Latest news with #CollegeofMarineScience
Yahoo
11-06-2025
- Science
- Yahoo
Rivers can supercharge Gulf hurricanes, USF study finds
Hurricane Idalia caught forecasters by surprise in 2023 when the storm rapidly intensified into a major hurricane overnight as it hurtled toward Florida's west coast. The Gulf of Mexico was record-hot that summer, fueling tropical activity and a mass coral reef die-off, but Idalia's jump from a Category 1 to a Category 4 still seemed extreme to experts. A new study led by researchers at the University of South Florida's St. Petersburg campus has found another unreported boost to the deadliest storm to strike the U.S. that season: fresh water from nearby rivers. Their research also pointed out a blind spot in forecasting hard-to-predict storm intensification that has become increasingly common in recent hurricane seasons. Weeks before Idalia formed, intense rain fed rivers along the Florida Panhandle and coastal Alabama, flushing a massive plume of fresh water into the Gulf of Mexico, researchers found. This clear river water mixing with the salty Gulf created a barrier that trapped ocean heat and helped supercharge a strengthening Idalia, said Chuanmin Hu, an author of the study and professor of oceanography at the university's College of Marine Science. These plumes aren't uncommon in the gulf, which is fed by 33 rivers. But this one's size, which stretched from the Mississippi River to the Florida Keys, combined with Idalia's path north to create conditions ripe for rapid intensification. 'In order for this to happen, you need to have the hurricane at the right time, at the right location, and that is pretty rare,' Hu said. 'But this time, it's like a perfect storm.' Hurricanes undergo rapid intensification when wind speeds catapult more than 35 mph within 24 hours. Ocean heat acts as an energy source for hurricanes, allowing them to strengthen quickly over especially hot patches. But a storm's high winds often mix up cooler water that lies deeper below the surface, sapping its energy. Idalia's hurricane-force winds weren't powerful enough to disrupt waters trapped beneath the freshwater plume, Hu said. 'This barrier layer reduced mixing of ocean water so the cold water was not brought up to the surface enough to cool down the hurricane,' he said. Hu and his team came across their discovery while studying harmful algal blooms. One of their underwater gliders — fully autonomous vehicles used to gather ocean data — passed just over 40 miles away from Idalia's eye and another was swallowed in the storm's path. The devices collected salinity and temperature data that showed how the storm had benefitted from the freshwater plume. Hu was careful not to overstate river plumes' significance to hurricane strength, but said experts need to pay attention to every ingredient in a forecast. Current hurricane models that are relied heavily upon by national forecasters take into account factors like vertical wind shear, water temperature and air moisture, but neglect others like the water's salinity, Hu said. For example, high wind shear, which tears down hurricane strength, was expected to hamper Idalia as it approached landfall, forecasters said at the time. 'There are many things that can impact hurricane trajectory and intensity, so this is only one of those,' he said. 'This is just one story, but it's important for the gulf.' The Tampa Bay Times launched the Environment Hub in 2025 to focus on some of Florida's most urgent and enduring challenges. You can contribute through our journalism fund by clicking here. • • • Here's a look at the 2025 hurricane season forecasts so far. What to know about river flooding in Tampa Bay this hurricane season. Here are the lessons you learned from Tampa Bay's historic 2024 hurricane season. Checklists for building all kinds of storm kits
Yahoo
10-04-2025
- Science
- Yahoo
What's contaminating Tampa Bay's fish? These scientists are angling for answers
IN A BOAT OFF APOLLO BEACH — A slow morning on the water erupted into a frenzy when line began whizzing out of Steve Murawski's fishing rod. 'I'm on!' Murawksi yelled, scattering the boat's crew into action. A tan fish launched from the glassy, shallow water tucked in this hidden pocket of Tampa Bay mangrove forest. It was exactly the type of fish Murawski's team of scientists came here to find: Centropomus undecimalis, the common snook. This one was a beauty. At 22 inches and with a jet-black line running horizontally across its body, Murawski proudly called his catch a 'double bagger' — it would take two bags to store on ice. The snook was the 681st fish caught by the Tampa Bay Surveillance Project, a sweeping research initiative that aims to study contaminants found in the bay's most coveted fish species: spotted seatrout, redfish, sheepshead and snook. Fish No. 682 came minutes later, also a snook, in an equally riveting fight. A handful of the region's top recreational fishing charter captains have partnered with scientists from the University of South Florida's College of Marine Science in St. Petersburg for the five-year, $3.4-million study to catch and sample the popular species along the shores of the estuary's 400 square miles. Researchers are focusing on the inshore fish most commonly caught for food, Murawksi said, which is why studying their chemistry is so crucial. After scientists reel in a catch, they bring them ashore to test the fish in the university's lab for a cocktail of contaminants, including pesticides, pharmaceuticals, a durable group of slow-to-break-down 'forever chemicals' and more. 