While the US Fish and Wildlife Service takes into consideration changing the status of manatees from “endangered species” to “threatened”, new casualties appear in Florida where nine animals have been found dead in the last two months. Experts blame the algal blooms.
In 1978, Florida was designed a sanctuary for manatees. Since then, the state officials have set speed limits to decrease the number of road kills and have placed boat interdiction in their favorite areas.
However, all conservation efforts are being annulled by the effects of the algae blooms. The manatees depend on the warm water created by power plants, and the outbreak of microorganisms impairs its proper function.
In July 2012, an algal bloom outbreak led to 166 manatees being killed. The phenomenon lasted nine months, but the number of victims continued to rise as years went by. Alga blooms usually do not disappear completely after an invasion, and they revive when waters become warm again at the end of spring.
The biologists believe that the alga blooms are guilty of the deaths of the manatees, even if they are to blame only indirectly. The spread of microorganisms leads to a loss of seagrass, which is the primary food source for manatees.
As their favorite nutrient becomes scarce, the mammals started to feed off macro algae, which are in fact toxic and kills the animals.
The manatees were found to have seagrass in the digestive systems, but not in their stomachs.
“They seem to be in good condition, they’re healthy, big animals, and suddenly they get an acute shock, and a lot of them drown on the spot,” said Martine de Wit, lead veterinarian at the Marine Mammal Pathobiology Laboratory.
The algal blooms are caused by pollution, and the biologists urge the authorities to implement more efficient strategies against environmental degradation.
The main threat for manatees is the watercraft collision. Almost a hundred animals had been killed in boat accidents during 2009, and the annual average of victims rise to 80. The manatees move very slowly, and they cannot avoid speedboats, propellers or boat hulls.
Most of the mammals have scars left by collisions, and the experts suggest that speed limits are the only thing that saved the animals from being wiped out by boats.
Another factor that negatively influences the manatees is the loss of habitat. They prefer warm waters, thus during the winter they have to migrate to other sites with a higher temperature. These places can be natural springs or areas around power plants.
The latter are interesting for the aquatic mammals because they take in ocean water and use it to cool down the engines, and afterward they release it again. The warmer waters draw the mammals.
There are approximately 6,300 manatees in Florida. The US Fish and Wildlife Service proposed to delist the species from the endangered directory, but some experts say the action would be hasty as the mammals are still facing challenges in the state.
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