Despite its name, giant salvinia (Salvinia molesta) is actually pretty small. The floating plant starts out with a cluster of leaves no bigger than a dime. They don’t stay that way, though, and perhaps their outsized influence and spread gives the “giant” a little more credence.
Giant salvinia is an invasive aquatic plant that was introduced to the United States as an ornamental plant (for aquariums and backyard ponds) from South America. Once it managed to escape to the wild, however, salvinia really took off. More than 20 states report salvinia popping up in their waters, although Texas and Louisiana seem to have the biggest battles with it. The plant has choked up entire freshwater lakes and sections of rivers, requiring a major eradication effort just to regain access to the water. Even small craft like kayaks and canoes cannot make it through a water body clogged with this plant. It is often spread by small pieces lodging in boat motors and trailers, so if you boat frequently in an area of known salvinia, be sure to remove any fragments of the plant once you are back on land. Preventing the spread from one water body to another is crucial.
Our native birds, fish, and aquatic mammals don’t eat giant salvinia—it appears not to have much nutritional value—and therefore its growth goes unchecked. The thick mats of plant growth block sunlight into the water column, preventing other aquatic plants from growing. Die-offs of large numbers of salvinia can eat up oxygen levels in the water, causing fish kills.
Giant salvinia overgrowth in a backwater section of Bayou Chico in Escambia County. Photo credit: Escambia County Natural Resource Management
There are several approaches to managing the plant. Mechanical or hand removal can take out significant amounts of salvinia, but is ineffective in the long run. Any small piece of chopped up plant left behind in the process will regrow into new spreading plants, so leaving any fragments in the water ends up increasing the population. More effective methods include applying herbicides or using a biocontrol insect called the salvinia weevil. This South American beetle (Cyrtobagous salviniae) is very small (only 2 mm as an adult) but feeds exclusively on salvinia plants, stunting their growth and causing them to sink underwater. A well-established salvinia weevil population can effectively manage large infestations of the plant, dropping coverage by 90%.
One natural check to unfettered growth in our area is that salvinia tends to thrive only in freshwater or very low salinity water bodies. We have identified populations of salvinia in the upper reaches of local bayous in Escambia County, but as salinity levels increase closer to the bay, the plant seems unable to establish itself.
Identification of giant salvinia is rather fascinating, as you need a hand lens to definitively distinguish it from a very similar nonnative species called water spangles or water fern (Salvinia minima). Both species have small clear-white, upright hairs covering the leaves. When examined closely, the observer will note that in giant salvinia that double pairs of hairs form a structure very similar to an egg beater, whereas in water spangles the leaf hairs do not connect.
Giant salvinia can be distinguished from its cousin, common salvinia (Salvinia minima) by the shape of its trichomes, or leaf-hairs. Giant salvinia’s leaf hairs (right) are closed at the tip, forming an “egg-beater” shape, whereas common salvinia’s leaf hairs (left) are branched at the tip. Giant salvinia is a larger plant that forms thicker, denser mats. Common salvinia can cover large areas but typically forms thinner mats and does not pose as much risk to boating traffic. Photos and caption courtesy LSU AgCenter
If you think you see giant salvinia in a local water body, we would love to know. It is an aggressive invasive plant that is relatively new to the area, and we have a chance to keep this from spreading with your help. What can you do?
Contact the Escambia County Division of Water Quality and Land Management – (850) 595-3496
Contact the Escambia County Extension Office – (850) 475-5230 ext. 1111
Report in the EDDMapS national database – https://www.eddmaps.org – select “report sightings”
If you find just a small amount, remove it and allow to dry out on your property. Once dried you can double bag and dispose of it.
There are more invasive plants issues in Escambia County than animal ones; but we do have animal invasives. Some have been with us for some time, like the feral hogs which will be posted in a different article, some are more recent. In this article we are going to focus on two species that could become real problems for us without some management plan – the lionfish and the Cuban treefrog.
The Invasive Lionfish
The red lionfish (Pterois volitans) has been in the local news for some time – but as a Gulf of Mexico problem. The fish is from the Indo-Pacific region of the world and was brough here for the pet trade. The first records we have of it in the wild were in southeast Florida in the 1980s. We are not 100% sure how they reached the Atlantic Ocean, but they did – and they did well.
