by Rick O'Connor | May 4, 2018
Humans have inhabited the shores of Pensacola Bay for centuries. Impacts on the ecology have happened all along, but the major impacts have occurred in the latter half of the 20th century. There has been an increase in human population, an increase in development, a decrease in water clarity, a decrease in seagrasses, and a decrease in the abundance of some marine organisms – like horseshoe crabs, scallops, and some marine fishes. There has also been an increase in inorganic and organic compounds from stormwater run-off, fish kills, and health advisories due excessive nutrients and fecal bacteria in local waters.
A view of Pensacola Bay from Santa Rosa Island.
Photo: Rick O’Connor
Since the 1970’s, there have been efforts to help restore the health of the bay. Seagrasses have returned in some areas, fish kills have significantly reduced, and occasionally residents find scallops and horseshoe crabs – but there is still more to do. In this series of articles, I will present information provided in a recent publication (Lewis, et. al. 2016) and from citizen science monitoring. We will begin with an introduction to the bay itself.
The Pensacola Bay System is the fourth largest estuarine system in the state of Florida. The system includes Blackwater, Escambia, East, and Pensacola Bays. There are numerous smaller bayous, such as Indian, Mulat, and Hoffman, and three larger ones, which include Texar, Chico, and Grande. There are two lagoons that extend east and west of the pass. To the west is Big Lagoon and to the east is Santa Rosa Sound. The surface area of this bay system is about 144 mi2 and the coastline runs about 552 miles in length. There are four rivers that discharge into the system: the Escambia, Blackwater, Yellow, and East Rivers. The majority of watershed is in Alabama and covers about 7000 mi2. The mouth of the bay is located at the Pensacola Pass near Ft. Pickens and is 0.5 miles across. Depending on the source, the flush time for the entire bay has been reported between 18 and 200 days.
There are several ecosystems found within the bay system. Seagrasses are be found throughout the bay and bayous, but are more prevalent in Big Lagoon and Santa Rosa Sound. Oyster reefs have provided income for some in the East Bay area in the past, but production has declined in the last 50 years. Salt marshes are found throughout the bay as well, but the greatest acreage is in the Garcon area of Santa Rosa County. There are, of course, freshwater marshes near the mouths of the rivers with the largest being at the mouth of the Escambia River.
Members of the herring family are ones who are most often found during a fish kill triggered by hypoxia.
Photo: Madeline
Members of the drum family are one of the more common fishes found in the system and would include fish like the Spot and Atlantic Croaker. However, speckled trout, striped mullet, redfish, several species of flounder, have also been targets for local fishermen. Target fish include sardines, silversides, stingrays, pinfish, and killifish. Brown shrimp, oysters, and blue crab have historically provided a fishery for locals, but other invertebrates include several species of jellyfish, stone crabs, fiddler crabs, hermit crabs, grass shrimp, several species of snails, clams, bay squid, octopus, and even starfish. There is also a variety of benthic worms found within the sediments.
A finger of a salt marsh on Santa Rosa Island. The water here is saline, particularly during high tide. Photo: Rick O’Connor
There has been a decline in overall environmental quality since 1900 but, again, the biggest impacts have been between 1950 and 1970. Fish kills, a reduction in shrimp harvest, and hypoxia (a lack of dissolved oxygen) have all been problems.
In the articles to follow we will look deeper into specific environmental topics concerning the health of Pensacola Bay.
References
Lewis, M.J., J.T. Kirschenfeld, T. Goodhart. 2016. Environmental Quality of the Pensacola Bay System: Retrospective Review for Future Resource Management and Rehabilitation. U.S. Environmental Protection Agency. Gulf Breeze FL. EPA/600/R-16/169.
by Rick O'Connor | Apr 14, 2018
Shoal grass. One of the common seagrasses in Florida.
Photo: Leroy Creswell
For many, it really does not matter. But is there a difference? Yes… there is. Seagrass is what typically washes ashore on the Sound side – seaweed is what we typically see on the Gulf.
So what is the difference?
