Algae Blooms and Seagrass Loss

Last update: May 25, 2023
This page will be updated as new information becomes available.

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Thousands of acres of seagrass in Florida have died because of nutrient pollution that has caused algae blooms and left manatees without an adequate food source. Learn more about this issue, projects that are being undertaken, and ways you can help.

The Indian River Lagoon (IRL) stretches for 156 miles along Florida’s east central coast. There are more than 4,400 species of plants and animals—including manatees—that are found in the lagoon watershed. Unfortunately, as the direct result of human derelictions over many decades, the Indian River Lagoon has suffered a series of harmful algal blooms, leading to massive losses in seagrass coverage and, in turn, the recent deaths of a heart-rending number of manatees equal to over 25% of the estimated manatee population.

Trouble for Manatees in the Indian River Lagoon

Note: data is preliminary. As of February 6, 2023, there were 800 confirmed carcasses recovered in 2022. Click to view a full-size version of this map.

An excess of nitrogen and phosphorus in waterways can fuel algae and cause it to grow faster than the ecosystem can tolerate. In the IRL, a combination of improperly treated sewage, leaking septic systems, fertilizers, and stormwater runoff has led to eutrophication. This means that frequent harmful algal blooms have blocked the light necessary for photosynthesis. The result: the tragic loss of more than 90% of the seagrass biomass within the Indian River Lagoon.

Before the IRL can be functionally restored, it will be necessary to prevent new sources of nutrient pollution from entering the lagoon as well as strategically removing or sequestering legacy nutrients to make them unavailable as a source of new Harmful Algal Blooms (HAB). Ideally, seagrasses will begin to reestablish on their own, but the process may be facilitated through the restoration of filter feeding organisms and selective pilot seagrass restoration projects. Ultimately, we must reverse those conditions that lead to the loss of seagrasses in the first place if we are going to restore seagrasses.

In 2021, the U.S. Fish and Wildlife Service (FWS) declared an Unusual Mortality Event (UME) for manatees. A UME involves a significant die-off of any marine mammal population and demands immediate response.

Manatees gathering at warm water locations—such as power plants—along the IRL have faced an additional threat, beginning with the 2020-2021 winter season, because there has been very little seagrass or other vegetation for them to eat in the immediate vicinity. Traveling further for forage would mean deadly exposure to cold water, so the manatees ultimately choose to forgo feeding over dying from the cold.
Between December 2020 and December 2022, over 2,000 manatees perished in Florida. 744 of those deaths occurred in Brevard County, which is considered the epicenter of the Unusual Mortality Event.

See our opinion editorial: A State of Emergency for Manatees in the Indian River Lagoon and Beyond.
Get more information from the Florida Fish and Wildlife Conservation Commission (FWC) on the Manatee UME.
Watch Indian River Lagoon: Why All of Us Should Love Seagrass, an informative webinar from the Marine Discovery Center.
Florida Department of Environmental Protection – Algal Bloom Sampling Status.
MOTE Marine Laboratory – Beach Conditions Reporting System.

In a healthy ecosystem, free-ranging manatee grazing makes seagrass communities more productive.

Manatees have evolved along with seagrass communities for millions of years and primarily crop the grasses rather than uprooting entire plants, which can actually stimulate the grasses to grow. The loss of seagrass in the IRL is largely due to persistent and recurring environmental events that have changed the ecosystem over time—especially from human sources of pollution.

What Else Is Being Done to Help Malnourished Manatees?

Save the Manatee Club is a founding member of the Manatee Rescue and Rehabilitation Partnership (MRP), a network of partners who participate in the rescue, rehabilitation, release, and post-release monitoring of sick or injured manatees. We are working together with our partners in the MRP to identify manatees in distress due to devastating seagrass losses in Indian River Lagoon.

Save the Manatee Club and our partners are also working diligently on improving water quality to enable natural regrowth of seagrasses and to replant areas where replanting is feasible now.

See Save the Manatee Club’s Work below for more information on our activities to help manatees during the UME.

An emaciated manatee is rescued by the Florida Fish & Wildlife Conservation Commission (FWC). Photo courtesy FWC.

