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What Cause the Toxic Algal Bloom in South Florida and Could It Happen Here?

One of the locks on Lake Okeechobee that control water flow. Photo: Florida Sea Grant

One of the locks on Lake Okeechobee that control water flow.
Photo: Florida Sea Grant

Most of us have heard about the toxic algal blooms plaguing south Florida waters. If not, check out http://www.cnbc.com/2016/07/05/.  This bloom has caused several major fish kills, bad odors, and has kept tourist away from the area.  What happen? Could it happen in the panhandle?

 

First we have to understand what happened there. The source of the problem is Lake Okeechobee.  This large freshwater lake has been diked and channeled over the years to supply water to cities and farms in south Florida.  The flow of water in and out of the lake is controlled by the Army Corp of Engineers.  Typically, this time of year they manage the level of water within the lake to prepare for both the rainy and hurricane seasons.  To do this they allow water to flow out into local rivers and canals.  However, the water within the lake is heavy with nutrients.  Fertilizers, leave matter, and animal waste are discharged into the lake from neighboring communities and agriculture fields.  These nutrients fuel the rapid growth of plants and algae, which we call a bloom.  These blooms can contain toxic forms of algae that can cause skin irritation and intestinal problems in humans, and can kill many forms of wildlife.  Because the state is trying to restore the Everglades, polluted water cannot be released in a southern direction (unless nutrient levels are low enough) but rather east and west towards the populated coasts.

 

But this year was different…

 

Due to heavy rainfall in spring the Corp had to release more water than they typically would. It was after this release that the large blooms along the east coast began to occur.  The state declared a state of emergency and the flow of water out of the lake was altered.  But for east Florida, the damage is done.

 

Could this happen in other parts of the state? Could it happen in the panhandle?

 

Well first, we have very few controlled water systems for drinking water (reservoirs) so that exact same scenario is a low probability. During a recent trip out west I camped several times along a reservoir designed to hold drinking water for municipalities.  At each there were information signs warning swimmers about the potential of high levels of toxic cyanobacteria, particularly in late summer and early fall.  But here most of our rivers flow unimpeded (relatively) to the Gulf of Mexico.  Our drinking water instead comes from the ground.

 

But could our local waterways become contaminated with algae?

 

Yes…

With the situation going on in south Florida people of have pointed fingers at the Corp for releasing too much water. But because the water was already polluted, others have pointed the finger at the fact that we do not regulate nutrient discharge as well as we should.  We have cities and farms here as well, and each produce and release nutrients in the form of leaf litter, animal waste, and fertilizers.  Actually large fish kills have happened here.  I remember seeing large masses of dead fish on the surface of Bayou Texar in Pensacola when I was younger; Bayou’s Chico and Grande had their problems as well.

When I first joined Sea Grant I was told that water quality was a concern in the Pensacola area. Many remembered these large fish kills from a few decades ago and were still concerned about the quality of water in our area, particularly the bayous.  I have worked with local non-profits, as well as state and county agencies, and the local high schools to monitor nutrients in the area.  The nutrient of concern here is nitrogen.  Several groups including the Bream Fishermen’s Association, Escambia County, UF/IFAS LAKEWATCH, and the School District’s Marine Science Academy routinely monitor for nitrogen.  Others, such as the University of West Florida and the U.S. EPA, do so when they are working on such projects.  Low nitrogen levels could mean less being discharged, but it could also mean that the algae have consumed it – so monitoring for chlorophyll (indicator for the presence of algae) is also important; and these groups do this as well.  High levels of algae can trigger declines in dissolved oxygen, so this is monitored also.  Low dissolved oxygen can trigger fish kills, and this data is collected by the Florida Fish and Wildlife Conservation Commission.  I try to collect as much of this data as I can and post it on our website each Friday.

Yes, we have areas with relative high levels of nitrogen, when compared to other locations sampled. Dissolved oxygen levels are typically okay, but most of the monitors are sampling in shallow water.  A UF/IFAS LAKEWATCH volunteer has recently started to monitor DO at depth in Perdido Bay.  But fish kills are down.  There are a few here and there, but the numbers are much lower than they were a few decades ago and many are not related to the nutrient issue.  We did have a large red tide in the fall of 2015 that was probably nutrient related, but these too are rare in the panhandle –we will have to watch this over the coming years.

South Florida waterway covered with algae.   Photo: University of South Florida News

South Florida waterway covered with algae.
Photo: University of South Florida News

What we do have a problem with are health advisories. Some agencies, FDEP and Escambia County, monitor for fecal coliform bacteria.  These are bacteria associated with the digestive system of birds and mammals, including humans, and are non-toxic.  However, they are indicators that animal waste is in the water and that pathogenic bacteria associated with animals could be also.  When samples are collected the number of bacteria colonies are counted.  If the number is above what is allowed a re-sample is taken.  If the second count is high as well a health advisory is issued.  Many coastal waterways in the panhandle are fighting this problem.  Based on FDEP data, the bayous of the Pensacola area average between 8-10 advisories each year.  Not all bodies of water are monitored at the same frequency but our bayous are issued advisories between 25-35% of the time they are sampled.  Most of the advisories occur after a heavy rainfall, suggesting the source of the animal waste is from run-off, but it could be related to leaky septic tanks systems as well.

 

So though the scenario that is occurring in south Florida is a low risk for our area, we do have some concerns and there are many things residents and citizens can do to help reduce the risk of a large problem occurring.

  1. Manage the amount of fertilizer you use. Whether you are a farmer, a lawn care company, or property owner, think about how much you are using and use only what your plants need. For assistance on this, contact your extension office.
  2. Reduce leaf litter from entering waterways. When raking we recommend you bag your leaves using the new paper bags. These can be composted at the landfill. If you have large amounts of leaves that cannot be bagged, consider composting yourself. The demonstration garden at your local extension office can show you several methods of composting.
  3. Pick up your animal waste. Our streets and parks are littered with pet waste that owners have not removed, even with the city and county providing plastic bag dispensers to do so. Please be aware of the problem with animal waste and help keep our streets and waterways clean.
  4. If you have a septic tank, maintain it properly. If you are not sure how to do this, contact your local extension office for advice.

We will continue to work with local water quality monitoring groups and present data each Friday. I will also have a complete report at the end of each year.  If you have any questions, please contact me at the Escambia County Extension office.

Permanent link to this article: http://escambia.ifas.ufl.edu/blog/2016/07/30/what-cause-the-toxic-algal-bloom-in-south-florida-and-could-it-happen-here/