But there could be reason to keep an eye out. We are not talking about the common ribbed or hooked mussels we found in the Pensacola Bay area. We are talking about an invasive species called the green mussel (Perna viridis).
The green mussel differs from the local species by having a smooth shell and the green margin. Photo: Maia McGuire Florida Sea Grant
Why be concerned?
By nature, invasive species can be environmentally and/or economically problematic. In this case, it is more economic – which is unusual, most are more environmental concerns. The big problem is as a fouling organism. Like zebra mussels (Dreissena polymorpha), green mussels grow in dense clusters, covering intact screens to power plants, intact pipes to water plants, and can displace native spaces by competing for space. It has been determined they can grow to densities of 9600 mussels / m2 (that’s about 10 ft2) and they can do this on local oyster reefs – displacing native, and economically important, oysters. They grow quickly, being sexually mature in just a few months, and disperse their larva via the currents. To make things more interesting, they may be host to diseases that could impact oyster health.
So, what is the situation?
They are from the Indo-Pacific region, found all across southeast Asia and into the Persian Gulf. In this part of the world they are an aquaculture product. There was interest in starting green mussel aquaculture in China, and in Trinidad-Tobago. After they arrived in Trinidad, they were discovered in Venezuela, Jamaica, and Cuba – it is not believed this was due to re-locating aquaculture, but rather by larva dispersal across the sea… they got away.
This cluster of green mussels occupies space that could be occupied by bivavles like osyters.
It would be an easy jump from Cuba to Florida – and they came. The first record was in 1999 in Tampa Bay. They were found while divers were cleaning an underwater intake screen. Dispersal could have happened via larva transport in the currents, but it could have also occurred via ship ballast discharge at the port – this is how folks think it got there, they really do not know. From there they began to spread across the peninsula part of the state. They have been reported in 19 counties, most on the Gulf coast, and there is a record from Escambia County – however, that one was not confirmed.
How would I know one if I saw it?
They prefer shallow water and are often found in the intertidal zones – attached to pilings, seawalls, rocks. As mentioned, they grow in dense clusters and should be easy to find. They are long and smooth, with a mean length of 3.5 inches. There was one found in Florida measuring 6.8 inches, which they believe is a world record. Mussels differ from oysters in that they attach using “hairy” fibrous byssal threads – in lieu of cementing themselves as oysters do. As mentioned, the shell is smooth and may have growth rings, but it lacks the “ribbed” pattern we see on the local ribbed and hooked mussel. It will have a green coloration along the margin – hence its name, and the interior of the shell will be pearly white.
The shell at the far right is the common ribbed mussel native to our local salt marshes. Just to the left is the invasive green mussel. Can you tell them apart? Photo: Maia McGuire Florida Sea Grant
They prefer salinities between 20-28‰, which would be the lower portions of the Pensacola Bay system (Santa Rosa Sound, Big Lagoon, maybe portions of Pensacola Bay). They are not a fan of cold water. They do not like to be in water at (or colder) than 60°F. Some biologist believe it is too cold in the panhandle for these bivalves, but we should report any we think may be them – to be sure.
What do we do if found?
1) Get a location and photos. Pull some off and get up close photos of an individual.
2) Report it. You can do this by contact the Escambia County extension office (850-475-5230 ext.111), or email me at roc1@ufl.edu.
3) If there is a method of removing all of them, do so. But this should be done only after the identification is verified. When removing try to collect all the shell material. The fertilized gametes within, if left, can still disperse the animal.
4) They are suggesting boat owners check their vessels when trailering. Avoid transporting them from one body of water to another.
5) I would recommend that marina owners do the same – check boats and pilings.
It appears the mean temperature of the Gulf is increasing. With this change it is possible some of the tropical species common in south Florida could disperse to our region, and that could include the green mussel. The most effective (and cheapest) way to manage an invasive species is catch them early and remove them before they can become established.
Chinese Tallow, also known as the Popcorn Tree, was introduced in the US over 200 years ago. Ben Franklin sent seeds over in 1772. Although Franklin was blamed for the invasion in the U.S. Gulf Coast, scientists performed genetic testing and have concluded that the blame actually lies with federal biologists who imported some Chinese tallow trees around 1905. Popcorn trees have continued to spread throughout the US since then.