Lionfish display a courtship dance where, near sunset, the males and females rise off the reef in a rotating swimming pattern and then fertilize their eggs. On average, each female will fertilize 30,000 eggs every four days! These fertilized eggs are encased in a gelatinous sac that drifts with the currents and is a method of spreading the species across the region. Originating in southeast Florida, the Gulf Stream dispersed them north along the coasts of Georgia and the Carolina’s. From here the invasion moved east to Bermuda where the Atlantic currents cycled them back south to the Caribbean, here they invaded every reef system in the region. From the Caribbean they found there way to the Florida Keys and eventually into the Gulf of Mexico. The first record in Escambia County was in 2010. It has been described as one of the most prolific, and successful, invasions of a non-native species ever.
Studies show that the invasion in the Pensacola area was particularly bad. One study showed that the densities in our area were some of the highest in the south Atlantic region. Another study showed they had preference for artificial over natural reefs. In response, the Escambia County Division of Marine Resources, partnering with Florida Sea Grant, developed a series of local workshops to educate the public about the issue.
From these meetings nonprofits formed that began to have “rodeos” and “roundups” providing prizes to divers who could remove the most, the largest, and even the smallest lionfish. Eventually the Florida Fish and Wildlife Conservation Commission (FWC) joined in and created the Lionfish Removal and Awareness Day (LRAD). This event, which began in Pensacola, attracted thousands of curious people, chefs cooking samples, and divers from across the region. These efforts, along with an increase in commercial harvest (the fish is edible) have made a significant impact on populations in waters less than 200 feet (where divers can safely work) – but lionfish can live as deep as 1000 feet.
In 2019 a gentlemen fishing on the pier at Ft. Pickens caught one on hook and line. Charter captains have been catching them on hook and line for a few years but it was not common and usually in low numbers. Over the nine years since the first record, there had also been three records within Big Lagoon, so – finding one inside of the pass was not new, but concerning. Partnering with the Ocean Strike Team, Sea Grant conducted a series of survey dives to assess the status of lionfish near the pier and jetties of Ft. Pickens. They found them – though in small numbers, lionfish were present.
The question now is how far within the bay has this invasion spread. The concern is two things.
Lionfish are gregarious feeders – eating just about anything they can get into their mouths. Offshore they are known to eat no fewer than 70 species of small reef fish, including the commercially important vermilion snapper, and several invertebrates, including shovel nosed lobsters. If they invade the bay, we are now looking at juvenile shrimp, blue crabs, flounder, redfish, and more. The impact could be very big.
They are venomous. Not by bite, but by spines. Though it has not killed anyone, the “sting” of a lionfish is extremely painful and placed some in the hospital. With numerous locals and visitors swimming in our estuarine waters, encounters with this fish will occur, and problems with envenomation will follow.
The response needed from the county is to develop a management plan for this fish in our bay. Studies show that the most effective, and least costly, methods occur at the early stages of the invasion – Early Detection Rapid Response. There are several agencies, including Florida Sea Grant, ready to assist with this.
Cuban Treefrog
Photo: UF IFAS
As the name implies, the Cuban treefrog (Osteopilus septentrionalis) is from Cuba – though it is native the Bahamas and the Cayman Islands as well. Records show they arrived in the Florida Keys in the 1920s – most likely “hitchhiking” on boats crossing the Florida straits.
This is a large treefrog, can reach six inches – compared to the two inches of our native frogs, and quickly moved in consuming local wildlife. As with many invasive species, their numbers increased quickly, and they became common across the landscape. In most locations where Cuban treefrogs were present, NO native frogs could be found. Studies show that in pools where Cuban treefrog tadpoles exist, no native tadpoles survive. Native frog populations began to decline. This is a large treefrog, not only do they consume native frogs, but they also consume small lizards, snakes, and all sorts of insects.
But the problem goes beyond native ecology. These treefrogs love to be around humans. Residents complain of the numbers of these large frogs on their doors and windows in the evening. They defecate making a large mess and the calls of the males sounds like a squeaky screen door keeping folks up at night – especially when they are abundant and there are no other frogs in the neighborhood. They are known to enter vent pipes in the plumbing, sometimes clogging these pipes, often appearing in your commode when you lift the lid to use the restroom. People do not like them. They are also known to hideout in electric panels and often short circuit home electrical and HVAC systems. Some of these problems become costly to the property owners.
