The classic model of ecological succession begins with new land. This could be new land formed by a sand bar, or a new landscape formed after a volcanic eruption, but new land none the less. Then the pioneer community begins. Based on the model, the plants need to be first, herbivores cannot survive unless there are plants already present. When we teach students about maintaining aquaria, we actually begin with the bacteria community needed to breakdown the organic waste from the plants and animals when they arrive. So, some would say “begin there”. As the pioneer plant communities form, the pioneer herbivores arrive. This would be followed by more advanced communities of plants and then more advanced communities of animals, until you reach the climax community.
Beach
The open beach is how most barrier island ecosystems begin awaiting the arrival of the pioneer community.
Phot: Rick O’Connor
But science understands that it is more complicated than that. Each new member of the community would make chemical and physical changes to the environment that could allow new species to thrive while other existing ones die off. Then those would make changes as well and the process is ALWAYS changing. That there is never a true climax community, change is happening all of the time. Then there was the case of Mt. St. Helens.
St. Helens erupted in 1980 destroying 229 square miles of habitat. This new landscape gave ecologists an opportunity to witness ecological succession firsthand. Like everyone, they expected the pioneer plant community to arrive first, and so on. But in some areas, it was the carnivores that arrived first, completely against the classic model. These carnivores apparently survived the blast and began to wonder the new landscape. How did they survive? They survived by feeding on each other. But eventually the pioneer plants did arrive, all creatures “got in line” and the world was good once again. The interesting thing was it did not happen the way they thought it would. It also shows the resiliency of life.
Mt. St. Helens destroyed almost 300 square miles and produced new habitat.
Photo: University of Washington.
So, how did this process unfold on our barrier islands? I do not know. You would guess that it unfolded the way the model suggests – pioneer plants first, pioneer animals, more complex plants, more complex animals, barrier island ecosystem. But as we have seen, there are several ways it could have started.
What we do know is that the animals who made it to the islands had to do so by either swimming, flying, or walking. For those who reached our islands on foot – beach mice, ants, etc. this must have happened at a time when the island was still connected to the mainland.
The Choctawhatchee Beach Mouse is one of four Florida Panhandle Species classified as endangered or threatened. Beach mice provide important ecological roles promoting the health of our coastal dunes and beaches. Photo provided by Jeff Tabbert
For the swimmers, short swims like Indian Pass could be achieved by several species. Deer and other small mammals may have been able to do this. I have seen bears swim and assume coyotes could make short swims. As the island continued to move with the tide and currents, the distance to the island would have increased. The pass across the mouth of our estuaries, or across the intracoastal waterway, is now daunting for many of these swimmers – but not all. I have seen eastern diamondback rattlesnakes swim across the ICW and have heard bears can still make this trip. For the flyers, these distances do not seem to be an issue. They easily, and often, do so.
Eastern diamondback rattlesnake swimming in intracoastal waterway near Ft. McRee in Pensacola.
Photo: Sue Saffron
If you imagine the early days of an island being low elevated sand, the new wildlife arrivals would face a daunting landscape. Burrowers, such as ghost crabs, could easily make a living here. Their burrows protect them from the elements and being scavengers, they would feed on anything the Gulf washed ashore – something they still do. Sea turtles and shorebirds could easily use the sand bars for nesting, and probably preferred it due to the few predators around. But eventually, the pioneer plants would become more established, allowing selected herbivores (who could survive in low elevation sand) to move in. Next the dunes would form, providing new habitat (read part 2 of this series). Additional herbivores, if they could reach the island, could now become established and at some point, the carnivores would enter the picture.
The line of seaweed and debris along the surf zone is called wrack. Photo: Rick O’Connor
There would initially be a finite amount of space for inhabitation and competition for that space and its resources would be high. Some would be more adapted to the environment than others, or physically stronger, or have a higher reproductive rate, to give them an edge over the others and the island wildlife community would begin. This community would include such things as insects, worms, amphibians, reptiles, birds and mammals. The marsh habitat would include aquatic species such as snails, clams, crabs, shrimp, and fish. All would have had to be able to reach the island, find a suitable habitat for their needs, find suitable food, and out compete others who had made the trip across as well. I was asked once as a college student – “who is a rhinoceros’s greatest competition?” It was an oral exam, and I was very nervous. My mind began reeling in all directions trying to think of what a rhino would have to compete for and WHO would be their greatest competitor. And then, with a little discussion from my professors, it dawned on me. Their greatest competitor would be another rhino. The other rhino would be seeking the same resources, habitat, and mates as the original one. Your first problem is with your own kind. And so, it would be for barrier island wildlife.
The bizarre looking armadillo enjoys a walk on the beach.
