Latest news with #HarborBranchOceanographicInstitute
Miami Herald
7 days ago
- Science
- Miami Herald
Are sharks an ‘overwhelming problem' in Florida? What the experts say
Florida anglers say sharks are snatching their catches at unprecedented rates, calling it an 'overwhelming problem' and blaming a boom in Gulf shark numbers. But scientific research paints a more complicated picture. Scientists who study sharks acknowledge that depredation — the act of fish being eaten by an underwater predator while on a fisherman's line — is a growing concern in some areas, especially Florida. They cite several potential drivers of increased shark-human conflict, including climate change-related shifts in shark behavior and rebounding populations of some species. But they note that changes in human behavior — such as more people fishing and heightened awareness of shark encounters through social media — may also play a role. Now, researchers are working to learn when and why these encounters happen and how to prevent them. Matt Ajemian, an associate research professor studying the issue at Florida Atlantic University's Harbor Branch Oceanographic Institute, cautions against calling shark depredation a crisis, noting that historical accounts show similar encounters have long occurred. 'I don't call it a problem,' he said. 'I try to call it a challenge.' Ajemian and research coordinator Mike McCallister are leading a NOAA-funded project launched in 2021 to study when and where depredation happens and what might reduce it. Their team has turned to anglers for help, gathering information through surveys, video footage, genetic testing and social media reports to identify patterns. In their surveys, about 43% of Florida anglers said sharks had stolen their catch, with rates ranging from 10% to 60% depending on the region, season and species, researchers said. When it happened, sharks took nearly a third to almost half of the day's haul. The data came from quarterly surveys of 4,000 randomly selected saltwater fishing license holders over a year, with about 2,200 responding. Because participation was voluntary and limited to license holders, researchers said, the results don't represent all Florida anglers. They also tracked posts in a Facebook group with more than 6,500 members, logging real-time reports from offshore anglers across the state. Researchers said survey responses and online reports point to clear patterns in when and where depredation occurs. It was most common in the spring and summer, with hotspots in Southeast Florida, the Keys and the Panhandle. Rates spiked during busy fishing periods such as red snapper and grouper season openings. Snapper and grouper were the most frequently lost catches, followed by king mackerel, cobia, tuna and sailfish, according to the study. McCallister said the data also showed longer fights gave sharks more time to strike, and anglers targeting deep-water or migratory species were more likely to be affected than those fishing inshore. Bull sharks and sandbar sharks were the main culprits, based on angler accounts and genetic swabs from bitten fish, but they weren't the only ones. 'The videos have shown us that it's not always sharks that are the problem,' said Mike McCallister, FAU research coordinator. McCallister said goliath grouper, a massive fish that can weigh up to 800 pounds, is another species that can target an angler's catch underwater. 'Most of these depredations occur below the water line, where people can't see them,' said McCallister. Many anglers blame a growing shark population for increasing depredation. Researchers say that while some shark populations appear to be rebounding after past declines, their numbers likely remain below historical levels. 'My inkling is that sharks are returning on an increasing trajectory thanks to solid management and a lot of federal effort,' Ajemian said. He and McCallister note that in the 1960s and 1970s, U.S. agencies even encouraged commercial shark fishing to diversify the seafood supply. But when shark populations declined sharply in the 1980s and early 1990s, it prompted the launch of national management plans in 1993. Recently, NOAA Fisheries credited these management efforts with increases in several shark species in the Atlantic, including blacktip, sandbar, tiger and white sharks. Mahmood Shivji, director of the Guy Harvey Research Institute at Nova Southeastern University, also cites research that juvenile bull shark numbers are rising in Gulf estuaries. However, scientists say that it's important to put the numbers in context. Mike Heithaus, a marine ecologist at Florida International University, says that while some populations are recovering, most remain below historical levels. For younger anglers, today's encounters may feel unprecedented, but researchers say they could be closer to historic norms. 'That shifting baseline concept is real,' McCallister said. Scientists say broader environmental changes may also be driving shark encounters. Overfishing and warming waters could be affecting where sharks go and what they eat, Shivji said, and climate change is altering how deep they dive and how they reproduce. 