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)

Bluegill

Bluefish

Several species of flounder

2 species of jacks

Largemouth bass

Sheepshead

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 – https://blogs.ifas.ufl.edu/escambiaco/2018/06/08/restoring-the-health-of-pensacola-bay-what-can-you-do-to-help-a-florida-friendly-yard/) 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.

 

Reference

 

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.

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

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

In the mid 1990’s, the Bay Area Resource Council was created. This multi-county (Escambia and Santa Rosa) organization included local scientists and decision makers to help better understand the health of Pensacola Bay, develop a plan for restoration, and work collaboratively to acquire funding to do so.  At the inaugural meeting, many different scientists spoke on a variety of topics.  There were several take-home messages – one of them was that sediments of Pensacola Bay were in poorer health than the water within the water column above it.

Grabs are used by marine scientist to collect samples of sediments from the bottom of the bay.
Photo: Coastal Science NOAA

So, what is wrong with the sediments, and how has this changed since the mid ‘90’s?

 

Based on sediment sample analysis, some researchers consider the Pensacola Bay System the most polluted in the state of Florida… but not everyone. The three bayous (Chico, Texar, and Grande), Escambia Bay, and the downtown waterfront of Pensacola Bay had some of the poorest sediment samples within the system.  Contaminants monitored include trace metals, mercury, non-nutrient organics, pesticides, and dioxins.   These contaminants are dense and do not remain in the water column long.  Instead, they sink into the sediments.  At that time, some suggested that attempts to remove the contaminants could increase their levels within the water column and do more harm than good – thinking it would be better to leave the sediments as they are.  Many of the compounds entered the estuary through run-off.  In some cases in the past, they were discharged directly into a bay or river.

 

Chemicals found in Pensacola estuarine sediments include Arsenic, Zinc, and Copper. Mercury levels at some locations in the bay are higher than other estuaries around the northern Gulf region.  Some non-nutrient organic compounds were not as high as other local estuaries however; bioaccumulation (the increase in contaminant concentrations via the food chain) has been occurring and should be monitored.  Many chemical compounds banned in the 1970’s have long half-lives and are still detected in the sediments today.  Chlorinated pesticides, such as dieldrin, chlordane, DDE, DDD, and DDT are still found in the bayous – and at higher concentrations than neighboring estuaries.

 

This all sounds bad, but are the levels high enough to be toxic to marine organisms?

Herbicides and pesticides can find their way into estuarine systems and contaminate the sediments.
Photo: UF IFAS Washington County Extension

One location, in upper Bayou Texar, seems to be quite toxic to the species of bacteria, invertebrates, fish, and plants tested. These toxic concentrations are partially from chemicals present in run-off, but there is also seepage coming from groundwater contaminated from a nearby Superfund site.  Most of the test suggest that the lethal concentrations are more chronic in nature than acute.

 

So what can be done? What can we do?

 

Well… removing and treating these sediments is quite expensive and is not an option at this time. There are plans to dredge portions of Bayou Chico but the process has undergone extensive scrutiny and permitting.  One thing we can do is reduce the amount that is still entering the bay.  How do we do this?

  • Consider re-landscaping your yard to be “Florida Friendly”. Using the suggestions given within this University of Florida program (http://fyn.ifas.ufl.edu/) you can reduce the amount of fertilizer, herbicide, and pesticides you use – thus reducing the amount entering the estuaries.
  • Florida Friendly Landscaping practices can also reduce the amount of watering your lawn needs. This reduces the amount of run-off reaching the bay and always reduces the amount of money you spend on watering and lawn chemicals.
  • The Florida Department of Environmental Protection’s Clean Boater program provides tips and suggestions that reduce the amount of hazardous chemicals that enter the bay from cleaning and maintaining vessels. https://floridadep.gov/fco/cva/content/clean-boater-program.

The sediments of the bay have suffered the abuse of the past. However, with better practices, we can reduce our impact in the future.

Florida Friendly Landscaping saves money and reduces our impact on the estuarine environment.
Photo: UF IFAS

Reference

 

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.