Seagrasses are actually grasses. They are true plants in the sense they have roots, stems, and leaves. They also produce flowers, but they are so small it is very hard to see them. Pollen and seed dispersal is via the currents. What the observer sees when snorkeling in seagrass meadows are the leaves – in this case called blades. The stems run horizontal beneath the sand, as many grasses in our lawns do. These are called rhizomes, and the roots extend from them. Turtle grass and Shoal grass are the two most common types we have here.
Seaweeds on the other hand, are not true plants because they lack roots, stems, and leaves. They are often called algae and must be submerged in water in order to absorb it. They are either float and drift in the currents, or can attach to hard objects on the seafloor using a structure called a holdfast. June grass and Sargassum are two common types that drift ashore.
So why don’t seagrasses grow in the Gulf?
Like all plants, seagrasses need sunlight. At least 25% of the sunlight reaching the surface must reach the bottom for them to photosynthesize. Near the shore, there is enough sunlight for seagrass, but they cannot tolerate the larger waves that our nearshore Gulf produces – thus they are restricted to the quieter waters of the Sound. We do have seagrasses growing in Big Lagoon, Old River, parts of Pensacola Bay, and even in some of the local bayous. This ecosystem is important to the overall health of our bay. It is known that 80-90% of the commercially and recreationally important finfish and shellfish require seagrasses, or salt marshes, for at least part of their life cycle – so they are important economically as well.
Seaweeds also need sunlight. In rocky areas, you can find them attached in sunlit waters. Much of our area is sand, so we do not see as many forms of seaweed as they do in the Keys or in California. However, we do have floating forms.
March is “Seagrass Awareness Month”. Many people provide opportunities to educate locals about our seagrasses and the issues they are facing. Excessive run-off from parking lots, ramps, homes, etc. – increase the turbidity and decrease the salinity of the water – both of which are detrimental to seagrass health. This run-off also contains pollutants that are problematic – particularly nutrients from fertilizers. The fertilizers trigger algal blooms which block sunlight and, in some cases, smoother the surface of the grass blades. Then there is prop scarring. The shallow waters where they live are also popular spots for boaters to visit. The propeller scarring leaves open tracts throughout the seagrass meadows and, unlike some grasses in our yards, can take years – even decades – to recover. There has been significant loss of seagrass all across the Gulf region, including Pensacola Bay. The loss of seagrass have also affected species such as bay scallop and horseshoe crabs. There are signs of recovery and we need to continue reducing our impact to keep this trend going. Florida Friendly Landscaping, Clean Boater practices, and Living Shorelines are some methods that can help. Contact your local County Extension Office to learn more about these programs.
by Rick O'Connor | Apr 14, 2018
In my job, I get many calls about snakes. Most people want to know how to tell a venomous from a nonvenomous one and how to keep them out of the yard. I was recently reading a new book out by Dr. Sean Graham entitled American Snakes and in the chapter on snake defenses, he provided a long litany of local creatures who consumed snakes – some surprised me. Check this out…
The “cottonmouth” gape of this venomous snakes is a warning. Notice the banded coloration of this individual.
Photo: UF IFAS Wildlife
First, most who do only consume smaller species of snakes – but the list is still surprising. Spiders… spiders were on the list. He specifically called out the black widow – who probably could kill a small snake, but indicated there were others. Scorpions, centipedes, fire ants, carpenter ants, giant water bugs, crayfish, and crabs made the list as well. Some of these may consume snakes only after they are dead – but some can kill small ones.
From the vertebrate world he mentions the larger salamanders (such as the hellbender), and other snakes (such as the short-tailed snake and the coral snake). There are several mammals including shrews, moles, and even the rodents themselves are consumers of snakes! He describes how hoofed mammals (such deer, goat, and horses) do not consume snakes, but can completely destroy one by raising and stopping on them – leaving only small segments remaining. They have found the remains of snakes in the stomachs of all predatory mammals but the snake’s greatest threat are birds… by a long shot. Species from passerines to raptors have been known to kill and consume snakes.
What about venomous snakes – who consumes rattlesnakes and cottonmouths?
There are surprises here as well…
Bullfrogs… bullfrogs basically consume what they can get into their mouths but this includes snakes – and venomous ones as well (though they would be small ones). From the fish world, both the gar and largemouth bass are known to consume venomous snakes.
