The Deepwater Horizon (DWH) oil spill occurred about 50 miles offshore of Louisiana in April 2010. Approximately 172 million gallons of oil entered the Gulf of Mexico. Five years after the incident, locals and tourists still have questions. This article addresses the five most common questions.
QUESTION #1: Is Gulf seafood safe to eat?
Ongoing monitoring has shown that Gulf seafood harvested from waters that are open to fishing is safe to eat. Over 22,000 seafood samples have been tested and not a single sample came back with levels above the level of concern. Testing continues today.
QUESTION #2: What are the impacts to wildlife?
This question is difficult to answer as the Gulf of Mexico is a complex ecosystem with many different species — from bacteria, fish, oysters, to whales, turtles, and birds. While oil affected individuals of some fish in the lab, scientists have not found that the spill impacted whole fish populations or communities in the wild. Some fish species populations declined, but eventually rebounded. The oil spill did affect at least one non-fish population, resulting in a mass die-off of bottlenose dolphins. Scientists continue to study fish populations to determine the long term impact of the spill.
Question #3: What cleanup techniques were used, and how were they implemented?
Several different methods were used to remove the oil. Offshore, oil was removed using skimmers, devices used for removing oil from the sea’s surface before it reaches the coastline. Controlled burns were also used, where surface oil was removed by surrounding it with fireproof booms and burning it. Chemical dispersants were used to break up the oil at the surface and below the surface. Shoreline cleanup on beaches involved sifting sand and removing tarballs and mats by hand.
QUESTION #4: Where did the oil go and where is it now?
The oil spill covered 29,000 square miles, approximately 4.7% of the Gulf of Mexico’s surface. During and after the spill, oil mixed with Gulf of Mexico waters and made its way into some coastal and deep-sea sediments. Oil moved with the ocean currents along the coast of Texas, Louisiana, Mississippi, Alabama, and Florida. Recent studies show that about 3-5% of the unaccounted oil has made its way onto the seafloor.
QUESTION #5: Do dispersants make it unsafe to swim in the water?
The dispersant used on the spill was a product called Corexit, with doctyl sodium sulfosuccinate (DOSS) as a primary ingredient. Corexit is a concern as exposure to high levels can cause respiratory problems and skin irritation. To evaluate the risk, scientists collected water from more than 26 sites. The highest level of DOSS detected was 425 times lower than the levels of DOSS known to cause harm to humans.
Maung-Douglass, E., Wilson, M., Graham, L., Hale, C., Sempier, S., and Swann, L. (2015). Oil Spill Science: Top 5 Frequently Asked Questions about the Deepwater Horizon oil spill. GOMSG-G-15-002.
An estimate of what happened to approximately 200 million gallons oil from the DWH oil spill. Data from Lehr, 2014. (Florida Sea Grant/Anna Hinkeldey)
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Giant Salvinia mats completely covering Bay County pond. This fast growing invasive can double in size every week! Photo by L. Scott Jackson
Matthew Phillips and Scott Jackson –
UF/IFAS Extension and Research works with many partners supporting invasive species management actions and strategies across Florida. One key partner is the Florida Fish & Wildlife Conservation Commission (FWC), Invasive Plant Management Section. FWC Biologists provide resources and expertise to address threats from Florida’s most disruptive invasive species. FWC and UF/IFAS have worked together for years. They have teamed-up to help residents make the best cost-effective management decisions to preserve unique habitats and ecosystems. Most days are filled with routine questions from land managers and pond owners but on rare occasions there are days we will never forget.
Active growing Giant Salvinia was observed growing out of the pond water on to moist soils and emerging cypress and tupelo tree trunks. Photo by L. Scott Jackson
Giant salvinia (Salvinia molesta) is an invasive free-floating aquatic fern from South America that is rarely observed in Northwest Florida. The species is on the Federal Noxious Weed List and the Florida Prohibited Aquatic Plants List. After a site visit with a pond owner, Scott Jackson, a University of Florida/IFAS Extension Agent, identified Salvinia molesta in the Bay County pond and notified the Florida Fish and Wildlife Conservation Commission’s (FWC) Invasive Plant Management Section. Their staff confirmed the identification of the specimen and a second voucher specimen was transferred to the Godfrey Herbarium at Florida State University.
