Seagrass Monitoring Underway in Pensacola

Seagrass Monitoring Underway in Pensacola

Most everyone knows the importance of submerged seagrass in our coastal estuaries. It has been estimated that 80% of the commercial and recreational important marine species depend on seagrasses for at least part of their life cycle.  One acre of submerged seagrass can produce 10 tons of leaves, support 40,000 fish, and 50 million invertebrate species.  Not everyone in the panhandle lives on the coast, but many who live inland enjoy fishing there, so the concern for the health of our grassbeds does extend inland.

Shoal grass. One of the common seagrasses in Florida.
Photo: Leroy Creswell

In the Pensacola Bay area, the decline of seagrass was first reported in the 1950s. A 95% decline occurred between 1950 and 1980.  The decline in local bay scallop and shrimp over the years has been attributed to the decline of these grassbeds.  Aerial surveys have shown steady decreases in acres until 2003.  From 2003 until 2010, there was an 8.4% increase in seagrass acreage in the Pensacola Bay System.  All bodies of water showed increases except Santa Rosa Sound and Big Lagoon, which had slight losses in seagrass coverage.  The most recent reports from an FWC study (2010-2015), suggest the seagrasses in the Big Lagoon and Santa Rosa Sound area have increased 13%.


Despite these recent gains, and anecdotal reports of “healthy seagrass”, many of the historic beds have not recovered. Historically, seagrass restoration efforts have not been very successful.  Natural restoration seems to be the best target at the moment.  To do this, you will need to reduce the stressors that caused the declines in the first place.  Some of the possible stressors include: dredging, trawling, decreased water clarity, prop scarring, dock shading, and armored shorelines – to name a few.


To this end, a citizen science project was developed by a partnership with the University of West Florida and the Florida Sea Grant Extension Programs in Santa Rosa and Escambia counties. Volunteers who live on, or near, these bodies of water were trained to monitor the seagrass beds near their homes.  Eleven 1-nautical mile square grids were set up in Big Lagoon and 55 were marked for Santa Rosa Sound.  Volunteers selected beaches within one of these grids to survey.  In 2018, five of the Big Lagoon and six of the Santa Rosa Sound grids were monitored.  Within their grids, volunteers selected four locations to monitor once a month between May and October.  Using snorkels, volunteers placed a 0.25m2 PVC square (quadrat) on the bottom over the grass.  The percent coverage was estimated and species of grass within identified and recorded.  Volunteers recorded whether drift algae was present on the grasses (these could be a problem for them) and a list of any marine animals they may have found.  They also collected a water sample to be analyzed for total suspended solids and nutrients by students at the University of West Florida.  UWF students also visited sites during the year to collect data on salinity, temperature, dissolved oxygen, nitrites, nitrates, ammonia, total phosphorus, and pH.

The darker areas in the water are seagrasses. Photo: Rick O’Connor

So how did the first year go?


Pretty good!

The average percent coverage of seagrass for all locations was between 60-70%, some locations in Santa Rosa Sound were 100% coverage for their stations. The percent coverage of the epiphytic drift algae was between 2-8%.  There was no real difference between Santa Rosa Sound and Big Lagoon in seagrass coverage however there was for the epiphytic drift algae – Big Lagoon had more.  The UWF environmental data also found a higher concentration of chlorophyll a in Big Lagoon.  This suggest either more runoff into Big Lagoon, or the runoff has more nutrients in it.  Overall nutrients were relatively low.  There was a decrease in salinity as the rain increased.  The more common species of seagrass are not fans of low salinity, but Widgeon grass (Ruppia maritima) is – and we did see increases in this species as we moved into September, again – probably due to lower salinities.


We will continue to monitor these grassbeds for several years and really hope we see signs of natural restoration.





Caffrey, J. 2018. Unpublished report on seagrass monitoring.


Lewis, M. J.T. Kirschenfeld, T. Goodheart. 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’s Water Quality Woes

Florida’s Water Quality Woes

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.
Photo: NOAA

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  


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


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 –


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


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


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.