Photo: Rick O’Connor
With the arrival of humans, with their bridges and boats, additional creatures would be able to reach the islands and play a role in the competition, but that is another story, and we will discuss this more down the road. In Part 4 we will look at the species that have inhabited the beaches of our barrier islands.
The habitats of a barrier island are defined and driven by the plant communities there. Seeds from the mainland must first reach the new island and they can do so using a variety of different methods. Some come by wind, some by water, some by birds and other wildlife. Some of these germinate, some do not. Those that do, do so on a sandy island with little or no relief and must deal with the winds off the Gulf, which has salt spray. Many of these mainland plants cannot tolerate this and never make it. But some can… and do.
The dune fields of panhandle barrier islands are awesome – so reaching over 50 ft. in height. This one is near the Big Sabine hike (notice white PVC markers).
These early plant communities are known as the pioneer community – meaning the earliest settlers. In the process of succession pioneer communities are made of creatures that can tolerate the harshest conditions, the early days of ecosystem development. There are usually few nutrients, extreme climatic conditions, and for the animals, few prey to select from. But these pioneers are adapted to survive in these conditions and over time alter the conditions so that other creatures can move in.
For the barrier islands, grasses seem to be the plants who do best in the early stages of succession. Though small shrubs and trees may reach the island, the high winds and salt spray will not allow growth. There are numerous species of grasses that can live here, the most famous are the sea oats (Uniola paniculata). This grass can be found on the smallest of barrier islands. Their fibrous root system runs beneath the ground sprouting new grasses all over. Their seed heads blow with the wind starting new populations of plants on other locations and the landscape is soon dominated by them. However, there are other species as well. Panic grass (Panicum amarium), salt hay (Spartina patens), and beach elder (Iva imbricata) to name a few. All these grasses can tolerate the wind and salt spray as well as the low nutrient, low rainfall often found on these islands. They also all have fibrous roots systems that not only connect grasses across the land scape but also trap blowing sand – forming dunes.
The primary dune is dominated by salt tolerant grasses like this sea oat. Photo: Rick O’Connor.
The dunes closest to the Gulf are dominated by grass due to the higher winds and salt spray there. These are called the primary dunes and create one of the first habitats on the island for wildlife. The primary dunes vary in height and how far from the Gulf they range but they do form a wind break for portions of the island landward of the Gulf.
Here smaller shrubs and plants like seaside golden (Solidago sempervirens) and seaside rosemary (Ceratiola ericoides) can grow. With less wind their seeds will germinate and survive. What wind is still there forces the plants to grow in a round shape resembling green sheep on a white field, instead of white sheep on a green field. My professor referred to them as “beach sheep”. This area of the barrier island is called the secondary dune and includes other species such as false rosemary (Conradina canescens), square flower (Odontonychia corymbosa), and sandhill milkweed (Asclepias humistrata). Though they cannot tolerate the high winds as grasses do, they do have to tolerate climatic extremes and low rainfall.
Small round shrubs and brown grasses within the swales are characteristic of the secondary dune field.
Photo: Rick O’Connor
These secondary dunes vary in elevation and can become taller than the primary dunes. In the low areas between dunes are areas where freshwater water can collect and form ephemeral ponds. These areas are known as swales and create unique habitats much sought after by some wildlife. More bog like plants grow here such as water dock (Rumex orbiculatus) and marsh pink (Rhexia nashii) but also includes the carnivorous plants like the sundew (Drosera rotundifolia). There are many insects who used these ephemeral ponds and many spiders and sundews to take advantage of this.
Behind the larger secondary dunes, the wind is even less, and the dune wind breaks higher. Here trees can germinate, if they can tolerate the climatic conditions, and grow. Though the species that grow out there are some of the same you find on the mainland, here they grow differently. Barrier island trees tend grow out, not up, to avoid direct contact with wind and salt spray. And, when they do reach the wind the portion of tree directly facing the wind tends to be stunted in growth, giving it the appearance that someone has “combed” the tree back towards the bay – something they call wind sculpting. Trees that seem do well in what they call the tertiary dune include sand live oak (Quercus geminata), pine (Pinus sp.), and magnolia (Magnolia grandiflora). Yaupon holly (Ilex vomitoria) and even cactus like the prickly pear (Opuntia humifusa) and the devil’s joint (Opuntia pusilla) can be found growing here.
The top of a pine tree within a tertiary dune.