Giant salvinia has caused severe economic and environmental problems in Texas and Louisiana and in many countries including New Zealand, Australia, and South Africa. Giant salvinia grows rapidly and produces a dense floating canopy on the surface of ponds, lakes, and rivers. It aggressively spreads by vegetative fragments and thrives in slow-moving, nutrient-rich warm fresh water. Floating mats of giant salvinia shade out native submersed vegetation and degrade water quality.
Mats also impede boating, fishing, swimming, and clog water intakes for irrigation and electrical generation.1 Salvinia molesta has been listed in The World’s Worst Weeds – Distribution and Biology2 since 1977. It was recently added to 100 of the World’s Worst Invasive Alien Species, an all taxa list compiled by invasion biologists with the Global Invasive Species Database.3
Photo by Barry Rice, sarracenia.com, Bugwood.org Rows of egg beater or light bulb shaped leaf hairs are a unique identifying characteristic of giant salvinia.
The location of the giant salvinia infestation found by Jackson is precariously close to Deer Point Lake, a 5,000 acre water body that is the main source of drinking water for Panama City and surrounding Bay County. The 2.5 acre infestation was on a 3.6 acre divided pond and both sections were treated. Treatment of the infestation was initiated by FWC in June 2013 at no expense to the property owners.
Bay County pond with no observed Giant Slavinia. Taken Oct 2013 by Derrek Fussell, FWC.
The pond continues to be monitored and, to date, there have not been any signs of living Salvinia molesta. We will continue to monitor the pond to make sure there is no re-establishment of giant salvinia. Investigations continue to try and learn more about the introduction of the pernicious species to this isolated pond.
Read more about the successful treatment regime FWC Biologists used to control giant salvinia in Northwest Florida. This was published in Florida Aquatic Plant Management Society’s publication “Aquatics” – see page 5.
This is a question I have been asked several times in the last week. As most of you know the red tide that has been occurring off the panhandle the last few months is still around. Dead fish were reported on Pensacola Beach again the weekend of Dec 12-13 and a few people said they were having eye and throat problems. This weekend I received a call of dead fish inside the bay but the caller was not suffering from eye and throat issues. Its December… what’s going on?
The dinoflagellate Karenia brevis. Photo: Smithsonian Marine Station-Ft. Pierce FL
Well let’s look again at what red tide is and what facilitates the bloom. Red tide is caused by small microscopic plants called dinoflagellates. Dinoflagellates, like all plants, develop defense against herbivores that may try and feed on them. A few of these dinoflagellates release toxins when disturbed as a defense. They are in the Gulf all of the time but usually in low numbers, maybe 300 cells per liter of water, and cause no problems. But when conditions favor growth and reproduction they do just that – grow and reproduce – in great numbers, maybe 3000 cells per liter. When this happens the water actually darkens with their presence and the amount of toxin they release increases due to the increase number of cells – now marine creatures other than those that feed on them are impacted by the toxin – this is a red tide.
So, what are these conditions?
Well, like all plants dinoflagellates like sunlight, warm temperatures, and nutrients (fertilizers). So you would think that these blooms would occur when most plants grow – summer… and you would be right. There is another condition that contributes and those are currents. If currents are strong it will spread the bloom and the concentrations are spread as well, lowering the concentration per liter of water and thus reducing or diminishing the red tide.
We generally have plenty of sunshine here in the panhandle – temperatures are relatively warm, though they are warmer in south Florida – and there are nutrients. Nutrients are available naturally in the Gulf but are increased when we have a lot of rain as the runoff brings nutrients from land. But remember red tides are not always the result of human pollution – they occur naturally but can be increased or extended with excess nutrients from human runoff. The currents here along the panhandle tend to keep red tides at bay most of the time – we do not see them often here, but that is not the case with southwest Florida. In the Port Charlotte area red tides are more common part of life. It is warmer, there is more agriculture and municipal nutrients entering the Gulf, and the currents there are slower/weaker than we have here.
