James Douglass is a Marine Biologist who lives in Bonita Springs and is Professor of Marine Biology at Florida Gulf Coast University.
EUTROPHICATION: A word every Floridian should know As of today, 28 July 2018, Florida is suffering from at least three different kinds of harmful algae blooms, happening at the same time.
1. We have a blue-green algae (cyanobacteria) bloom filling Lake Okeechobee and spilling out into the Caloosahatchee and St. Lucie rivers. The main species of cyanobacteria in that blue-green bloom is Microcystis aeruginosa, which is toxic to both humans and wildlife.
2. We also have "Florida Red Tide" extending along much of the Gulf Coast of the state. For many months it has been shifting and changing shape, flaring up in one spot or another but never going away. We've seen countless dead fishes of all kinds washed up on beaches from Tampa to Naples, hundreds of dead sea turtles, scores of manatees, and most recently a 7.9 meter long, otherwise-healthy young male Whale Shark whose corpse ended up rolling in the surf off the luxury vacation spot of Sanibel Island. The organism that causes Florida Red Tide is a type of single-celled algae called a dinoflagellate. It has two whip-like flagella and is covered in protective plates, like some kind of alien sperm. The species name is Karenia brevis, and it makes a toxin called brevitoxin.
3. Finally, we have seaweed (multicellular algae; macroalgae) blooms on both the Atlantic and Gulf coasts, with unprecedented volumes of stinky red and brown multicellular algae washing up on the beaches. On the Atlantic Coast, most of the seaweed washing up is brown macroalgae in the genus Sargassum. The Sargassum macroalgae bloom is affecting the entire Caribbean this year. On the Gulf Coast the red seaweed washing up on the beaches is a mix of hundreds of different species of macroalgae that normally grow attached to the bottom but easily break loose and drift around with the waves and currents.
What do these nasty algae blooms have in common? They are all examples of EUTROPHICATION.
Eutrophication is the excessive growth of algae or nuisance plants in a body of water.
Eutrophication is usually caused by nutrient enrichment. You can remember that nutrients cause eutrophication because eutrophication rhymes with “nutrification.”
Nutrients are dissolved chemicals like nitrate and phosphate, which all plants and algae need to grow. Nutrients usually occur in small concentrations that favor healthy amounts and type of plants and algae. But excessive nutrients lead to excessive growth of undesirable types of plants and algae.
Most problems we have with eutrophication are man-made problems, because the excessive nutrients come from man-made sources like sewage and fertilizer-laden runoff.
Eutrophic growth of algae is sometimes called an “algal bloom.” Both microscopic algae (known generally as phytoplankton) and macroscopic algae (known generally as seaweed) can “bloom” in response to eutrophication.
Besides excessive nutrients entering the water, another factor that contributes to eutrophication is a lack of the organisms that normally eat the problematic plants and algae. For example, seaweed blooms can be worsened by a lack of seaweed-eating fish, and phytoplankton blooms can be worsened by a lack of filter-feeding shellfish like oysters.
Eutrophication can have a variety of harmful effects. For example:
*Some of the types of algae that increase in response to eutrophication exude toxic chemicals that can kill wildlife and sicken humans. For example, the Karenia brevis red tide and Microcystis aeruginosa blue-green algae mentioned above.
*Even non-toxic algae can kill wildlife in an indirect way. The algae become so abundant that they run out of space and light and start dying off in mass. As the masses of algae decompose, the oxygen levels in the water go down, because the process of decomposition consumes oxygen. When the water is oxygen depleted, organisms that get their oxygen from the water, like fish, die. This phenomenon is called "hypoxia and anoxia" and it is the cause of the infamous "dead zone" in the ocean near the mouth of the Mississippi River. Hypoxia due to eutrophication has also been the cause of many fish kills recently in the Indian River Lagoon on the East Coast of Florida.
*Dense blooms of algae make the water murky green or brown, which reduces the amount of light penetrating the water. This can be fatal for the “good” plants, like seagrasses (not to be confused with seaweeds), that are trying to grow on the bottom underneath. (All plants and algae need light to grow.)
*Even when algal toxin levels are not concentrated enough to kill the aquatic organisms from direct exposure, they can be dangerous for animals higher in the food chain, like big fish, birds, and humans, who eat contaminated seafood. This is because the sea creatures we eat, like fish, clams, and oysters, can concentrate the toxins in their flesh to much higher levels than they were in the water itself. For example, direct exposure to Florida Red Tide waters irritates the eyes and respiratory system of humans, while eating shellfish contaminated with the red tide causes much more serious Neurotoxic Shellfish Poisoning (NSP).
The best way to prevent eutrophication is to avoid putting nutrients in the water in the first place. If the nutrients are already in the water, then you need to remove them. The best way to remove excess nutrients from the water before they cause eutrophication is to have the water run through lush wetlands, where the “good” wetland plants can suck up the excess nutrients before the water gets into rivers, lakes, or the ocean. The Florida Everglades are a giant wetlands that are great for storing water and filtering out excess nutrients. Unfortunately the man-made water flow in Florida mostly bypasses the Everglades, due to ill-conceived canal and dam projects begun over a century ago. The Everglades are now left dry and unused, while the unfiltered, nutrient-polluted water is ushered straight to the coasts, resulting in major eutrophication effects along the coasts. In addition to the "major plumbing problem" of Lake Okeechobee and the Everglades, we have the "death from 1000 paper cuts" eutrophication effect of nutrients leaking out from myriad sources in urban, suburban, and agricultural landscapes. I propose that we address those problems with some emergency regulations.
A Modest Proposal Whereas almost the entire coastline of Florida, and many of the state’s freshwater lakes and rivers are experiencing harmful algae blooms, Whereas these algae blooms are causing massive damage to the ecology, economy, and spirit of the state, Whereas these algae blooms flourish on nutrient-polluted runoff, And whereas a substantial portion of this nutrient-polluted runoff stems from commercial and residential landscape management practices that serve merely aesthetic purposes, We propose a moratorium on those non-essential landscape management practices that contribute to nutrient pollution, effective immediately and continuing until such time as the harmful algal blooms have abated.
The moratorium will include:
*The sale and use of fertilizers for all non-agricultural purposes. This shall include fertilizer-weed-killer mixtures.
*The chemical treatment of ponds and canals with herbicides such as Copper Sulfate, because this practice results in the release of nutrients to downstream waters from decomposing plants and algae. (The moratorium should also cover the sale of such chemicals.)
*The clearing, mowing, or poisoning of vegetation within stormwater detention areas or within five feet of the waterline in these areas, because destruction of such vegetation limits the nutrient-filtration and removal abilities of these areas.
What do you think? Would you support that proposal?