Photo: Molly O’Connor
Tertiary dunes are some of the largest on the island, with elevations reaching 50 feet or more. These provide excellent wind breaks from the Gulf and allow the formation of salt marshes along the bay side shoreline. Marshes are habitats dominated by grass, but these grasses must be able to tolerate periods emersed in salt water, at least at high tide. Close to the dunes the marsh is dominated by dense stands of black needlerush (Juncus roemerianus). In some locations within the needlerush marsh are areas of bare sand known as salt pans. These are low areas within the marsh where water remains when the tide recedes. These small marsh ponds begin to evaporate in the intense sunlight and the salinity increases to a level where it kills off much of the plant life leaving an area of bare sand. These salt pans are used by some wildlife on the islands. Eventually you will reach the waters edge where smooth cordgrass (Spartina alterniflora) grows. This marsh grass can tolerate water for longer periods than needlerush and supports both island wildlife and estuarine fisheries.
A finger of a salt marsh on Santa Rosa Island. The water here is saline, particularly during high tide. Photo: Rick O’Connor
As you can imagine, the process of establishing the pioneer community of grasses on a new, small sand bar, to an island filled with dunes and vegetation takes time – years, decades, maybe centuries – but eventually it will reach what we call the climax community and provides a variety of habitats to support wildlife.
In part 3 we will begin to look at how animal species colonize the islands as these habitats form.
First, the invasion seems to be silently spreading. A just a couple of years ago we had very few records, one off individuals that were removed by those reporting. But they have slowly, and quietly, been spreading. A couple of years ago there was a report of a small group of them near Tyndall AFB in Panama City. Dr. Steve Johnson, University of Florida, decided to see if this small group survived the winter, they did. It was confirmed as the first breeding population in the panhandle. Then the one off reports began increasing again.
Photo by: Dr. Steve Johnson
One area in Santa Rosa County was recording numerous individuals. These reports continued over the winter, and it seems they were breeding there as well. In my neck of the woods, Pensacola, I am getting more calls about them. EDDMapS currently list 18 records in the panhandle. This is definitely underreported. Most of those are in the Panama City area. The entire invasion reminds me of the Cuban (Brown) Anole; quietly increasing numbers while we watch and wonder what to do.
Second has to do with that issue… what to do. Managing invasive plants seems to be easier that invasive animals. People seem to be fine with pulling or spraying weeds. But euthanizing animals is another thing. And I get it, I like frogs too. Ending any life is hard to do. This makes managing this species much harder.
One way to look at next steps is to stop the introduction of any more species. We are pretty sure the primary method of introduction is what we call “hitchhiking”. Most of the plants we purchase for our landscaping projects come from large commercial nurseries in south Florida. Here they are grown by the hundreds of thousands, loading on trucks, and brought to our part of the state. Unbeknown to us, other small creatures are hitchhiking on these plants and their containers. Some of these are invasive species like the Cuban (Brown) Anole, and the Cuban Treefrog. At one time, this was not as much of a concern because they would not survive our cold winters. But our winters are not as cold anymore. Hard freezes do occur, and this may still be our best management plan, but with fewer hard freezes breeding populations will be allowed to continue the invasion. And it could be that with higher numbers of Cuban Treefrogs in the area, some will survive these freezes to continue. This has certainly happened with the Cuban (Brown) Anole.
Cuban Anole. Photo credit: Dr. Steve A. Johnson, University of Florida
So, I am not sure. The answer may be no to this one. One thing we can do is help monitor their populations. When we see a Cuban Treefrog report it to EDDMapS or your county extension office. This will give us a better idea of how the invasion is going and whether they are surviving our winters.
How do you know a Cuban Treefrog from our native species. Here are a couple of articles on how to do this.
If you choose to euthanize them, how do you do this humanely?
You can catch them using 3-foot sections of PVC pipe about 1.25” in diameter. These are placed vertically in the ground along the outside wall of a building near an exterior light source (where bugs are attracted). In the morning, check the inside of the pipes. If treefrogs are present, try to identify them. Cuban Treefrogs are the only ones in the panhandle that reach lengths of 4-6 inches. If they are all small, you will need to collect them and identify them using one of the publications listed above.
If you positively identify one, the first step is to confirm it. You can do this by contacting your county extension office. Second, report it to EDDMapS (www.EDDMapS.org). If confirmed, and you choose to euthanize it, the following link will explain how to do this humanely.
This situation is similar to the lionfish invasion we experienced 10 years ago. We know they are here, and we know they can be a serious problem. We are not sure we can eradicate them, but they should be managed. We will see how this goes.
There are a lot of cool and interesting creatures that live on the barrier islands of Northwest Florida. The conditions out there require they make changes and adaptations different from what they would do in a more upland or wetland environment. Some creatures are unique to these beach and dune systems and found nowhere else. But to begin this series lets first look at the islands themselves.
The white beaches of the Florida panhandle are primarily quartz. Photo: Rick O’Connor.