So what is up in the panhandle this year?
Well the sun is still shining! Feels great out there actually. The water temperatures were in the upper 60’s inside Pensacola Bay this week and that is typical, but the Gulf is still in the 70’s, and that is typical as well. What is not typical is the warmer air temperatures. This will slow the temperature drop of the Gulf and allow plants to extend their non-dormant season. H2O is a polar molecule(has an electric charge) and so the molecules are bonded together like two magnets. Because of this it takes more heat (energy) to warm the water and so area waters warm at a slower rate than the air. If the air temperatures remain warm it will be longer before the Gulf cools down. These warmer temperatures may extend the red tide a bit longer. As far as nutrients, heavy rains in October and November probably supplied more food for the plants and contributed to the beginning of the tide. Currents pushed the red tide inshore where we began to experience the eye problems and fish kills. The north winds from the recent fronts passing through may generate upwellings in the Gulf. Upwellingsare currents that bring water from the ocean floor to the surface, this would bring nutrients with it. So we still have sun, warm temperatures, and nutrients – and the bloom is still with us. What will reduce the problem will be wind and currents to drive it offshore… and time – the Gulf will eventually cool and the tide will be reduced. How long is anyone’s guess.
Many coastal Panhandlers woke up this week to the sight and smell of dead fish. Thousands of them washed ashore from Panama City to Pensacola. This mass die off included a variety of species including whiting, sheepshead, hake, cusk eels, and even lionfish; there were also reports of dead bass from the Dune Lakes in Walton and Okaloosa counties. What caused this mass die off of fish?
The suspect is red tide…
Most of us along the panhandle have heard of red tide but we may not know what it is or what causes it. Many attribute the red tide events to human impacts, stormwater runoff etc., but in fact they have been around for centuries. There are records suggesting that the European colonials experienced them and I have read one account that the Red Sea got its name from the frequency of these events there. So what is this “red tide” and what causes it?
Dead fish line the beaches of Panama City. Photo: Randy Robinson
It is actually a bloom of small single celled plants called dinoflagellates. There are thousands of species of dinoflagellates in the world’s oceans and not all cause red tide, but there are several species that do. These small microscopic plants drift near the surface of the ocean acquiring sunlight to photosynthesize. They possess two small “hairs” called flagella (hence the name “dinoflagellate”) to help orient themselves in the water column. Most have a shell covering their body called a theca and some shells have small spines to increase their surface area to resist sinking. One method of defense found in some dinoflagellates is the production of light – bioluminescence. This light is produced by a chemical reaction triggered by the creature as a flash of blue – many locals refer to it as “phosphorus”. Other dinoflagellates instead will release a toxin… some of these are ones we call “red tide”.
Red tide organisms are always in the water column of marine environments but are usually in low concentrations, maybe 300-500 cells per milliliter of water. But under favorable conditions, warm water with nutrients, they multiple… sometimes in great numbers, such as 3000-5000 cells/ml, and we have a “bloom”. The number of cells within these blooms can be high enough that we can actually see the water change color… hence “red tide”.
The dinoflagellate Karenia brevis. Photo: Smithsonian Marine Station-Ft. Pierce FL
The most common red tide dinoflagellate associated with the Gulf of Mexico is Karenia brevis. Karenia blooms typically form offshore and are of little impact to the coastal communities. However when the wind and tides are right these blooms will drift towards shore. When they do fish kills occur and humans have eye and throat irritations. Marine mammals in particular struggle with red tide. As the bloom comes near shore it reaches the bottom of the water column and many of the bottom dwelling fish suffer. Most of the photos of fish I saw in the October 2015 fish kill were bottom dwellers, including many invasive lionfish.
Is there anything we can do to prevent red tides?