A coyote moving on Pensacola Beach near dawn.
Photo provided by Shelley Johnson.
Opossums are known to consume at least 12 species of snakes, including venomous ones. They also consume ticks, fire ants, and have a very low occurrence of rabies – a cool animal to have around.
Other mammal consumers of venomous snakes include raccoons, otters, fox, bobcats, coyotes, and black bears. It is understood they must take smaller members of the venomous snake population – but a snake control is snake control.
Most wading birds in our marshes consume snakes, including venomous ones, but it is the red-tailed hawk and the great horned owl that are the masters. Red-tailed hawks are known to consume at least 35 species of snakes, including venomous ones, and – unlike other snake predators – are a larger part of their diet, they seek them out. Great Horned Owls consume at least 13 species, and venomous ones are on the menu.
From the reptile world we begin with the alligator, who has little problem consuming large specimens of both the rattlesnake and the cottonmouth. However, many are snakes… yes, snakes eat snakes and some consume venomous ones. Coral snakes, coachwhips, and cottonmouths have been known to consume other snakes. However, it is the Eastern Indigo and the Kingsnakes who actively seek out venomous species. It is known that kingsnakes have a protein in their blood that makes them immune to the viper’s venoms – and it appears the vipers know this and avoid them. It is not known whether the indigo is immune, but it is known they will seek out venomous snakes and consume. Both of these snakes can take relatively large venomous species.
Of these two, it is the Kingsnake who is the “king” – consuming at least 40 species of snakes. However, both the kingsnakes and the indigo are on the declined. The eastern indigo is currently federally listed as endangered – there has not been a verified record of one in the Florida panhandle since 1997. However, there are anecdotal reports and we encourage anyone who has seen one to send us a photograph. There is an active indigo restoration program going on in Alabama and in the Apalachicola River area. These are the largest native snakes in the U.S. (about 8 feet) and, along with the six-foot kingsnakes, are frequently killed. There is evidence that as the eastern kingsnake populations decline copperhead populations increase, and Vis versa. Some areas near Atlanta are currently experiencing a copperhead “boom”. Clearly, we should reconsider killing both the indigo and kingsnakes. We also understand that habitat loss is another cause of their decline, particularly in the case of the indigo.
When looking at this list of snake consumers we see species that cause other problems – alligators, raccoons, coyotes, and bears have all have had their negative issues. But many we just do not like, such as the opossum, really cause us no harm and control snake populations. Everything has its place in the local environment and not one species seeks out humans for the purpose of harming us – this would include snakes. The negative encounters are for other reasons. But for those who have a deep fear, or are currently experiencing high snake numbers, seeing one of the animals on this in the neighborhood could be a relief.
References
Graham, S. 2018. American Snakes. John Hopkins University Press. Baltimore MD. Pp 293.
O’Connor, M. 2018. Personal communication.
by Rick O'Connor | Mar 10, 2018
As we come to the end of National Invasive Species Awareness Week (NISAW), I need to educate everyone on a potential invasive threat, a classic Early Detection Rapid Response (EDRR) species – the Cuban Treefrog.
is this a Cuban Tree Frog? Do I have to rely on DNA barconding to know for sure – before I decide to euthanize it? Could I be making a mistake?
Image by Dr. Steve A Johnson 2005.
This treefrog was first introduced into to south Florida in the 1920’s. Like lionfish, it quickly became established and began its slow dispersal northward. It is a large predatory frog (reaching about 5”) which began to consume native treefrogs, reducing their populations wherever they were found. In addition to consuming native frogs, Cuban Treefrogs eat snails, millipedes, spiders, and many other small creatures. They can produce a call that is somewhat annoying to many residents where it is found. It is currently listed as established as far north as Gainesville FL.
A few years ago, I received a call from a resident near Big Lagoon in southwest Escambia County. They had just purchased plants from a local chain store to plant in their yard the following day. They had left the plants on the front porch that night and, at some point, noticed this large treefrog on their front door. They wanted to know if this was a non-native frog. It was – it was the Cuban Treefrog. The animal was collected and sent to the University of Florida.
