When I joined Florida Sea Grant in 2012 my advisory committee told me water quality was one of their major concerns. Makes sense really. Some members were from the tourism and boating industry. Some were from commercial and recreational fishing. Others were homeowners. ALL had concerns. ALL depended on clean water for the success of their business and for the quality of their own lives. It is a big concern.
Since that time, we have been training volunteers to monitor nutrients and salinity. We just recently added harmful algae monitoring and we report fecal bacteria data collect by the Department of Health. All to (a) get people out there so they can see what is happening themselves, and (b) provide information we share with the members of the community.
Local bayous in the Pensacola Bay area have experienced fish kills due excessive nutrients in the past. The Lakewatch Program trains volunteers to monitor nutrients in these waterways today.
Photo: Rick O’Connor
Lakewatch is a program where volunteers use their boats to monitor nutrients at three locations in a particular waterway within the bay system. Excessive nitrogen and phosphorus can lead to agal blooms, which in themselves can be a problem, just ask the folks in south Florida. But when these organisms die, they form dense mats of organic matter that sink and decay. The decaying process is oxygen demanding and the dissolved oxygen in the system decreases to levels where fish kills can happen. Many may remember the large fish kills our bayous experienced in the 1960s and 1970s.
Their samples are analyzed by the Lakewatch lab in Gainesville for total nitrogen, total phosphorus, and total chlorophyll a (which is a proxy for phytoplankton in the water column – algae). The volunteers also measure the water clarity using a secchi disk. Water clarity decreases with increase algal blooms and this can be a problem for submerged seagrasses. The lab provides us with the salinity when they analyze the samples.
Below is a table of data since sampling began in 2007. However, some locations are JUST getting started.
Table 1. Nutrients in the Pensacola Bay Area
All values are the geometric means.
Body of Water
Total Phosphorus (µg/L)
Total Nitrogen (µg/L)
Total Chlorophyll a(µg/L)
Water Clarity (Feet)
Salinity (parts per thousand)
Pensacola Bay
Station 1
Station 2
15
275
5
7.3
Station 3
Bayou Texar
Station 1
17
803
6
3.5
8
Station 2
18
673
8
3.8
10
Station 3
17
592
8
3.8
10
Bayou Chico
Station 1
29
533
16
3.2
7
Station 2
27
548
13
1.0
7
Station 3
22
353
8
4.1
7
Bayou Grande
Station 1
15
311
4
4.5
14
Station 2
15
290
4
5.5
15
Station 3
17
312
5
5.4
16
Big Lagoon
Station 1
13
252
3
8.9
18
Station 2
Station 3
12
213
2
10.0
8
Lower Perdido Bay
Station 1
15
327
5
6.4
15
Station 2
15
324
5
5.4
15
Station 3
15
328
5
5.8
15
Pensacola Bay was only sampled for one year (2019-2020). These three stations extend from the near the mouth of Bayou Texar, along the east side of the 3-Mile Bridge to the middle where the “hill” is in the bridge. This site is open and in need a volunteer. If interested, contact me. You will notice as you glance at the data table there is very little information on this location. The data provided in this table is the geometric means over the period of monitoring. Only data from station #2 was enough to report on and the values for nutrients are on the lower side. The water clarity is one of the better locations at 7.3 feet and there is insufficient data to report on the salinity.
Again, this site was not monitored for long and there is not enough to see short- or long-term trends here. But based on the little information provided, there does not appear to be nutrient issue here.
Bayou Texar has been monitored the longest in this Lakewatch program. One volunteer monitored from 2000-2002 before stopping. A second volunteer began in 2007 and monitored until 2013 when a third volunteer took on these sites. There is a current need for a new volunteer to continue monitoring this location beginning in 2023 – contact me if interested. The Lakewatch data is provided in two sections, one covering the 2000-2002 monitoring period, and the other the 2007-present. The data provided in this report are those collected between 2007-present. The sample stations run north to south with #3 being closest to the mouth near Cervantes Bridge.
A quick glance at the data shows significantly high nitrogen values, particularly at station #1 (near the 12th Avenue Bridge). Most bodies of water monitored in this project have nitrogen values running between 200-400 µg/L (Bayou Chico being an exception – more on that next). The total nitrogen in Bayou Texar runs between 600-800 µg/L – MUCH higher than the others. Though the total nitrogen is higher, the total phosphorus and chlorophyll numbers are not much above other locations (again, Bayou Chico is an exception). Water clarity, between 3-4 feet, is low for most locations. The salinity is also lower than most.
Since 2007 there have been significant improvements in total phosphorus at stations #2 and #3 – meaning improvements as you go from the 12th Avenue Bridge to the Cervantes Street Bridge. Water clarity has significantly improved at all locations. This is all good news. However, the total nitrogen numbers have not changed significantly over that time and are much higher than other bodies of water sampled. When you look at the number of health advisories issued for Bayou Texar it tends to be around 30% of the samples collected. Much better than Bayou Chico but higher than other bodies of water monitored by the Health Department.