Not really… Again, they are naturally occurring event. We may increase the frequency of the events by discharging excessive nutrients into the water from our run-off but they would probably occur anyway. Red tide events are not as common in the panhandle as they are in southwest Florida. The Gulf waters near Charlotte Harbor are shallow, warm, and near the many manicured lawns, gold courses, and the discharge of much of the agriculture in the state. Occasionally blooms formed in that part of the state drift north but this year a bloom formed off of Bay and Gulf counties in early October. The recent storm that passed through probably pushed the bloom inland and to the west. The biggest hazard of humans is eye, throat, and skin irritation. It is quite uncomfortable to be around these blooms. In 1996 a local bloom was concentrated enough that the campground at Ft. Pickens had to be closed. I was in Galveston Texas when I heard about the red tide occurring in the Florida panhandle. As I was leaving Galveston the newspaper reported the closer of all oyster harvesting in Texas due to a red tide generated in the Padre Island area and was moving north. Seems that red tide is covering a large portion of the Gulf coast the last week of October. That said… anything communities can do to reduce nutrient runoff will certain decrease the frequency of red tides.
The carcass of the invasive lionfish was part of the October red tide kill. Photo: Shelly Marshall
The Florida Fish and Wildlife Conservation Commission post red tide updates from around the state on their website and the Escambia County Extension Office post a local water quality update each Friday that has red tide information as well.
The red area indicates where dissolved oxygen levels are low.
I don’t want this to sound like a “Debbie Downer”… but there are problems with our estuaries and panhandle residents should be aware of them. There are things you can do to correct them – which we will discuss in the final issues of this series – but you need to understand the problem to be able to solve it. Unfortunately there are many issues and problems our bays and bayous face and we do not have time in this short article to discuss them all, but we will discuss some.
We’ll start at the top… with our rivers. Since the founding of our nation many communities were built on estuaries; those that were not were built on the rivers. Water was an easy way to move throughout the country – much easier than wagon crossing over the Appalachians or through a bog. There are several communities that developed along the rivers that feed the panhandle bays. Though the situation has improved in the last few decades, most of these communities have used these rivers as a place to dump their waste. Assorted chemicals, sewage, and solid waste were discharged… and it all came down to us. The Mississippi River is an example of this problem. Discovered in the 1990’s the Louisiana Dead Zoneis an area in the Gulf where the levels of dissolved oxygen are so low that little or no life can be found on the ocean floor there. It is believed to be trigger by nutrients, chemical fertilizers and animal waste, being discharged upstream. These nutrients create a bloom of plankton, which can darken the water. Though thephytoplankton can produce oxygen during the daylight hours, they consume it in the evening, lowering the concentration of dissolved oxygen within the water column. The plankton are relatively short lived and eventually die. As the dead plankton fall out to the seafloor bacteria begin to decompose their bodies thus dropping the dissolved oxygen levels further. When the dissolved oxygen concentrations drop below 4.0 millgrams/liter we say the water is hypoxic (low in oxygen). Many species of aquatic organisms begin to stress. At 2.0 mg/L many species will die and we have a “dead zone”. If it reaches 0.0 mg/L we say the water is anoxic (without oxygen). This process is called eutrophication and not only a problem at the mouth of the Mississippi River, it occurs in almost all of the bays and bayous of the panhandle and is the primary cause of local fish kills.
A more recent issue with our rivers has been the reduction of water. In the so called “Water Wars” the state of Georgia has used its damn system to block the flow of the Chattahoochee River to create electricity and a reservoir of drinking water for river communities. Under normal conditions this has not created a problem however in recent years the southeast has experienced drought and the state of Georgia has had the need to hold back water for large communities – such as Atlanta. This has reduced the amount of water flowing towards the Gulf and has impacted communities all along the way. It is not the only issue but is the primary factor triggering the collapse of the oyster industry in Apalachicola. The reduced freshwater flow has increased salinities in the bay. This has disrupted the life cycle of the eastern oyster and has increased both predation and disease within these populations. Apalachicola produces over 90% of Florida’s oysters and 10% of the oysters for the entire country! Oysters are a huge industry in this town. Many are oystermen and many others process the product when it is landed… the industry is on the verge of collapsing. (Learn more).