'Environmental conditions also impact the distribution of natural prey species that sharks eat, and as these prey species move to different locations, the sharks follow their food,' Shivji said. Sharks themselves are also vulnerable. Heithaus says that climate change could further disrupt food webs, create low-oxygen zones and push predators and prey into new areas. 'Climate change is also going to have big effects on shark prey and their competitors, which is likely to disrupt predator-prey interactions,' Heithaus said. Researchers say more study is needed to pinpoint the causes of angler-shark encounters and whether depredation is actually increasing or simply being reported more often, including through social media. To help answer that question, McCallister is examining long-term recreational fishing records for his doctoral research. In the meantime, McCallister says many frustrated anglers are already adjusting tactics, switching gear, moving spots or cutting trips short to account for shark behavior. 'Most anglers are trying to reduce depredation on their own,' McCallister said. Researchers are also testing ways to keep sharks at bay, including deterrent devices that use magnets to disrupt their electrical senses. So far, they've shown mixed results. One device, called the Zeppelin, showed early promise but only works for bottom fishing, as it can cling to metal parts of a boat or tackle, fouling lines, researchers said. It costs around $80. Other deterrents being tested, such as devices that emit electric pulses, can cost more than $1,000. Some anglers told Ajemian and McCallister the price is too high, especially since the device can be lost during use. The search for answers is also playing out at the federal level. The SHARKED Act passed the House in January. If it gets signed into law, it would create a federal task force to study shark depredation and recommend solutions. Until then, scientists say continued research will be key to helping anglers, policymakers and the public better understand the challenge and the best ways to address it. While recognizing that shark activity can frustrate anglers, scientists also emphasize that the predators play a vital role in the ecosystem — one that is important to protect as their populations continue to decline globally. 'We are still learning a lot about how important they can be, but they can keep populations of prey in check and help protect the base of food webs, like seagrasses, by keeping them from being overgrazed,' Heithaus said. 'The big picture is that many shark species have been severely overfished worldwide, and many species, especially the ones that live in the open ocean and on reefs, have declined by around 50 to 90%,' Shivji said. 'Their now-rapid population declines are very concerning given the essential roles that sharks play in keeping our oceans in balance and healthy,' Shivji added, 'making it very important to appreciate these amazing animals, their essential place and role in ocean ecosystems, and helping to prevent many species from going extinct.'
CNN
15-05-2025
- Science
- CNN
31 million tons of supercharged seaweed is creeping toward beaches in Florida and around the Caribbean
The Atlantic Ocean has a toxic seaweed problem. Floating in brown islands of algae, this year's sargassum bloom has already broken its own size record by millions of tons — and the growing season isn't done yet. Now stretching across some 5,500 miles of ocean, the annual bloom is more than just an eyesore: Sargassum hurts ecosystems and economies wherever its overgrown arms reach. And they are spreading into Florida's waterways, coating marinas and beaches in the Miami area. 'Sargassum goes from being a very beneficial resource of the North Atlantic to becoming what we refer to as … a harmful algal bloom, when it comes ashore in excessive biomass,' said Brian LaPointe, a research professor at Florida Atlantic University's Harbor Branch Oceanographic Institute. 'What we have seen since 2011 are excessive inundation events all around the Caribbean region, the Gulf, as well as the South Florida region,' explained LaPointe, who has studied the seaweed for decades. As it rots on shore, it emits harmful gases— an infamous stench. It's a blight on beaches that repels tourists during the high-travel season, ultimately hurting towns that rely on tourism to fuel their economy. Rising ocean temperatures due to human-caused climate change have spurred this sargassum surplus, supercharging the seaweed. In April, the University of South Florida estimated this year's bloom is already at 31 million tons — '40% more' than the previous record from June 2022, according to LaPointe. The sargassum bloom itself is not a new phenomenon. It's long provided a home to species from sea turtles to fish as winds and tides push it from the coast of West Africa toward Brazil, up into the Caribbean and the Gulf of Mexico. 'Sargassum has been around for eons. Colombus ran into it right in the Sargasso Sea,' La Pointe told CNN. 