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.
Dodder vines covering an oak seedling. The vines always wrap counterclockwise. Photo Credit: Jed Dillard
Vampires of all types and genetic modifications are hot topics these days, and a common, but uncommon looking and acting Florida weed may have combined the two subjects. Dodder, a native invasive, parasitic plant, reproduces by seed but does not have enough leaves or chlorophyll to feed itself. Its thin, golden vines and tendrils must attach to a host plant in the seven to ten days it takes the plant to exhaust the carbohydrates in its small seed. Once dodder attaches to a plant, it connects to the inside of the host using small structures called haustoria which press into the stem and begin to draw nutrients from the host. At this point the dodder roots atrophy.
Single dodder plants are not a big issue, but once enough plants build up in an area large mats of vines can reduce growth and vitality of the host. (See photo) Frequently, the pest has reached this stage before it’s noticed, leaving the problem of treating a rootless, nearly leafless plant that is wrapped around a more desirable plant. Not only are the typical routes of herbicidal entry minimized, the hosts are at as much risk as the pest. Hand removal may be practical in small outbreaks, but the plant can reemerge from any small piece left attached to the host. In most cases, the solution is to destroy the host and the dodder and apply a pre-emergent herbicide to stop germination from any seeds remaining in the soil.
What about the GMO angle?
Work published last year in the journal Science by Jim Westwood of Virginia Tech reveals the dodder plant exchanges messenger RNA with tomato and Arabidopsis plants when it extracts the juices from the host plant. Scientists speculate this exchange of genetic material makes the host plant less resistant to attack by the parasite and that this holds promise for learning more about controlling other parasitic plants.
If plants are exchanging messenger RNA, a critical part of protein and gene synthesis, what other genetic exchanges are occurring naturally without our knowledge? Scientific progress hinges on unpredictable events and sources. Learning more from a “vampire weed” that has no easy means of control may be one of those.
To see the dodder plant go from seed to golden mat, watch this time lapse video Virginia Tech has posted on Vimeo. http://www.vtnews.vt.edu/articles/2014/08/081514-cals-talkingplants.html
After the recent report of a fatality due to the Vibrio bacteria near Tampa many locals have become concerned about their safety when entering the Gulf of Mexico this time of year. So what are the risks and how do you protect yourself?
The rod-shaped bacterium known as Vibrio. Courtesy: Florida International University
What is the Flesh Eating Disease Vibrio?
Vibrio vulnificus is a salt-loving rod-shaped bacteria that is common in brackish waters. As with many bacteria, their numbers increase with increasing temperatures. Though the organism can be found year round they tend peak in July and August and remain elevated until temperature decline.
How do people contract Vibrio?
The most common methods of contact with Vibrio are entrance through open wounds exposed to seawater or marine animals and by consuming raw or undercooked shellfish, primarily oysters. The bacterium can also be contracted by eating food that is either served, and has made contact with, raw or undercooked shellfish or the juice of raw or undercooked shellfish.
What is the risk of serious health problems after contracting Vibrio?
Cases of Vibrio infection are rare and the risk of serious health problems is much higher for humans who are have a suppressed or compromised immune system, liver disease or blood disorders such as iron overload (hemochromatosis). Examples include HIV positive, in the process of cancer treatment, and studies show a particularly high risk for those with a chronic liver disease. The Center for Disease Control indicates that humans who are immunocompromised have an 80 times higher chance of serious health issues from Vibrio than healthy people. He also found that most cases involve males over the age of 40. According to the Center for Disease Control there were about 900 cases reported between 1988 and 2006; averaging around 50 cases each year. The Florida Department of Healthreported 32 cases of Vibrio infections within Florida in 2014 with 7 of these begin fatal. Five of the cases were in the Florida panhandle but none were fatal. So far this year in Florida there have been 11 cases statewide, 5 of those fatal. Only 1 case was in the panhandle and it was nonfatal. Though 43 cases and 12 fatalities over the last two years in Florida are reasons for concern, when compared to the number of humans who enter marine and brackish water systems every day across the state, the numbers are quite low.