'Tampa Bay is one of the fishing hotspots of western Florida and the Gulf, so if there are any threats to consuming these fish, it's important for us to know about them,' said Murawski, a professor of oceanography at the College of Marine Science and the project's principal investigator. 'The animals that we're catching are top predators,' Murawski said. 'But the ultimate top predator is people. Are these chemicals being transferred at higher and higher levels of concentration? We think that's true.' Not only are researchers testing fish for pollutants, they also want to learn whether the people who fish in Tampa Bay for food are more at risk of contamination. A three-year, $750,000 survey of people in the region who fish for food should shed light on seafood-eating habits and help scientists come up with risk assessments for safer consumption, according to the project. Matt Santiago, 41, has been fishing in the bay since he could walk, and he regularly eats the fish he catches. That's why the professional charter captain of more than 17 years happily agreed to help the university's researchers determine what's fouling fish. 'Our industry is heavily dependent on the sustainability of our natural resources. We need to take good care of our water,' Santiago said. 'The more information that we can gather about these chemicals, the better. It's a really important thing.' Plus, the project's results could help local governments pinpoint where the bay's pollution is coming from. For instance, if a redfish caught in northern Tampa Bay has more pharmaceuticals, like opioids, in its system than a redfish caught in the bay's southern end, that could signal there is a wastewater pollution problem in the northern bay. It's difficult for treatment plants to filter out trace amounts of pharmaceuticals, so when humans urinate chemicals from the pills they ingest, that can ultimately end up in the bay. Or perhaps a sheepshead, with its iconic black-and-white bars, is caught near a part of the estuary with a heavy agriculture footprint. The presence of pesticides in that fish could tell officials that more needs to be done to control rainfall runoff from area farms. 'This is not just a bellwether, it's the largest open-water estuary in Florida,' Murawksi said. 'We ought to understand this pretty well... If we can help identify the source of some of these pollutants, it helps.' The project is building on recent studies that have showed 'potentially problematic' levels of pollution in Tampa Bay's water, sediment and fish. The project should inspire other scientists looking to pinpoint pollutants in other large waterbodies, according to Murawski. The team should begin seeing results over the next year. With the project now in its second year, students in Murawski's lab have boated into the bay each week searching for fish. Tampa Bay has a broad mix of industries near its shores, from ports and cities to phosphate plants and agriculture, Murawski said. So to make sure scientists are capturing possible pollutants on a wide scale, they've divided the bay geographically into six segments. The team's goal is to catch 10 animals of all the desired species in each segment every season — or 960 fish each year, according to the project. Spending so much time on the water, there's no shortage of fish tales among the team: Alexandra Lee, a masters student studying marine preservation and conservation, said there was one day last year when the team caught nearly 30 fish over a few hours. Last week, researchers reeled in their biggest catch yet: a snook measuring an impressive 32 inches. The heaviest fish so far? A hunker of a redfish caught Aug. 12 last year weighing more than 12½ pounds. 'When I joined this project, I knew I'd be working on contaminants in fish, but being in the field this much has been a pleasant surprise,' Lee said. 'Not every researcher can be in the field all the time, and our project is so encompassing that we can be.' With one or even two fishing trips a week, Lee estimates she's been out on the water at least 30 times since research began last year. She's fished all over Tampa Bay, from the bluish green waters on the east side of secluded Egmont Key to Manbirtee Key, a 60-acre dredge island near Port Manatee where ships barrel by in the channel. The team has even been granted permission to study fish near MacDill Air Force Base, an area closed off to anglers. The fish population there is an interesting case study in what the fishery looked like decades ago, with little human interaction, according to researchers. On the recent outing into Hillsborough Bay, the team caught three trout and three snook. The morning after, students in Murawski's lab convened in the university's marine science lab to dissect the fish and collect samples. Kylee Rullo, a masters student in Murawski's lab, held up a stony piece of white bone pulled from a dissected snook. Scientists call this an otolith, or the fish's ear bone. You can learn a lot from an otolith, Rullo explained: Like counting rings in a tree, you can determine a fish's age and growth rate. A few rooms down the hall, scientists use a row of humming, expensive devises like a mass spectrometer to sort ultra-small particles and help paint a clearer picture of the chemical makeup in each fish species. 'What do these contaminants mean for our environment? What do they mean for people who are eating fish — and how does that influence their health and their decision-making?" Lee said. 'We just really want to educate people.'
