Manatee deaths in Florida. Are they dying off from spraying herbicides? Let’s examine.

Florida Manatee
Florida Manatee

The U.S. Fish and Wildlife Service said they estimate about 6,500 manatees remain in the Southeast United States, most of them in Florida. We will be witnessing a total manatee extinction very soon if nothing is done about it. 

In 2017, manatees were taken off the endangered list because of a population boom. Now, their status is listed as “threatened.”

In all of 2020, there were 593 manatee deaths across Florida, including 90, due to boat strikes. What’s even more staggering is that more than 500 manatees have already died in 2021, in Florida alone.

To learn more about the problem, we must find out what’s going on in Brevard County, where many manatees are dying. There is no evidence of a manatee die-off in Sebastian. Unfortunately, some have been killed by boaters and other reasons. 

For the most part, the lagoon in Sebastian is full of wildlife. There are plenty of dolphins, turtles, manatees, and other wildlife in the lagoon. However, seagrass, a vital food source for the manatees, is disappearing. 

A Decline in Water Quality

We reached out to Libby Lavette, founder of the Facebook page and group Edgewater Environmental Alliance in Brevard County. She has witnessed the problem firsthand and has partnered in the Indian River Lagoon clam restoration project.

“We actually began noticing a decline in the water quality at Max Brewer Causeway (Titusville) over the summer when we began doing bridge walks to raise awareness. It is my firm belief that the SandPoint Park sewage break was leaking long before the main break in December,” Lavette told Sebastian Daily.

More than 7 million gallons of raw sewage leaked from a Titusville sewer pipe at SandPoint Park in December 2020. The Florida Department of Environmental Protection told Sebastian Daily that most of the sewage was contained in the park’s ponds. Soon after, fish and other wildlife began to die in and around the ponds. However, many people witnessed raw sewage in the lagoon during the spill.

Lavette said the sewage problem in northern Brevard County has been coming for a long time, and she believes it’s at a tipping point. She said the spill created a brown tide.

“I do believe this massive sewage spill pushed us over the edge, and we still can’t get testing and water quality reports. What was left of the seagrass disappeared this year,” Lavette added.

Dr. Edward J. Phlips, who works for the Department of Fisheries and Aquatic Sciences for the University of Florida, has been testing some of the water, but those tests are sent to the state for evaluation before they are made public.

We then reached out to Kim Haigler, Environmental Planner/GIS Specialist for the City of Sebastian. She has a BA in Environmental Management in Natural Resources & MS in Environmental Science, both from the University of Florida. 

Haigler’s Graduate Thesis is on the nutrient uptake of aquatic plants in the Indian River Lagoon Basin and was published in Ecological Engineering in 2017. She also interned at the University of Florida’s Biological Control facility in Ft. Pierce.

She says Brevard County has a number of widely known factors working against the manatees. 

“First, there is a dense aggregation of septic tanks along the waterfront. Then, the Mosquito Lagoon and Banana River are blocked from the influx and flushing from the tidal waters that the rest of the Indian River Lagoon receives. Manatee populations have been increasing exponentially since the 1990s. There are more manatees and less seagrass, and many are hungry and weak,” Haigler told Sebastian Daily.

Haigler said the manatees are gathering in large aggregations around small seagrass beds and isolated pockets of warmer waters, which further increases the threat of disease. 

“This recent die-off will not likely be attributed to one factor, but rather a combination of human-induced factors,” said Haigler.

Herbicides and Seagrass

The City of Sebastian is using a product to treat selected invasive plants. The product contains an active ingredient that inhibits the plant’s ability to produce amino acids, cell walls, pigment, hormones, and things needed for growth.

Haigler says that the primary factors affecting seagrass are light availability and nutrients.

“The primary way that many experts agree herbicides harm seagrass is by creating masses of dead vegetation, which sink to the bottom and become part of the fine, silty muck that coats the grasses and suspends in the water column, decreasing light availability,” said Haigler. 

Haigler says seagrasses have a very specific, high light requirement for photosynthesis. This process is especially a concern surrounding areas where lateral canals meet the lagoon, where even live vegetation dies as soon as it hits the estuarine water and sinks. 

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“It is also possible that decaying vegetation releases nutrients into the water that aid in algal growth, which then prevents sunlight penetration to the seagrasses. All of Sebastian’s outfalls are spillover, which block any bottom sediments or muck from entering the Indian River Lagoon or the St. Sebastian River,” said Haigler.

Most research on herbicides and seagrass are focused on the PS II herbicides, according to Haigler. They are inexpensive and usually broadcast sprayed over entire crops. 

But what about glyphosate having an effect on seagrass?

“Glyphosate and 2-4D have also been found to have an effect on seagrasses at very high concentrations. These high concentrations are occurring in areas where a genetically modified crop is designed to be resistant to the pesticide, and the crops are sprayed liberally and often, with much of the chemical traveling with the stormwater run-off. This would especially be a concern in the waters surrounding the giant sugar cane monoculture north of the Everglades,” said Haigler.

