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The ABC’s of Algae Bloom Concerns

What is an algae?  Algae are simple plant-like organisms that grow through photosynthesis; they use sunlight to metabolize nutrients, like phosphorus and nitrogen, to create biomass. Algae are a basic component of the food web and can be found in marine, estuarine, fresh water lakes, rivers, canal systems and even swimming pools. Algae appear as green, red or yellowish brown particles that float in the water, or as a thick scum that floats on the water surface.  Most algae, while visually unappealing and sometimes foul smelling, is not harmful to human health. However some types, like “Blue-green” algae, which is actually a cyanobacteria, and algae that produce “red tide” in ocean waters secrete toxins that can be harmful.

What causes algae blooms? Although algae is a normal component of the aquatic ecosystem, nutrient-rich waters, especially slow moving water warmed by the long days of warm summer sun, provide a favorable medium for the overgrowth of algae, called an algae bloom.   The algae bloom affecting the Treasure Coast stems from urban and agricultural land uses that contribute nutrient-rich surface waters to the natural drainage within the St. Lucie River and Indian River Lagoon watersheds, as well as releases of water from Lake Okeechobee. This polluted stormwater is conveyed by canals and tributaries that feed into the coastal estuaries. While little can be done about warm temperatures, the key to preventing algae blooms is to minimize the leaching of fertilizers, a large source of phosphorus and nitrogen, from surrounding farm land and residential developments into water bodies and canals.   

What are the impacts of algae blooms? Algae blooms have environmental, health and economic impacts.  The algae blooms can coat the water surface, limiting the penetration of sunlight to plants on the lake or lagoon bottom.  As plants and algae die, sink to the bottom and decompose, the levels of dissolved oxygen in the water drop, a condition called hypoxia. Fish and plants suffocate in these conditions, resulting in fish kills and aquatic “dead zones.”  These conditions impact fisheries and reduce the environmental quality of the coastline, subsequently impacting coastal tourism and related businesses. Moreover, algae blooms impact public health. The bacterial concentration in algae water resulting from dead fish and plant life can pose a risk of infections to humans and animals.

Can’t we fix this? Residents of the impacted areas have demanded that the water management districts halt discharges from Lake Okeechobee. This would reduce the flow of contaminated water, allowing the salinity levels in coastal estuaries to rise and help fend off the algae overproduction.   The situation however, is not so simple.  The water management district must balance the concerns about the fresh water discharge with need to manage, and at times lower water levels in the lake, in order to reduce strain on aging Herbert Hoover Dike on the lake’s southern shore.  After a particularly wet spring and summer, Lake Okeechobee levels have risen, and the discharges are necessary to protect life and property from a potential catastrophic failure.  Thus, residents and visitors of coastal communities may have to be patient and endure, until the bloom dissipates and dies out in cooler ocean waters.  The long-term solution lies in the completion of the Comprehensive Everglades Restoration project, which would help manage both water levels and contaminants in a more ecologically responsible fashion.

What do residents need to know about toxic algae?   It’s not possible to distinguish between toxic and non-toxic algae by looking at or smelling the water. Report algae blooms to local or state authorities so the water can be tested (see contact information below).

  • Don’t swim or wade in water with algae and keep children and pets away from algae waters.
  • Do not fish or eat shell fish from contaminated areas. Toxic algae can cause neurological liver and kidney problems if eaten.
  • The algae toxins can be aerosolized by waves and wind and inhaled by people living around the ponds and streams. It will aggravate respiratory illnesses like asthma, and thus persons with respiratory illnesses are cautioned to stay away from contaminated areas.
  • Symptoms of exposure to toxic algae include difficulty breathing, wheezing, skin rashes, headaches, and possibly tingling in the fingers and toes if the water was consumed.

 Additional information on Toxic Algae can be found at websites of the US Environmental Protection Agency and the Center for Disease Control. See the links below.



Report suspected algae blooms to the Department of Environmental Protection Bureau of Labs, Biology Section in Tallahassee   (850)245-8159    http://www.dep.state.fl.us/labs/ or the  Department of Health Aquatic Toxins Program (850) 245-4250 phtoxicology@FLHealth.gov



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