The major goal of the Wakulla Springs Basin Management Action Plan (BMAP) is to reduce nitrogen loads to Wakulla Springs. Septic systems are identified as the primary source of this nitrogen. Photo: A. Albertin
A Basin Management Action Plan, or BMAP, is a management plan developed for a waterbody (like a spring, river, lake, or estuary) that does not meet the water quality standards set by the state. One or more pollutants can impair a waterbody. In Florida, the most common pollutants are nutrients (particularly nitrate), pathogens (fecal coliform bacteria) and mercury.
The goal of the BMAP is to reduce the pollutant load to meet water quality standards set by the Florida Department of Environmental Protection (FDEP). BMAPS are roadmaps with a list of projects and management action items to reach these standards. FDEP develops them with stakeholder input. Targets are set at 20 years, and progress towards those targets is assessed every five years.
It’s important to understand that a BMAP encompasses the entire land area that contributes water to a given waterbody. For example, the land area that contributes water to Jackson Blue Springs and Merritts Mill Pond (either from surface waters or groundwater flow) is 154 square miles, while the Wakulla Springs Basin covers an area of 1,325 square miles.
BMAPs in the Panhandle
There are 33 adopted BMAPS in the state, and 5 that are pending adoption. Here in the Panhandle, we have three adopted BMAPS. They are the Bayou Chico BMAP in Escambia County, the Wakulla Springs BMAP in Wakulla, Leon, Gadsden and small parts of Jefferson County, and the Jackson Blue/Merritts Mill Pond BMAP in Jackson County. All three are impaired for different reasons.
- Bayou Chico discharges into Pensacola Bay and is polluted by fecal coliform bacteria. The BMAP addresses ways to reduce coliforms from humans and pets, which includes sewer expansion projects, stormwater runoff management, septic tank inspections, pet waste ordinances and a Clean Marina and Boatyard program.
- Wakulla Springs Nitrate from human waste is the main pollutant to Wakulla Springs, and Tallahassee’s wastewater treatment facility and the city’s Southeast Sprayfield were identified as the main sources. Both sites were upgraded (the sprayfield was moved), greatly reducing nitrate contributions to the spring basin. The BMAP is focused on septic systems and septic to sewer hookups.
- Jackson Blue/Merritts Mill Pond Nitrate is also the primary pollutant to the Jackson Blue/Merritts Mill Pond Basin, but nitrogen fertilizer from agriculture is identified as the main source. This BMAP focuses on farmers implementing Best Management Practices (BMPs), land acquisition by the Northwest Florida Water Management District , as well as septic tanks, recognizing their nitrogen contribution to Merritts Mill Pond.
Once all the BMAPS are adopted, FDEP states that almost 14 million acres will be under active basin management, an area that includes more than 6.5 million Floridians.
Adopted and pending BMAPS in Florida. Source: FDEP Statewide Annual Report, June 2018
How are residents living in an area with a BMAP affected? It varies by BMAP and specifically land use within its boundaries. For example, in BMAPs where nitrogen from septic systems are found to be a major source of nutrient impairment to a water body, septic to sewer hookups, or septic system upgrades to more advanced treatment units will be required in specific areas. In urban areas where nitrogen fertilizer is an important source, municipalities are required to adopt fertilizer ordinances. Where nitrogen fertilizer from agricultural production is a major source of impairment, producers are required to implement Best Management Practices to reduce nitrogen loads.
More information about BMAPS
For specific information on BMAPS, FDEP has an excellent website: https://floridadep.gov/dear/water-quality-restoration/content/basin-management-action-plans-bmaps All BMAPs (full reports with specific action items listed) can be found there, along with maps, information about upcoming meetings and webinars and other pertinent information.
Your local Health Department Office is the best resource regarding septic systems and any ordinances that may apply to you depending on where you live. Your Water Management District (in the Panhandle it’s the Northwest Florida Water Management District) is also an excellent resource and staff can let you know whether or not you live or farm in an area with a BMAP and how that may affect you.