If you are at all concerned that a manatee may be sick, injured, entangled, or orphaned, or if you see a manatee that is being harassed or wearing a "tag" or tracking device, please immediately report it to the Florida Fish and Wildlife Conservation Commission (FWC) 24-hour Wildlife Alert Hotline by calling 1-888-404-3922 (FWCC).

What You Can Do

Excessive human-produced nutrient pollution is a growing threat to all seagrass communities. When combined with the warming effects of climate change and sea level rise, these excess nutrients present an even greater danger to the future of seagrasses wherever they are found.

While there are many large-scale sources of pollution, it’s impossible to overstate the value of individual actions. What you do at home can make a big impact—whether you live near the Indian River Lagoon or not. Most people in the United States live in a watershed (a land area that drains to a river, lake, ocean, or other waterway)!

Please don’t feed or give manatees water. Giving food or water to manatees is illegal and teaches them to associate people and/or boats with handouts, which changes their behavior and puts them in harm’s way.

Here are some examples of direct actions you can take to protect our waterways

While Save the Manatee Club works with our partners to strengthen policies that protect water quality, the individual actions of each Florida resident can make a big difference for the health of our waterways. Learn how to do your part and take Save the Manatee Club's pledge to be Fertilizer-Free for Manatees.

Help reduce pollution and prevent harmful algal blooms from forming.
- Fertilize less, or not at all. Many established landscapes may not need fertilizer. When in doubt, if you must use fertilizer, apply slow-release nitrogen fertilizers to your lawn only once per year. Your local UF-IFAS Extension Office can assist with soil tests, plant recommendations, and specific lawn questions.
  - Follow Florida Friendly Landscaping™ principles.
  - Know your local fertilizer regulations.
  - Take Save the Manatee Club’s Pledge to be Fertilizer-Free.
- Keep yard debris like grass clippings away from stormwater drains.
- Properly maintain your home septic system to ensure it does not leak.
  Have your systems inspected every 3-5 years. If you can, consider transferring your home to a city sewer system.
- Pick up and properly dispose of your pet’s waste.
- Sign up for cleanups and other events to help protect the manatee’s aquatic habitat. You can find them on the Save the Manatee Club Upcoming Events and Facebook Events. You can sign up to volunteer for future seagrass planting projects here.
- Learn more tips to reduce lagoon pollution:

More actions you can take for the environment

Be seagrass safe while you are out on the water.
Prevent damage to seagrasses by avoiding boating over seagrass beds. If you must boat over seagrass beds, trim up your motor and idle to a safe depth before getting on plane, and carefully push your boat away if you run aground.
Send a message to President Biden and your U.S. senators and representative urging them to come to the aid of manatees and the Indian River Lagoon.
Send a message to Florida governor Ron DeSantis, asking him to stop the degradation of Florida’s waterways and lead the way in safeguarding the aquatic environment for manatees, other wildlife, and for people, too.

More Information

Save the Manatee Club's Work

Save the Manatee Club is engaged in numerous activities to protect critical habitat for manatees and water quality standards in Florida.

Legal and Political Activities

SMC advocates for stronger protections for manatees and their aquatic habitat both at the state level in Florida and federally, pressing agencies to address the decades of excess nutrient pollution entering our waterways and leading to Harmful Algal Blooms (HABs) that devastate seagrasses and other manatee forage. We also advocate for the addition of Aquatic Ecosystem Restoration as a component of President Biden’s Infrastructure Improvement Initiative.
Together with the Center for Biological Diversity and Defenders of Wildlife, we filed suit against the U.S. Fish & Wildlife Service in order to compel the agency to update the manatee’s critical habitat under the Endangered Species Act. In June, FWS committed to do so by September 2024.
In May 2022, Save the Manatee Club joined the Center for Biological Diversity and Defenders of Wildlife in filing suit against the U.S. Environmental Protection Agency for failing to protect manatees and sea turtles from water pollution in Florida.
SMC is also urging FWS to restore the manatee’s status as an endangered species, as they were prematurely downgraded in 2017.
Save the Manatee Club has a long and continuing history of working with the state of Florida to develop stronger Basin Management Action Plans (BMAPs), which are “blueprints” for restoring impaired waters by reducing pollutant loadings. SMC advocates for more conservative Minimum Flows and Levels (MFLs), which help protect water resources from significant harm from water withdrawals, as well as waterway restoration plans.

