Manatees and Aquatic Grass Restoration

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The Florida Manatee is a pretty easy going marine mammal. They eat various aquatic vegetation, seek warm water sites in the winter and peaceful shallow waters to raise their calves. With these rather simple demands one would think the manatee has a seemingly bucolic existence.

Doesn’t this manatee look contented while taking a breath? It’s been munching on an area of restored seagrass near the entrance to Three Sisters Spring, Crystal River, Florida. Photograph from November 2020.Well fed manatee taking a breath in between grazing on restored aquatic grasses

Unfortunately a totally carefree existence is not in the cards for our beloved manatees as they face many challenges throughout their range. Florida manatees have been in the news lately regarding the high manatee mortality numbers for 2021, as well as reports of scores of starving manatees.

I’m not going to focus on all the details of the manatees that have had difficulty finding food earlier this year. The experts at FWC (Florida Fish and Wildlife Conservation Commission) along with manatee researchers can tackle the true information and statistics of the hungry manatee problem. I am not a scientist, but I am a Florida Master Naturalist with hundreds and hundreds of hours of direct underwater observation of manatee behavior. The way I understand it the manatee’s food scarcity is centered on a collapse of it’s food sources in and around the Indian River Lagoon on Florida’s East Coast. During the early colder months of 2021, manatees were faced with having to stay warm in areas on the east coast near where the seagrass beds had collapsed. The situation is enormously concerning and particularly sad as this problem was years in the making.

In this post I wanted to focus on some of the positive steps that have been taken to help the Florida manatees. On the West Coast of Florida where I live there are still many large tracks of healthy seagrass and other aquatic vegetation for our manatees to eat. If we have a rise in manatee mortalities here it’s usually due to some other cause than hunger. And in Crystal River there is a successful restoration effort to replant aquatic grass where it disappeared years ago.

Large seagrass cages are placed in various waterways around Crystal River. The company doing the work is Sea & Shoreline under the supervision of the Crystal River National Wildlife Refuge and various local and state partners. The grass is named rockstar eelgrass and it’s been very successful in many areas of King’s Bay. After invasive mats of Lyngbya algae are removed by divers, large cages with eelgrass are placed out of navigational areas. You can see from the photograph below the aquatic grass really takes off in areas with sunlight and good tidal flow. The cages protect the grass until it has proliferated and is firmly rooted. These grass cages were a distance from the main freshwater springs near Three Sisters Springs where no grass has grown for quite some time.

Aquatic grass cages are placed on clean substrate. After the eelgrass takes root it spills over into surrounding areas bolstered by a strong tidal flow. Photograph from November 2020.
Aquatic grass restoration cages Crystal River Florida

While eelgrass first had success in and around the Hunter Springs area of Crystal River, it’s been many years since any aquatic grass rooted near Three Sisters Springs. While I haven’t been able to observe manatees munching in front of Three Sisters yet this year due to weather conditions, here’s what it looked like last November 2020. Right in front of Three Sisters Springs! And the grass lasted well into December for feeding Kings Bay’s manatees and it will come back every year now.

This manatee is grazing on restored eelgrass right in front of Three Sisters Springs. Note, this manatee is not at all skinny. Photographs are from November 2020.Well fed manatee grazing on restored aquatic grasses

Manatee takes a satisfying break from grazing on replanted eelgrass beds right in front of Three Sisters Springs.Manatee taking a break after grazing

And the grass was still around for grazing manatees in December 2020!Manatee feeding on restored seagrass in December

It seems the rockstar eelgrass thrives in areas with clear water, sunlight and tidal flow. But the restoration of aquatic grass can also clear up the water in many areas.

You may recognize the front sanctuary of Three Sisters in the background of this photograph. No manatees are in the sanctuary because they are out and about in various water areas, many munching to their heart’s content! Look at that lovely rooted grass and clear blue water!Restored eelgrass beds in front of Three Sisters Spring

More views of the eelgrass in front of Three Sisters Springs.Restored eelgrass beds in front of Three Sisters Spring

After manatees have grazed, some clumps of grass can dislodge but they will often take root in another area.Restored rockstar eelgrass thrives in sunlight

I hope I’ve had a chance to spread some enlightenment regarding the news reports of hungry manatees in Florida. It is, indeed, a serious problem, but one that very fortunately is not state wide. With this and other aquatic grass restoration efforts underway, along with the possibility of a dam removal opening up seagrass rich areas around the Silver River to east coast manatees traveling inland, the Florida manatee will have a fighting chance.

Best, Carol