By Vance Crain and Andrea Albertin
Fisherman with a large Shoal Bass in the Apalachicola-Chattahootchee-Flint River Basin. Photo credit: S. Sammons
Along the Chipola River in Florida’s Panhandle, farmers are doing their part to protect critical Shoal Bass habitat by implementing agricultural Best Management Practices (BMPs) that reduce sediment and nutrient runoff, and help conserve water.
Florida’s Shoal Bass
Lurking in the clear spring-fed Chipola River among limerock shoals and eel grass, is a predatory powerhouse, perfectly camouflaged in green and olive with tiger stripes along its body. The Shoal Bass (a species of Black Bass) tips the scale at just under 6 lbs. But what it lacks in size, it makes up for in power. Unlike any other bass, and found nowhere else in Florida, anglers travel long distances for a chance to pursue it. Floating along the swift current, rocks, and shoals will make you feel like you’ve been transported hundreds of miles away to the Georgia Piedmont, and it’s only the Live Oaks and palms overhanging the river that remind you that you’re still in Florida, and in a truly unique place.
Native to only one river basin in the world, the Apalachicola-Chattahoochee-Flint (ACF) River Basin, habitat loss is putting this species at risk. The Shoal Bass is a fluvial specialist, which means it can only survive in flowing water. Dams and reservoirs have eliminated habitat and isolated populations. Sediment runoff into waterways smothers habitat and prevents the species from reproducing.
In the Chipola River, the population is stable but its range is limited. Some of the most robust Shoal Bass numbers are found in a 6.5-mile section between the Peacock Bridge and Johnny Boy boat ramp. The Florida Fish and Wildlife Conservation Commission has turned this section into a Shoal Bass catch and release only zone to protect the population. However, impacts from agricultural production and ranching, like erosion and nutrient runoff can degrade the habitat needed for the Shoal Bass to spawn.
Preferred Shoal Bass habitat, a shoal in the Chipola River. Photo credit: V. Crain
Shoal Bass habitat conservation and BMPs
In 2010, the Southeast Aquatic Resources Partnership (SARP), the National Fish and Wildlife Foundation and a group of scientists (the Black Bass Committee) developed the Native Black Bass Initiative. The goal of the initiative is to increase research and the protection of three Black Bass species native to the Southeast, including the Shoal Bass. It also defined the Shoal Bass as a keystone species, meaning protection of this apex predators’ habitat benefits a host of other threatened and endangered species.
Along the Chipola River, farmers are teaming up with SARP and other partners to protect Shoal Bass habitat and improve farming operations through BMP implementation. A major goal is to protect the river’s riparian zones (the areas along the borders). When healthy, these areas act like sponges by absorbing nutrients and sediment runoff. Livestock often degrade riparian zones by trampling vegetation and destroying the streambank when they go down to a river to drink. Farmers are installing alternative water supplies, like water wells and troughs in fields, and fencing out cattle from waterways to protect these buffer areas and improve water quality. Row crop farmers are helping conserve water in the river basin by using advanced irrigation technologies like soil moisture sensors to better inform irrigation scheduling and variable rate irrigation to increase irrigation efficiency. Cost-share funding from SARP, the USDA-NRCS and FDACS provide resources and technical expertise for farmers to implement these BMPs.
Holstein drinking from a water trough in the field, instead of going down to the river to get water which can cause erosion and problems with water quality. Photo credit: V. Crain
By working together in the Chipola River Basin, farmers, fisheries scientists and resource managers are helping ensure that critical habitat for Shoal Bass remains healthy. Not only is this important for the species and resource, but it will ensure that future generations can continue to enjoy this unique river and seeing one of these fish. So the next time you catch a Shoal Bass, thank a farmer.
For more information about BMPs and cost-share opportunities available for farmers and ranchers, contact your local FDACS field technician: https://www.freshfromflorida.com/Divisions-Offices/Agricultural-Water-Policy/Organization-Staff and NRCS field office USDA-NRCS field office: https://www.nrcs.usda.gov/wps/portal/nrcs/main/fl/contact/local/ For questions regarding the Native Black Bass Initiative or Shoal Bass habitat conservation, contact Vance Crain at email@example.com
Vance Crain is the Native Black Bass Initiative Coordinator for the Southeast Aquatic Resource Partnership (SARP).
