Conservationists in southwest Florida have reported a hundreds of Sea Turtles washing up dead on beaches in the area over the past ten months, including species such as the Critically Endangered Kemp’s Ridley Sea Turtle, Lepidochelys kempii, and the Endangered Loggerhead Turtle, Caretta caretta. The deaths are thought to be due to blooms of toxic Red Algae. Such Algae can poison a wide range of animals, including predatory animals such as Turtles, which can either consume the toxic algae along with desired prey, or be poisoned by consuming prey that had itself ingested the harmful algae.The southwest Florida area suffers from such blooms (and associated deaths of Turtles and other animals) every year, but these are usually short-lived events, whereas in this case the Algae have been more-or-less continuously present since October 2017, almost certainly due to the exceptionally warm conditions in the area this year.
Scientists from the Sanibel Captiva Conservation Foundation examines a dead Loggerhead Turtle, Caretta caretta, on Sanibel Island, Florida. Andrew West/The News-Press.
A variety of single-celled Algae can produce blooms, sudden population explosions that discolour the water, and can be toxic and cause problems by absorbing oxygen from the water, causing other aquatic organisms to asphyxiate. Red Algal Blooms (or Red Tides) are particularly notorious as many single-celled red Algae produce potent toxins. Such blooms are typically associated with warm weather, local drops in salinity, which can be caused by high rainfall levels or runoff from land, or rises in nutrient levels, which can again are often associated with runoff from land, but can be caused by large storms or other event stirring up nutrients from the ocean floor.
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