by Rick O'Connor | Jan 27, 2022
Members of the family Poeciliidae are what many call “livebearers”. Live bearing meaning they do lay eggs as most fish do, but rather give birth to live young. But this is not to be confused with live-bearing you find in mammals – which is different.
Most fish lay eggs. The females and males typically have a courtship ritual that ends with the female’s eggs (roe) being laid on some substrate, or released into the water column, and the male’s sperm (milt) are released over them. Once fertilized the gelatinous covered eggs begin to develop.
Everything the developing young need to survive is provide within the egg. The embryo is suspended in a semi-gelatinous fluid called the amnion. Oxygen and carbon dioxide gas exchange occurs through this amnion and through the gelatinous covering of the egg itself. Food is provided in the form of yolk, which is found in a sac attached to the embryo. There is a second sac, the allantois, where waste is deposited. When the yolk is low and the allantois full – it is time to hatch. This usually occurs in just a few days and often the baby fish (fry) are born with the yolk sac still attached. Parental care is rare, they are usually on their own.
With “livebearers” in the family Poecillidae it is different.
The males have a modified anal fin called a gonopodium. They fertilize the roe not externally but rather internally – more like mammals. The fertilized eggs develop the same as those of other fish. There is a yolk sac and allantois, and the embryo is covered in amnion within the gelatinous egg covering. But these eggs are held WITHIN the female, not laid on the substrate or released into the water column. When they hatch the live fry swim from the mother into the bright new world – hence the term “livebearer”.
There are advantages to this method. The eggs are protected inside the mother, and she obviously provides parental care to her offspring. However, this does make her much slower and an easier target for predators. There is some give and take.
This differs from the “live-bearing” of most mammals in that there is still an egg. Mammals do still have a yolk sac but feeding and removing waste is done THROUGH THE MOTHER. Meaning the embryo is attached to the mother via an umbilical cord where the mother provides food and removes waste trough her placenta. There is no classic egg in this case. I say most mammals because there are two who live in Australia that still do lay eggs – the platypus and the spiny anteater, and the marsupials (kangaroos and opossums) are a little different as well – but marsupials do no lay eggs.
Biologists have terms for these. Oviparous are vertebrates that lay eggs – such as fish, frogs, turtles, and birds. Ovoviviparous are vertebrates that produce eggs but keep them within the mother where they hatch – such as some sharks, some snakes, and the live bearing fish we are talking about here. Then there are the viviparous vertebrates that do not have an egg but rather the embryo is attached, and fed by, the mother herself – like most mammals.
Sailfin Molly. The male is the fish above with the large “sailfin”. Note the gonopodium on his ventral side.
Photo: University of Florida
The livebearers of the family Poeciliidae are ovoviviparous. They are primarily small freshwater fish that are very popular in the aquarium trade. But there are two species that can tolerate saltwater and enter the estuaries of the northern Gulf of Mexico: the sailfin molly and the mosquitofish.
The Sailfin Molly (Poecilia latipinna) is the same fish sold in aquarium stores as the black molly. The black phase is quite common in freshwater habitats, but in the estuarine marshes the fish is more of a gray color with lateral stripes that is made up of a series of dots. They are short-stout bodied fish and the males possess the large sail-like dorsal fin from which the species gets its common name. The females resemble the males albeit no large sailfin and most found are usually round and full of developing eggs. They are very common in local salt marshes and often found in isolated pools within these habitats. The biogeographic range of this species is restricted to the southern United States, reported from South Carolina throughout the Gulf of Mexico. One would guess temperature may be a barrier to their dispersal further north along the Atlantic seaboard.
The mosquitofish.
Photo: University of Florida
The Mosquitofish (Gambusia affinis) is familiar to many people whether they know it or not. Those who know the fish know they are famous for the habit of consuming mosquito larva and some, including our county mosquito control unit, use them to control these unwanted flying insects. For those who may they are not familiar with it, this is the fish frequently seen in roadside ditches, ephemeral ponds that show up after rainstorms, retention ponds, and other scattered bodies of freshwater within the community. Most who see them call them “minnows”. There is always the question as to “where did they come from?” You have a vacant lot – it rains one day – these small fish show up – where did they come from? The same can be said for community retention ponds. The county comes in a digs a hole – it rains one day, and the retention pond fills – and there are fish in it. One explanation to their source is the movement of fish by wading birds, where the fish incidentally become attached to their feet. Again, they are often released intentionally to help control local mosquito populations. This fish is found in our coastal estuaries but does not seem to like saltwater as well as the sailfin molly. It is found in cooler water ranging throughout the Gulf and as far north as New Jersey.