'But what we are seeing now is above and beyond what we had historically.' Sargassum's growth is also being driven by an excess of nitrogen in the water, LaPointe said — and that's a key factor behind this year's monster bloom. Some nitrogen may be coming from the atmosphere, carried in the air from the burning of fossil fuels or dust from the Sahara Desert. But there's one major source: agricultural fertilizers. Used in the American heartland as well as in the Amazon basin where there's been rapid deforestation for farming, the nitrogen-rich fertilizers are likely making their way into the Mississippi and Amazon Rivers as runoff, which then carries it into the Atlantic. And the Amazon basin has notched its lowest water levels on record amid two straight years of extreme drought — the worst since records began being kept in 1950. 'What happens when you have a severe drought in the world's largest watershed? You get all this organic matter that dries up. Plants dry up and die. And then, when the rain hits, what happens? All those nutrients wash out,' LaPointe hypothesized, adding that 'first flush' events like this are full of concentrations of nitrogen and phosphorus at peak levels, which go on to feed the bloom's growth explosion. Unsurprisingly, the constant inundation of stinky, brown seaweed along the coast is not good for economies driven by tourism. This year's bloom has already been making an appearance along Florida's east coast, from the Keys to Saint Augustine, according to reports on a sargassum monitoring site, and southeastern Florida could see more in the coming weeks. The unwanted algae has also been spotted in popular destinations from Mexico to Barbados and farther south. 'It's not good for the environment, because what you're smelling is hydrogen sulfide gas which is toxic,' LaPointe said. In some places, the beaches are cleared of seaweed from sunrise to sunset — an expensive endeavor combing up sargassum that inundates the coastline with every wave. Some of the machinery used to clean the beaches adds its own pollution to the scenic environment, too. 'Resorts have gone out to their beaches with heavy equipment like front-end loaders, bulldozers, dump trucks to try to remove the sargassum to make those beaches available,' LaPointe said, as tourists don't want mounds of sargassum to mar their tropical views. 'The tourists check out, and they don't come back.' This is a major tangle for places like Mexico's Yucatán Peninsula, which exists in the heart of the sargassum belt between the Gulf of Mexico and the Caribbean Sea. The problem has become so pronounced along the Riviera Maya, Mara Lezama, the governor of Quintana Roo, a state in the peninsula, has taken to social media to say her state is working with the Mexican Navy to collect the seaweed in the water while also installing a nearly 6-mile barrier in the water to protect Quintana Roo's Mahahual, Playa del Carmen and Puerto Morelos beaches. The barriers, which are similar to booms that contain oil spills, are just over a yard deep and are designed to keep the seaweed from reaching the coast. As it approaches, the decaying sargassum can also create health problems for animals and humans. 'When it arrives to the coastal area, it creates a shadow from the sun, so everything that is below — all the life is not getting sunlight. So, it starts to affect the ecosystem, coastal ecosystem, and many things die,' said Christian Appendini, professor at the Universidad Nacional Autónoma de México. 'Then when it gets over the beach, it starts to decompose. And when it decomposes, it releases all the contaminants it has.' Ammonia is another problem emitted by the decaying seaweed, LaPointe noted. The chemical compound 'strips the oxygen out of the waters along our coastal ecosystems like mangroves, coral reefs, seagrass beds,' he said. 'When you see the mass inundation events along the beaches, say in the Mexican Riviera, for example, you don't see many fish or crabs,' LaPointe continued. 'If you do, they're probably dead because there's no oxygen in that water.' With sargassum cementing itself as an ongoing problem, some are looking into putting the seaweed to good use, instead. Appendini says research is ongoing to find ways to use the sargassum for biofuel, building bricks, or as membranes for cleaning water, since it is particularly absorbent. 'They absorb all the heavy metals and contaminants in the water,' he told CNN. 'That's also why sargassum can be very toxic, because when it's drifting in the ocean it's just assimilating all the toxic elements in the ocean like cadmium, arsenic and other minerals and elements.' There's also the possibility of carbon sequestration by sinking the excessive biomass to the bottom of the ocean. And there's interest in possibly using sargassum to replace one of the globe's other problems: plastic. 'If we could harvest this sargassum and produce this biodegradable product that could replace single use plastics, that would begin to restore the oceans regarding the serious plastic pollution that we're seeing,' LaPointe said. As the sargassum situation remains pervasive for more than a decade now, Appendini said the record-breaking bloom should make the world pay attention. 'I think the sargassum blooms are like a warning that we need to be more mindful of how we are developing in this world,' Appendini said. 'We need to change … how we do things.' CNN's Norma Galeana contributed to this story.
