October is Dune Lake Awareness month and as part of the celebration, Walton and Okaloosa County UF/IFAS Extension Agents are joining together to host a Coastal Dune Lake Tour at Western Lake in Grayton Beach State Park. This free event will include a brief lecture and guided tour of the nature trail surrounding the lake. Laura Tiu, Marine Science Agent, will start the tour with a history of the lakes, the unique ecology and some of the local protections. Sheila Dunning, Horticulture Agent, will share information on the unique flora in the dunes including which plants have been used by native Americans and pioneers for food and medicine and the trees we find in the dune landscape surrounding the dune lakes and their adaptations to this sometimes-harsh environment. If you have an interest in our local dune lakes or the tour, you may visit the Walton County Dune Lake website at https://www.co.walton.fl.us/97/Coastal-Dune-Lakes. If you would like to register for this free tour go to https://www.eventbrite.com/e/panhandle-outdoor-live-2023-coastal-dune-lake-lecture-and-trail-tour-tickets-722764316527?aff=oddtdtcreator or use our Facebook event link https://www.facebook.com/events/811943803961304. Feel free to call our office, 850-892-8172, with any questions.
I attended a meeting recently where one of the participants stated – “We have been looking at a lot of water quality parameters within our bay in recent years, and plan to look at more, but has anyone been looking at temperature?”
What he was referring to was that the focus of most monitoring projects has been nutrients, dissolved oxygen, etc. But most agencies and universities who have been conducting long term monitoring in our bays are collecting temperature data as well. His question was not whether they have or not but has anyone looked at this long-term temperature data to see trends.
I know from some of the citizen science monitoring I have been involved with that temperature is collected but (anecdotally) does not vary much. It is like pH, we collect it, it is there, but does change drastically (anecdotally) over time. However, it has been a very hot year. This “heat dome” that has been sitting over the Midwest and southeast this summer has set records all across the region. Someone monitoring water temperature in East Bay recently reported surface water temperature at 96°F (36°C). Many have stated that swimming in our waters at the moment feels like swimming in bath water. It’s not just warm in your yard, it is warm in the bay. And this brings up the question of thermal tolerance of estuarine species.
All creatures have a temperature tolerance range. They resemble a bell curve where you have the thermal minimum at one end, the thermal maximum at the other, and the “preferred” temperatures near the top of the bell curve (see image below). Many creatures have a large tolerance for temperature shifts (their bell curves extend over a larger temperature range). You find such creatures in the temperate latitudes where temperature differences between summer and winter are larger. Others have a lower tolerance, such as those who are restricted to polar or tropical latitudes. Within an estuary you can find creatures with varying thermal tolerances. Some have a larger tolerance than others. Ectothermic (cold-blooded) creatures often have a wider range of temperatures they can survive at than endothermic (warm-blooded) ones. Homotherms (creatures who maintain their body temperature near a fixed point – such as humans 98.6°F/37°C) expend a lot of energy to do this. When environmental temperatures rise and fall, they have to expend more to maintain it at their fixed temperatures.
Image provide by Research Gate.
It is also true that most creatures prefer to exist near their thermal maximum. In other words, the bell curve is sort of skewed towards the warmer end of their range. But what is their thermal maximum? What happens when they reach it? How hot can they go?
Local waters are warmer this year.
Photo: Rick O’Connor
The studies I reviewed suggested that the thermal maximum is dependent on other environmental factors such as salinity and dissolved oxygen. In most cases, the higher the salinity, the higher the thermal maximum was. I looked at studies for the eastern oyster (Crassostrea virgincia), the brown shrimp (Farfantepenaeus aztectus), the blue crab (Callinectes sapidus), the Spot Croaker (Leiostomus xanthurus), and the pinfish (Lagodon rhomboides). The oyster, shrimp, and blue crab support important commercial fishery. The spot croaker is a dominant fish species in the upper estuary where the pinfish is a dominant species in the lower sections. These studies all suggested that again, depending on salinity, dissolved oxygen, pressure, and rate of temperature increase, the thermal maximum could happen as low as 30°C (86°F) and as high as 40°C (104°F), with many having a thermal maximum between 35-40°C.