Both of these fish make excellent aquarium pets, and the sailfin molly in particular can be beautiful to watch.
Reference
Hoese, H.D., Moore, R.H. 1977. Fishes of the Gulf of Mexico; Texas, Louisiana, and Adjacent Waters. Texas A&M Press, College Station TX. Pp. 327.
by Rick O'Connor | Jan 20, 2022
When hiking around the Florida panhandle in midwinter, most snakes are undercover trying to avoid the chilly cold fronts that pass through and can drop temperatures close to freezing. So, the probability of seeing one is low. But one species, the eastern garter snake, seems to tolerate cold temperatures better. They are often found basking on open areas this time of year and are quite common not only on the trails, but in our home landscapes as well.
But not to fear…
This is one of the 40 non-venomous snakes found in our state. Many are afraid of these animals because… well… because they are snakes, and that is all that need to be said – at least for some. But for others, they understand the benefits snakes provide to the ecosystem (controlling unwanted pests) and to see one is kind of exciting. Being non-venomous does not mean they will not bite, they certainly will, but no venom is associated with it. Larger non-venomous snake bites can be painful, but not deadly. Garter snake bites barely hurt.
The eastern garter snake is one of the few who are active during the cold months.
Photo: Molly O’Connor
Recently my wife and I were on a hike with our grandsons in central Escambia County. At one point my oldest grandson said “snake”. I am not sure how he saw it actually. It was a young eastern garter snake basking in the middle of the trail. These snakes have colorful patterns of stripes and squares that help them blend in well. We knew right away what it was and were all excited to see it. Knowing it was harmless we allowed him to pick it up but warned him that it would most likely bite. Garter snakes tend to flee when first alarmed but will turn and bite if cornered. They will sometimes rattle their tails in the leaves giving off a “buzzing” sound and can release a musk to warn the predator. But this young snake did neither, no rattling, no musk. However, it did try to bite him. After a few photos and the amazement of seeing one, we released it in a sunny spot to continue its midday basking. It was pretty cool.
Many reading this have seen many garter snakes and know this as a harmless animal. They are found all across the state of Florida and much of the eastern United States. There is a subspecies, the blue-striped garter snake, that can be found in the Big Bend area of Florida, but the differences are minor.
Eastern garter snakes are smaller snakes, usually reaching two feet but there is a four-footer on record. They like to inhabit areas that are near water where their favorite prey (amphibians) can be found. Preferring open grassy areas, they can be found in wooded habitats and are often found in lawns and gardens of local neighborhoods.
They hunt primarily during the daylight hours for amphibians but will also eat fish and earthworms. Some have been found to feed on snails, slugs, and even small snakes, birds, and mammals. They are not constrictors but rather grab their prey and swallow it whole.
They are famous for their large gatherings during breeding season. In spring, females will release a pheromone to attract the males, and the males will come, many of them at one time. There are locations in Canada where literally thousands gather at one location. The females do not lay eggs but rather give birth to about 20-30 live young in late summer or fall, it could be up to 100 in a litter. These large groups of slithering garters bring back images from movies where “snake pits” and “a den of snakes” are portrayed. I have never seen such a gathering, and in the southeast, they do not happen in such large numbers as these, but it would be cool.
This time of year, on sunny days in open basking areas, you may see this small but neat snake. The same could be true if hiking near an open sunny location. So, keep your eyes down and maybe you will get lucky.
References
Common Garter Snake. 2021. Florida Snake ID Guide. Florida Museum of Natural History. Common Gartersnake – Florida Snake ID Guide (ufl.edu).
Gibbons, W. 2017. Snakes of the Eastern United States. University of Georgia Press, Athens GA. Pp. 416.