Yahoo
15-05-2025
- Science
- Yahoo
31 million tons of toxic seaweed is creeping toward beaches in Florida and around the Caribbean
The Atlantic Ocean has a toxic seaweed problem. Floating in brown islands of algae, this year's sargassum bloom has already broken its own size record by millions of tons — and the growing season isn't done yet. Now stretching across some 5,500 miles of ocean, the annual bloom is more than just an eyesore: Sargassum hurts ecosystems and economies wherever its overgrown arms reach. And they are spreading into Florida's waterways, coating marinas and beaches in the Miami area. 'Sargassum goes from being a very beneficial resource of the North Atlantic to becoming what we refer to as … a harmful algal bloom, when it comes ashore in excessive biomass,' said Brian LaPointe, a research professor at Florida Atlantic University's Harbor Branch Oceanographic Institute. 'What we have seen since 2011 are excessive inundation events all around the Caribbean region, the Gulf, as well as the South Florida region,' explained LaPointe, who has studied the seaweed for decades. For more than a decade, Atlantic coastal communities have been inundated by more and more sargassum. Images of white sand beaches stretching into azure waters have been altered by the toxic and putrid invasion. In the water, it's home to larvae and other organisms that can irritate the skin of any passing swimmers. As it rots on shore, it emits harmful gases— an infamous stench. It's a blight on beaches that repels tourists during the high-travel season, ultimately hurting towns that rely on tourism to fuel their economy. Rising ocean temperatures due to human-caused climate change have spurred this sargassum surplus, supercharging the seaweed. In April, the University of South Florida estimated this year's bloom is already at 31 million tons — '40% more' than the previous record from June 2022, according to LaPointe. The sargassum bloom itself is not a new phenomenon. It's long provided a home to species from sea turtles to fish as winds and tides push it from the coast of West Africa toward Brazil, up into the Caribbean and the Gulf of Mexico. 'Sargassum has been around for eons. Colombus ran into it right in the Sargasso Sea,' La Pointe told CNN. 'But what we are seeing now is above and beyond what we had historically.' Sargassum's growth is also being driven by an excess of nitrogen in the water, LaPointe said — and that's a key factor behind this year's monster bloom. Some nitrogen may be coming from the atmosphere, carried in the air from the burning of fossil fuels or dust from the Sahara Desert. But there's one major source: agricultural fertilizers. Used in the American heartland as well as in the Amazon basin where there's been rapid deforestation for farming, the nitrogen-rich fertilizers are likely making their way into the Mississippi and Amazon Rivers as runoff, which then carries it into the Atlantic. And the Amazon basin has notched its lowest water levels on record amid two straight years of extreme drought — the worst since records began being kept in 1950. 'What happens when you have a severe drought in the world's largest watershed? You get all this organic matter that dries up. Plants dry up and die. And then, when the rain hits, what happens? All those nutrients wash out,' LaPointe hypothesized, adding that 'first flush' events like this are full of concentrations of nitrogen and phosphorus at peak levels, which go on to feed the bloom's growth explosion. Unsurprisingly, the constant inundation of stinky, brown seaweed along the coast is not good for economies driven by tourism. This year's bloom has already been making an appearance along Florida's east coast, from the Keys to Saint Augustine, according to reports on a sargassum monitoring site, and southeastern Florida could see more in the coming weeks. The unwanted algae has also been spotted in popular destinations from Mexico to Barbados and farther south. 