Dilution - NOT the solution to pollution
We are part of a beautiful, interconnected web of life which comes with a great responsibility to live in a way that enhances the environment and ecosystems of which we are a part. When we begin to see signs of degradation in our natural surroundings, we are asked to consider the cause. The health of all species, including humans, is dependent upon balance within the ecosystem. Ecological balance is “a state of dynamic equilibrium within a community of organisms in which genetic, species, and ecosystem diversity remain relatively stable, subject to gradual changes through natural succession…” and almost more importantly for our discussion here, “a stable balance in the numbers of each species in the ecosystem.” (https://wwf.panda.org/discover/knowledge_hub/teacher_resources/webfieldtrips/ecological_balance/).
Too Much of a Good Thing
Anyone who lives along Florida’s central/southwest coast or who has visited the area in the last few years has likely experienced an imbalance in the marine ecosystem known as Red Tide. Red Tides are harmful algal blooms (HABs) which occur when phytoplankton multiply to higher-than-normal concentrations. Most Red Tides along the Florida coast are caused by dinoflagellates, a single-celled species known as Karenia brevis. In a healthy and balanced ecosystem, phytoplankton are an essential part of the food web and provide nutrients for other sea life such as shrimp, snails and jellyfish (https://oceanservice.noaa.gov/facts/phyto.html). When growing out of control, however, Karenia brevis produce toxic and harmful effects on humans and marine life including fish, birds, invertebrates, turtles, and other sea mammals such as dolphins and manatees. In high concentrations, Karenia brevis produce brevetoxins which result in skin, eye, and respiratory irritation in humans and in neurotoxic poisoning and death in fish and other marine life. At their worst, such algal blooms can completely deplete the water of dissolved oxygen resulting in ocean “dead zones (https://myfwc.com/research/redtide/general/marine-animals/#:~:text=Red%20tides%20can%20also%20lead,oxygen%20conditions%20resulting%20from%20blooms).
Naturally Occurring…But There’s More
You may have heard that Red Tide is naturally occurring. This is true, but there is more to the story. To grow and reproduce, Karenia brevis need sunlight along with inorganic nutrients, such as nitrates, phosphate, and sulfur. Red Tides have been documented as far back as 1840 along the Florida Gulf Coast, but the extent, length, and frequency of Red Tides over the past few years have increased, likely from climate change, rising ocean temperatures, and high levels of carbon dioxide (https://oceanservice.noaa.gov/news/redtide-florida/). Red Tides typically form 10 to 40 miles offshore and are pushed inshore as a result of ocean currents and wind conditions where nutrient rich waters further exacerbate an imbalanced ecosystem.
EVERYTHING Ends Up In the Water
You may have heard the term, “everything flows downstream.” No matter where you live, you are part of a watershed, and if you live in the Tampa Bay area, you are part of the Tampa Bay Watershed. A watershed is an area of land that drains into a specific body of water (https://pubs.usgs.gov/circ/1348/pdf/Chapter%201_1-16.pdf). The Tampa Bay Watershed encompasses 2,200 square miles and approximately three million people. Although the watershed is made up of a variety of land uses, including agriculture, mining, wetlands, lakes, and forests, the Tampa Bay area consists primarily of urban and suburban development, and everything produced and/or disposed of on land eventually ends up in stormwater systems that flow into surrounding waterways including local lakes and streams, Tampa Bay, and the Gulf of Mexico.
Urbanization - Part of the Water Cycle
In 2022, Florida received 54.12 inches of rainfall, with the majority of rain falling in the summer months between June and September (https://climatecenter.fsu.edu/images/docs/Fla_Annual_climate_summary_2022.pdf). Stormwater systems are designed to manage runoff and prevent flooding during large precipitation events, such as Florida’s summer rains, but they are not designed to treat the water before it enters the Bay and Gulf. Historically, approximately 40% of this rainfall would evaporate, 10% would runoff into waterbodies, and 50% would infiltrate back into the earth. Fast forward to the post developed conditions of Tampa Bay and those statistics have significantly changed. Current urbanization has reduced evaporation and infiltration and increased runoff. Now, only 30% of rainfall evaporates, only 15% infiltrates into the ground, and 55% runs off into stormwater systems and waterbodies (https://www3.epa.gov/npdes/pubs/nps_urban-facts_final.pdf).
The Food Source
Prior to adoption of the Clean Water Act in 1972, much of the pollution entering Tampa Bay was the result of point source pollution - single, identifiable sources from which pollutants are directly discharged such as industrial factories or sewage treatment plants (https://oceanservice.noaa.gov/education/tutorial_pollution/03pointsource.html). Through the Clean Water Act, the National Pollutant Discharge Elimination System (NPDES) was created and required all point sources to obtain permits from the State and EPA prior to discharging pollutants or effluent into waterways. Although point source pollution, such as the 2021 disastrous discharges from the Piney Point phosphate plant, still play a role in nutrient overloading, the main sources of pollution for Tampa Bay today are nonpoint contributors not regulated by the Clean Water Act. Nonpoint source pollution consists of diffuse sources of nutrients and pollutants that are picked up by rainwater and carried into water bodies. Many of the pollutants entering the waterways are rich in nitrogen and phosphorus, the exact pollutants that Karenia brevis needs to survive and multiply. The Tampa Bay Estuary Program estimates that 60% of the nitrogen that has entered the Bay since 2010 has been from nonpoint source pollution (https://tbep.org/tampa-bay-nitrogen-loads/). Examples of nonpoint source pollutants are fertilizers, pesticides, pet waste, effluent from septic system leaks, yard debris and stormwater runoff.
You Can Help Starve K. Brevis
In the words of Benjamin Franklin, “An ounce of prevention is worth a pound of cure.” There are a lot of organizations and government agencies researching how to treat Red Tide, but what if there is a simpler solution? What if you can significantly reduce or even prevent it by starving Karenia brevis of the nutrients it needs to thrive? Here are some of the easiest ways to reduce the amount of nitrogen and phosphorus entering Tampa Bay and the Gulf of Mexico.
Pick up and dispose of pet waste
Wash your vehicle at commercial car washes where wastewater is collected
Get a lateral sewer line inspection to ensure piping to and from your home is not leaking
Check your irrigation system for leaks
Plant native or at least Florida Friendly plants that don’t require fertilizers or pesticide applications - Check out the Florida Native Plant Society
Never fertilize in the summer
Leave lawn clippings and leaves in your yard; Never blow them into the street - they are a great source of nutrients for your plants
Direct gutters and downspouts into your landscape to prevent runoff into the street
Plant a rain garden and/or use a rain barrel to collect runoff - Check out the City of St. Pete’s generous Rebate Program
Hire lawn care companies certified in Green Industry Best Management Practices
Skip driving and ride your bike or walk whenever possible - Cars emit 4x more nitrogen than power plants (https://www.83degreesmedia.com/features/how-to-help-stop-red-tide-outbreaks-in-Florida-110221.aspx).
Less nutrients = Less algae
Thank you for thinking upstream!