For many years, people have planted them in their landscape for shade and fall color. Once established, they invade natural areas, pastures, wetlands and yards. They out-compete native and non-invasive trees and shrubs. In 1998, Chinese Tallow was added to the Florida Department of Agriculture and Consumer Services Noxious Weed list. Plants on the Florida Noxious Weed list may not be introduced, possessed, moved, or released without a permit.
Landowners and homeowners can help with this problem tree by removing and replacing them with a native or non-invasive tree like black gum, maple, dogwood, or crepe myrtle. Mature trees can be cut down with a saw and the stump promptly treated with an herbicide with the active ingredient, triclopyr amine. You should try to make the final cut as low to the ground as possible. You can use a paint brush to apply the herbicide to the stump. A basal bark application of triclopyr ester plus a basal oil carrier can be used on smaller trees. Treat the trunk to a height of 12 to 15 inches from the ground, thoroughly wetting it with the herbicide mixture. Basal bark treatments are only effective on saplings and seedlings less than 6 inches in stem diameter. Sometimes suckers may sprout from remaining roots. A foliar application can be used on these sprouts from July to October, before onset of fall color.
February is a month filled with special celebrations and events like Valentine’s Day, President’s Day, Groundhog Day, and of course NISAW!
NISAW or National Invasive Species Awareness Week isn’t as famous or beloved as the other February dates. You likely won’t get a day off, have a special date or receive a present from your loved ones. However, NISAW is an important time to remember and learn about invasive species that impact our beloved natural areas.
Invasive species originate from other continents and have adverse impacts on our native habitats and species. Many of these problem non-natives have nothing to keep them in check since there’s nothing that eats or preys on them in their “new world”.
This year NISAW is being celebrated February 24 – 28. It is the largest invasive species awareness effort in the U.S. You can learn more at https://www.nisaw.org/nisaw-2020/
or on Facebook at @invasivespeciesweek. Search other social media outlets using #NISAW or #invasivespecies.
We would like you to help celebrate NISAW in a more meaningful way, beyond awareness and clicking a few links or sharing social media posts with your friends. Bay County and Northwest Florida need your help in fighting invasive species this year, especially the air potato vine.
Air potato vine originated in Asia and Africa. It was brought to Florida in the early 1900s. People moved this plant with them, having used it in the past for food and medicine. Today, we know raw forms of air potato are toxic and consumption is not recommended. This quick growing vine reproduces from tubers or “potatoes”. The potato drops from the vine and grows into the soil to start new vines. Air potato is especially a problem in disturbed areas like utility easements, which can provide easy entry into forests. Significant damage can occur in areas with heavy air potato infestation because vines can entirely cover large trees. Some sources report vine growth rates up to eight inches per day!
Air potato vines covering shrubs and trees in Bay County Florida. Photo: Scott Jackson
We plan to start local NISAW activities a few days early on February 22nd, with the collection of air potato vine tubers or potatoes also known as bulbils of this species. Bay County Conservancy will host an “Air Potato Round-Up” behind Panama City Orthopedics in the Audubon Nature Preserve which is located at State Ave and 19th Street. The collection and workday is scheduled from 9am until Noon. Volunteers are encouraged to wear long pants, gloves, comfortable shoes or waterproof boots. Expect a rewarding but dirty job! For details and specific information please contact Teresa Nooney at 850-814-4755.
Other communities are promoting other NISAW workdays and events known collectively as “Weed Wrangle”. UF/IFAS Extension Bay County and Escambia County will serve as collection sites for Air Potato vine bulbils through the last week of February as permitted and designated by the Florida Department of Agriculture and Consumer Services (FDACS). For additional details contact and coordinate delivery with your county UF/IFAS Extension Office.
Ron Houser weighs collected air potato bulbils. Photo: Teresa Nooney
Because air potato vine is a regulated invasive species, only UF/IFAS Extension offices working directly with FDACS under their permit will be able to accept air potatoes. Air potatoes must be delivered in person, you cannot mail or ship them. Participating offices are:
Unfortunately, mechanical removal of vines and herbicide applications is difficult and may cause harm to desirable plants making it very difficult to manage. Removing and collecting air potato vine tubers helps in the control of this plant. When the potatoes are left in place, they will produce new vines the following spring.