Restoring the Health of Pensacola Bay, What Can You Do to Help?  – Fecal Bacteria

Restoring the Health of Pensacola Bay, What Can You Do to Help? – Fecal Bacteria

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


Septic Systems

Maintain Your Septic Tank System to Save Money and Reduce Water Pollution


Septic Tanks: What You Should Do When a Flood Occurs

ACF Water War Update: US Supreme Court Rules on Florida v. Georgia

ACF Water War Update: US Supreme Court Rules on Florida v. Georgia

If you have not seen the news yet, the US Supreme Court provided a ruling on June 27, 2018 regarding the decades-long conflict between Florida and Georgia over water use in the Apalachicola-Chattahoochee-Flint tri-state river basin. Guess what; the battle continues. Following the previous findings of the court-appointed Special Master and his recommendation to deny Florida relief in the dispute, there were many disappointed people south of the border between the two states. The recent decision to remand the case back to the Special Master for further consideration has taken many by surprise; happy surprise south of the border and not so happy as you look northward (unless you talk to the attorneys litigating the case, maybe).

The resulting decision kept Florida’s hopes alive for an equitable allocation of water resources in the basin that spans nearly 20,000 square miles of the Southeastern US. At stake, from Florida’s perspective, is the productivity and ecosystem integrity of the Apalachicola River and Bay ecosystem. For Georgia, enough water to supply its growing population and thirsty agricultural interests in the Flint River Basin south of Atlanta.
The Court’s 5–4 decision, found that the Special Master had applied too high a standard regarding “harm and redressability” for Florida’s claims. They ordered the case to be reheard so that appropriate considerations could be given to Florida’s arguments. “The amount of extra water that reaches the Apalachicola may significantly redress the economic and ecological harm that Florida has suffered,” said Justice Breyer, who was joined by Chief Justice John Roberts and Justices Anthony Kennedy, Ruth Bader Ginsburg and Sonya Sotomayor. “Further findings, however, are needed.”

The Court’s opinion does not actually outline any specific solutions for the water battle, and it in no way guarantees a win for Florida, but it does keep the legal challenge alive – along with the hope of better days for Florida’s oyster industry, which has suffered a major fisheries collapse that began around 2012.  Visit this link if you would like to read the syllabus, as well as the full opinion of the High Court.

We should all consider the magnitude of the importance of the Apalachicola River and Bay for our region, due to its connection to the larger Gulf of Mexico. Estuaries like this are crucial links in the life-stages of countless marine organisms, including many we depend on for food and recreation. Blue crabs migrate tremendous distances to spawn in our near shore estuaries. Their young then disperse to populate large areas of coastline. Post-larval shrimp move into our estuaries to grow up after being spawned offshore. Later they swim out as adults to begin the cycle again. It is no wonder the shorelines of our Florida estuaries are dotted with prehistoric shell middens from peoples who thrived near these resource-rich ecosystems. Who knows if the Apalachicola Bay will ever recover to the productivity of its glory days, when a hard-working person could harvest 20 bags of oysters in a day? Regardless, we should all be thankful for what Apalachicola Bay has meant to so many generations of people over such a wide expanse of our Northern Gulf of Mexico coastline. Take just a moment to think about it, please.

Addressing Eutrophication in Florida, one watershed at a time

Addressing Eutrophication in Florida, one watershed at a time

Local estuaries are a beautiful place to explore with your family. Credit: Matthew Deitch, UF IFAS Extension

Florida’s rivers, springs, wetlands, and estuaries are central features to the identity of northwest Florida. They provide a wide range of services that benefit peoples’ health and well-being in our region. They create recreational opportunities for swimmers, canoers, and kayakers; support diverse wildlife for birders and plant enthusiasts; sustain a vibrant commercial and recreational fishery and shellfishery; serve as corridors for shipping and transportation; and support ecosystems that help to improve water quality. Maintaining these aquatic ecosystem services requires a low level of chemical inputs from the upstream areas that comprise their watersheds.

Aquatic ecosystems are especially sensitive to nitrogen and phosphorus, which are key nutrients for the growth of plants, algae, and bacteria that live in these waters. High levels of these nutrients combined with our sunny weather and warm summer temperatures create conditions that can lead to rapid growth of aquatic plants and algae, which can cover these water bodies and make them no longer enjoyable for people and wildlife. It can also cause dissolved oxygen levels to fall, as plants respire (especially at night, when they are not photosynthesizing) and as bacteria consume oxygen to break down dead plant material. Low dissolved oxygen can create conditions that are deadly for fish and shellfish.

