Manatees are starting to die again in Florida, and a previous algae bloom could be the culprit. Apparently, the animals are having problems to adapt to a new diet.
The Florida Fish and Wildlife Research Institute (FWRI) in St. Petersburg reported that the mass manatee deaths could be resuming. Between 2012 and 2015, the authorities found 158 dead manatees at the Indian River Lagoon. The findings stopped around last summer, but nine carcasses have been found since May this year.
The water mammals are endangered species, and the Indian River Lagoon is an important part of their life. Authorities keep a careful track on manatees. They have counted around five thousand of the also called “gentle mammals” living in Florida, and more than 30% of them currently inhabit the river or use it for transport and nesting. Along with manatees, more than 2000 species of different animals inhabited the zone in the past.
Humans have lived in the area for hundreds of years, but it was the arrival of the modern man that changed the ecosystem forever. Industrial activity and sewage were the polluters in the past until 1995 when the central government decided to ban related activities along the river. Agriculture and other human-related activities still take their toll on the environment. As a result, the river has lost much of its bio-diversity, including plants and animals. Over the years, different plagues have killed hundreds of local manatees, things like unknown diseases and direct human contact among others.
The blue-green algae that are visible from space have nothing to do with manatee deaths
In July, satellite imagery showed a huge part of the Okeechobee River covered by blue-greenish algae, and members of the community got alarmed. The authorities started an investigation on the algae patch that is still expanding. They are currently monitoring its progress.
However, Dr. Martine de Wit, who oversees the research on manatee’s corpses at the FWRI, said none of the mammals’ deaths had been attributed to the recently identified algae. Instead, she thinks a drastic change in the diet could be the responsible. Ironically, another kind of algae could be the culprit, one that darkened the water of the river back in 2012.
It was nicknamed the “brown tide”, and the Aureoumbra lagunensis caused it. The first records of this genus in the United States come from Texas where the authorities have been dealing with it for years. No one can explain how it got to Florida, but it blocked the sunlight from reaching the bottom of the river killing most of the seagrass. The latter is the back bone of the manatee’s menu, and by the time the waters returned to normality, around 50% of seagrass had died.
Dr. de Wit theorizes the big mammals were forced to start eating something else, and not all of them could handle the switch. She bases her theory on what was found inside the stomach of the last carcasses the institute analyzed. During the autopsy, the researching team noticed the content of the stomach was unusual, very different from what they usually see when studying manatee corpses.
So far, the authorities have not found a sole cause of death for the 158 mammals that died between 2012 and 2015, but all the causes have been associated with human activity. As a result, the Florida Fish and Wildlife Conservation Commission is planning to expand the manatee protection program further in the area. The organization held a “rule development workshop” to gather community feedback at the Collier County Commission Chambers today at 5:30 P.M.
Source: Tampa Bay