The Panhandle of Florida is home to many estuaries along the coast, from the Escambia Bay System in the west to the Apalachicola Bay System in the east. These estuaries are very important and are the intersection where rivers (fed from their respective watersheds) meet the Gulf of Mexico and contain many different organisms that help filter the waters before they reach the Gulf. These organisms include oysters, marsh plants, seagrasses, scallops, tunicates, and other invertebrates. In this two-part article, we will explore marsh plants, seagrasses, oysters, and scallops.
Marsh Plants
Marsh Plants is a broad term for a family of grasses that lines the shore and contain grasses like Smooth Cordgrass (Spartina alterniflora), Saltgrass (Distichlis spicata), and Gulf Cordgrass (Spartina spartinae). These plants help trap sediments before they enter the estuary and are excellent at erosion prevention. When the water encounters the plants, it slows the flow, and this allows for sediments to collect. Marsh Plants are a great tool for shoreline restoration and are a major part of the Living Shorelines Program. The roots of the plants are also very efficient at removing nutrient pollutants like excess nitrogen and phosphorus which are major influencers in eutrophication. Marsh Plants also absorb carbon dioxide from the atmosphere and have been tabbed as “superstars of CO2 capture and storage.” (CO2 and Marsh Plants)
Marsh Grass and Oyster Reef in Apalachicola, Florida – Thomas Derbes II
Seagrasses
Seagrasses are different than Marsh Grasses (seagrasses are ALWAYS submerged underwater), but they offer some of the same ecological services as Marsh Grasses. The term seagrasses include Turtle Grass (Thalassia testudinum), Shoal Grass (Halodule wrightii), Widgeon Grass (Ruppia maritima), and Manatee Grass (Syringodium filiforme) to name a few. Seagrasses help maintain water clarity by trapping suspended sediments and particles with their leaves and uptake excess nutrients in their roots. Seagrasses are very efficient at capturing carbon, capturing it at rates up to 35 times faster than tropical rainforests. (Carbon Capture and Seagrasses) They also provide habitat for crustaceans, fish, and shellfish (which can filter the water too) and food for other organisms like turtles and manatees.
Grassbeds are also full of life, albeit small creatures. Photo: Virginia Sea Grant
Oysters
Crassostrea virginica (or as we know them, the Eastern oyster) is a native species of oyster that is commonly found along the eastern coast of the USA, from the upper New England states all the way to the southernmost tip of Texas. Eastern oysters are prolific filter feeders and can filter between 30-50 gallons of water per day. As filter feeders, they trap nutrients like plankton and algae from the environment. In areas of high eutrophication, oysters can be very beneficial in clearing the waters by trapping and consuming the excess nutrients and sediments and depositing them on the bottom as pseudo-feces. With oyster farms popping up all over the Gulf Coast, the filtering potential of estuaries is on the rise. (Between the Hinge)
Oysters, The Powerful Filterers of the Estuary – Thomas Derbes II
Scallops
Bay Scallops (Agropecten irradians) were common along the whole Florida Gulf Coast, but their numbers have taken a recent decline and can only be found in abundance in the estuaries to the east of St. Andrews Bay in Panama City, Florida. Scallops make their home in seagrass beds and are filter feeders. While scallops do not contain the filtering potential of an oyster (scallops filter 3 gallons of water per day as an adult), they are still a key part of filtering the estuary. Just like oysters, scallops feed off of the suspended particles and plankton in the water column and deposit them as pseudo-feces on the bottom. The pseudo-feces also help provide nutrients to the seagrasses below.
Bay Scallop. Photo: FWC
I hope you enjoyed this first article on filterers in the estuary system. While oysters are known as the filterers of the estuary, I hope this has opened your eyes to the many different filterers that call our estuary home. Stay tuned for Part 2!