Bayou Texar does have a total nitrogen problem and the closer you get to the 12th Avenue Bridge, the worse it becomes. Sources of nitrogen can come from leaf litter, fertilizers, animal waste, and leaky septic tanks, or sanitary sewage overflows. Identifing which source is the problem will be difficult. Some suggest the issues may be coming further upstream in Carpenters Creek. It is recommended that local residents and businesses along the creek and bayou use some of the management practices listed at the end of this report to help reduce this problem. There is a large effort currently to try and improve conditions in and around Carpenters Creek. Many of the properties along the bayou might consider the BMPs listed at the end of the report. Based on the chlorophyll data, Bayou Texar is border lined eutrophic (excessive nutrients). Reduction of nitrogen would help.
There are records of seagrass growing in Bayou Texar as well as active ospreys, dolphins, and even manatee sightings.
Bayou Chico has been sampled since 2014. The stations run from west to east with station 3 being the closest to the mouth of the bayou (near the bridge). As you glance across the numbers you will notice the nutrient data is slightly higher than the other bodies of water. The other bodies of water have total phosphorus between 10-20 µg/L. However, Bayou Chico has the highest values running between 20-30 µg/L. Other than Bayou Texar, the total nitrogen values are between 200-400 µg/L. Though lower than Bayou Texar, Bayou Chico is high running between 300-600 µg/L. The same is true for the third nutrient parameter chlorophyll. At most locations, excluding again Bayou Texar, the chlorophyll values are less than 5 µg/L. Bayou Chico has the highest values running between 8-16 µg/L. Along with Bayou Texar it has the lowest water clarity between 3-4 feet and has the freshest water in our sample locations with salinities running at 7 ppt.
Though most parameters have improved slightly since 2014, there have been no significant changes in water quality. There has been a slight increase in nitrogen at two stations – but again, not significant.
These values do classify Bayou Chico as eutrophic (nutrient excessive). The lower water clarity and salinity suggest more freshwater input – possibly from stormwater runoff. The low water clarity could be from small algal blooms but could also be attributed to shore-based sediments entering the system via stormwater runoff. These excessive nutrients could be linked to the excessive health advisories issued here due to fecal bacteria entering the waters. Based on data from the Department of Health, over the years Bayou Chico has required a health advisory be issued 50-60% of the time they sampled – significantly more than the other bodies of water monitored. Since 2010, this is the only body of water currently being monitored that has experienced a large fish kill – though this fish kill was attributed excessive warm water (which, like algal blooms, is oxygen demanding). It is a body of water that has seen problems for decades and is the only body of water in our area that requires a state Basin Area Management Plan (BMAP).
There are records of seagrass growing in Bayou Chico – and this is good news. There are also reports of ospreys, dolphins, and manatee sightings here as well. The state has deployed oyster reefs to help remove nutrients. There is an invasive species present (giant salvinia – Salvinia molesta) that is of concern. The state is currently managing this plant. It prefers high nutrient, low energy (calm) freshwater water. The salinities of the other bayous may be too high for this plant, but we are trying to education residents about the situation and help monitor/remove it if it appears. You can contact the county extension office for more information on this plant if interested.
Bayou Grande has been monitored since 2012. The stations also run west to east with station #3 closest to the mouth near NAS main side bridge. As you glance across the numbers you will notice values at, or below, average for the areas sampled. Total phosphorus runs close to 15 µg/L. Total nitrogen values run close to 300 µg/L. Total chlorophylls are some of the lowest running close to 4 µg/L. Water clarity is the clearest of all three of the bayous running between 4.5-6 feet and is also the saltiest with salinities running around 15 ppt.
All though all parameters have shown improvement in water quality since 2012, most are not significant improvements. The one exception is water clarity at station #1 – it has shown significant improvement during this time.
In general Bayou Grande is in the best shape of the three bayous and compares well with the open bay stations being monitored. It is classified as mesotrophic – meaning nutrients are middle range (where you expect an estuary to be). The health advisory reports are usually between 20-30% of the samples taken and fish kills have not occurred here since we began monitoring. There have been improvements on septic to sewage conversions in these communities, as well as efforts to build living shorelines (which can help reduce nutrient runoff to the bayou coming directly from properties in lieu of storm drainpipes). It is also a larger bayou (hence its name) with less development along the southern shoreline. There are more efforts planned to try and improve sewage issues and in planting living shorelines using filter feeding oysters. Residents along Bayou Grande could also incorporate Florida Friendly Landscaping principals to help reduce nutrients further as well as incorporate clean boating practices. Information on these programs can be found at your county extension office.
