A nitrogen surge has turned floating sargassum brown algae into the world’s largest harmful bloom, researchers from Florida Atlantic University have found.
Researchers at the Harbor Oceanographic Institute, a branch of the Atlantic University of Florida, have examined the historical base since the 1980s and compared it with samples collected since 2010 on sargassum to trace changes in the chemistry and composition of algae.
Sargassum, or floating kelp, used to grow in nutrient-poor waters in the North Atlantic. Scientists have found that due to changes in the chemical composition, algae have turned into a toxic dead zone.
The authors concluded that increased availability of nitrogen from natural and anthropogenic sources, including wastewater, supports blooming, which in turn leads to harmful blooms and disastrous consequences for coastal ecosystems, economies and human health. Globally, harmful algal blooms are associated with increased nutrient pollution.
The results show that the percentage of algal tissue increased by 35% and simultaneously decreased the amount of phosphorus by 42% in sargassum tissue from the 1980s to the 2010s.
The authors believe that their work not only confirms the main role of phosphorus in limiting productivity, but also how it limits nutrients if nitrogen inputs to the environment are increased.
The removal of sargassum from the beaches of Texas during early and less severe floods was estimated at $ 2.9 million per year, while Miami-Dade County in Florida alone estimated the latest export costs at $ 45 million per year. Cleaning up the entire Caribbean in 2018 cost $ 120 million, excluding declining tourism revenues. The release of sargassum also affects marine life and also causes breathing difficulties due to decomposition and increases the number of faecal bacteria.