'It's not good for the environment, because what you're smelling is hydrogen sulfide gas which is toxic,' LaPointe said. In some places, the beaches are cleared of seaweed from sunrise to sunset — an expensive endeavor combing up sargassum that inundates the coastline with every wave. Some of the machinery used to clean the beaches adds its own pollution to the scenic environment, too. 'Resorts have gone out to their beaches with heavy equipment like front-end loaders, bulldozers, dump trucks to try to remove the sargassum to make those beaches available,' LaPointe said, as tourists don't want mounds of sargassum to mar their tropical views. 'The tourists check out, and they don't come back.' This is a major tangle for places like Mexico's Yucatán Peninsula, which exists in the heart of the sargassum belt between the Gulf of Mexico and the Caribbean Sea. The problem has become so pronounced along the Riviera Maya, Mara Lezama, the governor of Quintana Roo, a state in the peninsula, has taken to social media to say her state is working with the Mexican Navy to collect the seaweed in the water while also installing a nearly 6-mile barrier in the water to protect Quintana Roo's Mahahual, Playa del Carmen and Puerto Morelos beaches. The barriers, which are similar to booms that contain oil spills, are just over a yard deep and are designed to keep the seaweed from reaching the coast. As it approaches, the decaying sargassum can also create health problems for animals and humans. 'When it arrives to the coastal area, it creates a shadow from the sun, so everything that is below — all the life is not getting sunlight. So, it starts to affect the ecosystem, coastal ecosystem, and many things die,' said Christian Appendini, professor at the Universidad Nacional Autónoma de México. 'Then when it gets over the beach, it starts to decompose. And when it decomposes, it releases all the contaminants it has.' Ammonia is another problem emitted by the decaying seaweed, LaPointe noted. The chemical compound 'strips the oxygen out of the waters along our coastal ecosystems like mangroves, coral reefs, seagrass beds,' he said. 'When you see the mass inundation events along the beaches, say in the Mexican Riviera, for example, you don't see many fish or crabs,' LaPointe continued. 'If you do, they're probably dead because there's no oxygen in that water.' With sargassum cementing itself as an ongoing problem, some are looking into putting the seaweed to good use, instead. Appendini says research is ongoing to find ways to use the sargassum for biofuel, building bricks, or as membranes for cleaning water, since it is particularly absorbent. 'They absorb all the heavy metals and contaminants in the water,' he told CNN. 'That's also why sargassum can be very toxic, because when it's drifting in the ocean it's just assimilating all the toxic elements in the ocean like cadmium, arsenic and other minerals and elements.' There's also the possibility of carbon sequestration by sinking the excessive biomass to the bottom of the ocean. And there's interest in possibly using sargassum to replace one of the globe's other problems: plastic. 'If we could harvest this sargassum and produce this biodegradable product that could replace single use plastics, that would begin to restore the oceans regarding the serious plastic pollution that we're seeing,' LaPointe said. As the sargassum situation remains pervasive for more than a decade now, Appendini said the record-breaking bloom should make the world pay attention. 'I think the sargassum blooms are like a warning that we need to be more mindful of how we are developing in this world,' Appendini said. 'We need to change … how we do things.' CNN's Norma Galeana contributed to this story.