The bubils that are collected by local UF/IFAS Extension offices will be given to Florida Department of Consumer Services (FDACS) air potato beetle rearing labs. This will help them raise more beetles that can be distributed throughout the state for establishment and vine control.
Air potato beetle crawling on a leaf stem. Photo: Julie McConnell
The air potato leaf beetle was released in Florida in 2011. This beetle was originally identified as a natural predator of air potato vine within its native range and was found to be effective in keeping growth in check as well as being safe to other plants because it has such a specific dietary source. Air potato leaf beetles eat only air potato vines! Only after years of extensive research to ensure the safety of Florida ecosystems, was the air potato leaf beetle cleared as for use as a biological control insect to aid in the control of air potato vine. Air potato beetle releases are monitored and evaluated by United States Department of Agriculture (USDA) researchers and scientists as they continue to establish populations and monitor the work of air potato vine leaf beetles throughout the state.
An Equal Opportunity Institution. UF/IFAS Extension, University of Florida, Institute of Food and Agricultural Sciences, Nick T. Place, Dean for UF/IFAS Extension. Single copies of UF/IFAS Extension publications (excluding 4-H and youth publications) are available free to Florida residents from county UF/IFAS Extension offices.
Tordpedograss (Panicum reopens) is one of the most concerning weeds in Florida and now easily found in the Panhandle. This weed’s favorite habitat is in or near ponds and ditches, but will spread across lawns and pastures.
A native grass of both Africa and Asia, torpedograss was introduced through seed in the U.S in the late 1800’s as a forage crop for livestock. Torpedograss is in the family Poaceae, along with other grasses such as the persistent invasive threat, cogongrass, as well as common bermudagrass. It gets its name from the sharply pointed tip and not only is it exceptionally fast spreading, it can grow as tall as 3 feet. Torpedograss is a poor seed germinating species in our climate and primarily relies on rhizome expansion.
Photo: Tordpedograss (Panicum reopens).
Credit: Ray Bodrey, UF/IFAS Extension Gulf County.
This plant has a tendency to choke out and completely take over native vegetation. Agronomist in south Florida have been concerned about it for years. In 1950, the University of Florida agricultural experimental station warned: “Torpedograss is a serious weed when established in farm or grove land and indiscriminate planting without the regard to future crops or adjoining land is dangerous.” (Hodges and Jones).
Photo: Tordpedograss pond infestation.
Credit: Jeff Hutchinson, UF.
So, what is the impact of torpedograss on Florida?
Since 1992, torpedograss has taken over 70% of Florida’s public waterways. Lake Okeechobee is considered ground zero with approximately 7,000 acres of native marsh now displaced. These dense mats of grass can impede water flow in stormwater applications, and restrict usage of irrigation holding ponds and fish ponds.
How does one manage this invasive grass?
Infestation prevention can be accomplished by controlling the rhizome expansion. This is easier said than done, as a small rhizome fragment left behind will no doubt cause re-establishment. Keeping the infestation at bay, by controlling the spread at waterways is key.
For IPM (integrated pest management) solutions follow these steps:
For cultural management, invasive plants tend to quickly establish in open or recently tilled areas. So, prescribed burn and clearing by mowing are methods that tend to promote infestations. A healthy, diverse landscape with native plants, or species with non-invasive tendencies will provide a level of defense.
Mechanical control is not very effective. Tilling the land only spreads the rhizomes through fragmentation.
There are few biological controls, although cattle and goats will graze and they may continue to spread the grass.
Chemical control using Glyphosate (Roundup, etc.) at a 2-3% solution and imazapyr (Arsenal, Chopper or Habitat) at 0.5 to 1 % solution has been effective for on land use. Aquatic herbicides with glyphosate (Rodeo, etc.) are effective for ponds. This can be applied in a liquid or granular form. A non-ionic surfactant will be needed to adhere the liquid chemical with success. Keep in mind, these herbicides are systemic, meaning they are absorbed and move through out the plant tissue. Be sure to minimize over spray damage of desirable plants, especially related to drift. Imazapyr also has longer soil activity and could impact sensitive oaks. Torpedograss is much more difficult to treat in water and will require multiple applications to completely control whether in water or on land.