Big Lagoon has only been monitored since 2020. Thus, there are gaps in the data table where there are insufficient data to calculate a geometric mean. The sample stations run from east to west with #1 being closest to Ft. McRee and the mouth of the Pensacola Bay system itself. Glancing at the data where a geometric mean was able to be determined you will see that nutrient values are some of the lowest in the bay area. The total phosphorus runs between 12-13 µg/L, total nitrogen between 200-250 µg/L, and the total chlorophyll between 2-3 µg/L. The water clarity data are the clearest in the bay area, running from 9-10 feet. The salinity is interesting. At station #1 (near Ft. McRee) the geometric mean for salinity is 18 ppt, but at station #3 (near Big Lagoon State Park) it is only 8 ppt.
Since sampling only began two years ago, it has not been long enough to determine any long-term trends.
The chlorophyll numbers are actually low enough to classify Big Lagoon as oligotrophic (nutrient poor). This is unusual for an estuary, which are typically bodies of water with moderate amounts of nutrients due to natural runoff. But remember (a) Big Lagoon does not have a lot of natural runoff and (b) we have only been collecting samples there for two years.
The interesting thing about the salinity is how low it is. Station #3 (near Ft. McRee) is 18 ppt and being so close to the mouth of Pensacola Bay, and the Gulf of Mexico, you would expect this to be higher – maybe between 25-30 ppt. The fact that there are thick beds of turtle grass (Thalassia testdidnium) suggest that the actual mean is probably higher than the 18 ppt reported here. The opposite side of Big Lagoon is interesting as well. Station #3 reports a geometric mean of 8 ppt. This is equivalent to the upper end of Bayou Texar (near the 12th Avenue Bridge) and most of Bayou Chico. This too seems very low for this body of water. The Department of Health samples for fecal bacteria near Big Lagoon State Park and it does, at times, get high enough (> 70 colonies/100ml) for a high bacteria reading. DOH usually takes a second sample to confirm the reading and most often the second reading is lower, and a moderate classification is given for that week. That said health advisories have been given in this region, albeit less than 10% of the samples taken. All of this suggest that there may be some runoff issues at the west end of the Lagoon. Obviously more sampling is needed.
This body of water does support plenty of seagrass, ospreys, dolphins, and an increase in manatee reports. There are diamondback terrapins and horseshoe crabs both reported here as well. But it was also a location where bay scallops once thrived and no longer do. Scallop searches have been ongoing here for six years and only one live animal has been found. There are several possible reasons for their decline, decrease in salinity maybe one of them. Monitoring will continue. It is also a location where the state has measured a decline in seagrass – also concerning. Sea Grant is currently partnering with the University of West Florida to monitor both seagrass abundance and water quality within Big Lagoon.
Lower Perdido Bay has been monitored since 2014. The three stations run from south to north. Station #1 is near Innerarity Point and station #3 is near Tarkiln Bayou. Glancing across the numbers of the lower Perdido you will see that they are similar to most of the other bodies of water being monitored. The total phosphorus is 15 µg/L. The total nitrogen is between 320-330 µg/L. And the total chlorophyll is 5 µg/L classifying this area of Perdido Bay as mesotrophic. Being an open bay, the water clarity is higher, running between 5-6 feet, and the salinity is reported at 15 ppt. As with Big Lagoon, the salinity seems lower than one would expect but historic records suggest that Perdido Bay in general may have been lower than most other open bays. Historically the mouth of the bayou open and closed frequently giving the Spanish the reason to name it Perdido (“Lost Bay”). This closer may have made it more of a freshwater system – similar to the dune lakes of Walton County and the historic Choctawhatchee Bay – and may play a role in the lower salinity of Big Lagoon.
The trends over time show that most parameters have improved but not significantly. The one exception is total nitrogen. The total nitrogen in lower Perdido Bay has significantly decreased over the period Lakewatch has been monitoring – and this is good news.
Perdido Bay has had a history of poor water quality, but this is due more to industrial compounds being released through the tributary creeks. These compounds did cause other problems, including some species of fish altering sex, and whether these are still an issue cannot be determined by these data – this project is monitoring for nutrients. The nutrient driven algal blooms and fish kills found in the bayous 50 years ago were not as common in this body of water and these data suggest that the system is mesotrophic as most estuaries are. As with most of the other bodies of water, ospreys, dolphins, and manatees have all been recorded here. Seagrasses are present but being a less saline system than Big Lagoon and Santa Rosa Sound, the species composition is different and abundance is less. There have been efforts to survey for bay scallops in the lower portions of Pensacola Bay, but no efforts have been made in the lower Perdido due to salinities currently, and historically, not being high enough. Again, the lower salinity is thought to be more natural than from heavy development and urban runoff.
Summary
In summary, these data suggest that the nutrient problems area waterways experienced in 1960s and 1970s have improved. Algal blooms and fish kills are no longer common. But there still could be dissolved oxygen (DO) issues at the bottom of our bays and bayous that reduce biodiversity. This is not monitored by Lakewatch and we are not aware of any long term monitoring of DO to know how things have changed in the last 50 years.