CNN
15-05-2025
- Science
- CNN
31 million tons of toxic seaweed is creeping toward beaches in Florida and around the Caribbean
The Caribbean Mexico The AmazonFacebookTweetLink Follow The Atlantic Ocean has a toxic seaweed problem. Floating in brown islands of algae, this year's sargassum bloom has already broken its own size record by millions of tons — and the growing season isn't done yet. Now stretching across some 5,500 miles of ocean, the annual bloom is more than just an eyesore: Sargassum hurts ecosystems and economies wherever its overgrown arms reach. And they are spreading into Florida's waterways, coating marinas and beaches in the Miami area. 'Sargassum goes from being a very beneficial resource of the North Atlantic to becoming what we refer to as … a harmful algal bloom, when it comes ashore in excessive biomass,' said Brian LaPointe, a research professor at Florida Atlantic University's Harbor Branch Oceanographic Institute. 'What we have seen since 2011 are excessive inundation events all around the Caribbean region, the Gulf, as well as the South Florida region,' explained LaPointe, who has studied the seaweed for decades. As it rots on shore, it emits harmful gases— an infamous stench. It's a blight on beaches that repels tourists during the high-travel season, ultimately hurting towns that rely on tourism to fuel their economy. Rising ocean temperatures due to human-caused climate change have spurred this sargassum surplus, supercharging the seaweed. In April, the University of South Florida estimated this year's bloom is already at 31 million tons — '40% more' than the previous record from June 2022, according to LaPointe. The sargassum bloom itself is not a new phenomenon. It's long provided a home to species from sea turtles to fish as winds and tides push it from the coast of West Africa toward Brazil, up into the Caribbean and the Gulf of Mexico. 'Sargassum has been around for eons. Colombus ran into it right in the Sargasso Sea,' La Pointe told CNN. 'But what we are seeing now is above and beyond what we had historically.' Sargassum's growth is also being driven by an excess of nitrogen in the water, LaPointe said — and that's a key factor behind this year's monster bloom. Some nitrogen may be coming from the atmosphere, carried in the air from the burning of fossil fuels or dust from the Sahara Desert. But there's one major source: agricultural fertilizers. Used in the American heartland as well as in the Amazon basin where there's been rapid deforestation for farming, the nitrogen-rich fertilizers are likely making their way into the Mississippi and Amazon Rivers as runoff, which then carries it into the Atlantic. And the Amazon basin has notched its lowest water levels on record amid two straight years of extreme drought — the worst since records began being kept in 1950. 'What happens when you have a severe drought in the world's largest watershed? You get all this organic matter that dries up. Plants dry up and die. And then, when the rain hits, what happens? All those nutrients wash out,' LaPointe hypothesized, adding that 'first flush' events like this are full of concentrations of nitrogen and phosphorus at peak levels, which go on to feed the bloom's growth explosion. Unsurprisingly, the constant inundation of stinky, brown seaweed along the coast is not good for economies driven by tourism. This year's bloom has already been making an appearance along Florida's east coast, from the Keys to Saint Augustine, according to reports on a sargassum monitoring site, and southeastern Florida could see more in the coming weeks. The unwanted algae has also been spotted in popular destinations from Mexico to Barbados and farther south. 'It's not good for the environment, because what you're smelling is hydrogen sulfide gas which is toxic,' LaPointe said. In some places, the beaches are cleared of seaweed from sunrise to sunset — an expensive endeavor combing up sargassum that inundates the coastline with every wave. Some of the machinery used to clean the beaches adds its own pollution to the scenic environment, too. 'Resorts have gone out to their beaches with heavy equipment like front-end loaders, bulldozers, dump trucks to try to remove the sargassum to make those beaches available,' LaPointe said, as tourists don't want mounds of sargassum to mar their tropical views. 'The tourists check out, and they don't come back.' This is a major tangle for places like Mexico's Yucatán Peninsula, which exists in the heart of the sargassum belt between the Gulf of Mexico and the Caribbean Sea. The problem has become so pronounced along the Riviera Maya, Mara Lezama, the governor of Quintana Roo, a state in the peninsula, has taken to social media to say her state is working with the Mexican Navy to collect the seaweed in the water while also installing a nearly 6-mile barrier in the water to protect Quintana Roo's Mahahual, Playa del Carmen and Puerto Morelos beaches. The barriers, which are similar to booms that contain oil spills, are just over a yard deep and are designed to keep the seaweed from reaching the coast. As it approaches, the decaying sargassum can also create health problems for animals and humans. 