As a heat wave settled on the Red Sea in 2022, a patch of corals in a reef 15 kilometers (9.3 miles) off the coast of Saudi Arabia reacted differently than other corals. They’d been treated with probiotics, beneficial bacteria isolated from healthy corals, and those treatments prevented the corals from bleaching, scientists now report. Corals provide habitat for about one-third of marine species but are declining at an unprecedented rate, according to the latest report from the Global Coral Reef Monitoring Network. Rising temperatures lead to coral bleaching, a breakdown of the beneficial symbiosis between corals and algae that can result in coral death. Scientists estimate that if global temperatures rise by 1.5°Celsius (2.7°Fahrenheit) above pre-industrial levels, 70-90% of corals will be at risk of severe degradation worldwide by 2100. “Corals can acclimate and adapt, but only if they are alive,” principal investigator of the new study Raquel Peixoto, a microbial ecologist at the King Abdullah University of Science and Technology (KAUST) in Saudi Arabia, told Mongabay in a video call. She and other researchers around the world are investigating how manipulating the microscopic bacteria that live on corals can help them respond to threats ranging from oil spills to infectious disease. Though Peixoto previously showed that probiotics could stave off bleaching and keep corals alive in tanks, the new results, published Sept. 3 in Cell Reports, are the first to indicate that probiotics may help protect corals in the wild from marine heat waves. “It’s one thing to…This article was originally published on Mongabay

Between 2014 and 2015, a marine heatwave known as “The Blob” warmed an area of the Pacific Ocean larger than the United States and Mexico combined. The massive event fueled toxic algae blooms, collapsed fisheries, killed off millions of emaciated seabirds, sent dead fin whales (Balaenoptera physalus) and sea otters washing up on Alaska and British Columbia coasts, and dotted California shores with starving sea lions. Though best known as a marine heat wave, The Blob was also an extreme acidification event. Yet occurrences of these compound heat-acidity extreme events remain poorly understood. A new study, published in the journal AGU Advances in August, provides a detailed look at the frequency, intensity and duration of these compound events during the last four decades. The study reveals an understudied aspect of marine heat waves that could have implications for the developing 2026-2027 “super” El Niño, in which waters in the equatorial Pacific become unusually warm due to changing wind patterns. An underweight sea lion pup on a beach in February 2015. Image by NOAA Fisheries West Coast. Researchers from the Swiss Federal Institute of Technology (ETH Zurich) found compound heat-acidity events across the globe happen together “more frequently than would be expected by chance,” they wrote. Instead, the researchers attributed their occurrence to underlying ocean physics that allow marine heat waves to become unusually acidic in some regions. These events are mostly short-lived and small, with 67% of the 500 identified events lasting less than three months and extending to an…This article was originally published on Mongabay