Anecdotal reports suggest the coverage of seagrasses in these systems are improving. Though there are seagrasses in Big Lagoon, some reports suggest there has been a decline in recent decades. There is a current citizen science project entitled Eyes on Seagrass where Sea Grant and the University of West Florida train volunteers to monitor both coverage and species composition. Data from this project will presented in a separate report later in the year. There are also separate citizen science efforts monitoring the presence of bay scallops, horseshoe crabs, and diamondback terrapins in the bay area. Horseshoe crabs are being encountered more often, as are terrapins, but bay scallops seem to still be missing. As with the seagrass monitoring, these reports will be coming later this year.
There are still concerns with both Bayou Chico and Bayou Texar – these being the only two nutrient eutrophic systems in this monitoring project (based on chlorophyll data). Efforts to better understand the sources of nutrients, and enact better management practices, should be considered for these waterways. Things such as reducing fertilizer use, mitigating fertilizer runoff with living shorelines, converting from septic to sewers, better maintenance of septic systems, and reduction of sanitary sewage overflows are all actions that citizens can take now to help improve these waterways. For information on how to do these, contact your county extension office and we will be glad to assist.
Lakewatch is a citizen science volunteer supported by the University of Florida IFAS
The University of Florida/IFAS Extension faculty are reintroducing their acclaimed “Panhandle Outdoors LIVE!” series. Conservation lands and aquatic systems have vulnerabilities and face future threats to their ecological integrity. Come learn about the important role of these ecosystems.
The St. Joseph Bay and Buffer Preserve Ecosystems are home to some of the one richest concentrations of flora and fauna along the Northern Gulf Coast. This area supports an amazing diversity of fish, aquatic invertebrates, turtles, salt marshes and pine flatwoods uplands.
This one-day educational adventure is based at the St. Joseph Bay State Buffer Preserve near the coastal town of Port. St. Joe, Florida. It includes field tours of the unique coastal uplands and shoreline as well as presentations by area Extension Agents.
Details:
Registration fee is $45.
Meals: breakfast, lunch, drinks & snacks provided (you may bring your own)
Attire: outdoor wear, water shoes, bug spray and sun screen
*if afternoon rain is in forecast, outdoor activities may be switched to the morning schedule
Space is limited! Register now! See below.
Tentative schedule:
All Times Eastern
8:00 – 8:30 am Welcome! Breakfast & Overview with Ray Bodrey, Gulf County Extension
8:30 – 9:35 am Diamondback Terrapin Ecology, with Rick O’Connor, Escambia County Extension
9:35 – 9:45 am Q&A
9:45- 10:20 am The Bay Scallop & Habitat, with Ray Bodrey, Gulf County Extension
10:20 – 10:30 am Q&A
10:30 – 10:45 am Break
10:45 – 11:20 am The Hard Structures: Artificial Reefs & Marine Debris, with Scott Jackson, Bay County Extension
11:20 – 11:30 am Q&A
11:30 – 12:05 am The Apalachicola Oyster, Then, Now and What’s Next, with Erik Lovestrand, Franklin County Extension
12:05 – 12:15 pm Q&A
12:15 – 1:00 pm Lunch
1:00 – 2:30 pm Tram Tour of the Buffer Preserve (St. Joseph Bay State Buffer Preserve Staff)
2:30 – 2:40 pm Break
2:40 – 3:20 pm A Walk Among the Black Mangroves (All Extension Agents)
3:20 – 3:30 pm Wrap Up
To attend, you must register for the event at this site:
Imperiled (verb) – put at risk of being harmed, injured, or destroyed.
In 2021 the Florida Department of Environmental Protection classified 44 area waterways in the Pensacola Bay System as imperiled. Such designations are based on an environmental parameter making it unhealthy for one reason or another. When we think of an unhealthy body of water, many times we think of sewage. There are nine bodies of water in the Pensacola Bay System classified as imperiled due to the fecal bacteria concentrations within. There are another seven for bacteria levels high enough to close them for shellfish harvesting. This is a total of 16 bodies of water having bacteria issues (36% of the 44 designations).
Closed due to bacteria. Photo: Rick O’Connor
Low dissolved oxygen and fish kills is another parameter we think of. There are four waterways designated imperiled due to high nutrients (a cause of hypoxia and fish kills), and one for low dissolved oxygen readings itself. This is a total of five (11% of the 44 designations).
Dead redfish on the eastern shore of Mobile Bay. Photo: Jimbo Meador
But you may be surprised to learn that 23 of the 44 imperiled water bodies (52%) are designated based on the mercury content of the fish sampled there.
Most people are aware of the mercury issue in fish. Many of those living in the Pensacola Bay area are aware of this issue locally, but they may not be aware that with the 2021 designations, it is the primary reason for many listed. To be fair, it is not that mercury issues are increasing, it may be more that there are 97 waterways in the Pensacola Bay System being considered for delisting in 2021 and those are listed for a variety of other issues. What it is stating is that with the 44 that remain imperiled, mercury is the primary cause.