Oysterman on Apalachicola Bay. Photo: Sea Grant
These are just some the issues stemming from the rivers… what about the issues initiated from the communities that live along the bay…
How about the seafood? We discussed the oyster industry in Apalachicola Bay but oyster production in other local bays has declined as well (for other reasons). Scallops are gone from many of their historic estuaries, shrimp and blue crab landings are down, this year mullet seem to be hard to find. What is going on here? For the most part the decline in seafood products can be tied to either a decline in water quality or from over harvesting. The harvesting issue is easy… do not harvest as much. However these fisheries management decisions impact many lives and has caused a lot of debate. First you need to determine whether the decline is due to overharvesting or some other environmental factor… easier said than done. Certainly the biology of your target species will give you an idea of how many animals you can remove from the system and sustain a healthy population (maximum sustainable yield) but this method has triggered debate as well. Most fishermen do not want to see the fishery collapse and are willing to work with fishery managers to assure this – but they do have bills to pay. Fishery managers have a responsibility to assure the fishery remain for current and future generations of fishermen and they are basing their decisions on the best available science. It is a touchy subject for many and a problem within our estuaries.
The other cause of declining seafood is poor water quality. You can talk to any “ole timer” and they will tell you about the days when the water was clearer, the grass was thicker, and the fish were more abundant… what happen? I spoke with my father-in-law before he passed away about the changes he saw in Bayou Texar in Pensacola. He remembers being able to see the bottom, more seagrass, and being able to catch a variety of finfish as well as shrimp the size of your hand. The first change he remembered was a change in water clarity… it became murkier… and this happen about the time they began to develop the east side of the bayou. As our communities grew more land was cleared for development. The cleared land allowed more runoff to reach the creeks, bayous, and bays. Infrastructure had to be placed to reduce flooding of yards and streets – Bayou Texar has 38 storm drains. All of this led to more runoff into our water ways. With the increase in turbidity the amount of sunlight reaching the bottom was reduced and seagrasses began to decline. Many species of seagrass require salinities of 25 parts per thousand or higher and the increase in freshwater runoff lowered the salinity which also stressed these grasses. Much of this runoff included sand and silt and the grasses were basically buried. All in all seagrasses declined… and with them many of the marine creatures. Salt marshes were removed for coastal developments, industries were located on our rivers and bays and introduced their chemical discharge, and boating activity increased… our estuaries were being literally “loved to death”. I have seen in my lifetime the decline of sea urchins and scallops from our bay, the increase in turbidity, and the decline of seagrasses. But we cannot blame all of this on habitat loss and pollution. Speaking recently with fisheries managers they believe the recent decline in blue crab landings is due to drought. Reduction in rainfall means reduction in river discharge, which means an increase in salinity and a disruption of the crab reproductive cycle.
Power plant on one of the panhandle estuaries. Photo: Flickr
Another problem that is associated with runoff has been the increase in bacteria. Fecal coliform bacteria are found in the stomachs of birds and mammals. They assist with our digestion and are released into the environment whenever we (or they) go to the bathroom. So finding fecal coliforms in the water is not unusual… the problem is TOO many fecal coliforms. As mentioned coliforms are not a threat to us but they are used as an indicator of how much waste is in the water. Feces harbors many other microbes in addition to coliforms – hepatitis and cholera outbreaks have been linked to sewage in the water. So agencies monitor for these each week. Most agencies will monitor for E. coliwhen sampling freshwater and Enterococcusin saline waters. E. coli values of 800 colonies / 100 milliters of sample or higher, and Enterococcus values of 104 colonies / 100 ml of sample will trigger a health advisory being issued – and some bodies of water being closed. In the Pensacola area the Florida Department of Environmental Protection and the Escambia County Health Department both monitor for bacteria. They post their results each week and I, in turn, post to the community. Our local bayous are averaging between 8-10 advisories each year. The problem with these advisories is that residents who live on the waterways, businesses (such as hotels and ecotours) who use the waterways become concerned about entering the water. It is not good for business or property values if the body of water you are on has high levels of bacteria and signs posting “no swimming”.