Restoring the Health of Pensacola Bay, what can you do to help? Biodiversity

Restoring the Health of Pensacola Bay, what can you do to help? Biodiversity

Records of the variety of aquatic life in Pensacola Bay go back to the 18th century.  According to these reports, over 1400 species of plants and animals call Pensacola Bay home.  Many of them depend on seagrass, oyster reefs, or marshes to complete their life cycle.  The greatest diversity and abundance are found on the oyster reefs.  Finfish and shellfish in the bay have sustained humans as a food source for centuries.  However, we know that the alligator, turtles, and a variety of birds and mammals have also been important.  In this article, we will focus on the aquatic species.

Red Drum – photo credit Florida Fish and Wildlife

When people think of aquatic life in the bay, they first think of fish. About 200 species call Pensacola Bay home.  The most abundant are the true estuarine fish, such as croakers, sardines, and minnows.  There are a variety of marine transient fish that can be found such as jacks, mackerels, and some species of sharks.  Spot and Atlantic Croaker are the most abundant members of the croaker family, and are still an important target fish for locals.  Anyone who has snorkeled or cast a line with cut bait knows how common pinfish can be, and those who have pulled bait nets are very familiar with the silverside minnows and anchovies.

 

I have pulled many a seine net over the years assessing the diversity and abundance of the nearshore fish populations and logged 101 species. In addition to those listed above, killifish (also locally known as “bull minnows”) are a common capture.  For a few years, we were involved in trawling in deeper waters where we collected a variety of flounder, silver perch, grunts and snapper.  Sea robins are an interesting member of our community and gag grouper were captured occasionally.  The number and variety of fish found varies with seasons and is greatest in June.  The diversity and abundance of estuarine fishes in our bay is very similar to neighboring estuaries.

 

The second thing people think of when they think of aquatic life in the bay are shellfish. These would include the crabs, shrimp, and oysters.  However, the most abundant macro-invertebrates in our bay are those that can tolerate environmental stress and live in the surface layers of the sediments – these are the worms and crustaceans.  There are numerous varieties of segmented polychaete worms, who are famous for building tunnels with “volcano” openings.  They are also common within oyster reefs, feeding on all sorts of organic debris.  Blue crab are common throughout the bay and provided both a commercial and recreational fishery for years.  Brown and white shrimp are both found and have been the most popular seafood with locals for years.

The famous blue crab.
Photo: FWC

During my lifetime, the only marine mammal commonly seen has been the Atlantic Bottlenose Dolphin, and these are found in many parts of the bay. Years back, I heard accounts of harbor porpoise, but never actually saw one.  An historic occurring marine mammal, who seems to be making a comeback, is the Florida Manatee.  Sightings of this animal have been reported in a variety of locations in recent years.

 

Snakes, turtles, and alligators are all found in the bay area. There is really only one saline snake and this is the gulf coast salt marsh snake.  However, nontraditional estuarine snakes, such as the cottonmouth, are becoming more common in and near the bay.  Though we have a great variety of turtles in our rivers, only one true estuarine turtle exist in the country, the diamondback terrapin – and this turtle can be found in parts of our bay.  Sea turtles do venture into the bay searching for food, particularly the green turtle who is fond of seagrasses.

 

Many forget the small planktonic animals that drift in the water column, but they are there – about 100 species of them. Copepods are small roach looking crustaceans that are by far the most abundant member of the zooplankton, particularly the species known as Acartia tonsa – which makes up 82% of the abundance in our bay.  These small animals are an important link in the food chain of almost every other member of the bay community.  The zooplankton variety in Pensacola Bay is very similar to those of neighboring estuaries.

 

And then there are the plants…

By far, the most diverse group of organisms in the bay are the microscopic plants known as phytoplankton – with over 400 species reported. Much of the bay is too deep to support traditional forms of plants and so these become a key producer of food for many species.  The diversity and abundance is greatest in the spring and fall.  70% of the phytoplankton are from a group called dinoflagellates, small plants that have two hair-like flagella to orient, and even propel, themselves.  Some of them produce the bioluminescence we sometimes see and others produce what we call red tide.  During the summer, the populations change and the more abundant forms are diatoms.  These lack the flagella of the dinoflagellates, but they do produce beautiful shells of silica.

There are at least 400 species of periphytic algae (attaching). Green algae are the most abundant and are most common in the local bayous.  Cyanobacteria, which were once thought to be algae, are the most abundant in the marshes and periphytic diatoms dominate in the Sound.

 

And last, are the submergent and emergent grasses.