At these temperatures proteins begin to denature and biological systems begin to shut down. Most of the studies determined the endpoint at “loss of equilibrium” and not actually death. Our estuaries can certainly reach these temperatures in the summer. Again, one recent reading in East Bay (within the Pensacola Bay system) was 96°F (36°C).
So, what do these creatures do when such temperatures are reached?
The most obvious response is to move, find cooler water. These are often found in deeper portions of the bay below the thermocline (a point in the water column where water temperatures significantly change – usually decreasing with depth). However, many sections of our estuaries are shallow and deep water cannot be found. In these cases, they may move great distances to seek deeper water areas, or even move to the Gulf of Mexico. In some cases – like with oysters – they cannot move, and large die-offs can occur. Other responses include lower metabolic rates and decline in reproduction.
We know that throughout history, there have been warmer summers than others and heat waves have happened. In each case, depending on other environmental factors, estuarine creatures have adapted, and some members have survived, to keep their populations going.
We know that large scale die-offs have occurred in the past and the tougher species have continued on.
We also know that the planet is warming, and it would be interesting to look at how the water temperatures have changed over the last few decades. Are they increasing? Are they reaching the thermal maximums of the creatures within our bay? How will these creatures respond to this?
There is a term that all oyster farmers dislike, it is almost like that one villain from a famous book/movie series where they shouldn’t say his name. That term is “unexplained spring/summer mortality” and it has been a growing issue along with the expansion of oyster farming throughout the southeast. While the art of oyster farming has been around since the time of the Romans, it is a relatively new venture here in the Gulf of Mexico, and Florida is home to over one hundred oyster farms. These farms are meticulously cared for by the oyster farm crew, with many different anti-fouling techniques and biosecurity measures in practice to provide the customer with a safe, clean product that you can consume even in the months without an R (another article on that coming later). Each year, farm managers can expect a 10-30% mortality event during the transition from winter into spring/summer, hence the term “unexplained spring/summer mortality.” Researchers and scientists from all over the southeast have been actively working to find a cause for this phenomenon, but the answer has been hard to find.
Dead, market ready oysters from one bag. Cause of death, “Unexplained Mortality Event 2022” Photo by: Thomas Derbes II
Our Pensacola Bay has been a hotbed for oysters lately; The Nature Conservancy recently constructed 33 oyster beds along Escribano Point in East Bay, the establishment of the Pensacola & Perdido Bay Estuary Program, acquisition of a $23 million restoration grant with $ 10 million towards 1,482 acres of oyster restoration, and the establishment of oyster farms and hatcheries. In Pensacola Bay, there are currently 5 oyster farms in operation, one of those farms being a family-owned and operated Grayson Bay Oyster Company. Brandon Smith has been managing the business and farm for over 4 years now and has experienced mortality events during those prime spring/summer months. In recent years, they have experienced mortality events ranging from minimal to what many would consider “catastrophic,” and reports from around Florida and the Southeast convey a similar message. Concerned for not only the future of his family farm, but other oyster farms in the Southeast, he has been working with the most experienced institutions and groups in 2022 to possibly get an answer on his and other local “unexplained mortality events.” Each road led to the same answer of “we aren’t quite sure,” but this didn’t deter Smith or other the farmers who are dealing with similar issues.
In 2023, Smith was invited to participate in a Florida-Wide program to track water quality on their farm. This project, led by Florida Sea Grant’s Leslie Sturmer from the Nature Coast Biological Station in Cedar Key, Florida, hopes to shed some light on the changes in water quality during the transition from winter to spring and spring to summer. Water samples have also been taken weekly to preserve plankton abundance and the presence of any harmful algae if a mortality event does occur. With the hottest July on record occurring in 2023, temperature could play a role in mortality events, and now researchers are equipped with the right tools and open lines of communication to possibly find a solution to the problem.
3-month-old seed being deployed out on Grayson Bay Oyster Company’s farm in Pensacola, Florida (2023). Photo by: Thomas Derbes II
As with traditional farming on land, oyster farming takes a mentally strong individual with an incredible work ethic and the ability to adapt to change. The Southeast has a resilient system of oyster farmers who display these traits and continue to put their noses down and “plant” seed every year for the continuation of a growing yet small industry, even through the hardest of trials and tribulations. Through collaboration with local and state institutions, stakeholders, programs, and citizens, oyster farmers are hopeful that they can solve this “unexplained mortality event” and help develop resilient farming techniques. An important message is local farms that have environmental and economic impacts cannot exist without the support of their community.
If you’re interested in tracking water quality on select farms, including Grayson Bay Oyster Company, the website is https://shellfish.ifas.ufl.edu/farms-2023/ and it is updated monthly.
“I can’t do what? – because of a mouse? – it’s only a mouse.”
This was a comment made by many who lived on Perdido Key when a small beach mouse found only there was added to the endangered species list. It is a comment heard often when many species are listed. A major reason most species begin to decline and become endangered is loss of habitat. We enter and change the habitat to suit our needs. Much of this includes construction of buildings and altering landscapes to a more artificial setting and much of the local wildlife is lost. So is the case with this little mouse.
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
The Perdido Key beach mouse (Peromyscus polionotus trissyllepsis) is one of seven subspecies of beach mice found in Florida, five of those found in the Florida panhandle. Beach mice are a subspecies of the Old-Field mouse (Peromyscus polionotus). They are small, about 5 inches long, with tails that have hair (which are an additional 2 inches). Beach mice typically have a brown/gray color on top and a lighter white underbelly allowing them to blend into their environment very well. The difference between the subspecies is the extent of the coloration.
The subspecies status, and genetic isolation, is part of the reason these mice are listed. Members of a population who are genetically isolated from others can undergo a process called speciation where the genetic changes that occur in one isolated group cannot/do not flow through the gene pool of the other isolated group. Over time, the genetics, and morphology, of one isolated group becomes different enough that a new subspecies, or even species, develops. This is the case with the Perdido Key beach mouse. It is isolated on Perdido Key, a barrier island, and does not interbreed with their closest neighbors – the Alabama beach mouse (P.p. ammobates) and the Santa Rosa beach mouse (P.p. leucocephalus). Because of this, ALL of the Perdido Key beach mice in the world live on Perdido Key. Their population is small and vulnerable.
These mice are dune dwellers living in small burrows. They prefer the primary dunes (closest to the Gulf) which are dominated by the grasses whose seeds they like to feed on. They forage at night (nocturnal) feeding on the seeds of the sea oat (Uniola paniculate), panic grass (Panicum amarum), and blue stem (Schizachrium maritimum) usually in the secondary dunes. Highly vegetated swales (low wet areas between the primary and secondary dunes) are used to move between these habitats, and they are also found in the tertiary dunes (on the backside of the island where trees can be found) where their burrows are more protected from storm surge during hurricanes. During periods when seeds are not available, beach mice will turn to small invertebrates to support their diet. Their foraging range averages around 50,000 ft2.
Breeding takes place in the winter, though can occur anytime of year if enough food is available. They are monogamous (males pairing with only one female for life) with the females giving birth after 23 days to four pups. New members of the family can move up to half a mile in search of a foraging range for themselves. It is understood that with limited available habitat on an isolated island, the carry capacity of the beach mouse would be low. Owls and snakes are some of the predators they face, but the beach mice have evolved to deal with few predator issues.
The increase of humans onto the barrier islands has negatively impacted them. The leveling of dunes for houses, condos, swimming pools, and shopping centers has significantly reduced suitable habitat for them as well as reduced the seed food source. Introduced feral and free roaming domestic cats have also been a large problem. Bridges connecting these islands to the mainland have allowed foxes and coyotes to reach, and increase pressure on, them. With these increased pressures, and small populations, these mice are now listed under the Endangered Species Act.
Conservation measures have included, predator control, building and landscaping restrictions, translocation (moving mice from large populations to those that are smaller), and reintroduction (releasing mice into areas where they once existed but no longer do). There has been success with the Choctawhatchee beach mouse in the Grayton Beach area, as well as the Perdido Key beach mouse in Gulf Islands National Seashore. Things that beach residents can do to help beach mice populations include keeping your pets inside at night, plant native grasses in your landscape, reduce night lighting, do not walk over dunes – use the cross walks.
Things seem to be improving for beach mice, but the development pressure is still there. Hopefully we will have these creatures as part of our panhandle barrier island communities for many years to come.
References
Beach Mouse Fun Facts. Gulf Islands National Seashore. U.S. Department of Interior.
When visiting and exploring seagrass beds, most are hoping, and expecting, to see fish. As we have seen in this series, there are a lot of creatures that can be found living within a seagrass meadow, but it is the fish that get our attention and what we talk most about afterwards.
According to Hoese and Moore’s Fishes of the Gulf of Mexico; Texas, Louisiana, and Adjacent Waters, there are 497 species of fish found in the Gulf of Mexico. In my surveys of Pensacola Bay over the years, I have logged 101 of those in the estuary. I am sure there are more, but I can confirm there are at least those. Many spend all or part of their time in our seagrasses. As you seine or snorkel in the grassbeds you will notice most of them are very small. Much of this is due to the fact that the seagrasses are nursery areas for many species, and it is the young that we find here. But many are also small as adults, and the grass provides food and shelter for them. There are far too many to mention in an article like this, but let’s look at some of them.
Sardines and Anchovies
As you snorkel through the grass, or even look at it from a boat or dock, you see numerous silver colored baitfish flashing as they dart in and out of the grass. There are all sorts of silver baitfish in the seagrasses with sardines and anchovies being two of them. In my experience seining for fish, they appear to be seasonal. I did not capture them all year but when I did, I would capture a lot. These species are famous for being the ones in small tins that people consume, though there is no fishery for them here locally. Anchovies have also been considered an indicator species; their presence suggests good water quality.
The striped anchovy is a fish often found in our seagrass beds.
Photo: NOAA.
Silverside Minnows
Also known as silversides and glass minnows, these are one of the most common fish collected in seine nets. They are abundant year-round and are an important food source for many of the larger predators living here. Small and transparent, you do not see them while snorkeling. Their huge presence is only discovered when you pull a seine net through the grass. There are several species of them, but they are not easily identified and more often are just logged as “silversides”. They are an important member of the seagrass community.
The silverside, or “glass” minnow.
Photo: U.S. Geological Survey
Seahorses and Pipefish
These two fish are highly specialized for living in seagrasses. They look like grass and move very little making them hard to detect. Like silverside minnows, it is rare to see them while snorkeling but make their presence known when seining. Their bodies are covered in armor-like scales, and they have tubed mouths for “vacuuming” small invertebrates from the water column. They are very slow swimmers and have to avoid detection by blending in with the environment. And yes, it is the males that carry the eggs in their brood pouches. These are amazing fish and always bring excitement when they are captured in the net. There are two species of seahorses and seven species of pipefish found in our waters.
The seahorse-like pipefish.
Photo: University of Florida
Killifish
Often called “bull minnows” by anglers, these small fish are, at times, very abundant. There are seven species of killifish in our bays but the Gulf Killifish, Longnose Killifish, and the Bayou Killifish are the ones we most often collected.
This longnose killifish has the rounded fins of a bottom dwelling fish.
Needlefish
These are common, frequently seen, fish swimming at the surface of the water. Long and needle-shaped, these fish have long snouts full of sharp teeth indicating they are one of the predators of this system. There are four species of them, and they are not easy to tell apart. They are harmless to humans unless you capture them in your net at which time they will try to bite.
Swimming near the surface is a common place to find needlefish.
Photo: Florida Springs Institute
Mullet
Another very common fish found year-round here. This species are the ones famous for jumping while you are fishing, paddling, or just watching from the beach. Those who do not visit the Gulf coast often always ask “I just saw a fish jump!” and the reply from a local (without even looking up to see what it was) will reply “It’s a mullet”. These schooling fish can get pretty large (average length is 30 inches) and it is common to see fishermen out with their cast nets trying to catch a few. It is a popular food fish for those along the Gulf coast. Mullet fries, with beans and grits, are a way of life here. The fish are easily seen swimming and darting over the grass as you paddle by, and their young are found seasonally in seine nets. They are bottom feeders, feeding mostly on algae from the grass blades. There are actually two species, the white and the striped mullet. The striped mullet, also known as the black mullet, is the one most often sold in the seafood markets.
The Striped Mullet.
Image: LSU Extension
Drums and Croakers
With 18 species within this family, this is the largest family of inshore fish in the Gulf. Growing up along the panhandle people learn quickly about croakers. Back in the day when gill nets were used to harvest mullet, croakers were a common catch as well, and often consumed. Today they are still sought by some shore-based anglers and juveniles are common in seine nets. The species I most often captured were the spot and Atlantic croaker. Spot croakers were common year-round, Atlantic croakers were more seasonal.
Drums are larger members of this family. There are several species more associated with sandy bottoms and the shoreline of the Gulf, many of these are called whiting, but the red drum (redfish) and black drum can be found in the grassbeds. Redfish are particularly common here and one of the reasons many anglers get out of bed in the morning. They are very popular sportfish across the region. Black drums are not found as often, and like being around pilings and structures that offer certain foods they prefer. Both species can get quite large. Redfish average 5 feet while black drums can reach an average of 3 feet.
All of the fish in this family are famous for their “croaking” “drum” sounds they make using their swim bladder, and it is rare not to capture at least one kind in a seine net.
The classic look of a bottom fish. This is the redfish, or red drum.
Photo: NOAA
Spotted Seatrout; Speckled Trout; “Specks”
There is no “trout family” in the fish world. Most freshwater trout are members of the salmon family while the marine versions are members of the drum/croaker family. This is the case with the famous speckled trout – or speck. There are white trout and silver seatrout in this family, and all are sought after by anglers, but it is the speckled trout that is most associated with seagrasses, most sought after by anglers, and is one of the top predators in this system. They reach an average length of 4 feet.
From my experience both snorkeling and seining the grasses, I would say – hands down – that pinfish is the most common species found in our grasses. For many young anglers this is the first fish they ever catch. You can see them easily while snorkeling and they are the most numerous species in the nets throughout the year. Their huge numbers play an important role in the food web of this system. Feeding on a variety of small invertebrates in and around the grass blades, pinfish are a large part of the diet of the larger sportfish we target. Throwing cast nets and dropping pinfish traps is popular with anglers to collect this abundant baitfish for their life bait fishing efforts. They are called pinfish because of the sharp spines in their dorsal fins. These are also the fish that nip at your ankles while you are standing still in the water.
Sheepsheads are larger members of the porgy family (the ones these two species belong to). As adults sheepsheads prefer hard structure where they can use their incisors to chip away at barnacles and other shellfish, but they are sometimes found roaming the grassbeds and their young will spend their growing years hiding and feeding in the grass.
One of the most common fish in our grassbeds; the pinfish.
Photo: Nicholls State University.
Pigfish
When first captured in the seine net, pigfish are often confused with pinfish – they look very similar. But a closer look at the striping/spotted pattern on their sides, and the position of their mouth, you realize you have something different. Being members of the grunt family, they also “croak” like croakers and drums – hence their common name “pigfish” – due to the grunting sounds. This helps with identifying which fish you have. Though common in the grasses, I did not catch these as frequently as pinfish and they were not as abundant.
Spotfin Mojarra
This is a common silver baitfish that resembles the pinfish and is frequently collected in our seine nets. The mojarra is in a different family than pinfish. They lack sharp spines and incisor teeth, rather they have a sort of “vacuum” like mouth which they use to suck small invertebrates from the sand.
Gag Grouper
This is a popular sport and commercial fish from the wrecks and reefs of the Gulf of Mexico. But gags begin their lives in the seagrass beds, and we have collected medium sized individuals in our seine nets. This underscores the importance of these grassbeds to the fisheries so many love. We need to protect these systems from our activity both on land and in the water.
Gag grouper.
Photo: National Oceanic and Atmospheric Administration
Jacks
Another popular group with anglers, many species of jacks use these grasses as their nurseries. We most often collected juvenile lookdowns, pompano, and crevalle in our nets. At times we caught a small member of the family called a leatherjacket. These were seasonal and associated with breeding. Once again, underscoring the importance of having healthy seagrasses.
Jacks have the sleek, fast design of the typical open water marine fish.
Photo: NOAA
Toadfish
One of the creeper looking fish in the seagrass community is the Gulf toadfish (also known as the oyster dog). This monstrous looking bottom fish lives in burrows scattered around the grassbeds where they lie in wait to ambush prey. Their large mouths and sharp teeth can grab a variety of creatures, including the human finger. At times small toadfish will move into an empty can or bottle discarded by people instead of a burrow where they grow to a size they can no longer escape. It is said there may be a mild venom associated with their bite. Though no one has ever died, or been sent to the hospital, due their bite, it is painful and should be avoided.