Farm ponds are used in a number of different ways, including fishing, irrigation, water control, and wildlife viewing. UF/IFAS Photo by Tyler Jones.
Farm ponds of all shapes and sizes are common in rural Northwest Florida. They are built for a number of reasons such as irrigation, water management, boating, fishing, wildlife viewing, livestock watering, and food production. Each of these uses guides the way the pond is managed to maintain its function, as well as its ecological beauty, but a factor that is important to all uses is having enough oxygen!
As you have probably observed, your pond is a dynamic system, which is influenced literally from the ground up! Much of the water’s basic chemical and physical characteristics reflect those of underlying soils (sand, clay, organic, etc.) and major sources of water (ground water, rainfall, runoff, etc.). The pond’s characteristics also influence how much oxygen is available for use by the plants and animals that live in it.
Why is Dissolved Oxygen and Aeration so Important?
Fish kills are often the result of low dissolved oxygen levels and occur in both natural waters and man-made ponds. Photo by Vic Ramey.
The idea of oxygen being dissolved in water is a little counter-intuitive. Especially to us, as air-breathing humans! Think of your pond as a giant living, breathing organism. Its atmosphere is the water itself, and it contains dissolved oxygen gas for the fish, aquatic plants, insects, and zooplankton to “breathe.” Even bacteria need to breathe, and one of their fundamental roles in your pond is the decomposition of organic wastes like un-eaten fish food, and dead plant and animal materials.
Having enough dissolved oxygen in the water is one of the driving forces sustaining the health of your pond. Oxygen is dissolved into water directly from the atmosphere, wind and wave action, and by plant photosynthesis. Because warm water “holds” less dissolved oxygen than cold water, your pond’s dissolved oxygen levels can be lower in the summer than in the winter, especially in the early morning hours before plants begin to photosynthesize and produce oxygen. While longer days and warmer temperatures mean more sunlight for plants to photosynthesize and produce oxygen, the demand or need for oxygen by fish, bacteria, and other aquatic organisms is also increased. Periods of rainy, overcast days during the summer can greatly reduce oxygen production by plant photosynthesis. Combined that with the increased oxygen demand by other organisms, and dissolved oxygen levels can drop fast. These drops in dissolved oxygen levels often result in fish kills. Productive, nutrient-rich ponds with high levels of organic materials, and a high fish density are at a greater risk of the devastating effects of low dissolved oxygen levels.
What Can You Do to Insure Your Pond Has Enough Oxygen?
Do not be tempted to overfeed your fish. Feed them floating fish food so you can see how much they will consume in 10 to 15 minutes at each feeding. Consider feeding them every other day. In addition, as recommended in Managing Florida Ponds for Fishing “do not feed them when the water temperature is below 60° F, or, above 95° F. Fish do not actively feed at these times.” Use fish feeding behavior as your guide. Uneaten food will only add excess organic matter to the pond. The decomposition of this excess organic matter by bacteria increases the oxygen demand and likewise increases the chances of low oxygen levels and a fish kill.
Reduce nutrient inputs from runoff, livestock waste, excess fertilizer, and uneaten foods as described above, to help reduce the demand for oxygen in the system. Additionally, remove as much excess debris as possible that may have been blown into your pond as a result of October’s Hurricane Michael that affected much of Florida’s panhandle. Excess nutrients from these sources are freely available for use by hungry algae and other plants, which can then proliferate and, in turn, cause demand for more oxygen. This increased demand for oxygen can cause fish kills due to low oxygen levels as described above.
If you have an aerator, keep it operative especially during extended periods of cloudy and rainy weather. Watch your fish for signs of oxygen stress (not eating, remaining near and gulping at the surface) and aerate accordingly. Oxygen levels naturally fluctuate, and the lowest levels occur in the late evening through early morning hours when plants are not photosynthesizing and replenishing oxygen. Therefore, most important time to routinely operate the aerator is the late overnight hours into early morning.
If you don’t have an aerator, consider purchasing one, especially as your pond ages and grows more fish, plants, and algae. It is certainly less costly in the end to be proactive when it comes to maintaining adequate dissolved oxygen in your pond.
Recreation and fishing are important uses of many rural farm ponds. Photo by UF/IFAS Tyler Jones.