The Cuban treefrogs have dispersed out of south Florida. They are now established as far north as Gainesville, Jacksonville, and Cedar Key. But records in the Florida panhandle, including Escambia County, are increasing.
Our part of the state was once immune to invasions of tropical species such as this frog. Our winters were cold enough to eradicate the few that made it here. We think the most frequent method of invasion is by hitchhiking – just as they originally did. Many of the landscaping plants we purchase for our homes and neighborhoods are grown at large nurseries in south Florida. These plants are loaded onto trucks and brought here – bringing Cuban treefrogs, Brown anoles, and many other small frogs and lizards that can be a problem for us. It appears that our winters are becoming milder, and these invaders are now surviving. Dr. Steve Johnson (University of Florida) has verified a breeding colony of Cuban treefrogs in Bay County. Records and calls from Escambia and Santa Rosa counties are increasing. We do not know whether these populations are breeding – but the concern is there.
Florida Sea Grant plans to develop a citizen science monitoring project in the spring of 2023 to assess the status of these frogs in our county. As with the lionfish, early detection – rapid response is the key to managing them.
If you are interested in participating in either the bay lionfish surveys, or the Cuban treefrogs surveys in Escambia County, contact Rick O’Connor at the Escambia County Extension Office.
National Invasive Species Awareness Week (NISAW) is a national initiative where agencies and organizations provide information on invasive species issues to decision and policy makers. It can also be a time where we provide that information to the general public.
Invasive species are a global problem threatening biodiversity everywhere. Many create economic problems for the communities they invade, and management can be costly. The University of South Florida has estimated the cost to be around $21 billion a year in the U.S. alone. The most effective method of management is to detect the invader early and respond rapidly.
The Invasive Species Curve
Florida is certainly no stranger to invasive species. In fact, with our climate and international travel, we have some of the largest problems. The Burmese python is a well known, but we also have problems with lizards, frogs, snakes, fish, snails, insects, mussels, and a large variety of plants. The state is divided into 15 Cooperative Invasive Species Management Areas (CISMAs). Two of these – Six Rivers and the Apalachicola Regional Stewardship Alliance (ARSA) cover the panhandle. Members of these CISMAs (which includes UF IFAS Extension) conduct management and education projects on local invasive species within their areas and also have a EDRR list for that area. An EDRR list is the Early Detection Rapid Response – the ones to be on the look out for.
Over the next few days UF IFAS Extension Agents from across the panhandle will be posting articles about the larger threats in their counties. We will be posting these by county so that both decision makers and the general public will be able to see which species are of most concern in their region.
If you have questions about invasive species in your area, or how to manage them, you can contact your county extension office for help.
During this week we have read about what an invasive species is, how they got here, which ones have been here awhile, which are new potential threats, and why we should even care about this. All important things to know when you are trying to understand invasive species. But what can you do about it? Is there anything that can be done from your side?
Yes… there is.
The first step in helping to manage invasive species is to learn which plants and animals in your landscape are invasive. Many of the animals are easy, but the plants not so much. I have already heard from a few of you about Mimosa – like me, we had no idea it was on the list. But we should know which plants are and are not. How do you learn this?
Unfortunately, Six Rivers CISMA’s new website is not live yet. It should be by April 1, 2022, and when it is there will be information for you there. Another way is to check EDDMapS (www.EDDMapS.org). You can search the distribution map at the tool bar, type in the name of the species you have a question about and see if there are records. If it is, this does not mean it is invasive in Florida, just that it is invasive somewhere, but it is a start. If it is a plant (and most have questions about plants more than animals) you can search the University of Florida IFAS Assessment (https://assessment.ifas.ufl.edu/). This database will give you the status of the plant in Florida. However, you will need to know the scientific name of the plant. You can find this by googling the common name and finding it that way. Of course, you can always contact your county extension office.