We have all heard of mercury in fish, but where is it coming from? What health problems does it cause? And is there anything that can be done to make these bodies of water healthier?
Mercury is a naturally occurring element on the periodic table. It is element #80, meaning it has 80 protons and electrons, one of the larger naturally occurring elements. It is a silver-colored liquid at room temperature, one of only two naturally occurring elements in the liquid phase at these temperatures – the other being bromine. It is sporadically found throughout the earth’s crust, usually combined with other elements. There are two forms of mercury – mercury (I) and mercury (II) – indicating the number of cations available for sharing or transferring in compound bonding. Mercury (II) is more common in nature.
The element has been of interest to humans for centuries. There are records of it buried beneath the Mayan pyramids, though we are not sure how it was used, and it was used in Chinese medicine centuries ago. The Spanish used it to help extract silver from mines during their colonial period around the world. It was also used in separating fir from skin in felt hat making in the 19th century. Hatters who used this method eventually had neurological problems and became known as “mad hatters”, an idea used in Lewis Carol’s Alice’s Adventures in Wonderland.
In more modern times it has been used in fillings for tooth cavities (including my own) and preserving specific vaccines. Being a good conductor of electricity and not of heat, it is used in numerous electrical components, fluorescent lighting, and batteries. Some cultures used it to help “whiten their skin” and a common use is in the processing and production of certain industrial chemicals. Today, due to the toxic properties of mercury, many of these uses are no longer.
Fluorescent lighting contains mercury.
Mercury is obtained for these uses by mining their ores. The most sought after ore is cinnabar, a red-colored rock found around the world. Mercury (II) sulflide (HgS) is a common compound found in cinnabar. When heated and oxidized it will produce sulfur dioxide and elemental mercury.
HgS + O2 à Hg + SO2
Cinnabar is the most common ore mined for mercury. Photo: Classic Crystal
The problem with mercury is that it is toxic, and some forms of mercury are more toxic than others. The element is known to cause brain, kidney, and lung issues. It also can weaken the immune system. It is most known for the neurological problems it causes. Sensory impairment, lack of motor skill coordination, psychotic reactions, hallucinations, tremors and spasms have all been connected to exposure to mercury. There are concerns with the neurological development within the fetus if exposed to mercury and many of the health advisories target women of childbearing age who are pregnant or considering it. They have included the very young and the very old in their recommendations that these members of the population do not eat more than 6 ounces of fish (or shellfish) that have high mercury contamination.
Mercury contamination in fish. Image: BBC
The organic forms of mercury, dimethylmercury and methylmercury, are the more toxic forms. These are introduced to the environment both naturally and from human activity. Once in the aquatic environment they are absorbed by the phytoplankton (microscopic plants in aquatic environments). Methylmercury accumulates in lipids (fats) within the cell at relatively low concentrations (phytoplankton are not large). However, they are not passed by the creature. The slightly larger zooplankton (microscopic animals) feed on the phytoplankton and accumulate the mercury they have stored. Feeding on a lot of these, they accumulate even more mercury. The zooplankton are consumed by small fish, who eat a lot and accumulate even more mercury. Then the mid-sized fish consume them, and the larger fish consume those, and on and on. The top predators have accumulated enough methylmercury to be hazardous to human health IF they are consumed by people. This process of increasing the concentration of mercury through the food chain is known as biomagnification – “magnifying the problem”.
So, which fish are of concern?
Based on the Florida Department of Health for freshwater systems in Escambia County.
Bluegill, Channel catfish, Largemouth bass, Long-eared sunfish, Red-eared sunfish, Spotted sunfish and Warmouth from the Escambia River system – you should not eat more than one/week.
Do not eat chain pickerel or largemouth bass – and do not consume more than two red-eared sunfish from Crescent Lake.
Lake Stone near Century FL – no more than two bluegill and sunfish per week and no more than one largemouth bass each week.
From the Perdido River do not eat more than two bluegill or sunfish each week and do not eat largemouth bass from the Perdido River.
The same species and regulations apply for the Yellow River system as well.
The following marine species are of concern….
Almaco jack, Atlantic spadefish, Atlantic croaker, Weakfish (trout), Black drum, Black grouper, Blackfin tuna, Bluefish, Cobia, Dolphin, Pompano, Gafftop catfish, Gag, Greater amberjack, Gulf flounder, Hardhead catfish, King mackerel, Ladyfish, Lane snapper, Bonito, Mutton snapper, Pigfish, Red grouper, Red snapper, Sand seatrout, Scamp, Shark, Sheepshead, Snowy grouper, Southern flounder, Southern kingfish, Spanish mackerel, Spot, Striped mullet, Vermillion snapper, Wahoo, White mullet, Yellow-edge grouper, and Yellowfin tuna.
In each case it is not recommended eating more than two servings a week. For a few, it is recommended that the most vulnerable people mentioned earlier not at ANY… Those would include Blackfin tuna, Cobia, King mackerel, Bonito, and Shark.