For more information on torpedograss, contact your local county extension office.
I found one in Escambia County, near Perdido Key. It was dead, roadkill, and was quite large. Needless to say, working with invasive species and trying to stay ahead of any new potential problems, I was surprised. I immediately turned around to confirm what I saw as I drove by – it was a nutria.
A dead nutria found along a roadside in Escambia County. Photo: Rick O’Connor
Many of us have heard of this large rodent (Myocastor coypus), and all the problems it has caused in the state of Louisiana. With the loss of their marshes at stake, it was “all hands” to battle this guy. From reading, it appears it was released across the United States as a potential fur product. I found statements that they may have been brought here from their home in South America as early as the 19th century. Certainly, by the 1920s and 1930s they were here. Today there are records in 18 states across the southeast, the Chesapeake Bay area, and the Pacific northwest – a widespread release and distribution.
It is another classic invasive species story. A nonnative creature is brought to the United States for some specific reason, sometimes accidentally; escapes into the local environment, or is intentionally released; has no natural predators so begins to reproduce at a high rate; and causes environmental and/or economic problems. The United States spends hundreds of millions of each year battling such species.
In the nutria’s case, it is from South America. It was hard to determine whether they were brought over here in small increments to different locations over time, or whether they were brought here in bulk and released into habitats they could survive in, but they were released. It is a large rodent and resembles a beaver except that its tail is round, and not flat, and the profile of their back has an arch to it. They can reach two feet in length, not counting tail, and can weigh up to 20 pounds.
They are herbivores, and some used this animal to control aquatic plants in their ponds. Like many rodents, they have an aggressive reproductive rate to overcoming predation. Nutria become sexually mature within 4-6 months and can produce their first litter at eight months. They breed year-round and typically have three litters / year with 2-13 young / litter. Gestation is 128-130 days and the females are ready to breed within 48 hours of birth.
Nutria like water and can survive in brackish conditions. They live in small social groups that typically have a dominant male, 2-3 females, and the young. Activity is usually at night, moving through the habitat consuming 25% of their body weight in plants each day. They can be seen during daylight hours if food is scarce.
Photo Courtesy of US Fish & Wildlife National Digital Library
So, what’s the problem?
They eat a lot and burrow for denning. Many waterways are endangered due to their destructive habits. The tunneling and burrowing can compromise the integrity of banks and shorelines around these waterways. Louisiana, being a state with many levees holding water back from communities, you can understand their concern; but communities in Washington, Oregon, and Maryland are facing the same issues. They are carries of certain pathogens and parasites, such as tuberculosis, septicemia, and liver flukes which can be a threat to humans and pets. They also carry nematodes which can trigger a condition known as “nutria itch” in waterways where they are found.
In 1938, 20 nutria were released in Louisiana. By 1958 there were 20 million in the state. There did not seem to be any natural control and the state began losing its marshes. The interesting thing is there are records of releases in Florida as far back as 1955. There are records of this animal in the Pensacola area dating back to 1956. Yet, we do not see the overwhelming numbers found in Louisiana, or with lionfish in our area. I spoke with long time Mobile Delta natural historian Jimbo Meador about the problem there. He said there were lots of nutria at one time and they had hunting tournaments to control them. But when the state began protecting alligators the nutria problem went away – a natural predator after all. He said today you can still find nutria in the Mobile area, but they are restricted to the more brackish areas where alligators are not as common.
Which brings us back to the Pensacola issue.
Many believe that the best method for controlling a new potential invasive species is discover and manage them early before they become widespread and established. Even though this is the first one I have seen in Escambia County, they apparently have been in the area for over 60 years. Something seems to be controlling their populations, which is a good thing. That said, any populations found should be monitored so they do not become more widespread. Currently, the Florida Fish and Wildlife Conservation Commission considers them as one of the furbearers and manages them as such. Live trapping is allowed but you must have a trapping permit to do so. You can actually sell the fur, but you will need a license for this. This may be like the tiger shrimp story, an invasive we are aware of but is not becoming a widespread problem in the county, but I do recommend anyone seeing the creature report to the website data base www.EDDMapS.org so that we can all keep track of where they are and whether they are spreading.
References
California’s Invaders: Nutria (Myocastor coypus), California Department of Fish and Wildlife