What kind of Aerator should I get?
There are a few basic aerator types. There are surface water agitators or fountains, and there are bottom air diffusers. They can be powered by electricity, wind, or solar power.
Diffuser aerators can help achieve a uniform oxygen distribution in your pond from top to bottom. This is especially important in deeper ponds (greater than 6-10 feet average depth) where temperature and oxygen stratification can occur. Diffuser aerators pump surface air through the base sitting on the bottom of the pond causing bubbles of air to rise to the surface. Diffusers also increase circulation and keep the deeper parts of your pond from becoming oxygen depleted. In a new pond, or one with flocculent sediments, a diffuser may cause turbidity due to the physical action of the diffuser base sitting on the pond bottom circulating oxygen from the bottom to the surface.
Other aerator options are the fountain sprays or surface agitators that aerate surface water. At a bare minimum, this can be a hose shooting water out over the water surface. Surface fountains and agitators work well in small shallow ponds, but are generally not recommended for larger more productive ponds that need more oxygen. In some commercial or farm ponds, paddle wheel agitators powered by a tractor’s pto are used during periods of low oxygen as an emergency measure when a fish kill is just beginning to occur.
Where Can I Purchase One?
The type or types of aerators you need for your pond will depend on the pond’s size, depth, level of productivity (nutrient level, number of fish), use, and water quality. There are a number of shopping options online for pond aerators. Try searching using the term “pond aerators Florida.” Also, some local Panhandle fingerling fish farms sell these products too. Here is a list of fish farms from the Florida Fish and Wildlife Conservation Commission: FWC Freshwater Fish Stocking List. Additionally, there are dissolved oxygen meters you can purchase which accurately read the amount of oxygen in your ponds. This is yet another tool to use in the overall management of your pond.
Simple surface agitators can be used to aerate small shallow ponds, but are generally not recommended for larger more productive ponds that need more oxygen. Photo by Judy Biss
More information about pond management can be found in the following references used for this article:
Overview of Florida Waters – Dissolved Oxygen
Clemson Cooperative Extension: Aeration, Circulation, and Fountains
Southern Regional Aquaculture Center: Pond Aeration
Managing Florida Ponds for Fishing
The Role of Aeration in Pond Management
Being in the panhandle of Florida you may, or may not, have heard about the water quality issues hindering the southern part of the state. Water discharged from Lake Okeechobee is full of nutrients. These nutrients are coming from agriculture, unmaintained septic tanks, and developed landscaping – among other things. The discharges that head east lead to the Indian River Lagoon and other Intracoastal Waterways. Those heading west, head towards the estuaries of Sarasota Bay and Charlotte Harbor.
A large bloom of blue-green algae (cyanobacteria) in south Florida waters.
Those heading east have created large algal blooms of blue-green algae (cyanobacteria). The blooms are so thick the water has become a slime green color and, in some locations, difficult to wade. Some of developed skin rashes from contacting this water. These algal blooms block needed sunlight for seagrasses, slow water movement, and in the evenings – decrease needed dissolved oxygen. When the algae die, they begin to decompose – thus lower the dissolved oxygen and triggering fish kills. It is a mess – both environmentally and economically.
On the west coast, there are red tides. These naturally occurring events happen most years in southwest Florida. They form offshore and vary in intensity from year to year. Some years beachcombers and fishermen barely notice them, other years it is difficult for people to walk the beaches. This year is one of the worst in recent memories. The increase in intensity is believed to be triggered by the increase in nutrient-filled waters being discharged towards their area.
Dead fish line the beaches of Panama City during a red tide event in the past.
Photo: Randy Robinson
On both coasts, the economic impact has been huge and the quality of life for local residents has diminished. Many are pointing the finger at the federal government who, through the Army Corp of Engineers, controls flow in the lake. Others are pointing the finger at shortsighted state government, who have not done enough to provide a reserve to discharge this water, not enforced nutrient loads being discharged by those entities mentioned above. Either way, it is a big problem that has been coming for some time.
As bad as all of this is, how does this impact us here in the Florida panhandle?