Understanding Salinity in Northwest Florida’s Waters with a Family Activity
Dana Stephens, 4-H Agent
Salinity is the amount of total dissolved salts in water. This includes all salts not just sodium chloride, or table salt. Salinity is important in aquatic environments as many flora and fauna depend on salt and the level of dissolved salts in the water for survival. People interested in the composition of water frequently measure chemical and physical components of water. Salinity is one of the vital chemical components measured and often measured by a device determining how readily electrical conductance passes between two metal plates or electrodes. These units of electrical conductance, the estimate of total dissolved salts in water, is described in units of measurement of parts per thousand (PPT).
At the large scale, Earth processes, such as weathering of rocks, evaporation of ocean waters, and ice formation in the ocean, add salt to the aquatic environment. Earth processes, such as freshwater input from rivers, rain and snow precipitation, and ice melting, decrease the concentration of salt in the aquatic environment. Anthropogenic (human-induced) activities, such as urbanization or atmospheric deposition, can also contribute to changes in salinity.
Salinity and changes in salinity affect how water moves on Earth due to contrasts in the density of water. Water containing no dissolved salts is less dense than water containing dissolved salts. Density is weight per volume, so water with no dissolved salts (less dense) will float on top of water with dissolved salts (denser). This is why swimming in the ocean may feel easier than swimming in a lake because the denser water provides increased buoyancy.
Northwest Florida is a unique place because we have a variety of surface waters that range in salinity. There are ponds, lakes, streams, rivers, and springs, which have no to low salinity levels (0 to 0.5 PPT), and commonly referred to as freshwater systems. We house six estuaries—Perdido Bay, Pensacola/Escambia Bay, Choctawhatchee Bay, St. Andrews Bay, St. Joseph Bay, and Apalachicola Bay. Estuaries are bodies of water with freshwater input(s) (e.g., rivers) and a permanent opening to the ocean (e.g., Destin Pass in the Choctawhatchee Bay). Estuarine waters are termed brackish water (0.5 to 30 PPT) due to the dynamic changes in salinity at spatial and temporal scales. Waterbodies with an even more dynamic change in salinity are the coastal dune lakes Northwest Florida’s Walton and Bay Counties. Coastal dune lakes are waterbodies perched on sand dunes that intermittently open and close to the Gulf of Mexico. Sometimes these waterbodies are fresh and sometimes they have the same salinity as the Gulf of Mexico, like after a large storm event. Finally, the Gulf of Mexico, or ocean, has the highest salinity (> 30 PPT) among the waterbodies of Northwest Florida.
Here is an educational activity for the family to explore salinity and how salinity differs among Northwest Florida waters.
In 2005 I was leading a field trip with high school students in a salt marsh on Santa Rosa Island near Pensacola Beach. As we explored a brackish water creek, we came across a three-foot red mangrove tree, prop roots and all. To say we were surprised and excited would be an understatement.
Most know that mangroves are trees that can tolerate seawater and grow along estuarine shorelines across the tropics, including south Florida. They can form dense forests that support all sorts of aquatic and terrestrial wildlife. They need calm protected waters to establish themselves but once established are excellent at protecting shoreline communities during hurricanes. However, they cannot tolerate cold weather, only surviving freezing temperatures for one or two nights.
The red mangrove. Photo: University of Florida
Growing up in Pensacola we would often find red mangrove propagules (seedlings) washed ashore arriving from the tropical parts of the Gulf. They were generally on the Gulf side of Santa Rosa Island and Perdido Key but never germinated. If they were carried into the estuary, and found a protected lagoon to begin germination, they would not survive our winters. This is what made finding an established three-foot mangrove in a lagoon off Santa Rosa Sound in 2005 so surprising.
Mangrove propagule washed ashore. Photo: Rick O’Connor
Historically mangroves were not found north of Tampa Bay. However, in recent decades they have become established as far north as Cedar Key. Trying to determine whether the mangrove we found was the northern most in Florida I found that they were also expanding along the east coast of Florida as far north as St. Augustine, and there were records in the Jacksonville area. Many attribute this to climate change. Our winters are milder than they were when I was a kid, and this may be leading to what many are calling the “tropicalization of northern Gulf of Mexico”. Not only mangroves, but other historically south Florida species, such as snook and bonefish, have been reported along the panhandle.
