Lake Okeechobee News: Humans- The most ‘harmful invasive’ of all? Human waste adds millions of pounds of phosphorus and nitrogen to Florida’s ecosystems

Article Posted on February 17, 2019

By: Katrina Elsken, Lake Okeechobee News

OKEECHOBEE — For decades, South Florida has been plagued by harmful invasive plants and animals that wreak havoc on the native ecosystems. Waterways are choked with hydrilla, originally imported from Asia for aquariums. Melaleuca, imported from Australia in a misguided plan to “drain the swamp,” grows so thick it squeezes out native vegetation and animals.

Burmese pythons, released by owners tired of their pets, grow large enough to compete with alligators for prey, and sometimes even target gators AS prey. The list of harmful invasives in Florida is long … and it keeps growing.

The most harmful invasive of all could well be humans.

Dr. Dan Canfield, a professor of Limnology in the University of Florida, explains that once a human enters an ecosystem, that ecosystem is changed forever.

It’s human nature to make changes, to build shelter from the weather, to plant crops and raise animals to eat, to build roads to make it easier to travel.

Early Florida pioneers changed the ecosystem. They dug canals to create liquid highways for their boats. Later, state and federal government agencies expanded the canals to drain land for development and agriculture.

The more humans move into the ecosystem, the more it changes. Florida’s population is growing at around 1,000 persons per day.

Humans continue to change the ecosystem by importing other things into it … things like invasive plants that look pretty in an aquarium but somehow wind up in a waterway or a pet snake that gets too big to keep in the house … and things like foods from all over the world.

Much has been studied and written about the impact of farm animals and other agriculture on the ecosystem, how much phosphorus is used to fertilize grass, how much grass a cow eats, how much phosphorus leaves the system when a calf goes to market, and how much phosphorus is in the manure that might wind up in runoff after a heavy rain. Today’s ranchers do a lot of math trying to keep that phosphorus load in balance to prevent excess nutrient load from winding up in the waterways.

Farmers may fertilize their fields, but they also take away nutrient load when they harvest a crop. In some cases, as with sugar cane, the harvest actually reduces the total nutrient load in the watershed.

Little, however, has been written about the nutrient load from human waste…

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