It is recommended that NO ONE eat king mackerel over 31 inches and any shark species over 43 inches in length.
I guess as you look at this list, you see fish species that you like. This list can lead folks to think… “I am just not going to eat seafood”. This would be a mistake. The Department of Health has found there are essential vitamins and nutrients provided be seafood that are missing if you do not eat them. They found additional problems in fetal development when seafood protein was left out of the mothers’ diet. So, the response would be… eat other seafood species you do not see on this list… or, if you see something you do like, no more than 1-2 6-ounce servings per week.
So, is there anything we can do about the mercury issue in our bay system?
Well, to have the biggest impact you will need to determine the biggest source. 33% of the mercury in our environment comes from natural sources, such as volcanic eruptions. We can do nothing about volcanic eruptions, or other natural sources, so we will need to look at anthropogenic (human) sources.
The larger sources would be anthropogenic, which account for 67% of the known mercury in the environment, focusing on these can make a large impact. Coming in at No.1 – producing electricity by burning coal. This accounts for 65% of the anthropogenic sources. Moving away from burning coal would make a huge difference. But that is easier said than done. Mining and burning coal are important for the economy of many communities. It is one of the cheaper methods of producing much needed electricity. But in addition to producing mercury compounds during the heating process, many other toxic compounds are produced and released as well – not to mention the amount of greenhouse gases produced during this process. Hence the name “dirty coal”. There are other methods of producing electricity and the solution would be to convert not only the power plants to these methods, but the coal dependent communities to this line of work. This one step would make a big difference.
Power plant on one of the panhandle estuaries. Photo: Flickr
At a much smaller scale, mining for gold produces 11% of the mercury from the mine tailings, cement production (7%), and incinerating garbage (3%). Though not a large player in this game, reducing the amount of solid waste burned each year would help reduce the mercury issue.
The takeaway here is that the number of imperiled waterways in the Pensacola Bay System have been reduced over recent years and we will look at this in another article. But for those that remain, mercury is the prime reason. It is also important to understand that mercury is a naturally occurring element and can not be broken down, so we have what we have – but, we can stop adding to the problem. Third, eating some seafood each week is good for you. You will just need to select species that are not problems or watch how much you eat if you prefer some of the listed species.
For more information on the 2021 imperiled waterways list visit
This began with a call from one of my volunteers who was checking salinity at Shoreline Park. She reported the salinity, but also reported to smell of dead fish – though she could not see them. I visited Shoreline Park the following day on another project and could smell it as well. There was a large amount of dead seagrass washed ashore from a recent storm and I thought this may be the cause of the smell because I did not see the dead fish either.
When I got home, I checked the FWC fish kill database. It reported a redfish kill in Pensacola Bay. It is unusual to see a kill of only one species. Many times, these are releases from fishing activity, particularly bait, and thought this must be the case – FWC did not mention the cause. I let the volunteer know and asked to keep an eye out.
I reported this to the Escambia County Division of Marine Resources to (a) let them know, and (b) to find out if they had any idea of cause. They replied that the location was incorrect. The kill was actually near Galvez Landing on Innerarity Point. He (Robert Turpin) had visited the site and did find any dead fish. I have a lot of volunteers over that way so asked each to take a look. They did not see any dead fish. I asked them to keep an eye out and collect a dead fish if they saw one for testing. Often when a large fish kill occurs, and it is only one species, the suspect cause is disease. Tissue samples could confirm this.
And then came another call.
This time it was from one of our Master Naturalist who lives on the eastern shore of Mobile Bay. He wanted to know what was up with all of the dead redfish along the shore of the bay. He sent photos and his beach was littered with them. I reached out to Mississippi/Alabama Sea Grant to see if they knew what was going on. They had heard about the situation and knew the Alabama Department of Natural Resources was collecting samples. The Gulf Islands National Seashore then reported large numbers of dead redfish along the National Shores property in Mississippi, something was up.
Dead redfish on the eastern shore of Mobile Bay. Photo: Jimbo Meador
I eventually got word from Dr. Marcus Drymon at the Dauphin Island Sea Lab. They had a team working on this. Their team reported that stratification of the Gulf had created a hypoxic (low dissolved oxygen) layer on the bottom and the male “bull redfish” had gathered for breeding and died.
So, we are back to our title – what is stratification and how did this cause the fish kill?
Stratification is the layering of the water. Less dense water will sit atop the more dense. Water temperature or salinity can cause this density difference and layering. Colder and/or saltier water is denser and will form the bottom layer. If you have high winds, it will mix the water and the stratification disappears. Tides and currents can affect this as well.