'When it arrives to the coastal area, it creates a shadow from the sun, so everything that is below — all the life is not getting sunlight. So, it starts to affect the ecosystem, coastal ecosystem, and many things die,' said Christian Appendini, professor at the Universidad Nacional Autónoma de México. 'Then when it gets over the beach, it starts to decompose. And when it decomposes, it releases all the contaminants it has.' Ammonia is another problem emitted by the decaying seaweed, LaPointe noted. The chemical compound 'strips the oxygen out of the waters along our coastal ecosystems like mangroves, coral reefs, seagrass beds,' he said. 'When you see the mass inundation events along the beaches, say in the Mexican Riviera, for example, you don't see many fish or crabs,' LaPointe continued. 'If you do, they're probably dead because there's no oxygen in that water.' With sargassum cementing itself as an ongoing problem, some are looking into putting the seaweed to good use, instead. Appendini says research is ongoing to find ways to use the sargassum for biofuel, building bricks, or as membranes for cleaning water, since it is particularly absorbent. 'They absorb all the heavy metals and contaminants in the water,' he told CNN. 'That's also why sargassum can be very toxic, because when it's drifting in the ocean it's just assimilating all the toxic elements in the ocean like cadmium, arsenic and other minerals and elements.' There's also the possibility of carbon sequestration by sinking the excessive biomass to the bottom of the ocean. And there's interest in possibly using sargassum to replace one of the globe's other problems: plastic. 'If we could harvest this sargassum and produce this biodegradable product that could replace single use plastics, that would begin to restore the oceans regarding the serious plastic pollution that we're seeing,' LaPointe said. As the sargassum situation remains pervasive for more than a decade now, Appendini said the record-breaking bloom should make the world pay attention. 'I think the sargassum blooms are like a warning that we need to be more mindful of how we are developing in this world,' Appendini said. 'We need to change … how we do things.' CNN's Norma Galeana contributed to this story.
CNN
15-05-2025
- Science
- CNN
31 million tons of toxic seaweed is creeping toward beaches in Florida and around the Caribbean
The Atlantic Ocean has a toxic seaweed problem. Floating in brown islands of algae, this year's sargassum bloom has already broken its own size record by millions of tons — and the growing season isn't done yet. Now stretching across some 5,500 miles of ocean, the annual bloom is more than just an eyesore: Sargassum hurts ecosystems and economies wherever its overgrown arms reach. And they are spreading into Florida's waterways, coating marinas and beaches in the Miami area. 'Sargassum goes from being a very beneficial resource of the North Atlantic to becoming what we refer to as … a harmful algal bloom, when it comes ashore in excessive biomass,' said Brian LaPointe, a research professor at Florida Atlantic University's Harbor Branch Oceanographic Institute. 'What we have seen since 2011 are excessive inundation events all around the Caribbean region, the Gulf, as well as the South Florida region,' explained LaPointe, who has studied the seaweed for decades. As it rots on shore, it emits harmful gases— an infamous stench. It's a blight on beaches that repels tourists during the high-travel season, ultimately hurting towns that rely on tourism to fuel their economy. Rising ocean temperatures due to human-caused climate change have spurred this sargassum surplus, supercharging the seaweed. In April, the University of South Florida estimated this year's bloom is already at 31 million tons — '40% more' than the previous record from June 2022, according to LaPointe. The sargassum bloom itself is not a new phenomenon. It's long provided a home to species from sea turtles to fish as winds and tides push it from the coast of West Africa toward Brazil, up into the Caribbean and the Gulf of Mexico. 'Sargassum has been around for eons. Colombus ran into it right in the Sargasso Sea,' La Pointe told CNN. 'But what we are seeing now is above and beyond what we had historically.' Sargassum's growth is also being driven by an excess of nitrogen in the water, LaPointe said — and that's a key factor behind this year's monster bloom. Some nitrogen may be coming from the atmosphere, carried in the air from the burning of fossil fuels or dust from the Sahara Desert. But there's one major source: agricultural fertilizers. Used in the American heartland as well as in the Amazon basin where there's been rapid deforestation for farming, the nitrogen-rich fertilizers are likely making their way into the Mississippi and Amazon Rivers as runoff, which then carries it into the Atlantic. And the Amazon basin has notched its lowest water levels on record amid two straight years of extreme drought — the worst since records began being kept in 1950. 