Have you ever come across a pond or lake thats surface was overgrown with mucky green plants and algae? If so, you might have seen some of the symptoms of a eutrophic water body.

Eutrophication, an increase in the rate of supply of organic matter to an ecosystem, is caused when nutrients are in excess. Eutrophication is a big issue in Florida. Fish kills, blue-green algae blooms and dead zones are some of the problems caused by this phenomenon that you might have heard about in the news.

Eutrophication can be natural or human-caused. Cultural, or human-caused, eutrophication starts when certain forms of nutrients like phosphorus or nitrogen are transported to a water body by human activities.

Nutrients like nitrogen and phosphorus can often be found in fertilizers, sewage and wastewater and even household products like detergents and soaps. When too much of these nutrients make their way into a water body and they are in excess of what naturally occurs, problems can arise. In normal amounts, nutrients can help aquatic plants grow, but in excess they can lead to the overgrowth of algae and plants like duckweed, which can block sunlight from penetrating the water and reaching beneficial plants, like submerged aquatic vegetation.

The limited sunlight means photosynthesis, or the process by which plants use sunlight to synthesize food and make energy from carbon dioxide and water, is impeded. Oxygen is the end product of photosynthesis, so this blockage limits the amount of oxygen produced by plants. Plants die because they can’t photosynthesize, and other animals in the water are hurt by the lack of oxygen.

Decomposers like bacteria use up even more oxygen when they break down dead plants and animals, further depleting the oxygen levels. Through decomposition of these dead organisms, more nutrients are added to the water body. The cycle of low oxygen, death and decomposition may continue until the body of water is entirely anoxic (devoid of oxygen).

There are five indicators of eutrophication according to the National Oceanic and Atmospheric Administration: less submerged aquatic vegetation, more chlorophyll A, more toxic blooms and macro-algae and the lack of dissolved oxygen.

Eutrophication can happen in any body of water, including ponds or small lakes, or even in the ocean. In the ocean, anoxic areas are sometimes called dead zones. The dead zone in the Gulf of Mexico is one of the world’s largest. Fish can often swim and move out of these low oxygen areas, but sessile organisms like corals or sponges, which aren’t mobile, are more heavily impacted.

As mentioned earlier, not all eutrophication is manmade. Many of Florida’s waterways are naturally eutrophic because they are shallow and highly productive, meaning they produce a lot of energy and nutrients naturally. In addition, it is hard to pinpoint exactly where nutrients come from. They can be point source, coming from an easily identifiable place, or nonpoint source, coming from many places in the landscape.

Stopping nutrients before they cause problems can be difficult, but scientists are researching ways to prevent Florida water bodies from becoming eutrophic. For example, because Florida’s water table is so high, faulty septic systems can leak waste rich in nutrients into Florida’s groundwater, leading to nutrient pollution. Recent legislation in the state has looked at finding alternatives to septic systems. Many farmers in Florida are also working on using best management practices to stop excess nutrients from fertilizers or livestock from reaching waterways, such as applying proper amounts of fertilizer at the right times of year and planting cover crops to reduce erosion and runoff.

You can have an impact on reducing nutrient pollution, too. Solutions include fertilizing your lawn or home garden responsibly, planting native plants that soak up nitrogen, phosphorus and storm water,  using a commercial carwash instead of doing it yourself to stop chemicals from reaching storm drains, and always picking up your pet’s waste (which can contain many nutrients).

While nutrient pollution and eutrophication is a big problem in Florida, impacts can be lessened if citizens continue to push legislators to regulate and improve the state’s best management practices and support more research into solutions for healthy waterways.

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