At dry times of the year, the most abundant source of fresh water may come from water used for irrigation when it runs off landscapes in coastal neighborhoods. It often runs directly into nearby canals where manatees wait at outfalls that may drain dozens or even hundreds of lawns.
“The freshwater floats on the top and so you’ll see manatees lined up at the stormwater outfalls waiting for a drink,” says Holly Edwards, who directs manatee research for the Florida Fish and Wildlife Research Institute. “It’s a very routine behavior for them.”
[easy-media med=”297″ size=”250,250″ align=”right”]While no danger to manatees has been documented, most runoff is not treated before it pours into canals, she adds. “They seem to be fairly impervious to even very polluted water because we’re not seeing a lot of animals dying or overly susceptible to disease.”Still, pesticides are formulated specifically to be toxic and high levels of nitrates in water can be lethal to infants. In foods, nitrates have been linked to diseases like leukemia, non-Hodgkin lymphoma, and ovarian, colon, rectal, bladder, stomach, esophageal, pancreatic and thyroid cancers.
The biggest issue with inappropriate landscape practices for manatees is the loss of seagrasses that occur when an overload of nutrients fuels the growth of algae that block sunlight and causes seagrasses to die back, Edwards adds.
Even though canals aren’t usually a good source of food – because seagrasses typically don’t grow in water deeper than about six feet – manatees like to hang out in them. “Canals are deeper than most of the bay and they’re generally protected from wave action so it’s a nice place to rest,” she said. “There may be a lot of boaters coming and going, but they’re typically moving slowly to protect their neighbors’ docked boats.”
Abundance study to be released later this year
Not a lot of data has been collected on why or how many manatees hang out in canals, but the state’s first “abundance” data is expected to be released later this year. Current data on manatees is compiled by counting them from airplanes, but that limits researchers to including only the animals they actually see.
“Even with two people in a plane, there are a lot of variables – how deep are they swimming, are there whitecaps, or is the water cloudy so they’re harder to see. We end up counting a minimum number of animals, not the true population. This study helps estimate the number of animals we missed.”
It began with a model manatee. Researchers flew over the model, tracking how deep it could go before they could no longer see it. That data formed the basis of a computer model that was developed to determine how many manatees could have been overlooked in deeper water, Edwards said. “We’re crunching the numbers now to see how many animals we are likely to have missed.”
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Winter is the best time to actually see manatees because they gather in warm locations, like Crystal River in Citrus County or the outfall at the Manatee Viewing Center at TECO’s Big Bend power plant in Apollo Beach, where the visitor’s center opens Nov. 1. They’re also commonly seen in canals throughout the Tampa Bay region, although most of the property bordering the canals is privately owned.
Snooty, the world’s oldest known manatee at 65 years, lives at the South Florida Museum in Bradenton, where live videocams follow his actions during daylight hours. Although researchers strongly discourage human interaction with manatees, that rule is not important with an animal like Snooty who will never be released into the wild. Working with Snooty has demonstrated that manatees are very smart animals who were perfectly adapted to their environment before humans became part of it.
Two distinct books offer even more insights into Florida manatees:
- The Florida Manatee: Biology and Conservation was written by Roger Reed, a neuroscientist and professor at the University of Florida’s vet school, and Robert Bonde, a biologist with the U.S. Geological Survey who has been researching manatees for 25 years.
- Manatee Insanity, by Tampa Bay Times environmental reporter Craig Pittman, looks at both the biology of these fascinating creatures and the political decisions that have impacted manatees since the first laws protecting them were passed in 1893.
Both books are published by the University Press of Florida.
[su_note note_color=”#fefed2″]Manatee Zones Coming to Pinellas County?
Record numbers of manatees now live in Pinellas County waters, but there are still no manatee protection zones.
“We have a good number of slow-speed areas, but they’re for the safety of boaters, not resource protection, and they’re not necessarily correlated with where we’re finding manatees,” notes Scott Calleson, who coordinates manatee zones for the Florida Fish and Wildlife Conservation Commission.
There have been 39 boat-related deaths since 1990 – six times the number of deaths documented over the past 28 years, he adds. Seventeen dead manatees were found in the northern part of the county in that time – but 15 of those occurred since the year 2000. In the southern section, a total of 28 manatees have died, including 24 since 2000.
Part of the problem may be the growing number of manatees, plus the ease of reporting manatee deaths as cell phones have become more common, he notes, but deaths are clearly increasing. The lack of enforcement also is an issue, he adds. “However, our compliance study shows that one-half to three-quarters of boaters are in compliance with the slow speeds even when there is no law enforcement nearby.”
At this point, the FWC is researching options, not proposing increased manatee zones, he stresses. “We’re holding some preliminary meetings with boaters and environmental groups because we want the word out that we’re looking at our options, but we haven’t made any decisions yet.”
If the state formally proposes manatee zones, they will notify the county which will convene a Local Rule Review Committee comprised of half environmental representatives and half representatives from the boating and waterways community. The committee will hold hearings and formally present their findings to the FWC. The full commission must approve the final rules, probably within 18 months.
Although the Tampa Bay zones were adopted about 10 years ago, there are no plans to review them, Calleson added. “Some of the plans we’re reviewing now were written 25 years ago.”
To contact Calleson, email him at scott.calleson@myfwc.com or call 850-922-4330.
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