In 2017 I was leading another high school group on a field trip in a salt marsh in Big Lagoon State Park. We found a germinated seedling of a red mangrove doing very well. We explored more and found seven others in the nearby area. How many more were growing in the Pensacola Bay area?
A small red mangrove growing in Big Lagoon near Pensacola FL Photo: Rick O’Connor
We partnered with a research team from Dauphin Island Sea Lab who was looking into this as well. The team included extension agents and specialists from Florida and Mississippi-Alabama Sea Grant, as well as biologists from the National Estuarine Research Reserves in Mississippi, Alabama, and Florida panhandle. Each county/region selected 10 transect sites that had the highest probability of mangroves to monitor each year. Mangroves appear to be established on some of the Mississippi barrier islands, as well as in St. Joe Bay. Individuals have been reported from Bay County. A ninth mangrove was found in Escambia County but a hard freeze in 2018 killed them all. Since then, one young multi-year red mangrove was found on NAS Pensacola. It died in the hard freeze of 2023. Despite the hard freezes, those established in St. Joe Bay seem to be holding on. I decided to make a visit and see.
A red mangrove growing at NAS Pensacola. Photo: Whitney Scheffel.
Black mangroves growing near St. George Island in Franklin County. Photo: Joshua Hodson
Wading out from the buffer preserve with Gulf County Sea Grant Agent Ray Bodrey, we found relatively large patches of mangroves, and seeds suggesting active expansion was ongoing. But I noticed the species we were seeing were black mangroves. I mentioned to Ray that what we had seen in Pensacola were red mangroves. He said that the red mangroves have a hard time here as well. Black mangroves are more tolerant of cold weather, and it is they who are establishing these large patches. There are reports of large patches of mangroves on the Mississippi barrier islands – and they are the black mangroves as well. I know that black mangroves have been established in the Chandeleur Islands in Louisiana for decades. I am convinced that if black mangroves seeds were to reach protected lagoons in Pensacola Bay, they would probably do well here as well.
I continue to conduct our transects each year in the Pensacola Bay area. I have a couple of trained volunteers helping me but could always use more. If you think you have seen a mangrove growing in the Florida panhandle, we would love to know and document their location. We know they are established in Gulf County, so our focus is now Escambia to Bay counties. If you think you have seen one, contact me at roc1@ul.edu or your county Sea Grant Agent.
Even though oysters have a hard shell that even humans have a hard time opening, they do have natural predators in our waters that can easily slurp up a couple dozen. Your usual oyster slurping suspects include oyster drills, blue crabs, and fish (such as the black drum). In this article, we will focus on the 3 major predators that contribute the most toward natural mortality in oysters here in the Florida Panhandle.
The Oyster Drill
When it comes to the marine snail world, oyster drills would win an oyster-eating contest. Oyster drills (Urosalpinx cinerea) are marine gastropods that grow to sizes of 0.5 – 1 inch. Oyster drills can be found all along the Atlantic coast of North America and the Gulf of Mexico, and they have been accidentally introduced into Northern Europe and the West Coast of North America. These small but mighty snails have become specialized in consuming oysters. Using chemotaxis, they locate their prey oyster. Once they find it, they secrete an enzyme to soften a portion of the oyster shell. Once softened, they drill into the shell and siphon out oyster meat. Oyster drills have been known to occur in great numbers when the environmental conditions are prime and can wipe out not only entire oyster beds but also clam beds. Oyster drills do have natural predators as well, but these predators also consume oysters.