Closed due to bacteria. Photo: Rick O’Connor
There are many problems our estuaries are facing but for this article we will end with solid waste. Trash and garbage has been a problem since I can remember. Campaigns have been launched each decade to try and reduce the problem but the problem still exist. Plastics and monofilament litter the beaches and waterways creating problems for marine life and an “eye soar” for those enjoying the bay. I am currently working with the Wildlife Sanctuary of Northwest Florida and CleanPeace to monitor solid waste in Pensacola Bay. Each week CleanPeace host a Saturday event they call “Ocean Hour” where they select a location on the bay and clean for an hour. They submit the top three items to me each week and have been doing this since January… it has been pretty consistent… cigarette butts, plastic food wrappers, and plastic drink containers. We are not going to get rid of garbage on our beaches but if we can consistently reduce the “top three” we should be able to reduce the problem.
More on what we can do to help in the final issue.
What is the Gulf of Mexico Dead Zone you ask? Well…it’s a layer of hypoxic water (low in dissolved oxygen) on the bottom of the Gulf of Mexico. It was first detected in the 1970’s but reached its peak in size in the 1990’s. The low levels of dissolved oxygen decrease the amount of marine life on the bottom of the Gulf within this zone, including many commercially valuable species supporting the Gulf seafood industry.
The red area indicates where dissolved oxygen levels are low.
What Causes this Dead Zone?
Drops in concentrations of dissolved oxygen within the water column can occur for a variety of reasons but is usually caused by one of two reasons. (1) Increasing water temperatures—as water temperature increases, its ability to hold dissolved oxygen decreases. (2) A process called eutrophication.
What is eutrophication?
Eutrophication is a process where an increase of nutrients in an aquatic system triggers an algal bloom of microscopic phytoplankton. These phytoplankton produce oxygen during the daylight hours but consume it in the evening. Once the bloom dies, decomposing bacteria begin to break them down and consume larger amounts of dissolved oxygen in doing so. When the dissolved oxygen concentrations drop below 2.0 mg/L we say the water is hypoxic and many marine organisms either begin to move out or die. The nutrients that trigger such blooms are primarily nitrates and phosphates. These can be introduced to the water column with plant and animal waste and with synthetically produced fertilizers we use on our fields and lawns. There is natural eutrophication, but when the process is triggered or accelerated by human activity we use the term cultural eutrophication.
So which is it; warming waters or eutrophication?
The Gulf of Mexico Dead Zone usually forms in spring and lasts through September. These are certainly the warmer months of the year, but the warmer waters are near the surface and much of the water column is not warm enough to cause this. Another point is that the Dead Zone is near Louisiana and there are warm locations in other parts of the Gulf where dead zones do not occur. However the Mississippi River does discharge near Louisiana. This river drains 41% of the continental United States, which contains 52% of the nation’s farms. The agricultural waste (plant, animal, and synthetic fertilizers) discharged into the Mississippi River contains nitrogen and phosphorus, the two key nutrients that trigger algal blooms. Based on this, most scientists agree that cultural eutrophication is the primary cause of the Gulf Dead Zone.
When they say it will be a “typical year”, what does that mean – what is a “typical year”?
Scientists from NOAA, the U.S. Geological Survey, and six partnering universities have released their annual forecast of the Dead Zone. The 2015 prediction has the area of the dead zone about equal to the size of Connecticut, which has been the average size for the past several years. This is what they mean by typical.
Can these dead zones occur in our area waters?
Yes, and they do. We do not typically call them “dead zones” but the same process occurs all over the world, including the bays of the Florida panhandle.
What can we do to reduce cultural eutrophication locally?
If you can do without fertilizing your lawn (or field), then do. If this is not an option then only put the amount of fertilizer required for your land/lawn. Most people over fertilize, which not only reduces water quality but is expensive for the property owners. If you can compost your plant waste, do so. With animal waste, please dispose of properly, in a manner where it not reach local waterways.
For more information on hypoxia, eutrophication, and solutions to reduce this problem, contact your county Extension office.
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