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dead fish on beach due to red tide

We all contribute to nitrogen pollution

NOTE: This is the first post in a series devoted to what you can do to reduce the duration of the next harmful algal bloom.

As we endure a terrible red tide outbreak on our coast, coupled with blue-green algae clogging inland waters, I hear many people ask what they can do to prevent the next algal bloom. Number one on that list is:

Reduce your nitrogen footprint.

You might be thinking, “Me? No. I don’t contribute nitrogen.” Unfortunately, you do. I do. In fact, we all contribute to increased levels of nitrogen entering our waterways. As a result, it is important to think about the individual actions each of us can take to help reduce the fuel (nitrogen) sustaining these blooms.

While there are still many questions that need to be answered about bloom dynamics, one thing remains certain: we need to reduce the flow of nitrogen entering our waterways. The good news is this isn’t a lost cause. We all can take actions right now to reduce our own nitrogen footprint, including:

  1. Only fertilize your turfgrass and landscape plants when they need it. Plants tell you when they need nutrients. Look for signs of deficiency before applying fertilizer. Also, use no more than the UF/IFAS Extension recommendations, as found beginning on page 23 in the “Florida Yards & Neighborhoods Handbook.”
  2. Always pick up your pet waste, even in your own yard. According to Access Sarasota: “Twenty-six tons of pet waste is dropped every day in Sarasota and Manatee counties” (2014). That is one source of nitrogen and harmful bacteria that easily can be eliminated just by scooping the poop and putting it in the trash.
  3. Get your neighborhood ponds and lakes back into ecological balance. Build and support the natural food web and create a native-vegetation buffer along the shoreline. For more information, contact me at the Extension office (941-861-9818) or Mollie Holland of Sarasota County’s Neighborhood Environmental Stewardship Team at (941-861-5000).
  4. Collect your stormwater by creating mini-wetlands in your yards and neighborhoods. Wetland loss has contributed to the increase flow of nitrogen into our streams, bays, and the gulf. Read my May 2018 post on the importance of Florida’s wetlands for more information.
  5. Be an informed voter. Laws and regulations to protect our waters from nutrient pollution are in constant upheaval. From what defines a pollutant and what constitutes a protected body of water in the Clean Water Act to conservation program funds in the Farm Bill. There is too much at stake to sit on the sidelines.
  6. Last, but one of the most important, find out the other ways you contribute nitrogen pollution (such as driving your vehicle) by calculating your Nitrogen Footprint. Then, come up with strategies to shrink your footprint.
Nitrogen pollution

Figure 1. Idealized nitrogen cycle with human (red) and natural (green) contributions highlighted. [CREDIT: Encyclopedia Britannica, 2011]

Since the 1950s, humans have saturated the nitrogen cycle (Figure 1) beyond plant nutritional needs. This has caused landscapes to leach nutrients, disrupting the balance of Earth’s systems. Sources of nitrogen introduced by humans and human activities include:

  • burning fossil fuels;
  • synthetic fertilizer use on golf courses, yards, and farms;
  • reliance on septic tanks; and
  • raising livestock and domestic animals (manure).

These and other manmade sources have more than doubled the natural amount of nitrogen inputs to the land, and changed the natural cycle of nitrogen in rivers, lakes, bays, and oceans.

Figure 2. The locations of the more than 500 coastal water sites with harmfully low-oxygen (“dead”) zones since 1950. [CREDIT: Breitburg et al., Science Magazine, 2018]

This rush of reactive nitrogen into our waterways has helped fuel algal blooms, which in turn consume precious oxygen and create the harmful low-oxygen zones in coastal waters we know as hypoxic or “dead” zones. More than 500 dead zones have been reported worldwide since 1950 (Figure 2).

Too much nitrogen, globally

As of 2015, earth system scientists noted that we had crossed four of the nine planetary boundaries, including the nitrogen flow into waterways (Figure 3) (Steffen et al., 2015). Planetary boundaries represent the essential processes that regulate the Earth, such as nitrogen cycling. They also provide a framework for science-based understanding of human impacts to the Earth.

Figure 3. Current status of 7 of the 9 planetary boundaries identified by earth system scientists. Nitrogen flows have been calculated as extending beyond the zone of uncertainty creating a high risk to the balance of Earth’s systems, particularly water systems. [CREDIT: deVries et al., 2013, and Stephen et al., 2015.]

The authors of the planetary boundary framework state that “…transgressing a boundary increases the risk that human activities could inadvertently drive the Earth System into a much less hospitable state, damaging efforts to reduce poverty and leading to a deterioration of human well-being in many parts of the world, including wealthy countries.

A less-hospitable state is certainly one way to describe the harmful algal blooms taking over southern Florida. The symptoms of the disrupted nitrogen system are so widespread and concerning that an International Nitrogen Management System is being planned to study global nitrogen cycling and propose strategies to increase nitrogen efficiency in order to eliminate surplus. This group has been said to be the nitrogen equivalent to the Intergovernmental Panel on Climate Change (Pearce, 2018).

Local waterway impacts

Excess nitrogen runoff is not just a problem when there are huge, newsworthy algae blooms, but has been a consistent source of pollution for local waterways. Excess nutrient pollution impacts native flora and fauna by harming or even eliminating suitable habitats that should be present in water bodies. And local waters listed under the Clean Water Act, Section 303(d), as “impaired” for nutrient pollution include:

  • Elligraw Bayou
  • Myakka River
  • Lake Myakka (upper segment)
  • North Lemon Bay
  • Lemon Bay (north segment)
  • North Creek (tidal)
  • Dona Bay
  • Curry Creek (freshwater portion)
  • Roberts Bay
  • Intracoastal Waterway (Sarasota County, near venice)
  • Forked Creek

We have literally made our Florida waters less fishable due to local nutrient pollution.


Nitrogen use and runoff will continue to cause problems as long as they remain unchecked. It is important to look at the ways in which you contribute nitrogen and scale back your use. Shrink your nitrogen footprint, so that we once again can enjoy the bounties of Florida’s waters.


For more information on Florida’s algae crisis:

For information on planetary boundaries:

For more information on nitrogen and nitrogen pollution:

For more information on water laws and the Farm Bill:

For more information about hypoxic zones:

3 Comments on “We all contribute to nitrogen pollution

  1. This past summer I visited both the Tampa and Orlando municipal wastewater reclamation facilities. Staff at each one boasted of their sales of biosolids to farmers for fertilizer use. What is known and not known about the qualities (nitrogen, phosphate content, for example) of these biolsolids when they leave these and other plants and in what quantities are they being applied in areas that drain to the St. Lucile River and/or Calooahatchee River, and if they are applied properly or subject to best management practices or state or federal regulations? I understand there is a state biolsolids committee that recently began meeting to study this issue.