Though we are not seeing the impacts central and south Florida are currently experiencing, we are not without our nutrient discharge issues. Most of Florida’s world-class springs are in our part of the state. In recent years, the water within these springs have seen an increase in nutrients. This clouds the water, changing the ecology of these systems and has already affected glass bottom boat tours at some of the classic springs. There has also been a decline in water entering the springs due to excessive withdrawals from neighboring communities. The increase in nutrients are generally from the same sources as those affecting south Florida.
Florida’s springs are world famous. They attracted native Americans and settlers; as well as tourists and locals today.
Photo: Erik Lovestrand
Though we are not seeing large algal blooms in our local estuaries, there are some problems. St. Joe Bay has experienced some algal blooms, and a red tide event, in recent years that has forced the state to shorten the scallop season there – this obviously hurts the local economy. Due to stormwater runoff issues and septic tanks maintenance problems, health advisories are being issued due to high fecal bacteria loads in the water. Some locations in the Pensacola area have levels high enough that advisories must be issued 30% of the time they are sampled – some as often as 40%. Health advisories obviously keep tourists out of those waterways and hurt neighboring businesses as well as lower the quality of life for those living there.
Then of course, there is the Apalachicola River issue. Here, water that normally flows from Georgia into the river, and eventually to the bay, has been held back for water needs in Georgia. This has changed flow and salinity within the bay, which has altered the ecology of the system, and has negatively impacted one of the more successful seafood industries in the state. The entire community of Apalachicola has felt the impact from the decision to hold the water back. Though the impacts may not be as dramatic as those of our cousins in south Florida, we do have our problems.
Bay Scallop Argopecten iradians
What can we do about it?
The quick answer is reduce our nutrient input.
The state has adopted Best Management Practices (BMPs) for farmers and ranchers to help them reduce their impact on ground water and surface water contamination from their lands. Many panhandle farmers and ranchers are already implementing these BMPs and others can. We encourage them to participate. Read more at Florida’s Rangeland Agriculture and the Environment: A Natural Partnership – http://nwdistrict.ifas.ufl.edu/nat/2015/07/18/floridas-rangeland-agriculture-and-the-environment-a-natural-partnership/.
As development continues to increase across the state, and in the panhandle, sewage infrastructure is having trouble keeping up. This forces developments to use septic tanks. Many of these septic systems are placed in low-lying areas or in soils where they should not be. Others still are not being maintained property. All of this leads to septic leaks and nutrients entering local waterways. We would encourage local communities to work with new developments to be on municipal sewer lines, and the conversion of septic to sewer in as many existing septic systems as possible. Read more at Maintaining Your Septic Tank – http://nwdistrict.ifas.ufl.edu/nat/2017/04/29/maintain-your-septic-system-to-save-money-and-reduce-water-pollution/.
And then there are the lawns. We all enjoy nice looking lawns. However, many of the landscaping plans include designs that encourage plants that need to be watered and fertilized frequently as well as elevations that encourage runoff from our properties. Following the BMPs of the Florida Friendly Landscaping ProgramTM can help reduce the impact your lawn has on the nutrient loads of neighboring waterways. Read more at Florida Friendly Yards – http://nwdistrict.ifas.ufl.edu/nat/2018/06/08/restoring-the-health-of-pensacola-bay-what-can-you-do-to-help-a-florida-friendly-yard/.
For those who have boats, there is the Clean Boater Program. This program gives advice on how boaters can reduce their impacts on local waterways. Read more at Clean Boater – https://floridadep.gov/fco/cva/content/clean-boater-program.
One last snippet, those who live along the waterways themselves. There is a living shoreline program. The idea is return your shoreline to a more natural state (similar to the concept of Florida Friendly LandscapingTM). Doing so will reduce erosion of your property, enhance local fisheries, as well as reduce the amount of nutrients reaching the waterways from surrounding land. Installing a living shoreline will take some help from your local extension office. The state actually owns the land below the mean high tide line and, thus, you will need permission (a permit) to do so. Like the principals of a Florida Friendly Yard, there are specific plants you should use and they should be planted in a specific zone. Again, your county extension office can help with this. Read more at The Benefits of a Living Shoreline – http://nwdistrict.ifas.ufl.edu/nat/2017/10/06/the-benefits-of-a-living-shoreline/.
