd never know this was a great white hotspot,' Hammerschlag says. For him, seeing how the whole ecosystem has changed shows the importance of enforcing shark protections and using non-lethal methods to protect beachgoers from shark bites. 'We can't change the orcas' behavior,' he says, 'But we can stop the netting program. That's kind of archaic.'