Gibbons, W., Dorcas, M. 2007. Snakes of the Southeast. University of Georgia Press, Athens GA. Pp. 253.
by Rick O'Connor | Jan 20, 2022
EDRR Invasive Species
Coral Ardisia (Ardisia crenata)
photo courtesy of Les Harrison
Define Invasive Species: must have ALL of the following –
- Is non-native to the area, in our case northwest Florida
- Introduced by humans, whether intentional or accidental
- Causing either an environmental or economic problem, possibly both
Define EDRR Species: Early Detection Rapid Response. These are species that are either –
- Not currently in the area, in our case the Six Rivers CISMA, but a potential threat
- In the area but in small numbers and could be eradicated
Native Range:
Japan and northern India
Introduction:
Was introduced intentionally as an ornamental plant in the early 1900s. In 1982 it escaped cultivation and spread through wooded areas of Florida and parts of the Gulf coast.
EDDMapS currently list 2,064 records of coral ardisia. Most are in Florida but there are records in the Gulf states, Georgia, and South Carolina. Records within Florida cover the state, but has not been reported from all counties.
Within Six Rivers CISMA there are 11 records including Baldwin, Santa Rosa, Okaloosa, and Holmes Counties.
Description:
Coral ardisia grows in clumps, many times multi-stemmed in wooded areas. It has long (8”) glossy leaves that are dark green in color and has scalloped margins. The flowers are whiteish pink and droop below the leaf cover. The fruit are bright red berries that also droop from the plant and are present much of the year.
Issues and Impacts:
Like many invasive plants, coral ardisia spreads aggressively replacing native plants where they can. Though no published literature, it is believed to be toxic to livestock, pets, and humans.
It is a Category I invasive plant and a Florida Noxious Weed. It is listed as prohibited by the UF IFAS Assessment.
Management:
Step 1 is to avoid planting coral ardisia in your landscape. It is listed as a Florida noxious weed, and thus should not be sold, but transplanting is prohibited. If it can be easily removed by hand from your landscape, do so before it goes to seed. Be careful not to spread seeds.
Disking and/or burning can be effective however (a) most areas where coral ardisia grows prohibits disking and/or burning and (b) unless you removed all of the deep rhizomes it may return, so annual surveys are still needed.
Chemical treatments typically use the active ingredient triclopyr. This herbicide can be applied directly to the leaves or by applying to the bark when the plant is relatively dry. For large areas needing treatment the formulas may change. Different mixtures can be found in the references below. Annual retreatment may be required. Contact your local county extension office if you have questions.
References
Ardisia crenata. 2022. University of Florida Center for Aquatic and Invasive Plants. https://plants.ifas.ufl.edu/plant-directory/ardisia-crenata/.
Ardisia crenata. 2019. University of Florida IFAS Assessment of Non-Native Plants. https://assessment.ifas.ufl.edu/assessments/ardisia-crenata/.
Sellers, B.A., Enloe, S.F., Minogue, P., Walter, J. 2021. Identification and Control of Coral Ardisia (Ardisia crenata): Potentially Poisonous Plant. University of Florida IFAS Electronic Digital Information System (EDIS) publication #SS AGR-276. https://edis.ifas.ufl.edu/publication/AG281.
Early Detection and Distribution Mapping System (EDDMapS)
https://www.eddmaps.org/
Six Rivers CISMA
https://www.floridainvasives.org/sixrivers/
by Rick O'Connor | Jan 13, 2022
Like many of you reading this article, I grew up here in the northern Gulf coast. I spent a lot of time at the beach and in the water enjoying this fantastic place people use to call the “miracle strip” and now call the “emerald coast”. I would spend hours swimming, fishing, crabbing, skiing (a sport that has all but disappeared around here), and just enjoying this place. With all the fishing and snorkeling we did we were familiar with many species in the area. Pinfish, flounder, mackerel, croaker to name a few. But one group of local fish I was not aware of were the killifish. I was not aware of them until I attended Dauphin Island Sea Lab to study marine biology. And then… I discovered them.
Like many who entered marine biology programs in the 1970s I was going to be an ocean going “Jacques Cousteau” studying sharks or something. But at Dauphin Island I was introduced to the amazing world of the estuary where we did a lot of work in Mobile Bay. Pulling seine nets through the numerous salt marshes over there I quickly found that one of the most abundant fish there were these fish known as killifish. They are small minnow type fish who typically run three inches or so in length. There are two who grow larger, the longnose killifish and the gulf killifish both can reach six inches and are known by local fishermen as “bull minnows”. Bull minnows are popular bait, but most fishermen do not know that the actual name of these fish are killifish. When I was in graduate school, I took a course in aquaculture, and we visited five states in five days stopping at federal, state, and private fish farms. One private farm was a “bull minnow” farm in Arkansas. This farmer was doing quite well. He had a collection of corvettes and was working on a collection of mustangs. Needless to say bull minnows are a popular bait.