This is a common method of transporting this frog north. They attach to ornamental plants grown in nurseries in south Florida. The plants are loaded on trucks and shipped to the panhandle and locations north and west. There are probably numerous species hitching rides this way, including the Cuban Anole (an invasive lizard). Lucky for us, in many cases these tropical problem species cannot tolerate our cold winters – this could also be said for some of the invasive plants. However, in recent years, the winters have been milder and some of these species are surviving. Most of us know and understand the impact lionfish have had on local small reef fish; no one is interested in another “lionfish problem” in the panhandle.
About a year ago, a second Cuban Treefrog was reported in Crestview.
Early this year I attended an amphibian/reptile conference in north Georgia. There was a presentation given by a scientist from the U.S. Geological Survey in Lafayette LA. He had a call from the Audubon Zoo in New Orleans about a strange frog they had been finding. They had recently purchased palm trees from south Florida for the elephant exhibit. The caretakers of the exhibit began to see strange frogs and reported it. When USGS arrived, they meandered through the park searching. They stopped by the public bathroom to look (a place I have found them in south Florida myself). They happen to pass an electric panel outside the restroom and decided to take a peak – 13 Cuban Treefrogs were within.
They began an exhaustive search and found CTFs everywhere. Most had moved into a public park between the zoo and the river called Riverview. I cannot remember how many they had found but it was in the hundreds, the animals were beginning to establish themselves in this area of New Orleans. USGS is currently working on the problem.
Just a few weeks ago, a Cuban Treefrog was found on Davenport Bayou off Bayou Grande.
There are many reports of single, individual CTFs across the northern Gulf coast, but none were established populations. However, as reports increase we should be looking for these animals and try to keep them under control before they do. No more “lionfish problems”.
How do we do this?
The following link provides information about the frog, how to identify it, how to set traps to determine if the animal is in your neighborhood, and what to do if you do find one. I would include reporting the finding on www.EDDMapS.org. I also recommend as you purchase plants for this spring’s landscaping projects, check the plants carefully for any hitchhikers. This “early detection” method is the most effective way to battle the movement of invasive species.
If you have questions about Cuban Treefrogs, let me know.
Johnson, S.A. 2017. The Cuban Treefrog (Osteopilus septentrionalis) in Florida. University of Florida Extension Electronic Data Information Source (EDIS) document WEC218.
http://edis.ifas.ufl.edu/uw259.
by Rick O'Connor | Mar 9, 2018
Most people know that snakes are ectothermic and the environment is what regulates their body temperature. However, many do not know that they like to maintain their temperature close to 98 F like us. To do this they must move to locations where they can either warm (like basking in the sun or lying on warm asphalt) or cool (like under rocks or logs). Unlike us, their temperature can rise to above 100 F or down close to 30 F with few health problems.
Eastern Diamondback Rattlesnake swimming across the Intracoastal Waterway near Pensacola Beach.
Photo: Andy Barnes
When environmental temperatures become colder, their heart and breathing rates slow significantly. Their blood oxygen levels decrease, and they become very slow and sluggish – a condition we call torpor. There are some advantages to this, such as not having to hunt for food for several weeks or months, but when the air temperatures begin to climb they become more active… Moreover, their hungry.
In the last two weeks, I have had numerous reports of snakes moving around in yards. There have been three records of diamondback rattlesnakes in the Pensacola Beach area alone.
Should I be concerned about doing outdoor activities?
No, not really – but you should be aware. As it warms, snakes will become more active early in the morning and late in the evening. Pit vipers, like rattlesnakes and cottonmouths, actually prefer hunting at night. However, when the temperatures are cool enough for mid-day movement, they will. Food and reproduction (for some species) are on their mind this time of year.
Stay on the trails – snakes typically do not like to be in the open because of predators but they do have to bask to increase their body metabolism; so they may be along the edge. If I am hiking, I tend to look down along the trail when walking. If I want to observe something in the trees, I stop.
These snake movements happen every year, and very people have problems, but with the recent increase in encounters it is could to be aware. I actually think snakes are pretty cool. I enjoy seeing them, especially ones that are not viewed very often like coral snakes and rattlesnakes. You should still go out and enjoy the Pensacola Bay area. It is a great time of year to do it.
