From the Extension: Algal blooms are common in Florida’s water bodies

Blue green algae and red tide, two types of harmful algal blooms, have been getting a lot of media attention in recent years — and for good reason. Algal blooms occur when populations of microscopic algae reach higher than normal numbers and are not an uncommon phenomenon in Florida’s water bodies. While not all algal blooms are harmful, some are beneficial to shellfish and microorganisms that feed on algae. Certain types of algal blooms can pose significant threats to ecosystems, wildlife, and human health.

Algal blooms commonly result from an excess of nutrients in combination with warmer water temperatures. Blooms are considered harmful when they are comprised of types of algae that are inedible, produce toxins and/or let off a foul odor. Harmful algal blooms can result in fish kills and cause skin and respiratory irritation in humans. Recreational water activities, such as swimming, boating, and fishing, decrease during harmful algal blooms and both the tourism industry and coastal housing markets suffer as a result.

The most common type of harmful algal blooms in freshwater systems are caused by blue green algae, also known as cyanobacteria. This type of algae can produce toxins that may be deadly to fish and other animals who encounter it. In ocean and brackish waters, harmful algal blooms are most often caused by a kind of algae known as a dinoflagellate which create conditions commonly known as “red tide”. Red tides can kill fish and cause respiratory problems for humans.

Predicting the timing and duration of harmful algal blooms is not a straightforward task. For a bloom to occur, a body of water but first develop favorable conditions that include warm temperature, adequate light, and a high concentration of the nutrients nitrogen and phosphorous. In freshwater systems these conditions become exacerbated during times of drought, when lake levels drop allowing for increased light penetration, warmer temperatures, and a less diluted concentration of nutrients. When all the above conditions are met a bloom can be triggered by specific weather conditions. The amount of sunshine, cloud cover, and rain all play a role in determining the length and severity of a bloom. Predicting red tides in saltwater systems is even more difficult as the particular triggers for a red tide event are not yet fully understood.

What can Floridians do to help decrease the incidence of harmful algal blooms? Humans play a major role in adding nutrients to water and should take steps to minimize these contributions. Septic tanks can be once source of excess nutrients. When feasible, neighborhoods should consider transitioning from septic to sewer to lower their negative impact on the environment. Fertilizer is another source of nutrients. Homeowners can reduce the the need for fertilizer by planting a Florida Friendly landscape. For more information on Florida Friendly Landscaping practices please visit https://ffl.ifas.ufl.edu. Farmers are also playing a role in reducing their environmental impact by adopting best management practices that reduce the chance of nutrient run off from farms. Precision agriculture technologies are allowing farmers to deliver nutrients directly to plants in exactly the quantity needed, further reducing the risk of runoff. UF/IFAS Extension is working with homeowners and farmers statewide to promote the adoption of practices that protect water quality.

For more information on algal blooms and what you can do to help prevent them, please visit http://edis.ifas.ufl.edu/sg153.

Megan Mann is interim director and a livestock agent at the UF/IFAS Lake County Extension Center. Email her at horsygrl@ufl.edu.