Algal Blooms: Cause and Effect
You may have seen in the news that unfortunately Florida is experiencing multiple algal blooms around the southern part of the state. The red tide in the Gulf of Mexico and blue-green algae inland. Seasonal algal blooms are a natural part of a water systems, but human activity and climate change are causing these blooms to become larger and more severe. Thousands of dead fish are washing ashore, and mammals are suffering too. Sea turtles, manatees, and even a young whale shark have died as a result of the red tide.
The red tide is getting the most air time because of the dramatic and disturbing photos of the effects. A seasonal red tide is a natural occurrence offshore that makes its way towards the coast, where it would naturally fade away - but warm waters and an increasing amount of pollution, including agricultural runoff, is creating a prime environment where the red tide is growing and sticking around. The organism that makes up the tide - kerenia brevis, a cyanobacteria - is toxic and poisonous to marine life. This is where the depressing pictures of dead fish and sea turtles washed ashore are coming from.
The freshwater counterpart to the red tide, blue-green algae blooms, is also apparent in Florida waters right now. This version of the cyanobacteria, adapted to the freshwater, is also toxic. In addition, it coats the surface of the water, blocks sunlight for aquatic plants, and reduces the amount of oxygen in the water which suffocates marine life.
Both blooms also affect humans. Humans can experience symptoms such as respiratory problems, skin irritation, and nausea from the toxicity. Also being talked about are the economic consequences. Many businesses rely on healthy waters and coasts, like commercial fishing and charter boats, outdoor recreation tours, and the hospitality industry. Florida is known for its beautiful scenery and natural landscapes, but is now left with deserted beaches except for the smelly water and dead animals.
So why are this summer's blooms so harsh? The main causes are agricultural runoff and stormwater system pollution. The pollution from commercial sugar plantations and even residentially used fertilizers affect the natural chemistry of the water, allowing the algae to thrive. So a very simple thing one could do to help avoid algal blooms is to avoid using synthetic fertilizers and pay attention to application and disposal of fertilizers. The nutrients in synthetic fertilizers do not get absorbed by the plants as readily as natural fertilizer, so much of it washes away, and the nitrates and phosphates end up in the water system, promoting the growth of algae. Plants can more easily absorb the nutrients from natural fertilizers, like compost or bone meal, and less fertilizer washes away.
To protect the stormwater system, which ends up leading into the ocean or rivers, do your best to make sure only rain goes down the drain. Do not blow leaves and grass clippings into the street. Go to a commercial car wash or wash your car in the yard, and make sure your gutters are directed to your lawn or vegetated area. All of these activities keep chemicals out of the water system.
And as always, contact your politicians - local, state, and federal - about the important issue of water pollution. Make sure they know updated infrastructure, public works funding, and pollution regulations will help solve this problem.
Great article with dramatic pictures from National Geographic:
Great guides from the South Florida Water Management District about water pollution and water systems:
About fertilizers:
