Growing up in the South, I was exposed to many “Old Wives’ Tales,” ranging from not cleaning your house or clothes on New Year’s Day to the one that everyone, including the northern states, knows, “don’t consume oysters in months without an R.” While most “tales” are full of superstition, the “R” tale was one of biosecurity, and was mainly truthful until two new types of “R” came about; Regulations and Refrigeration. The tale came about due to the rise in food poisonings from shellfish in the warmer summer months that do not contain a “R,” such as June and July. The rise in food poisoning came about from the practices used by the oyster “tongers” at the time. Commercial harvest of wild oysters is a very labor-intensive job that requires long days on the water and constant tonging, measuring, and sorting of oysters as they come off the bottom. During the summer, the oysters would sit on the deck of the boat for hours in the heat, causing microorganisms and bacteria to flourish inside the closed oyster. Bacteria, like Vibrio, would replicate to harmful levels inside of the oysters and when consumed by a human, could cause life-threatening illnesses.
That was then, and this is now. While the consumption of wild Florida oysters during the summer is not allowed (closed harvest season for wild oysters during the summer in Florida), you can still find oysters from all over the US, and farmed oysters from Florida are still allowed to be consumed during the summer. Biosecurity is a major factor involving food production and aquaculture, and without biosecurity, the consumption of Florida-farmed oysters would be prohibited. Oyster farmers in Florida must follow a very rigorous biosecurity plan that includes State-issued harvest times, water-to-refrigeration requirements, reporting of harvest and planting, and twice-daily temperature monitoring requirements. The regulations for harvest times and refrigeration requirements have scientific backing, showing a statistical difference in Vibrio concentrations between properly handled oysters and neglected oysters, with properly handled oysters having little to no concentrations of Vibrio. For instance, during the summer months, oyster farmers must have oysters harvested and in the cooler before 11am and down to 45°F within 2 hours of storing in cooler.
A farmer returns early morning from the lease with harvest oysters covered by burlap. This keeps the oysters “cool.” (Photo by: Thomas Derbes)
While there is an increased concentration of harmful bacteria during these warmer months, properly cared-for oysters help limit the growth and proliferation of the bacteria. Another myth is that Vibrio doesn’t exist in cold, winter waters. Vibrio can exist year-round, and people with health risks, including immune-suppressed patients and those with diabetes, should exercise extreme caution when consuming raw seafood. When purchasing seafood for personal consumption, make sure to bring a cooler with ice and place your seafood above the ice, making sure to not allow any fresh water to touch the seafood. When storing seafood at home, make sure they are in a container that can breathe, and cover with a moist paper towel to keep their gills wet. Oysters are typically good for 10-14 days after the harvest date, so make sure you check the tags and consume within time.
Next summer, when you see farmed oysters on the menu, remember the new R’s and order a couple dozen for the table. The need for support from your local oyster farmer is most needed during those months without R, so slurp them down all summer and thank your local oystermen and women!
Locally Farmed Oyster with French Mignonette (Photo by: Kelly Derbes)
Easy French Mignonette Recipe
Recipe for 2doz Oysters
¼ cup Red Wine Vinegar
¼ cup Champagne Vinegar
1 tablespoon of Finely Chopped Shallot
1 teaspoon of Fresh Crushed Black Pepper
Juice of ½ Lemon
Combine all ingredients together. Spoon over shucked, chilled raw oysters.
Bay scallops (Argopecten irradians) have been an important part of the economy of many gulf coast communities within the Florida Big Bend for decades. It was once abundant in all gulf coast counties of the state but beginning in the 1960s populations in many bays began to decline to levels where they are all but nonexistent. The cause of this decline has been associated with many factors including a decline in water quality, a decline in suitable habitat (sea turtle grass beds – Thalassia), and overharvesting. Most likely the cause included all of these. Since the collapse of both the commercial and recreational fishery, Gulf coast communities have been trying to address all three of the stressors above. Multiple monitoring projects are ongoing in the Pensacola Bay area and one of those is the Great Scallop Search.
The Great Scallop Search was developed by Sea Grant Agents in Southwest Florida and expanded, through Florida Sea Grant, to Northwest Florida. In each location volunteers snorkel a 50-meter transect line searching for live bay scallops, as well as monitoring the status of the seagrass habitat. Since 2015 317 volunteers have logged 634 hours surveying 407 50-meter transects in 106 grids in Big Lagoon or Santa Rosa Sound. In that time 4 live scallops have been logged, though we hear anecdotal reports of additional scallops being found in these bodies of water.
Survey Method
Volunteers select and survey one of 11 grids in Big Lagoon, or one of 55 grids in Santa Rosa Sound. Once on site, the volunteers anchor and record preliminary information on the data sheet provided. Two snorkelers enter the water and swim on opposite sides of a 50-meter transect line searching for live scallops. Any live scallop found is measured and returned. The species and density of the seagrass is recorded as well as the presence/absence of macroalgae on that seagrass. Four such transects are surveyed in each grid.
2023 Results
2023
SRS
BL
Total
Other
# of volunteers
72
No significant difference between 2022 and 2023
# of grids surveyed
8
8
16
Slight decrease from 2022. 16 of the 66 grids (24%) were surveyed.
# of transects surveyed
26
51
77
A decrease from 2022. More surveys were conducted in Big Lagoon than Santa Rosa Sound.
Area surveyed (m2)
2600
5100
7700
1.9 acres
# of scallop found
2
2
4
Four live scallops are a record for this project. It equals the sum of all other live scallops since the project began.
Scallop Size (cm)
4.5, 5.0
4.0, 4.5
Surveys with Seagrass
Halodule
5
12
17
17/21 surveys – 81%
Thalassia
8
11
19
19/21 surveys – 90%
Syringodium
0
2
2
2/21 surveys – 10%
Grass Density
100% grass
3
9
12
12/21 surveys (57%) were 100% grass
90%
1
0
1
Note: Volunteers typically select area for transects
75%
3
1
4
with a lot of grass.
70%
1
0
1
50%
3
9
12
5%
1
0
1
Macroalgae
Present
4
4
8
Absent
2
10
12
12/21 surveys (57%) had no macroalgae.
Abundant
2
2
4
Sediment Type
Mud
0
1
1
Sand
7
8
15
15/21 surveys (71%) were sandy.
Mixed
1
4
5
21 surveys were conducted covering 16 grids. 8 grids were surveyed in each body of water.
A total of 77 transects were conducted covering 7,700 m2 and four live scallops were found.
Two of the scallops were found in Big Lagoon and two in Santa Rosa Sound.
All scallops measured between 4-5cm (1.6-2”).
The number of live scallops found this year equaled the total number found over the last eight years.
Most of the transects included a mix of Halodule and Thalassia seagrass ranging from 100% coverage to 5%. The majority of the transects were between 50-100% grass. Four transects had 100% Thalassia. Three of those were in Santa Rosa Sound, one was in Big Lagoon. The diving depth of the volunteers ranged from 0 meters (0 feet) to 2.4 meters (8 feet). Macroalgae was present in 8 of the 21 surveys (38%) but was not abundant in most.
Volunteer measuring one of the four collected bay scallops in 2023 from Pensacola Bay.
Photo: Gina Hertz.
Summary of Project
Year
Volunteer
Grids Surveyed
Transects Surveyed
Live Scallops Found
2015
87
28
101
0
2016
96
31
111
1
2017
5
4
16
0
2018
20
7
32
0
2019
13
6
20
0
2020
5
2
16
1
2021
17
6
24
0
2022
74
22
87
2
2023
72
16
77
4
TOTAL
317
407
8
MEAN
35
14
45
0.4
To date we are averaging 35 volunteers each event, surveying 14 of the 55 possible grids (25%). We are averaging 45 transects each year (4500 m2), have logged 407 transects (40,700 m2) and have recorded 8 live scallops (< than one a year).
Discussion
Based on the results since 2016 this year was a record year for live scallops. Whether they are coming back on their own is still to be seen. Being mass spawners, bay scallop need high densities in order to reproduce successfully, and these numbers do not support that. The data, and comments from volunteers, suggest that the grasses look good and dense. Thalassia, a favorite of the bay scallop, appear to be becoming more abundant. This is a good sign.
Though small and few, bay scallops are trying to hold on in Pensacola Bay.
Photo: Gina Hertz
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.