But who are these abundant estuarine minnows that most are not aware of?
Well, as we said they are small. For most, their bodies are tube shaped (fusiform) and their fins are rounded, not forked. Rounded fins (truncate) are not designed for speed but for better maneuvering in and around grasses, rocks, and coral. Killifish live in the grasses of seagrass beds and shoreline marshes where these fins come in handy.
Most have an extreme tolerance for changes in salinity. The sheepshead minnow (Cyprinodon variegatus) can live in salinities as low as 0 ppt and as high as 100 ppt – mean seawater salinity is 35 ppt. Because of this high tolerance to salinity changes, many of these killifish can be found in a variety of habitats within the estuary and even in freshwater systems entering the bay. One species, the longnose killifish (Fundulus similis) seems to prefer more saline conditions. Because of this we are looking at a local project to determine which estuarine creeks this species is found. The absence of the longnose killifish could suggest freshwater discharge and, possibly, a run-off issue. But with the dramatic salinity shifts typically seen within estuaries due to tides and run-off, having a high tolerance for salinity shifts is a good adaptation to have.
According to Hoese and Moore1 there are seven species of killifish within the estuaries of the northern Gulf of Mexico.
This longnose killifish has the rounded fins of a bottom dwelling fish.
The longnose killifish (Funuduls similis) is elongated with vertical black stripes and a single dot at the base of the tail. It has an elongated snout that gives the name “longnose”. This is a very common killifish but, as mentioned above, disappears when salinities become too low. According to Hoese and Moore1 this fish is not that common along the Gulf coast of peninsula Florida. The biogeographical reason? Not sure. We know this fish does not like freshwater but the discharge in that part of the Gulf is not that different than the panhandle, in fact, it could more saline.
Saltmarsh topminnow
Photo: Florida Fish and Wildlife Conservation Commission
The saltmarsh topminnow (Fundulus jenkinsi) is not as common. Its geographic range extends from Galveston Bay to the western Florida panhandle. Here in Florida, it is so rare it is a listed species. It resembles the longnose in shape and vertical stripes, which are actually rows of black dots, but the snout is short. I am not sure why this fish has not expanded its range east into the Big Bend or west towards Corpus Christi. Both of those areas seem to be higher in salinity and this may be the reason.
The gulf killifish (Fundulus grandis) is the “big boy” of the group. With a mean length of six inches this fish is often confused with “fingerling mullet” and is very popular as bait. This is the fish most often called “bull minnow”. Young will have dark stripes like the longnose but lack the “longnose” and does not have a black spot at the base of the tail. Most lose their stripes when they become older. It is found throughout the Gulf region.
The bayou killifish (Funudulus pulvereus) is another very common killifish in our area. Smaller than the gulf killifish and longnose, it can be identified by the yellowish colored anal fin. Males will have stripes while females will have spots. The coloration of these is amazing and the breeding colors of the males even more so. Hoese and Moore1 report this fish only from southern Texas to Alabama, but we have often found them here in Pensacola. I am not sure how far east they exist, but there must be some barrier in Florida waters to impede their dispersal there.
Sheepshead Minnow
Photo: University of Florida
The sheepshead minnow (Cyprinodon variegatus) is the champion of salinity tolerance. They are found in many estuarine habitats and even some extreme ones where no other fish are found. Hoese and Moore1 report that it has the highest tolerance of any fish in the world. There are records of this fish living in waters over 100 ppt (note: the average salinity for the ocean is 35 ppt). As you might expect, it has the largest range as well. This fish had been reported from Maine, down the entire east coast, the Gulf of Mexico, and as far south as Venezuela. It is not as elongated as most killifish, having a more short and stout appearance. They have dark vertical bars on their bodies and the males produce a beautiful iridescent blue color on their backs during breeding.
Diamond Killifish
Photo: University of Florida
The diamond killifish (Adinia xenica) is one that I have not collected very often. It resembles the sheepshead minnow is shape and color but has a more pointed snout and the teeth are compressed instead of conical, as they are in the sheepshead minnow. This fish is restricted to the western Gulf of Mexico but is found here in the Florida panhandle. It usually is in a group with other killifish, so, you would have to look hard in your sample to see if you have it.