Though we may not be experiencing the dramatic problems that our friends in south Florida are currently experiencing, we do have our own problems here in the panhandle – and there is plenty we can do to keep the problems from getting worse. Please consider some of them. You can always contact your local county extension office for more information.
Of all the issues facing our local estuaries, high levels of fecal bacteria is the one that hinders commercial and recreational use the most. When bacteria levels increase and health advisories are issued, people become leery of swimming, paddling, or consuming seafood from these waterways.
Closed due to bacteria.
Photo: Rick O’Connor
I have been following the fecal bacteria situation in the Pensacola Bay system for several decades. Cheryl Bunch (Florida Department of Environmental Protection) has done an excellent job monitoring and reporting the bacteria levels, along with other parameters, for years – she has been fantastic.
The organisms used for monitoring have changed, so comparing numbers now and 30 years ago is somewhat difficult – but those changes came with good reason.
Fecal bacteria are organisms found in the large intestine of birds and mammals. They assist with digestion and are not a real threat to our health. Understanding that both birds and mammals in and near our estuaries must defecate, it is understandable that some levels of these bacteria are in the waterways. However, when levels are high there is a concern there are high levels of waste in the water. This waste can carry other organisms that can cause health problems for humans – such as hepatitis and cholera. So fecal bacteria monitoring is used as a proxy for other potential harmful organisms. No one wants to swim in sewage.
E. coli is a classic proxy for this type of monitoring and has been used for years. Recently it was found that saline water could kill some of the fecal bacteria – giving monitors’ low readings in estuarine systems – suggesting that there is little sewage in the water – when in fact there may be high levels of sewage undetected. They have found Enterococcus a better proxy for marine waters, particularly Enterococcus faecalis. Researchers have determined that a single sample of bay water should have more than 35 colonies of Enterococcus (ENT). If they find 35 or more colonies – a second sample is taken. If the counts are again high – a health advisory will be issued.
Over the last 30 years of monitoring FDEP’s reports on the Pensacola Bay area – there have been patterns. Most of the “hot spots” have been bayous and locations where rivers are discharging into an estuary. In addition, the periods of high fecal counts correspond well with periods of high rainfall. Locally, in the Pensacola Bay area, sampling has been reduced due to budget issues and some bodies of water are not sampled as often as others. Today both FDEP and the Florida Department of Health (FDOH) monitor and post their data via the Healthy Beaches Program. In this program, the sample stations are commonly used swimming areas – meaning some other locations are rarely, if ever, sampled. Based on these data, 30-40% of the samples from local bayous annually require a health advisory to be issued.
Health advisories can reduce interest in human related recreation activities, such as wakeboarding, paddling, or even fishing – and certainly impacts interest in swimming. Decades ago, swimming and skiing were very popular in local bayous. Today it is rare to see anyone doing so – most are motoring through heading to open bodies of water to spend their day. It may also be effecting property purchases. I have been contacted more than once with the question “would you buy on a house on XXX Bayou?”
Several local waterways are listed as impaired, and one is a BMAP area, due to high levels of bacteria. A BMAP (Basin Management Action Plan – read more at the link below) is a state designated body of water that is impaired (for some reason) and is required to make annual improvements to reduce the problem.
The spherical cells of the “coccus” bacteria Enterococcus.
Photo: National Institute of Health
So What Can We Do to Reduce This Problem?
In the Pensacola area, both the city and county have made efforts to modify and improve stormwater problems. Baffle boxes in east Pensacola have helped to reduce the amount of runoff entering the bayous and bays, thus reducing the frequency health advisories are being issued. That said, during heavy events the counts still increase – and rainfall seems to be increasing in the area in recent years. We will continue to monitor the frequency of advisories and post these on Sea Grant Notes through the Escambia County extension office each week.
From our side of the story (you and me) – anything you can do to reduce runoff will certainly help. Florida Friendly Landscaping techniques are a good start (see article on FFL posted below). Clean up after your pet, both in your yard and after walks – most people do… but not all. Septic systems have been a point of concern. If you have a septic system, maintain it (see article below on how). If the opportunity presents itself, you can move from septic to a sewer system. At many public places along the waterfront have signs asking everyone not to feed the birds. Congregating birds equals congregating bird feces and this can be a health issue.