Submergent grasses are known as seagrasses. We have three species that like the higher saline waters.  These are turtle, shoal, and widgeon grass.  Turtle and shoal grass need the water to be at least 25 parts per thousand and are the dominate species in the lower portions of the bay.  Widgeon grass can tolerate waters as low as 10 ppt and are found in the bayous and the upper portions of the bay system.  Tapegrass only survives in freshwater and are found in the lower reaches of the rivers where they meet the bay.

Emergent grasses are what we call marsh grasses. Two species, Black Needlerush and Smooth Cordgrass dominate these.  There are pockets of salt marshes found all over the bay system.

 

So how is the health of our aquatic life?

As you might expect, the diversity and abundance have declined over time, particularly since the 1950’s. One firsthand account of the change, describe a bayou that was clear, full of grass, and harbored shrimp the size of your hand.  Then they were gone.  He remembered the first change being water clarity.  As development along our waterfront increased, the clarity decreased and the aquatic life declined.  This has happened all over the bay system.  Increase in run-off not only brought sand and sediment lowering water clarity, it also brought chemicals that both the plants and animals could not tolerate.  Much of the point source pollution has been controlled but non-point pollution is still problematic.  Fertilizers, pesticides and herbicides, oils and grease, and sediment have all been problematic.  These can be reduced.  Following recommendations from the Florida Friendly Landscaping website, (http://www.floridayards.org/.) property owners can alter how they are currently managing their landscape to reduce their impact on the aquatic life on the bay.  Clean Marina (https://floridadep.gov/fco/clean-marina ) and Clean Boater (https://floridadep.gov/fco/cva/content/clean-boater-program ) recommendations can help reduce the impact from the boating community.  Sustainable fishing practices, such as safe catch and release methods for unwanted fish and removing all monofilament are good practices.  In 2019, Sea Grant will begin a program training local citizens how to monitor the diversity and abundance of aquatic species.  If interested in volunteering, stay tuned.

 

Reference

 

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.

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? Introduction

Humans have inhabited the shores of Pensacola Bay for centuries. Impacts on the ecology have happened all along, but the major impacts have occurred in the latter half of the 20th century.  There has been an increase in human population, an increase in development, a decrease in water clarity, a decrease in seagrasses, and a decrease in the abundance of some marine organisms – like horseshoe crabs, scallops, and some marine fishes.  There has also been an increase in inorganic and organic compounds from stormwater run-off, fish kills, and health advisories due excessive nutrients and fecal bacteria in local waters.

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

Since the 1970’s, there have been efforts to help restore the health of the bay. Seagrasses have returned in some areas, fish kills have significantly reduced, and occasionally residents find scallops and horseshoe crabs – but there is still more to do.  In this series of articles, I will present information provided in a recent publication (Lewis, et. al. 2016) and from citizen science monitoring.  We will begin with an introduction to the bay itself.

 

The Pensacola Bay System is the fourth largest estuarine system in the state of Florida. The system includes Blackwater, Escambia, East, and Pensacola Bays.  There are numerous smaller bayous, such as Indian, Mulat, and Hoffman, and three larger ones, which include Texar, Chico, and Grande.  There are two lagoons that extend east and west of the pass.  To the west is Big Lagoon and to the east is Santa Rosa Sound.  The surface area of this bay system is about 144 mi2 and the coastline runs about 552 miles in length.  There are four rivers that discharge into the system: the Escambia, Blackwater, Yellow, and East Rivers.  The majority of watershed is in Alabama and covers about 7000 mi2.  The mouth of the bay is located at the Pensacola Pass near Ft. Pickens and is 0.5 miles across.  Depending on the source, the flush time for the entire bay has been reported between 18 and 200 days.

 

There are several ecosystems found within the bay system. Seagrasses are be found throughout the bay and bayous, but are more prevalent in Big Lagoon and Santa Rosa Sound.  Oyster reefs have provided income for some in the East Bay area in the past, but production has declined in the last 50 years.  Salt marshes are found throughout the bay as well, but the greatest acreage is in the Garcon area of Santa Rosa County.  There are, of course, freshwater marshes near the mouths of the rivers with the largest being at the mouth of the Escambia River.