What they believe happened recently was excessive amounts of rainfall created a large layer of freshwater to move from Mobile Bay into the open Gulf. The combination of tides and wind allowed a stratified layer to form. The oxygen that marine life uses is dissolved into the water at the surface and referred to as dissolved oxygen (DO). If the system is stratified, then the oxygen dissolved at the surface will not reach the bottom and hypoxia (low DO) can happen. They this is what happen. It just so happens that the large male redfish (bull reds) had congregated just offshore for breeding. They are more sensitive to low DO than the smaller females and any juveniles. So, the males died. To answer the question as to why other fish did not die (what you typically see in a DO related fish kill) – the numbers were not mentioned by there was one reference to 4.0 ppm. This is the high threshold of hypoxia. Many fish can tolerate at this concentration, but the male redfish could not.
So, that is what we think happened. The perfect storm of the demise of a group of male redfish just off of Mobile, and the carcasses drifted to other locations.
A conventional septic system is composed of a septic tank and a drainfield, where most of the wastewater treatment takes place. Image: US EPA
Why do you need to maintain a septic system?
Conventional septic systems are made up of a septic tank (a watertight container buried in the ground) and a drain field, or leach field. In the septic tank, solids settle on the bottom (the sludge layer), and oils and grease float to the top and form a scum layer. The liquid wastewater, which is in the middle layer of the tank, flows out through perforated pipes into the drainfield, where it percolates down through the ground. Most wastewater treatment takes place in the drainfield.
Solids settle to the bottom of a septic tank (sludge), oils and greases float to the top (scum) and wastewater (effluent) flows out of the tank into the drainfield for further treatment. Image: Soil and Water Science Lab, UF GREC.
Although bacteria continually work on breaking down the organic matter in your septic tank, sludge and scum will build up, which is why a system needs to be cleaned out periodically. If not, sludge and scum can flow into the drainfield clogging the pipes and sewage can back up into your house. Overloading the system with water also reduces its ability to work properly by not leaving enough time for material to separate out in the tank, and by flooding the system.
Should you use additives in your septic system?
Septic systems do not need any additives to function properly and treat wastewater. Although there are many commercial microbiological and enzyme additives sold on the market that claim to enhance bacterial populations and reduce the time between septic system pumping, there really isn’t any peer-reviewed scientific literature that shows that these additives are effective in doing what they claim.
In Florida, the Department of Health (DOH) reviews commercially sold additives to ensure that they are safe to use in septic systems. DOH clearly states that although products are approved, it does not mean that this is an endorsement or a product recommendation. Approval simply means that as required by Florida law, the additive doesn’t interfere with septic system function and that when an additive is used, the effluent (wastewater) leaving the septic system meets Florida’s water quality standards. Only products in compliance with this law can be sold or used in septic systems in Florida. You can find a list of approved products and more information regarding additives on the Florida Department of Environmental Protection (FDEP) septic system website. Access the list of products directly here (updated 10/18/2021).
How can you properly care for your septic system?
The best way to keep your system functioning properly is to follow some common-sense practices.
Only flush human waste and toilet paper down the toilet. Wet wipes do not break down in the septic system even though the packaging labels them as septic-safe!
Be mindful of what you put down sinks and flush down toilets. All drains in your home lead to the septic tank. Image: A. Albertin
Think at the sink. Avoid pouring oil and fat down the kitchen drain. Avoid excessive use of harsh cleaning products and detergents which can affect the microbes in your septic tank (regular weekly cleaning is fine). Prescription drugs and antibiotics should never be flushed down the toilet.
Limit your use of the garbage disposal. Disposals add organic matter and additional water to your septic system, which results in the need for more frequent pumping.
Take care at the surface of your tank and drainfield. Don’t drive vehicles or heavy equipment over the system. Avoid planting trees or shrubs with deep roots that could disrupt the system or plug pipes.
Conserve water. Reduce the amount of water pumped into your septic tank through water conservation practices like (1) repairing leaky faucets, toilets, and pipes, (2) installing, low-flush toilets, low-flow showerheads and faucet aerators, and (3) only running the washing machine and dishwasher when full.
Have your septic system pumped by a certified professional. The general rule of thumb is every 3-5 years, but it will depend on household size, the size of your septic tank, how much wastewater you produce and what you flush down your toilet.
Even when conventional septic systems are well maintained, they are still a source of nutrients, particularly nitrogen, to groundwater. They were designed from a public health perspective to remove pathogens, not nutrients.
For many in the Pensacola Bay area, water quality is a top concern. Excessive nutrients, heavy metals, and fecal bacteria from run-off have all been problems. In recent years fecal bacteria has become a major concern, forcing both health advisories at public swimming areas, and shellfish harvesting closures. In a report from the Florida Department of Environmental Protection last modified in 2021, 43 sites in the Pensacola Bay area were verified as impaired and 11 of those (22%) were due to high levels of fecal bacteria1.
Closed due to bacteria. Photo: Rick O’Connor
As the name implies, these are bacteria associated with the digestive tract and find their way into waterbodies via animal waste. Animal waste can harbor pathogenic organisms and contribute to algal blooms which leads to hypoxia (low dissolved oxygen in the water), and potential fish kills. As bad as hypoxia and fish kills can be, it is the health issue from the pathogens that are often the larger concern.