The name barrier island comes from the fact that they do serve as a barrier between the open Gulf of Mexico and the mainland of the Florida panhandle, protecting coastal communities from storm surge and waves of the all too frequent hurricanes and tropical storms. They are basically sandbars formed with sands from the Appalachian Mountains. There the wind, rain, and temperature erode the granite rock into its mineral components and wash them downstream. First in the fast-moving mountain streams, then into creeks, into rivers which eventually discharge into the Gulf. The different minerals settle out based on their size, type, and densities. Quartz is one of the less dense and is the dominant mineral forming the coastal barrier islands, making them some of the whitest beaches on the planet.
When these quartz sands reach the Gulf, they encounter longshore currents that are formed from the winds blowing across the open water. In this part of the Gulf of Mexico these currents tend to move from the east to the west in most cases. As the rivers reach the passes that connect the estuaries to the open Gulf and the longshore currents move the sand into long thin spits at the mouth of the bays running parallel to the coastline. In some cases, the sand bars form perpendicular to the coastline, and we call them capes. Initially still connecting to land, many creatures can venture out on these sand spits searching for food. Some of the sand spits are very small and seem to come and go as the winds and waves move them. At times these smaller spits may actually close off the opening into the bay as they once did on Perdido Bay and still do with the Walton County dune lakes. In other cases, the spits accumulate more sand, become long and can eventually break contact with the mainland forming an island.
From the Pensacola Lighthouse you get a great view of the open Gulf and the eastern end of Perdido Key. Here the pass separates Perdido Key (on the left) and Santa Rosa Island. Photo: Molly O’Connor.
At first these islands can be nothing more than sand bars. Barely above sea level, moving and changing very quickly, sometimes disappearing and reappearing in slightly different locations after storms, such as Sand Island off Dauphin Island Alabama. In others they are larger, harder to move quickly and may be vegetated so that movement is slower and the island more established, such as Santa Rosa Island near Pensacola. The creatures on any of these islands will need to be able to adapt to the new conditions. Some will be able to leave and return the mainland when they need or want to. Birds are very common on all forms of barrier islands due to the fact they can fly. In some cases, the distance from the mainland is not a far swim for those who can, such at Indian Pass near St. Vincent Island. In some cases, the distance may not be as close and the currents between very swift during tide changes making crossing more difficult. In these cases, the creatures who find themselves on these islands must adapt to the new conditions or risk losing their populations entirely.
Island conditions can be tough. There is a lot of wind, and this wind carries salt spray. There is little cover from the intense sun during the summer months. Needed freshwater can be hard to find. Some islands will develop freshwater systems, but others will not. And then there is the fact that it is an island. Thus, a finite amount of resources and space for each species, and, at times, fierce competition for those.
In Part 2 we will explore the different habitats that developed on these islands that available for the different wildlife that exploit them.
The wind sculpted plants of the tertiary dunes. Photo: Rick O’Connor.
Based on the number of EDDMapS records for the panhandle – yes… we can.
And if these records are accurate – yes… we should.
I have seen the impact this plant can make. It has invaded Texas and Louisiana and has caused enough problems for the USDA to list it as one of America’s most noxious weeds. In Texas they have had “all calls” for anyone able to come to the state and help with management.
Giant Salvinia mats completely covering Bay County pond. This fast growing invasive can double in coverage every two weeks! Photo by L. Scott Jackson
I was camping in a state park near Shreveport LA. After we set up camp my grandson and I went to look at the lake. You could tell it was once clear water and cypress trees, but the water was completely covered with plant growth that looked, from a distance, like dollar weed and that there was no visible water at all. Completely covered. And then it hit me… THIS IS SALVINIA! Shortly after I saw the sign along the shoreline describing the plant and what to do to avoid spreading it. There was a yellow boom stretched across the surfacce to keep the plant from getting into the swimming area – but no one was swimming. The bottom was muck and I did not see any fish. There was no recreational activity at all. The boat ramp was completely choked with the weed, and I am not sure you could paddle through it anyway. It was a mess.
According to EDDMaps, there are only 14 records statewide, 11 of those are in the panhandle, and 9 of those are in Pensacola. We are certainly ground zero for the problem and FWC has been working over the last couple of years to eradicate it. All nine records are in Bayou Chico, and if FWC is successful at eradicating it, this will significantly make strides to eliminating the plant from the state. The other two locations in the panhandle are a retention pond at the northern arm of Deer Point Lake in Bay County, and a pond near Quincy FL.
Is this all of it?
Are there other sites with this plant that we do not know about?
I have been following EDDMapS records for a couple of years now and there are new records in central and south Florida -so, maybe.
If so, they need to be reported so that FWC can begin treatment. How would you know if the plant is present? How do you identify it?
Here are links to learn more about the plant. It prefers quiet/slow moving freshwater systems with plenty of nutrients. If you think the plant is present in your community, contact your county extension office to verify and report it.