The Florida Department of Environmental Protection (FDEP) lists more than 1,400 water bodies (including rivers, springs, wetlands, and estuaries) as impaired by pollutants. Many of these are impaired by excessive nitrogen or phosphorus. It is a daunting challenge to reduce pollutants in these water bodies because their inputs frequently come from all over the landscape, rather than a specific point—nutrients can come from agricultural fields, residential landscapes, septic tanks, atmospheric deposition, and livestock throughout the watershed.

In Florida, FDEP has begun a program to reduce nutrient concentrations in impaired watersheds by collaborating with landowners and other stakeholders to develop management programs to reduce pollutants entering the state’s waters. This pollutant reduction program is currently focused on Florida’s spring systems, including Jackson Blue Spring and Merritt’s Mill Pond in Jackson County. Merritt’s Mill Pond is a 4-mile long, 270-acre pond located near Marianna, and it is a popular regional destination for swimming, boating, kayaking, and fishing in the Panhandle. Its main source is Jackson Blue Spring, which produces, on average, more than 70 million gallons of water each day. Excessive growth of aquatic plants and algae in the pond during summer reduces the area available for swimming and boating. In 2014, FDEP began working with agricultural producers, residents, developers, local government officials, and other stakeholders to identify nutrient contributions in the Merritt’s Mill Pond watershed and develop an action plan to reduce nutrients entering the pond in the coming decades. Collaborations with stakeholders help to improve the accuracy of pollutant estimates, and to ensure the plan is designed appropriately to achieve desired ecological outcomes.

This Action Plan for reducing nutrients into Merritt’s Mill Pond provides an opportunity for land managers to implement their own plans to reduce nutrient contributions without FDEP imposing rigid regulations or mandating particular actions. People can choose from an array of Best Management Practices designed to reduce nutrient contributions, and the state has made funds available for people to help implement these plans. Implementing this Action Plan will restore the wonders of Merritt’s Mill through the 21st Century.

This article was written by: Matthew J Deitch, PhD,  Assistant Professor, Watershed Management with the UF IFAS Soil and Water Sciences Department at the West Florida Research and Education Center. For more information, you can contact him at or 850-377-2592.


Restoring the Health of Pensacola Bay, What Can You Do to Help?  – Bioaccumulation of Toxins

Restoring the Health of Pensacola Bay, What Can You Do to Help? – Bioaccumulation of Toxins

What is bioaccumulation of toxins?


Our bodies come in contact, and produce, toxins every day. The production of toxins can result during simple metabolism of food.  However, our bodies are designed with a system to rid us of these toxins.  Toxins are processed by our immune system and removed via our kidneys.  Some chemical compounds are structured in a way that they are not as easily removed, thus they accumulate in our bodies over time, often in fatty tissues, and sometimes they are toxic – this is bioaccumulation.

A view of Pensacola Bay from Santa Rosa Island.
Photo: Rick O’Connor

Biomagnification takes it a step further. In many cases, the concentrations of bioaccumulating toxic substances in the water may be in low enough concentrations to have little effect on human health.  They are ingested by small organisms in the environment, such as plankton or juvenile marine fish, and – again are at low concentrations.  However, they are accumulated in their tissues and as the next level of the food chain begin to consume them – they too accumulate the toxic compounds in their tissues.  Small fish consume large amounts of plankton and thus, large amounts of the toxins they have accumulated – increasing the concentration within their own tissues.  This continues up the food chain to a point where, in the larger predators, the concentrations of these toxins have increased enough that they now pose a threat to human health – this is biomagnification.


The presence, and amount, of any one bioaccumulating compound varies with species, their size, their age, their gender, their life stage, whether they are mobile or not, their diet, and whether the sample included the skin (which is lipid heavy and a common location for accumulated toxins). In the Pensacola Bay System, about 30 species of marine plants and animals have been analyzed for the presence of these accumulating compounds.