The spherical cells of the “coccus” bacteria Enterococcus. Photo: National Institute of Health
In saline waters, the fecal bacterium Enterococcus is the species used for indication of animal waste. This bacterium is more tolerant of salt water than E. coli, or other fecal bacteria, and a better choice as an indicator for this reason. Enterococcus is found in the intestines for birds and mammals and enters waterways through their feces. Waterfowl, pets, and livestock can all be sources, but it is human waste that many point to when the bacteria counts are over the environmental thresholds set. Human waste enters the waterways either by septic or sewer overflows. It is the septic systems we will look at in this article.
A conventional septic system is made up of a septic tank (a watertight container buried in the ground) and a drain field. Image: Soil and Water Science Lab UF/IFAS GREC.
How the septic system works…
The process of course begins when you flush. The wastewater leaves the commode and enters a pipe which leads to the septic tank outside. Here the wastewater separates. The solid waste will settle to the bottom forming a layer called sludge. Fats, oils, and grease float on water and form a top layer called scum. The untreated wastewater settles in the middle. This wastewater will drain from the septic tank into a series of smaller pipes and leach into a drain field. The drain field should be made of large grain material, like sand or gravel, that allows the filtration of the water as it dissipates into the environment. On paper this system should work well, and often does, but you can see where problems can occur.
Was the septic system placed in the correct area? Often as a homeowner you have no control over where the tank is placed but there are regulations on this, and they should have been followed.
Is there sufficient drain material for the effluent to effectively drain and filter (plenty of sand/gravel)?
Is the site too close to the water table? Saturated ground will not allow for proper filtration and can create layers of untreated water to settle near the surface creating foul odors and leach into local waterways. Over the last decade the Pensacola area has seen an increase in the annual amount of rain. This increase can turn what was a suitable location into one that is no longer.
Again, many homeowners have no control over the placement of the septic but doing your due diligence when purchasing a home, you can do. Checking the situation of the septic can save you a lot of problems down the road.
1-gallon container provided free to dispose of your oil and grease. Photo: Rick O’Connor
The FOG gallon containers are found in these metal cabinets placed around the county. Photo: Rick O’Connor
What are you flushing down the commode? Here you DO have control.
Excessive amounts of fats, oils, and grease will increase the scum layer, and this can enter the pipes leading to the drain field causing clogging of those. Clogs can cause backups into the tank and leaks near the top as well as backups into your home. Not only can these overflows create problems in the home, but they can also end in our waterways creating water quality problems. So, what do you do with the oil and grease left over from cooking? In Escambia County, the Emerald Coast Utility authority provides what they call the FOG program2. This program provides free 1-gallon plastic jugs to place your oil and grease in. You can find these in metal cages at locations around the county, there is one at the extension office. You take it home, fill it up, and return it for a new one.
Disposable wipes can be flushed, but they do not degrade. Excessive amounts of disposal products flushed into your septic system will certainly create clogs in the drainpipes and backups into the lawn, waterways, and your home. Do not flush these! Toss them into the trash can.
Interestingly we are learning that milk will solidify after pouring down the drain. It forms solid chunks resembling concrete and can also create backups and overflows. This is relatively newly discovered problem. One suggestion is to pour unwanted milk on your garden, but you do not want to flush it down the drain to your septic tank.
There has been discussion on chemical products marketed to clean your septic. Many of our experts believe that these can alter the good microbes within the tank that breakdown the solid waste layer, the sludge. This is not something you want.
The last one is water itself. Not that you cannot flush water down the drain, but excessive amounts can create situations where either the scum or the sludge layers reach the drainpipes and form clogs. Do not use excessive amounts of water from different sources in your home at the same time. Do not overload the system.
Driving over the septic tank or drain field.
Most understand that this can cause problems. It can compact the soil being used for the drain field, thus making it less effective at draining and filtering. It can also cause cracks in both the tank and the drainpipes, which can create leaks that allow untreated wastewater to travel away from the drain field. Be careful where you use heavy vehicle traffic on your lawn.
Pumping out your septic system.
This is something few people do. The untreated wastewater should flow into the drain field and percolate through the sand/gravel bed. However, the scum and sludge do not drain and need to be pumped periodically. The recommended cycle for pump outs is once every 3-5 years. Again, this is something most homeowners do not do until backup problems occur. We do recommend having your system pumped on that cycle.
Convert to a sewer system.
This is not an option for everyone, and we know for some in which it is, they are not eager to do so. But converting to a sewer takes the maintenance issue off the homeowner and onto the local utility. The conversion can be expensive but, in some communities, there are cost share programs to help with this. Check with your local utility for more information.
If placed, used, and maintained properly septic systems can last 25-30 years and not be a major problem for local waterways. Converting to a sewer system can help, but there are also problems here. We will address those in our next post.
Reference
1 Florida Department of Environmental Protection. 2021. Verified Lists for Group 4 Basins Cycle 2 – Pensacola Bay.