Members of the herring family are ones who are most often found during a fish kill triggered by hypoxia.
Photo: Madeline

Members of the drum family are one of the more common fishes found in the system and would include fish like the Spot and Atlantic Croaker. However, speckled trout, striped mullet, redfish, several species of flounder, have also been targets for local fishermen.  Target fish include sardines, silversides, stingrays, pinfish, and killifish.  Brown shrimp, oysters, and blue crab have historically provided a fishery for locals, but other invertebrates include several species of jellyfish, stone crabs, fiddler crabs, hermit crabs, grass shrimp, several species of snails, clams, bay squid, octopus, and even starfish.  There is also a variety of benthic worms found within the sediments.

A finger of a salt marsh on Santa Rosa Island. The water here is saline, particularly during high tide. Photo: Rick O’Connor

There has been a decline in overall environmental quality since 1900 but, again, the biggest impacts have been between 1950 and 1970. Fish kills, a reduction in shrimp harvest, and hypoxia (a lack of dissolved oxygen) have all been problems.

 

In the articles to follow we will look deeper into specific environmental topics concerning the health of Pensacola Bay.

 

 

References

 

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.

Panhandle Estuaries – National Estuaries Week

Panhandle Estuaries – National Estuaries Week

Humans have been settling on, and around, coastal estuaries since they first arrived in the panhandle over 10,000 years ago. These bodies of water have provided food and recreation as long as anyone can remember.  They are a magnet for those looking to build homes or businesses – and we continue to be attracted to them today.

Black Needlerush is one of the species of marsh grasses that live in brackish conditions.

Black Needlerush is one of the species of marsh grasses that live in brackish conditions.

Estuaries are defined as semi-enclosed bodies of water where fresh and sea water mix.  The point where the freshwater enters is called the head of the bay; the point where seawater enters is called the mouth. Seawater is denser than freshwater so during incoming tides the saline water tends to “wedge” it’s way into the upper estuary along the bottom.  Under certain conditions, it is possible to catch freshwater fish near the surface and marine species on the bottom at the same location.  The mixture of fresh and seawater makes for an interesting cocktail of salinities termed brackish water – which is required for the development of almost 90% of the commercially valuable seafood species we enjoy.  This ecosystem supports stands of vegetation which are also important in the development of some species – some of these systems are the most biologically productive on the planet.

 

We are lucky to have several large estuaries along the Florida panhandle. All of our bays are what are called drowned river valleys.  Most are very wide and pretty shallow, with the highest average depth being 17 feet in Choctawhatchee Bay.  The rivers that feed these estuaries begin in states north of us and bring with them needed freshwater and nutrients.  Each of the panhandle estuaries is unique and provides different resources for their neighboring communities.  Below is a breakdown of some of these characteristics.  This information was provided by GulfBase.org.

 

Bay Surface Area (km2) Drainage Area (km2) Avg. Daily Inflow (m3/sec) Avg. Depth (m) Avg. Salinity (ppt) Area of Wetlands (km2) Area of Submerged Vegetation (km2)
Perdido 130 3,100 62 3.0 15 688 ND
Pensacola 370 18,100 328 4.0 23 991 32
Choctawhatchee 334 14,000 241 5.0 25 1,133 12
St. Andrews 243 2,800 127 4.0 31 1,016 53
St. Joseph    ND
Apalachicola 554 53,100 824 3.0 22 2,396 36
Apalachee 412 11,900 150 3.0 30 2,813 130

 

You can see some of our estuaries have large areas and tremendous amounts of freshwater inflow. Others not so much, the bays with less freshwater inflow have higher salinities – and support a different ecology than the others.  Is one better than the other?… no… certainly our ancestors understood this.  Higher salinities meant more seagrass, scallops, and urchins – certain species of fish and maybe even marine turtles could be found here.  Lower salinities meant a different group of fish, oysters, and crabs.  It’s all good!  Residents should benefit from what the bay provides – and not try to make “your bay” more like “another bay”.

 

They have suffered some over the years – discharge containing organic and inorganic chemicals have tainted some drinking water supplies as well as reduce valuable aquatic resources. Increased sediments from development have darkened the waters reducing light and reducing submerged plants.  Heavily fishing and recreation have impacted both the habitats and the species that inhabit them.  Through the efforts of universities, government agencies, non-profit organizations, and private citizens many of the problems have been addressed – and recovery is occurring… but there is still more to do.

 

National Estuaries Week is a chance for all who live in the panhandle to realize how important these bodies of water are to our locally economy and to our quality of life. We hope you will appreciate them and do your part to help protect them. HAPPY NATIONAL ESTUARIES WEEK!