What are the symptoms of Vibrio infection?
For healthy people who consume Vibrio containing shellfish symptoms could include vomiting, diarrhea, and abdominal pain. Wounds exposed to seawater that become infected will show redness and swelling. For the at-risk populations described above the bacteria will enter the bloodstream and rapidly cause fever and chills, decreased blood pressure, and blistering skin lesions. For these at-risk population 50% of the cases are fatal and death generally occurs within 48 hours.
It is important that anyone who believes they are at high risk and have the above symptoms that they seek medical attention as quickly as possible.
How can I protect myself from Vibrio infection?
We recommend anyone who has a chronic liver condition, hemochromatosis, or any other immune suppressing medical condition, not consume raw or undercooked filter-feeding shellfish and not enter the water if they have an open wound.
The Center of Disease Control recommends
If harvesting or purchasing uncooked shellfish do not consume any whose shells are already open
Keep all shellfish on ice and drain melted ice
If steaming, do so until the shell opens and then for 9 more minutes
If frying, do so for 10 minutes at 375°F
Avoid foods served, and has had contact with, raw or poorly cooked shellfish or that has had contact with raw shellfish juice
If shucking oysters at a fish house or restaurant, wear protective gloves
It is also important to know that the bacteria does NOT change the appearance or odor of the shellfish product, so you cannot tell by looking at them whether they are good or bad.
This past week hundreds of dead fish washed ashore between Escambia and Okaloosa counties. Most were of one species but there were others who died and it appeared they had been in the water for quite a while. Determining the cause of fish kill can be tricky. You can observe how many different species were involved, and how many of each species. You can also review changes in the biological and chemical environment of the water system impacted. Fish kills occur for a variety of reasons but many are connected to either a decline in dissolved oxygen, the presence of red tide, or some pathogen that may be affecting the fish.
Dead fish near Ft. Pickens in Pensacola. Photo: Rick O’Connor
Excessive nutrients, many times associated with heavy rain, can trigger algal bloomsthat can eventually lower the concentration of dissolved oxygen; however high water temperatures can do the same. When dissolved oxygen levels drop below 4.0 mg/L most fish are stressed, and most fish leave. Some fish however are very sensitive to these changes and die, menhaden are one of them. The Florida Fish and Wildlife Conservation Commission listed menhaden as one of the species found on the beach but there were others as well, actually the majority were scaled sardines. The Florida Department of Environmental Protection monitors dissolved oxygen at the beach each week and their data indicated no problems prior to the kill. The Escambia County Division of Marine Resources measured the dissolved oxygen after the kill and found levels to be normal. Some would point to the abundant amount of green algae, “June grass”, as a sign of an algal bloom but mass amounts of June grass appear each summer and fish kills typically do not follow them.
Red tides are blooms of a particular microscopic single celled creature called Karenia brevis. When these photosynthetic protist are disturbed they can release a toxin which dissipates through the water and can become part of the aersols produced by waves. Many species of fish and marine mammals struggle with red tides and mortality due these outbreaks are common. Records of red tide blooms go back as far as the early colonial period and have been part of Florida for centuries. They typically form offshore and move inland with the wind and currents. Once they reach shallow waters human released nutrients can increase populations of K. brevis and enhance the problems they cause. They are more common in southwest Florida but do occur in the panhandle. Agencies along the Gulf coast monitor for red tide outbreaks each week. The Escambia County Division of Marine Resources does so here and found no traces of K. brevis before or after the kill.