The Guardian
22-03-2025
- Science
- The Guardian
Scientists identify ‘tipping point' that caused clumps of toxic Florida seaweed
Scientists in Florida believe they have identified a 'tipping point' in atmospheric conditions in the Atlantic Ocean they say caused giant clumps of toxic seaweed to inundate beaches around the Caribbean in recent summers. Previous theories for the Great Atlantic Sargassum Belt that has killed marine animals, harmed human health and plagued the tourism industry in several countries include a surfeit of nutrients in the water, such as nitrogen and phosphorus in runoff from intensive farming and carried into the ocean in the Congo, Amazon and Mississippi rivers. While marine scientists at the University of South Florida (USF) acknowledge that as a contributory factor, they say the primary source of nutrients is a seasonal phenomenon known as vertical mixing in which shifting winds churn up the ocean and deepwater nutrient concentrations are brought to the surface. They identified atmospheric pressure changes over the Atlantic beginning around 2009 as the tipping point, with variations in circulation and wind patterns pushing more sargassum into the warmer waters of the tropics, where it grew through photosynthesis into the massive blooms that eventually ended up on the beaches of the Caribbean and the US Gulf coast. 'This was a surprising result,' said Frank Muller-Karger, distinguished professor and biological oceanographer at USF's College of Marine Science. His team of international researchers used computer modeling to replicate the transport of blooms on strong currents controlled by negative North Atlantic oscillation (NAO), and how the changing atmospheric conditions helped create the giant sargassum belt. 'We had posed the hypothesis before that it is not the rivers that feed the formation of the sargassum blooms in the tropical Atlantic. This model supports the idea that nutrients from slightly deeper layers in the ocean feed the blooms.' Muller-Karger continued, saying that 'models showed that some patches of the sargassum were swept up by the wind and currents from the Sargasso Sea toward Europe, then moved southward, and from there were injected into the tropical Atlantic. 'At first, we saw just a few patches being pushed south by the NAO. But these algae patches were met with the right conditions to grow and perpetuate blooms. This population of algae, now separated from the Sargasso Sea, forms new blooms every year thanks to having enough light, nutrients and warmer temperatures,' he said. Almost annually for more than a decade, giant clumps of goop from the 5,000-mile-wide sargassum belt have washed ashore in the Caribbean, and from Florida to Mexico, creating problems for local authorities and businesses that rely on tourism. There are also significant health concerns. The rotting sargassum releases large quantities of hydrogen sulfide, which fills the air with an acrid odor similar to rotting eggs, and can provoke asthma and other respiratory issues. Sign up to Headlines US Get the most important US headlines and highlights emailed direct to you every morning after newsletter promotion In 2023, scientists at Florida Atlantic University (FAU) warned of a 'perfect pathogen storm [with] implications for both marine life and public health', having found high levels of the flesh-eating Vibrio bacteria lurking in the decomposing vegetation. They said plastic debris in ocean pollution mixed with the sargassum to create a proliferation of the bacteria, creating an additional health risk for tourists, municipal crews clearing the seaweed and volunteers conducting beach clean-ups. 'These Vibrio are extremely aggressive and can seek out and stick to plastic within minutes,' Tracy Mincer, assistant professor of biology at FAU's Harbor Branch Oceanographic Institute and Harriet L Wilkes Honors College, said. 'We really want to make the public aware of these associated risks. In particular, caution should be exercised regarding the harvest and processing of sargassum biomass until the risks are explored more thoroughly.' The USF research, a collaboration with scientists from the University of Toulouse, Sorbonne University and the Center for Scientific Research and Higher Education, was published in Nature Communications. Their report analyzed decades of wind, currents and 3D nutrient measurements from the Atlantic to model the annual blooms.