The common estuarine Gulf toadfish.
Photo: Flickr
Barracuda
Yes, barracuda can be found in seagrasses. But in our case, these have all been juveniles. There are three species of them, and they are not easy to tell apart. They also appeared to be seasonal in our collections. We never found them high numbers, usually one or two in a seine. But they are present.
The Great Barracuda. Photo: NOAA
Lizardfish
This is another medium sized, sharp toothed, bottom dwelling predator of the grassbed community. There are seven species of them, and all have that “snake” “lizard” look to them having many sharp canine teeth. They spend their time buried in the sand waiting to ambush potential prey. Snorkelers may see them as they dart away tossing up sand when we get too close. I rarely see them snorkeling but occasionally capture them in the seine net to the delight of the students assisting.
Blennies and Gobies
These are very small fish that are almost impossible to find while snorkeling but are often collected in the seine net. They resemble the freshwater darters and, lacking a swim bladder, spend their time on the bottom. There are many species associated with rocks and artificial reefs but there are some who call the seagrasses home. They use their incisor teeth to feed on small invertebrates in and on the grasses. Being territorial, they can give a little nip to your hand. Gobies differ from blennies in that their two pelvic fins are fused together to form a sort of “cup” or “sucker disk”.
Puffers
Another one of the more popular fish with students who help me seine. Everyone loves to see them inflate with either water or air into a “balloon” to make it very difficult for predators to consume them. There are eight species of puffers in the Gulf of Mexico, five of them have been captured in our seines. Most are small with little “bumps” on their bodies instead of spines. But there is the Burrfish, who is a member of a different family that is medium sized, has spines, and is very common in the grassbeds.
Striped Burrfish
Photo: NOAA
Filefish
Our grassbeds are full of a small cousin to the triggerfish – the planehead filefish. Like triggerfish, filefish have a thick sharp spine that is found at the front of the dorsal fin – called a “trigger” on the triggerfish. The planehead filefish is a small species (nine inches average length), green to brown in color, and very common in the grassbeds; though you will probably not see one unless you catch it in a net.
Planehead Filefish.
Photo: NOAA.
Flounders and Soles
A favorite food fish for many locals, flounders spend a lot of time buried in the sand near grassbeds to ambush prey. Born with a typical fish design, early in development one of their eyes will move to the other side of the head, giving them two eyes on one side. By doing this, they have increased their binocular vision, improving their ability to judge accurate distance of the prey, and making hunting easier. They lose color on the side where the eye has left and have chromatophores (cells) on the side where the eyes are that, like octopus and squid, allow them to change colors and blend in. In our part of the Gulf, if the eyes move to the left side of the head, they are called flounders. If they move to the right, they are called soles. Soles in our part of the Gulf of small not of much interest to anglers. One small species is often collected by shrimpers who feed them to hogs. This sole can “cup” their body in defense making like a suction cup and they do this in the throat of the hogs sometimes killing them. They are called “hogchokers”. Flounders on the other hand are very popular with anglers. Some fish for them using rod and reel, others prefer gigging them at night using lanterns. There are 17 species of flounder, some reaching lengths of three feet.
A flounder scurrying across the seafoor.
Photo: NOAA
Tonguefish
Tonguefish are small flat fish with eyes on one side of their heads like flounder. They differ than that their tails come to a point and there is no caudal fin present, as there is in flounders. As mentioned, they are small – ranging from 3 to 8 inches in length. The Blackcheek tonguefish is particularly common in our grassbeds. But like so many, you will not see it unless you catch it in a net.
Snook
This is a very popular gamefish from south Florida associated with several habitats including grassbeds. Due to a process some call “tropicalization” – the movement of tropical species north due to climate change – snook are now, albeit in small numbers, reported in the Florida panhandle. This is a new species you may see while exploring or fishing out there.
This snook was captured near Cedar Key. These tropical fish are becoming more common in the northern Gulf of Mexico.
Photo: UF IFAS
There are many more species of fish found in our grassbeds we could talk about, but we will end it here. As we mentioned in the beginning, this is a group of animals that many come to the beach to find. Whether for fun or for food, finding fish makes for a good day. See how many different species you can find.