'What happens when you have a severe drought in the world's largest watershed? You get all this organic matter that dries up. Plants dry up and die. And then, when the rain hits, what happens? All those nutrients wash out,' LaPointe hypothesized, adding that 'first flush' events like this are full of concentrations of nitrogen and phosphorus at peak levels, which go on to feed the bloom's growth explosion. Unsurprisingly, the constant inundation of stinky, brown seaweed along the coast is not good for economies driven by tourism. This year's bloom has already been making an appearance along Florida's east coast, from the Keys to Saint Augustine, according to reports on a sargassum monitoring site, and southeastern Florida could see more in the coming weeks. The unwanted algae has also been spotted in popular destinations from Mexico to Barbados and farther south. 'It's not good for the environment, because what you're smelling is hydrogen sulfide gas which is toxic,' LaPointe said. In some places, the beaches are cleared of seaweed from sunrise to sunset — an expensive endeavor combing up sargassum that inundates the coastline with every wave. Some of the machinery used to clean the beaches adds its own pollution to the scenic environment, too. 'Resorts have gone out to their beaches with heavy equipment like front-end loaders, bulldozers, dump trucks to try to remove the sargassum to make those beaches available,' LaPointe said, as tourists don't want mounds of sargassum to mar their tropical views. 'The tourists check out, and they don't come back.' This is a major tangle for places like Mexico's Yucatán Peninsula, which exists in the heart of the sargassum belt between the Gulf of Mexico and the Caribbean Sea. The problem has become so pronounced along the Riviera Maya, Mara Lezama, the governor of Quintana Roo, a state in the peninsula, has taken to social media to say her state is working with the Mexican Navy to collect the seaweed in the water while also installing a nearly 6-mile barrier in the water to protect Quintana Roo's Mahahual, Playa del Carmen and Puerto Morelos beaches. The barriers, which are similar to booms that contain oil spills, are just over a yard deep and are designed to keep the seaweed from reaching the coast. As it approaches, the decaying sargassum can also create health problems for animals and humans. 'When it arrives to the coastal area, it creates a shadow from the sun, so everything that is below — all the life is not getting sunlight. So, it starts to affect the ecosystem, coastal ecosystem, and many things die,' said Christian Appendini, professor at the Universidad Nacional Autónoma de México. 'Then when it gets over the beach, it starts to decompose. And when it decomposes, it releases all the contaminants it has.' Ammonia is another problem emitted by the decaying seaweed, LaPointe noted. The chemical compound 'strips the oxygen out of the waters along our coastal ecosystems like mangroves, coral reefs, seagrass beds,' he said. 'When you see the mass inundation events along the beaches, say in the Mexican Riviera, for example, you don't see many fish or crabs,' LaPointe continued. 'If you do, they're probably dead because there's no oxygen in that water.' With sargassum cementing itself as an ongoing problem, some are looking into putting the seaweed to good use, instead. Appendini says research is ongoing to find ways to use the sargassum for biofuel, building bricks, or as membranes for cleaning water, since it is particularly absorbent. 'They absorb all the heavy metals and contaminants in the water,' he told CNN. 'That's also why sargassum can be very toxic, because when it's drifting in the ocean it's just assimilating all the toxic elements in the ocean like cadmium, arsenic and other minerals and elements.' There's also the possibility of carbon sequestration by sinking the excessive biomass to the bottom of the ocean. And there's interest in possibly using sargassum to replace one of the globe's other problems: plastic. 'If we could harvest this sargassum and produce this biodegradable product that could replace single use plastics, that would begin to restore the oceans regarding the serious plastic pollution that we're seeing,' LaPointe said. As the sargassum situation remains pervasive for more than a decade now, Appendini said the record-breaking bloom should make the world pay attention. 'I think the sargassum blooms are like a warning that we need to be more mindful of how we are developing in this world,' Appendini said. 'We need to change … how we do things.' CNN's Norma Galeana contributed to this story.
