Warnings similar for very different hazards

OKEECHOBEE — Warnings given by Florida State agencies about potential hazards in Florida waterways give the same advice for two very different potential hazards. Some of the Florida Wildlife Commission rules for living with alligators can also apply to algae.

For example: Don’t feed the alligators/algae. Keep pets away from alligators/algae. Do not swim in areas where alligators/algae are present.

A warning sign advises the public that it is against the law to feed alligators. Photo by K. Elsken.

There are some common factors.

• Both algae and alligators are found year round in Lake Okeechobee, as well as waterways throughout the state. According to the Florida Wildlife Commission, there are an estimated 1.3 million alligators in Florida. They live in all 67 counties. According to the Florida Department of Environment Regulation, algae (and cyanobacteria which is called “blue-green” algae) can be found naturally in all freshwater and brackish water. There are thousands of types of algae and cyanobacteria. About a dozen types of blue-green have been documented in Lake Okeechobee by the University of Florida.

• Both algae and alligators are more noticeable during certain seasons. Alligators are more active during mating season. Algae is more likely to be visible in the summer when the heat and rainfall provide the right conditions for it to reproduce.

• Just because you don’t see algae or alligators doesn’t mean they are not there. Blue-green algae are microscopic. An algae bloom occurs when algae reproduce rapidly into a concentration that is visible. Blue-green algae can rise and fall in the water column, so it might not be visible on the water surface. According to Florida-alligator.com, alligators often stay submerged for 20 to 30 minutes at a time, and under certain conditions can stay underwater much longer. Most of the time, this is not a problem. Alligator attacks on humans are rare. Most algae and cyanobacteria is not toxic. Even cyanobacteria that can produce toxins does not always do so.

• Both the algae and the alligators are part of the natural ecosystem. Algae and alligators were here before the humans arrived.

• Feeding algae or alligators can result in situations harmful to humans. When humans feed alligators, it causes them to connect humans with food and causes them to lose their natural aversion to people. Feeding the algae is also dangerous. High levels of phosphorus and nitrogen, along with hot weather, can result in high concentrations of algae in the water. Humans are responsible for increasing that nutrient load into the waterway, by using fertilizer on lawns, golf courses and farms and by creating a drainage systems that move water faster instead of slowly filtering through marshes. Human action also increases the nutrient load from leaking septic tanks, sewage spills and landspreading of biosolid waste.

Under certain conditions, some blue-green algae can produce toxins harmful to humans.

• FWC advises people to stay out of the water in area where alligators are seen. An alligator may react to splashing of a person swimming the same way it reacts to its normal prey. FDOH advises people stay out of the water if algae is visible. You can’t tell if an algae bloom is toxic just by looking at it. If toxins are present and you swim in the water, you might develop a rash. If you swallow water containing toxins, it could result in other health issues.

• FWC advises residents to keep pets out of the water if you see alligators. Alligators will treat a dog that is in or near the water as their prey. The Florida Department of Health advises keeping pets out of the water if you see algae, as pets may swallow some of the water and become ill.

• Development of cities and subdivisions has resulted in increased hazards from both algae and alligators. Development results in more runoff and higher levels of phosphorus and nitrogen in the runoff, which feed algae blooms. Development displaces alligators (and other wildlife) causing more interactions with people.

• Algae and alligators are both affected by temperature changes. Hot weather is a factor in algae blooms. According to the FWC, alligators rely on an external source of heat to regulate their body temperature. They become dormant when their body temperature drops below 55 degrees Fahreinheit.

• Too much algae … or too many alligators … creates problems. The State of Florida tries to control both.

If alligators overpopulate, it disrupts the ecosystem as they run out of food and become cannibals. Since 1988, Florida’s statewide alligator harvest has been nationally and internationally recognized as a model program for the sustainable use of a natural resource.

Each year, alligator management units are established with appropriate harvest quotas to provide recreational opportunities for Floridians and non-residents who are at least 18 years old to take up to 2 alligators per permit.

In 2017, the statewide alligator hunt harvested 6,281 alligators. Most alligator hunters try to harvest the biggest gators possible, The minimum harvest size is 18 inches in length. In 2017, the average alligator harvested was 8 ft. 3.1 inches in length. The Florida record for an alligator is 1,043 pounds.

For the 2018 hunt, 493 alligator hunting permits were issued for Lake Okeechobee.
Controlling algae is not so easy. According to Dr. Karl Havens, director of Florida Sea Grant, the key to controlling the algae is cleaning up the watersheds that flow into Lake Okeechobee, the Caloosahatchee River and the St. Lucie River to cut the excess phosphorus and nitrogen going into those waterways. “Control of dispersed sources of nutrients in those watersheds will be a huge challenge and while projects are underway by the state to accomplish them, it could take decades before substantive results are seen,” he stated in his blog on flaseagrant.org.

In July, the Florida Department of Environmental Protection announced a $3 million grant program to clean up algae in Glades, Hendry, Lee, Martin, Okeechobee, Palm Beach and St. Lucie counties. While various companies are proposing to vacuum up the algae, use robots to collect it or use chemicals to kill the algae blooms, none are based on peer-reviewed science, according to Dr. Havens.

It seems controlling the blue-green algae is not going to be as easy as living with alligators.

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