The City of Sebastian does not use glyphosate. However, some people believe that herbicides with Photosystem II Inhibitors are being used all around Sebastian. 

“Herbicides with Photosystem II (PSII) Inhibitors are commonly used on field crops to control broadleaf weeds. There are no PSII Herbicides approved for aquatic use. In fact, there are no PSII Herbicides on the list of approved pesticides for the Parks and Properties Integrated Pest Management (IPM) Plan either,” Haigler explained.

Glyphosate and Manatee Deaths

There was a 10-year study done that showed glyphosate in more than half of dead manatees. However, no study has confirmed if the deaths were caused by glyphosate. Glyphosate is the active chemical compound found in the product Roundup, which the City of Sebastian is no longer using.

Some of the local environmentalists in Sebastian, who like to join multiple nonprofit organizations and call themselves “Environmental Educators,” believe herbicides are killing off the manatees and everything else in the lagoon. They are part of the local misinformation campaign.

The real educators say different.

“A recently published study did find glyphosate in manatee blood samples taken across the state. However, this is the first study of its kind and mainly serves as exploratory. The original scientific study does not make conclusions as to how the glyphosate is affecting the manatees’ health. In fact the highest blood concentration found was 3.59 micrograms/liter and the average was 0.17- 0.47 micrograms/Liter. This is thousands less than the average blood concentration (61mg/L) found in humans, experiencing mild to moderate symptoms following glyphosate poisoning, and these people intentionally ingested 10oz or more of the herbicide (2013, Forensic Science International),” Haigler explained.

Haigler also said the original study uses data from previous studies on lab mice to predict what effect glyphosate may have on the manatees. 

“Manatees are more closely related to an armadillo than humans or mice and are physiologically highly specialized. For instance, they can tolerate a much higher concentration of heavy metals, without a toxicological response, compared to terrestrial mammals. It was determined that simply the presence of heavy metals does not imply that the metals have a toxic or adverse effect on the Manatees (2019, Environmental Research and Public Health). This isn’t to say that the presence of glyphosate doesn’t matter. It is the most widely used agro-chemical in the world, and it is found in our blood and food as well. However, at this point, there has been no study that can conclusively correlate prolonged or repeated glyphosate exposure to long-term human health, and the same can be said for the manatees,” Haigler explained.

Colder temperatures cause cold stress for manatees, known as Cold Stress Syndrome, or CSS. It affects all organs in manatees. The manatees would rather die of starvation in warm waters than relocate where other food sources are available.

Several seagrass restoration projects are going on in the Indian River Lagoon. One is operated by Laurilee Thompson, owner of Dixie Crossroads in Brevard County. Thompson’s seagrass restoration is doing well under the current circumstances. 

Why Spray?

The City of Sebastian isn’t always spraying and has been doing mechanical harvesting on most canals. They spray in areas that are impossible to reach with large equipment.

Sebastian faces drainage problems and area flooding if we do nothing, just like we saw during the failed moratorium. Some local non-profits say to leave it alone and allow “Mother Nature” to take its course. However, that’s not an option when it comes to invasive plants.

City of Sebastian is Helping Indian River Lagoon

The City of Sebastian has done a fantastic job protecting the environment and lagoon. They have done more than most municipalities that are near the lagoon.

What has the City of Sebastian done to help the Indian River Lagoon? 

  • Fertilizer ban each year from June through September
  • Community Oyster Garden Outreach Grant Project
  • Floating Mini Oyster Reef Installations
  • Manual harvesting of invasive plants
  • Storm Water treatment facility that removes nutrients.
  • Glysophate not in use
  • They are moving people from septic to sewer along the Indian River Lagoon by using grants to pay for the costs. 
  • Parks & Properties Integrated Pest Management Plan
  • Stormwater Integrated Pest Management Plan
  • 7 outfalls from US1 to the Indian River Lagoon have Baffle Boxes installed to trap pollutants, which are vacuumed out monthly
  • Sustainable Sebastian Initiative

We all care about our environment here in Sebastian, but we also need to stop the misinformation campaigns by environmentalists who have made false claims about the City of Sebastian and its spraying.

There have been propaganda videos recorded by people (and one received an award from the Pelican Island Audubon Society after tarnishing Sebastian) based on no evidence or science to back up their claims.

If you do have any questions, just ask City of Sebastian. They are very forthcoming with information and have nothing to hide.

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About Andy Hodges 2806 Articles
Andy Hodges was born in Annapolis, Maryland, and raised in Jupiter, Florida. He has been a radio and TV personality since the mid-1980s. He has worked for WFLX-TV (Fox 29), WIRK, WLIZ, WIXI, WKSY, WRMF, and others. In 1994, Andy took a break from broadcasting and was a software and systems engineer for various companies. In 2002, he permanently moved back to Sebastian, where Andy's family has lived for over 45 years. He returned to the broadcasting sector in 2005. Andy joined Sebastian Daily as our editor-in-chief in 2016.