© Matt @VisualPersistKemp's Ridley
Unprecedented numbers of sea turtles have been collected across Florida's Lee and Collier counties over the past week, and hundreds are thought to have died as the worst red tide algae bloom event since 2006 plagues southwest Florida. The Florida Fish and Wildlife Conservation Commission (FWC) is monitoring the current bloom since November 2017.
The FWC has documented 287 sea turtle deaths in Gulf of Mexico waters along the southwest Florida coast since the toxic bloom started late last year.
According to Allen Foley of the FWC's Fish and Wildlife Research Institute, that's about double the average number of turtle deaths in those waters every year.
Foley said turtles living in the area become sick and die when their food gets contaminated by the toxins.
Kemps' ridleys are one of the world's most endangered sea turtles.
"Our average for the entire year is usually around 30 or 35, but we've had 53 in June and July alone," Kelly Sloan, a sea turtle researcher at the Sanibel-Captiva Conservation Foundation on Sanibel told Fort Myers News-Press.
"Most of them have been mature adults, and only 1 in 1 000 make it to adulthood," Sloan said. "It takes a loggerhead 25 to 30 years to mature, so that really does have a significant impact on their recovery."
"It's really disheartening to see this mass mortality," Sloan said. "This is the 10th month of the red tide event, and it's the longest continued bloom since 2006."
Heather Barron, the head of the Center for the Rehabilitation of Wildlife veterinarian hospital on Sanibel said the red tide outbreak has collided with the height of sea turtle reproduction, something that doesn't often happen.
"This is way, way high," Barron said of the turtle numbers. "Normally red tide season is over in April. But now sea turtle nesting is at its peak, and you have adults in nearshore waters. And because of that, they're being affected."
Red Tide, or harmful algal bloom, is the rapid growth of microscopic algae. In Florida and Texas, it is primarily caused by the rapid growth of Karenia brevis.
Some algae produce toxins that have harmful effects on people, fish, marine mammals, and birds. It can result in varying levels of eye and respiratory irritation for people, which may be more severe for those with pre-existing respiratory conditions (such as asthma).
The blooms can also cause large fish kills and discolored water along the coast.
The FWC's Fish Kill Hotline has so far received over 300 fish kill reports associated with this event.
Comment: Algae blooms and dead zones have quadrupled since 1950 with Oman and the Baltic sea as some other recent examples. But what's causing them? Surely industrial agriculture will have contributed to their rise, but when we factor in the discovery of thousands of underwater volcanoes, the increasingly unstable methane deposits and the slowdown in the Gulf Stream, which all appear to be linked to a slowdown in the Sun and Earth's rotation, clearly there are other more significant drivers to take into consideration.
See also: Worldwide ocean anoxia driven by global cooling was possible factor in previous mass extinctions