As far as pathogens, or another possible cause, we are not sure. The Florida Fish and Wildlife Conservation Commission has officially listed the cause as “unknown”. Fish kill data in Escambia County shows changes over the years. In the 1970’s there were a fewer fish kills reported each year but each kill involved hundreds of thousands of fish, many times menhaden. Today there are more fish kills reported but many of these reports are a single fish or fewer than 10. This is the first large number kill we have had in a while. Escambia County Sea Grant reports water quality information, including fish kills and red tides, for the Pensacola Bay area each week on their website (http://escambia.ifas.ufl.edu). Fish kill information for the state of Florida can be found at http://myfwc.com/research/saltwater/health/fish-kills-hotline/. If you have any questions about local fish kills contact Sea Grant at your local county extension office.
Pregnant Bull Shark (Carcharhinus leucas) cruses the sandy seafloor. Credit Florida Sea Grant Stock Photo
Shark Safety Tips
UF/IFAS Extension – Florida Sea Grant
By L. Scott Jackson (Bay County) and Rick O’Connor (Escambia County)
Recently, two teens were victims of unusual shark attacks in North Carolina. The two attacks occurred within minutes and miles of each other. A similar incident happened in the Florida Panhandle in 2005. One teen lost her life and one lost his leg. The attacks were within days of each other and the distance between the two attacks was less than 100 miles. Experts identified Bull Sharks as being responsible for both Panhandle shark encounters.
Bull Sharks migrate north as ocean waters of the Gulf and Atlantic warm. As the nearshore environment cools in the late fall and winter, Bull Sharks follow the receding warm water and eventually move out of the local area. Bull Sharks are an aggressive shark responsible for a reported 100 attacks on humans resulting in 21 fatalities. (Reported from 1580 to 2014 Source: International Shark Attack Files).
Experts suggest Bull Sharks may be responsible for many shark attacks where the species is unknown or not identified.
Overall, the number of shark encounters is slowly trending higher as more people swim and participate in other water related activities. However, negativeencounters with sharks remain a rare occurrence. In 2014, Florida reported 28 shark bites with no fatalities. On average, only one shark attack fatality is reported every other year in the United States. The risk of shark attack is very low compared to other potential recreational hazards. For example, in 2014, 26 people died as a result of lightning strikes in the United States, with six of those being in Florida.
George Burgess with the International Shark Attack File has compiled a list of action strategies you can use to reduce the chances of a negative encounter with a shark:
Keep these tips in mind the next time you hit the beach!
Avoid being in the water from sunset to sunrise. This is when sharks are most active and have a competitive sensory advantage.
Stay in a group, and do not wander too far from shore. Isolated individuals are more likely to be attacked than large groups; in addition, the farther you are from shore, the farther you are from help.
Consider your clothing: avoid wearing shiny jewelry, because the reflected light resembles the sheen of fish scales.
Avoid brightly colored or patterned clothing, because sharks see contrast particularly well.
Do not enter waters being used by sport or commercial fisherman – sharks can sense the smells emitted from bait at incredible distances.
Avoid entering waters with sewage output and/or entering the water if you are bleeding. Such additions to the water can act as strong olfactory attractants to sharks.
Know your facts! Porpoise sightings do not indicate the absence of sharks. In fact, the opposite is often true. Also be on the lookout for signs of baitfish or feeding activity – diving seabirds are good indicators of such action. Animals that eat the same food items are often found in close proximity. Remember, a predator is never too far from its prey.
Refrain from excess splashing while in the water, and do not allow pets in the water because of their erratic movements.
Exercise caution when occupying the area between sandbars or near steep drop-offs, as these are favorite hangouts for sharks.
Do not enter the water if sharks are known to be present, and evacuate the water if sharks are seen while there. And, of course, do not harass a shark if you see one!
Stay calm if you do see a shark, and maintain your position in as quiet a manner as possible. Most sharks merely are curious and will leave on their own.
Our beautiful Emerald Coast is an alluring wild habitat. Simply put – Swimming at the beach is not the same as swimming in a backyard pool. Have fun at the beach but be mindful and respectful of potential hazards. Knowing what to do to be safe will actually help you enjoy time at the beach while keeping worry and concern at a minimum.
Follow these beach safety tips for helping your family enjoy the beach while protecting coastal wildlife.