An Oyster Drill (Urosalpinx cinerea) – Barnegat Bay Shellfish
The Blue Crab
Most of us know about the very tasty blue crab (Callinectes sapidus), but many do not know that it is a major consumer of oysters, especially on an oyster farm. Blue crabs are a decapod crab (meaning 10 legs) of the swimming crab family Portunidae. Blue crabs can indeed swim and their last leg on each side has developed into what are called paddle fins. Juvenile oysters are the main target for blue crabs, but they have been observed eating adult oysters when given the opportunity. On an oyster farm, blue crabs can get into an oyster bag when they are very small. Once inside, they have an all-you-can-eat buffet of oysters, and can quickly wipe out a bag of oysters. Oyster farmers have to be very cautious and must either remove the blue crabs manually or dry their bags out in hopes of destroying any blue crabs. Blue crabs can easily break open a juvenile oyster, but for them to consume an adult oyster, they will wait for it to open to feed before shoving a claw inside of the shell to keep the oyster open. Once they have their claw in the shell, they will use their other claw to consume the oyster.
Blue Crabs (Callinectes sapidus) Pulled Out Of Oyster Bags – Thomas Derbes II
The Fish
Even though oyster-eating fish like black drum (Pogonias cromis) and sheepshead (Archosargus probatocephalus) are much bigger than snails and crabs, they tend to contribute less to oyster mortality on oyster farms. However, during certain seasons wild oysters and other shelled invertebrates can contribute up to 33% of a black drum’s diet (more here). Fish will usually congregate around oyster beds and farms, but they are more interested in consuming oyster predators like crabs and snails. The black drum is a fish that was built for oyster consumption. While black drum lack sharp teeth, they have crushing plates in their throat that can crush an oyster shell which allows the drum to eat the oyster meat. Many oyster farmers welcome these fish on their farms as a free source of anti-fouling and predator deterrent (in the form of consumption).
Black Drum (Pogonias cromis) Caught On A Whole Oyster – Thomas Derbes II
There are many more oyster predators, but these are the top 3 in terms of threat and ability to consume/do detriment to oyster beds and farms in the Florida Panhandle. While oyster drills rank up towards the top, crabs and fish can also greatly contribute to natural mortality.
References
Flimlin, G., & F Beal, B. (n.d.). Major Predators of Cultured Shellfish. https://shellfish.ifas.ufl.edu/wp-content/uploads/Major-Predators-of-Cultured-Shellfish.pdf
Kayaking over seagrass beds and stingrays, hiking among pitcher plants, boating past diving ospreys, and meeting hundreds of fascinating, like-minded people—these are just some of the great experiences I’ve had while teaching the Florida Master Naturalist Program. More than 20 years since its inception, the Florida Master Naturalist Program (FMNP) has inspired the creation of dozens of similar courses in other states and proven itself to be one of the most popular outreach programs to come out of UF IFAS Extension.
Kayaking Santa Rosa Sound in Navarre is one of the highlights of our Coastal Systems FMNP class. Photo credit: Carrie Stevenson, UF IFAS Extension
The mission of the FMNP is simple—to promote awareness, understanding, and respect of Florida’s natural world among Florida’s citizens and visitors. I have always felt strongly that if you want people to care about something, they need to understand it. And to really understand something, you need to experience it. I know my own passion for science and ecology was ignited early on by teachers who took us outside and helped us encounter the many wondrous surprises in the natural world. With the FMNP, we seek to do just that.
Master Naturalist students conduct field work in small groups. Photo credit: Carrie Stevenson, UF IFAS Extension
Over a span of 40 hours in 6-7 weeks, we spend about half our time with classroom presentations and the other half in the field, seeing the plants, animals, and ecosystems we discuss in class. In addition to classes and field trips, students produce a final project and present it to the class. These can range from labeled collections and slide presentations to building bird houses and new trails. The program is composed of three 40-hour core courses; Coastal, Upland, and Freshwater Systems. Seven “short courses” with 24 hours of class/field time include the Land Steward series (Conservation Science, Habitat Evaluation, Wildlife Monitoring, and Environmental Interpretation) and the Restoration courses (Coastal Restoration, Marine Habitat Restoration, and Invasive Plants). Locally, we try to rotate the core modules every couple of years and incorporate the short courses periodically. Registration includes a detailed course manual and, upon completion, FMNP patch, certificate, and pin denoting area of expertise. There are a handful of scholarships available for those interested in applying to offset costs.