Species collected from Pensacola Bay that were analyzed for contaminants

Plants 3 species of seagrass

1 species of seaweed

Colonized algal periphyton

Invertebrates 4 species of freshwater mussels

Eastern oyster

1 species of brackish water clams

1 species of barnacle

Several species of shrimp

Blue crab

Oyster drill (snail)

Vertebrates 2 species of catfish

5 species of scaienids (drums, croakers, trout)



Several species of flounder

2 species of jacks

Largemouth bass


Striped mullet


Trace Metal Accumulation

Much of what has been studied in terms of metal accumulation has come from shellfish – particularly eastern oysters. Ten different metals have been found in oysters with zinc being in the highest concentration and lead the lowest.  A 2005 study found that levels of arsenic, lead, and nickel collected from mussels collected at selected locations in the PBS were regionally high (meaning higher than other estuaries in the region).  Another study (2003) found that levels of 16 different metals in shellfish were three times higher in Bayou Chico than samples from East Bay.  A 1993 study found that organisms attached to pieces of treated wood in Santa Rosa Sound had elevated levels of metals.  However, another study (2008) found low concentrations of metals in five species of fish collected in Escambia Bay near the I-10 Bridge.


The bioaccumulation potential within plants is less understood than animals. That said – concentrations within seagrass were relatively low when compared to the sediments they were growing in and periphytic algae attached to them.


Total Mercury Concentrations (ng/g – dry weight) for Local Marine Organisms

Lewis and Chaney (2008)

Range (ng/g) Species
0-200 Sediments, seagrass, oysters
200 – 400 Periphytic algae
400 – 600 Mussels
600 – 800 Brackish clams, blue crabs
800 and higher Fish


The above table shows biomagnification.


Comparing trace metal concentrations between Pensacola Bay and other Regional Estuaries

(USEPA unpublished data)

Pensacola Bay, Escambia Bay, Escambia River, Bayou Texar, Bayou Chico, Bayou Grande, Santa Rosa Sound Grand Lagoon (Bay Co.), Mississippi Sound, Old River, Suwannee River, Withlacoochee River, Bay La Launch
Cadmium Higher in PBS; highest in Bayou’s Grande and Texar
Chromium Similar to other estuaries
Copper Slightly elevated in Bayou Chico and Escambia River; highest in Withlacoochee
Total Mercury Much higher in PBS; particularly in the bayous
Nickel Lower in PBS
Lead Higher in PBS; particularly in the bayous
Zinc Higher in PBS; particularly in the bayous


There are higher concentrations of trace metals in PBS and particularly in the bayous.


One of 39 stormwater drains into Bayou Texar.
Photo: Rick O’Connor

Non-Nutrient Organic Chemicals

These are compounds such as PCBs, DDT, and PAHs; many are actually families of multiple forms of compounds. Information on the bioaccumulation of these compounds in PBS is less common than those of trace metals.  However, this information is important since they have long half-lives and magnify within the food web.


That said – there are studies on these compounds that go back to the 1970’s. They looked at DDT, pesticides, and PAHs in oysters and croakers.  One study (1986-96) found DDT concentrations in oysters at 60 ppb or less.  A follow up study (2004-05) at those same locations found concentrations between 8-20 ppb.  One study (2008) found the order of accumulating non-nutrient organic compounds with PAHs as the highest and dieldrin at the lowest.  Downward trends were reported (2004-05) for many of these compounds including PAHs and PCBs.


Some of these compounds have entered the PBS via unlined ponds associated with on-land Superfund sites. Creosote and pentachlorophenol were stored for years in such ponds and have leached into area waters such as Bayou Chico and portions of upper Pensacola Bay.  A study (1987-88) found oyster drills sampled in these areas had concentrations 10x higher than reference sites in other parts of the PBS.


So what can we do about this?


The compounds that are there – are there. Many of these trace metals are heavy and sink into the sediments.  There occurrence within the food web has decreased over time and some have suggested the safest thing to do is to leave them where they are.  No doubt, any project requiring sediment movement requires much review and permitting.

To try to remove these compounds would be extremely expensive – hence the Superfund Program. So if we cannot clean the sediments without a lot of labor and money, can we reduce the amount that enters the bay today?

Many of these compounds come from industrial processing of products we really want or need. Reduction of the production of some will be difficult, but there is much industry can do to reduce the chance of those compounds reaching our estuaries – and they are doing this.  Point source pollution (direct discharge from an industry) has reduced significantly since the 1970’s.  Non-point sources (indirect discharge from you and I) is still a problem.  We can choose products that contain less (or none) of the compounds we discussed.  Following an IPM program for dealing with household and lawn pests (see article on Florida Friendly Yards – can help a lot.  As can practices that reduce the amount of run-off reaching our bays.  Reducing your use of lawn watering, using rain barrels, or rain gardens, and planting living shorelines (all mentioned in the FFY article) can certainly help.




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.