Networking, Programming, and Outreach

In Summer 2022, Save the Manatee Club’s Fertilizer-Free for Manatees program saw hundreds of Florida residents take the pledge to be fertilizer-free. Campaign billboards in counties along Florida’s east coast reached over 2 million viewers. The program will continue into 2023.
We have worked to strengthen partnerships with agencies, universities and non-profits working to restore seagrass, clams, mangroves and water quality in the Indian River Lagoon.
SMC staff members attend conferences, working group meetings, and workshops, and participate in field work to learn about ongoing restoration work in the Indian River Lagoon and how Save the Manatee Club could best support these efforts.
SMC is a member of the Rivers Coalition and the Indian River Lagoon National Estuary Program Stem Advisory Committee.
We have partnered with the Marine Resources Council to host the Seagrass Assembly, a two-day gathering bringing together experts in the field of seagrass management, research and restoration in the Indian River Lagoon.
Save the Manatee Club has increased public awareness of these issues through numerous presentations, interviews, and media coverage.
- PBS: Changing Seas
- NPR: “Saving starving manatees will mean saving this crucial lagoon habitat”
- Christian Science Monitor: “Saving starving manatees: Can Florida solve a man-made crisis?”
- PBS News Hour: “Biologists take drastic measures to save Florida manatees at risk of starvation”
- Op-Ed: “A State of Emergency for Manatees in the Indian River Lagoon and Beyond”
- Florida Manatees are Dying of Starvation at an Alarming Rate
  Patrick Rose, Save the Manatee Club Executive Director is interviewed on The Weekly on News 6
- Webinar: What’s Going on With the Manatees in the Indian River Lagoon?
See our News page for more.

Manatee Rescue and Rehabilitation

Save the Manatee Club participates as a charter member and Fiduciary Sponsor of the Manatee Rescue and Rehabilitation Partnership (MRP) and sponsors many partner efforts in the MRP by providing equipment and funding.

We also work with partners to release rehabilitated manatees at Blue Spring State Park as an alternative to the IRL area as a safe, warm site with plenty of vegetation.

Funding

Save the Manatee Club has provided necessary funding for a variety of projects and programs, including to:

Florida Oceanographic Society in support the expansion of their Citizen Science Seagrass Network, which monitors seagrass in the lower Indian River Lagoon.
Ellie Schiller Homosassa Springs Wildlife State Park, a rehabilitation facility, for the care and feeding of manatees rescued because of sickness or injury and for orphaned calves.
IRL Drone monitoring project volunteers, for travel expenses related to work to better assess manatee body condition and inform rescue teams of manatees who may be in distress.
Sponsor the Marine Resource’s Council Indian River Lagoon Report Card, which shares data about the state of the Indian River Lagoon with federal and Florida legislators, the public, and other entities.
In cooperation with state and private partners, to fund aerial surveys of the IRL to study seagrass coverage and the health of manatee populations throughout the area.
University of Florida, for research to understand if there is glyphosate interference with submerged plants and if it is contributing to manatee starvation. A 2021 UF Aquatic Animal Health study found that 55.8% of the Florida manatees tested have glyphosate in their bloodstream, which may cause organ damage and cancerous tumors.
Directly and indirectly seek funds for Seagrass/Submerged Aquatic Vegetation (SAV) planting projects by our conservation partners at the Florida Fish and Wildlife Conservation Commission, the St. John’s River Water Management District, and others.

SMC actively works to support additional federal and state funding for contingency planning, research, and the implementation of additional emergency holding capacity for treating sick and injured manatees, and for the staffing and equipment necessary to rescue every manatee in need.

Red Tide

In Florida, red tide is caused by a naturally occuring marine plankton (microscopic algae) called Karenia brevis, abbreviated K. brevis. It is found most commonly in the Gulf of Mexico. K. brevis produces several types of neurotoxins, the most impactful of which are brevetoxins. Whether they are ingested or inhaled, brevetoxins can be extremely harmful to manatees and cause seizures that lead to drowning.