Master Naturalist students walk “The Way” boardwalk in Perdido Key. Photo credit: Carrie Stevenson
The classes do not count towards university credit but are an excellent certification and professional development opportunity that many will list on a resume. While we’ve had ecotour operators, park rangers, environmental consultants, teachers, and archaeologists participate, most of our FMNP students are not professionals in the field. They come from every background imaginable but share an interest in the outdoors. Because we meet weekly, class members often form long-lasting friendships during the courses.
Information on upcoming classes in northwest Florida and all around the state is available online. Classes range from fully in-person to hybrid and online options. FMNP classes are restricted to adults 18 and over, but a new “Florida Youth Naturalist” curriculum has been designed through our 4-H program for young people. For more information on that, check out their website.
You might have seen a floating oyster farm while driving over Garcon Point Bridge or along Scenic Highway. Many people know them for the beautiful, tasty oysters they produce, but those farms have a major ecological benefit that many aren’t aware of. First, the oysters in those cages act as a very efficient water filter, filtering upwards of 30 gallons per day. The floating farms also act as an oasis for other marine creatures, from crustaceans to finfish, and can help increase the biodiversity in the area. Oysters are also great at sequestering carbon into their shells. Today, we will go over these ecological benefits and proper etiquette when maneuvering around the farms to enjoy some of the ecological benefits of the oyster farm.
Florida Pompano Caught Off an Oyster Farm – Thomas Derbes II
Besides being tasty, oysters are very well known for their ability to filter massive amounts of water in a single day. Research has shown rates of up to 50 gallons per day in a laboratory setting, but they filter upwards of 30 gallons per day in the wild. With most oyster farms in the area having more than 500,000 oysters on their farm, that’s more than 15,000,000 gallons of water per day per farm! Oysters can filter out any excess sediments from the water, forming them into small packets and depositing the sediment on the bottom of the bay, keeping the sediments from being re-suspended. This is very beneficial to any bay or estuary as eutrophication (More Here on Eutrophication) has been an issue in almost every bay in the southern United States.
Another benefit to oyster farms is that it is a floating oasis for all types of marine creatures. Blue crabs and stone crabs are a common threat to oysters, and they love to congregate around oyster farms waiting for an easy meal from a dropped oyster or oyster spat on cages. Common bay fish, like the Spotted Seatrout, Sheepshead, and Red Drum, have been known to hang out under the cages consuming smaller finfish and crabs, but some uncommon fish like Tripletail and Florida Pompano also patrol the cages looking for a meal. Because of its ability to hold all types of fish, fishermen love to fish around the oyster farms. Fishing around oyster farms is allowed, but most farmers want the boats to stay on the boundary of the farm and not inside of it. This is due to there being lines under the surface of the water that could potentially damage any lower unit and can cut free a line of cages. Also, it is against state law to be within the boundary of the farm if you are not an authorized harvester of that lease, and I have personally seen FWC enforce those rules. As a seasoned oyster farmer once told me “We know our farm holds fish and it is okay for them to fish the farm, heck put out some blue crab traps around it, but do not mess with the cages and stay outside of the boundary and we can all live in harmony.”
Tripletail Caught Off An Oyster Farm – Brandon Smith
Last but not least is the ability of oysters to sequester carbon and excess nitrogen into their shells and pseudofaeces (aka bio-deposits). Carbon and nitrogen sequestration is a crucial service provided by oysters that helps battle global climate change. Just as they do with excess sediments, they deposit excess carbon and nitrogen into bio-deposits that accumulate on the bottom, keeping them from being re-suspended into the waters. Oyster reefs are currently on the decline around the world, and their decline has “resulted in a forfeiture of several ecosystem services” including carbon and nitrogen sequestration and water filtration. (More Here on Carbon Sequestration)
While oysters might be tasty, we have learned about some of the ecological services oysters provide to an estuarine environment. From water filtration to increasing biodiversity to carbon/nitrogen sequestration, oysters are a major benefit to any estuary and can help fight climate change and eutrophication. Next time you see an oyster farm or reef, give oysters (and farmers) a little appreciation for their hard work in helping make the world a healthier place!
