Florida manatees are already at risk, but with 80 reported deaths in Brevard County since July, there is cause for increased concern. There have also been 230 pelican deaths in the past several weeks and 23 dolphin deaths since January.
In an article in Florida Today, Kevin Baxter of Fish and Wildlife Research Institute reports twenty five of these manatees have died between March 10 and March 21 alone. They are drowning with signs of shock and intestinal problems. Digestive tracts are filled with macroalgae and show little sign of their usual seagrass diet.
Seagrass has almost vanished after a phytoplankton “superbloom” in 2011 followed by a brown algae bloom. Excess algae grows when too many nutrients from fertilizer runoff or septic tanks enter the estuary.
Tests run in February by US Geological Survey’s National Wildlife Health Center in Madison, WI for botulism in pelicans came back negative.
Biologists have not been able to identify any pathogen, algae toxin or other substance killing the manatees and pelicans. Currently, they are not even sure if the deaths are related. The lab is culturing samples to test for bacteria and viruses, which should take a few weeks.
NOAA is examining whether the manatee and dolphin deaths are linked. Blair Mase, NOAA’s southeast regional marine mammal stranding coordinator, stated, “Right now, we have a correlation in location, but we’re not seeing much else. We’re monitoring the area very close”. The dolphins are reported to by very skinny and were mainly adult females. A few had shark bites, but it is not clear whether the bites came before or after death. Tissue samples have been sent to veterinary pathologist for testing to look for heavy metals, contaminants and toxins.
Typically 600-700 dolphins reside in Indian River Lagoon.