Local and state governments are working to reduce the stormwater impacts on our local estuaries – which trigger other problems as well as high bacteria counts. Local residents and businesses can do the same.
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.
Florida Friendly Landscaping
Restoring the Health of Pensacola Bay, What You Can Do to Help? – Florida Friendly Landscaping
Maintain Your Septic Tank System to Save Money and Reduce Water Pollution
Septic Tanks: What You Should Do When a Flood Occurs
Shrimp, oysters, blue crab and fish have been harvested from the Pensacola Bay System (PBS) for decades, although there has been a decline in all in recent years. Annual landings (in pounds) have ranged from
- Fish 66,000 – 4,600,000 (most are scaienids)
- Brown shrimp 43,000 – 906,000
- Oysters 0 – 492,000
- Blue crab 400 – 137,000
There is a concern about the safety of seafood harvested from our estuary… sort of. Many local residents and visitors ask frequently about the safety of these products. However, when programs are held to provide this information they are not well attended, and when articles are posted – few view them. I think there is a concern for the safety of seafood products, particularly those from our estuaries – so I cannot explain the lack of interest in the presentations and articles.
Commercial seafood in Pensacola has a long history.
Photo: Rick O’Connor
One contaminant that gets a lot of press is mercury. The toxic form of mercury is methylmercury. This form of mercury impairs brain development of fetuses – hearing, vision, and muscle function in adults. Studies suggests that the primary source of mercury in the waters of the PBS is the atmosphere. Advisories have been issued for Escambia, Blackwater, and Yellow Rivers. There have also been advisories for local largemouth and king mackerel. This is one of the metals whose concentrations within the PBS is higher than neighboring estuaries – especially in our bayous (see https://blogs.ifas.ufl.edu/escambiaco/2018/06/13/restoring-the-health-of-pensacola-bay-what-can-you-do-to-help-bioaccumulation-of-toxins/.) Florida Department of Environmental Protection (FDEP) has issued Total Maximum Daily Loads (TDMLs) for mercury in the PBS.
So How Much is Too Much?
For monitoring purposes, total mercury (THg) is easier and less expensive to than the toxic form methylmercury (MHg). Many believe the amount of THg is equivalent to the concentration of MHg, and so it is used as a proxy for MHg.
Both the U.S. EPA and the FDEP recommend concentrations of THg not be higher than 0.3 ppm, and 0.1 ppm for pregnant women (or women planning a pregnancy).
Since 2000, four studies have been conducted on six species of fish in the PBS. Concentrations of THg ranged from 0.02 – 0.88 ppm and averaged between 0.2 – 0.4 ppm.
Two studies have been conducted since 2007 found mercury concentrations ranged from 0.07 – 1.1 ppm.
30 years ago, studies were finding concentrations of THg in oysters around 0.02 ppm. Repeated studies between 1986 and 1996 found an increase to 0.3 ppm.
Studies suggest that shrimp and oysters have lower concentrations of THg than blue crab and fish.
Seafood has a long history along Florida’s panhandle.
Photo: Betsy Walker
How often have samples exceeded the safe levels suggested by EPA, FDEP, and FDA?
||Recommended highest level
||% of times samples from PBS exceeded this limit
(89% for blue crab and oysters)
(88% for blue crab)
(12% for blue crabs)
(27% for fish)
|Food and Drug Administration recommendation
The concern for mercury in local seafood has led to a reduction of consuming all seafood by pregnant women – period. Recent studies have shown this can have negative effects on the developing baby as well. The recommendation is to avoid fish that have been tested high in THg. Most of these are high on the food chain – such as king mackerel, shark, and swordfish. You can find the latest on seafood safety and advisories at https://myescambia.com/our-services/natural-resources-management/marine-resources/seafood-safety. Another piece of this story is the belief, by many, that selenium can lower the toxicity of MHg. Many believe that molar ratios of selenium and mercury greater than 1.0 can reduce the toxicity. However, there have been no studies on molar ratios of these elements in the PBS.
The bottom line on this issue is to be selective on the seafood products you consume.
The most popular seafood species – shrimp.
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.