Here is one for the SCUBA divers out there. I met with a couple of experts a year ago or so to discuss a list of 20 potential nonnative fish threats to the Florida Keys. We discussed which of these could become threats in the northern Gulf, could tolerate our climate. It was decided that we should tell divers if they see any fish that looks out of place, never been here before sort of thing, get a photo and contact us at the extension office. We will go from there.
Survey your yard
The second step is to conduct a survey of your yard or business. You probably know your yard already, but most have crews handle the landscaping for their businesses. You can conduct the search for plants but let your landscaping crew know your interest in any unusual animals they may see. You can also participate in community surveys with the county extension office. As COVID restrictions begin to lift, we will be conducting more of these in public areas in the coming months. Check our website calendar.
Be aware of what you are buying and bringing home this spring during gardening time. Not just the plant that you are buying, but who might be hitchhiking on it. Many of the ornamental plants people purchase are grown in large nurseries in central and south Florida. We believe this is how the Brown Anole, and now, the Cuban Treefrog are getting here. Slugs, lizards, frogs, all sorts of creatures can hitchhike on your plants. Just give it a good look over and if you think you have a potential invasive, call us.
Cuban Anole. Photo credit: Dr. Steve A. Johnson, University of Florida
Photo by: Dr. Steve Johnson
The third step is to report them. As you saw in the numbers, and I did not post the Dirty Dozen numbers, but all of them are under reported. Having the public report these to EDDMapS gives managers a better idea of the extent of the problem. Note: You are not allowed to report an invasive species on private property without their permission, please get this first.
How do you report to EDDMapS?
There are two options.
One, go to their website (www.EDDMapS.org). You will see “report a sighting” on their tool bar. Report here. It will ask for a password, so you will need to set up an account. It will ask for area covered; estimating is fine. It will ask for Latitude and Longitude, most phones can give you this. Note: input longitude as a negative number or it will post the location in the eastern hemisphere. It will want a photograph so that it can be verified. This is important. Many are nervous reporting because they are not sure they have identified it correctly. No worries. All records sent in are verified before they are posted. A good photograph will allow the verifiers to do this. Send the record, if they believe it is incorrect, they will not post it.
The second option is to use the IveGotOne app. This app handles a lot of the needs for EDDMaps. You see the plant, aim the phone, take the picture, and tell it the area covered, send. Everything else is taken care of. REMEMBER, you must get permission to do this on private property. You can get this app from the EDDMapS website or your favorite app store.
The fourth step is to remove it. This is the hard part.
Hard in the sense that most can remove small weeds and vines and are happy to do so. It is harder when there is a large infestation or if it is an animal – it is not easy to euthanize an animal, for anyone. How do we handle those harder ones?
With plants, contact us at the extension office – or visit the Six Rivers CISMA website when it is live. There has been a lot of research conducted on different methods of removal that will be effective and little impact on the environment. Many do not want to use herbicides, and we get that, but in some cases that may be the only option. So, which herbicides are the safest to use and in what concentrations? Again, give us a call. Interestingly, I recently heard from a local contractor who removes aquatic plants from ponds. He said he could do the same for invasive species. We hope to find a lot of such contractors who might be able to help with large problems that you cannot do yourself. Stay tuned.
With animals it is even harder. Even though there are humane ways to do this, most people cannot just put animals to sleep. Most county animal control units do not deal with invasive species. Instead, you would call the Florida Fish and Wildlife Conservation Commission. They have a number you can call Monday – Friday during normal business hours – (888) 483-4681. If it is after hours, or on the weekend, call (888) 404-FWCC (3922). Either FWC, or a licensed contractor, will come to deal with it. I will let you know they are probably not coming for the Brown Anoles so many have in their yards at the moment. There are just too many of them. Note: it is illegal to transport an invasive species in Florida. If you have a problem please call, do not bring it in.
If you feel you could euthanize an invasive animal first make sure on the identification. Get a good photo and send to your county extension office. If it is, your extension office can give you information on how to humanely euthanize the animal.
Note that there is nothing illegal about having invasive species in your yard. You will not be cited for having such. It is just many do want to remove them.
We hope you have learned a lot this week about invasive species. If you have, email me at roc1@ufl.edu and let me know. And if you decide to report or remove a species, I would like to know this as well.