Rainwater Killifish
Photo: Florida Museum of Natural History
Finally, there is the rainwater killifish (Lucania parva). This is a more elongated form with no markings on the body at all. At first glance, after seeing other types of killifish, it would not appear to be a killifish at all. It is one of the smaller killifish (2 inches) and is often found in freshwater creeks feeding into the bays. The males will have a reddish-orange anal fin during breeding season. It does have a large range extending from New England to Mexico.
These are truly amazing fish. They are extremely abundant and hardy. For those prone to use small nets collecting fish along the shorelines, grassbeds, and salt marshes, they will find this group very common, and most do well in aquariums.
Reference
1 Hoese, H.D., Moore, R.H. 1977. Fishes of the Gulf of Mexico; Texas, Louisiana, and Adjacent Waters. Texas A&M Press, College Station TX. Pp. 327.
by Rick O'Connor | Jan 13, 2022
Six Rivers “Dirty Dozen” Invasive Species
Kudzu (Pueraria montana)
Kudzu is an aggressive growing vine found throughout the southeast.
Photo: UF IFAS Center for Aquatic and Invasive Plants.
Define Invasive Species: must have all of the following –
- Is non-native to the area, in our case northwest Florida
- Introduced by humans, whether intentional or accidental
- Causing either an environmental or economic problem, possibly both
Define “Dirty Dozen” Species:
These are species that are well established within the CISMA and are considered, by members of the CISMA, to be one of the top 12 worst problems in our area.
Native Range:
Eastern Asia.
Introduction:
Kudzu was first brought to the U.S. for the Philadelphia Centennial Exhibition in 1876. Seven years later it was presented at the New Orleans Exhibition. Seed was sold to grow ornamental vines to shade porches and was also tried as livestock feed. It now covers about 2 million acres of forest land in the southern U.S.
EDDMapS currently list 11,288 records of the plant in the U.S. As with many “dirty dozen” species, this is certainly under reported. Most are in the southeastern U.S. but there are records in Kansas, Illinois, and Oregon. It has been reported throughout the state of Florida including the Florida panhandle, and all of the Six Rivers CISMA.
Description:
This is a semi-woody vine that can grow up to 100 feet. Most who have seen it, recognize it immediately. The leaves are large (4”) and alternate on the vine forming three leaflets at each node. The leaves are lobed with hairy margins. The vines can reach 4” in diameter and one stump found in Georgia was 12” in diameter. The flowers are purple in color, hang in clusters, and appear in late summer.
Issues and Impacts:
It grows almost anywhere and over almost anything. Entire buildings have been completely covered by this plant and it has also been known to grow over and uproot trees. Any vegetation it covers will soon die due to a lack of sunlight and it is also known to harbor insects and disease for native legumes, many of which are important agricultural crops, such as soybeans. It is listed as a state noxious weed.
Management:
This is a tough plant to control. It has been reported to grow as much as a foot a day. The root and rhizomes system are extensive and reach depths of 10 feet. There are also tubers that store excess carbohydrates that help with surviving drought, freezing, and even fires.
Herbicides are effective on small patches, though repeated applications may be needed. They can be used on large areas of infestation but will certainly take repeated applications over years and can be very expensive. Many will include burning, disking, or mowing before chemical applications to weaken the root system. Chemicals that have had some success include glyphosate, chlopyraild, metsulfuron, and aminopyralid.
Many have had success using livestock grazing, such as goats or cattle. Research has shown that close grazing, where 80% of more of the plant is removed, can completely eradicate it over a couple of years. One source recommends eight goats / acre for best results. Others have had some success by cutting the plant back (like grazing) during the hottest times of the year.
No biological controls have been approved yet, but research continues.
In Asia the plant is used in a variety of ways including food, fiber, and medicine. These could be options for management as well.
For more information on this Dirty Dozen species, contact your local extension office.
References
University of Florida IFAS Center for Aquatic and Invasive Plants. Kudzu (Pueraria montana). https://plants.ifas.ufl.edu/plant-directory/pueraria-montana/.
Frank, M.S. 2021. Five Facts: Kudzu in Florida. Florida Museum of Natural History. https://www.floridamuseum.ufl.edu/science/five-facts-kudzu-in-florida/.
Early Detection and Distribution Mapping System (EDDMapS)
https://www.eddmaps.org/
Six Rivers CISMA
https://www.floridainvasives.org/sixrivers/
