What in the world is going on out there in the Gulf?
First it was the red tide that hit the coast of Southwest Florida, and fish started to die.
Then, as the bloom of tiny plants continued to expel toxins and gobbled up the available oxygen in the waters of the Gulf of Mexico and the bays, more critters died.
The bloom was then pushed to the bottom of the Gulf through a water temperature anomaly. An area from Pasco to Sarasota counties stretching out about 30 miles in the Gulf was impacted. Killed were conchs, crabs, Goliath grouper, bottom-dwelling fish and hard and soft coral. The affected area is estimated to cover more than 2,000 square miles.
Then sick and dead sea turtles and some dolphins started to wash ashore, possibly victims of swimming through the red tide zone.
According to Mote Marine Laboratory, "From July 24 through Aug. 16, the state recorded 89 sea turtle strandings from Pinellas County south to Sarasota County. The strandings included 50 loggerheads, 29 Kemp's ridleys, eight green turtles, one hawksbill and one sea turtle whose species could not be determined. Twelve of the turtles were found alive and taken to Mote Marine Laboratory or the Clearwater Marine Aquarium for rehab."
What's going on out there?
The original Gulf of Mexico dead zone
Historically, an annual "dead zone" is formed in the Gulf of Mexico every summer off the coast of Louisiana. It can encompass more than 7,000 square miles, and is caused when oxygen levels become too low to support marine life.
"The dead zone forms each spring as the Mississippi and Atchafalaya rivers empty into the Gulf, bringing nutrient rich waters that form a layer of fresh water above the existing salt water," according to Elizabeth Carlisle in "The Louisiana Environment: The Gulf of Mexico Dead Zone and Red Tides."
"It lasts until late August or September when it is broken up by hurricanes or tropical storms. The nutrients provide favorable conditions for excessive growth of algae that utilize the water's oxygen supply for respiration and when decomposing," Carlisle writes.
"The Mississippi River Basin covers 41 percent of the continental United States, contains 47 percent of the nation's rural population, and 52 percent of U.S. farms. The waste from this entire area drains into the Gulf of Mexico through the Mississippi River. Included in this agricultural waste are phosphorus and nitrogen, the primary nutrient responsible for algal blooms in the dead zone. Overall, nitrogen input to the Gulf from the Mississippi River Basin has increased between two and seven times over the past century. In addition to agricultural waste, inadequately treated or untreated sewage and other urban pollution is also dumped into these waters.
"Rivers carry greater quantities of water in the spring, along with greater quantities of dissolved nutrients, as the snow melts in northern areas and rainfall increases. Sunlight also increases in intensity and duration during this period, accompanied by warmer weather and fewer storms, all of which encourage algal growth."
Our dead zone
Scientists speculate that the dead zone off Central Florida started with a red tide bloom that has lingered off the coast since January. A thermocline - a layer of water either warmer or cooler than usual - pushed the red tide organisms close to the bottom of the Gulf. The red tide couldn't move through the layer of water, so it just sort of lingered near the bottom. As it killed the marine life there, decomposition of the dead critters and the bloom gobbled up all the available oxygen, and the mortalility rate was exacerbated.
According to the Florida Fish and Wildlife Conservation Commission's Fish and Wildlife Research Institute and the University of South Florida, scientists have made several excursions into the deep to take water samples and assess the damage, the latest early last week.
Sampling water both on the surface and on the bottom in an area generally north of Tampa Bay, the scientists found "well oxygenated surface waters in all but one station sampled. Anoxic (no oxygen) and hypoxic (low oxygen) conditions on the Gulf bottom were observed at selected stations sampled between northern Pinellas and Pasco counties during the cruise.
"The affected zone lies approximately 10 miles offshore. Comparison of these cruise results with data collected in previous weeks from the transect at the mouth of Tampa Bay suggest that the low oxygen conditions are transient; higher concentrations of oxygen are already returning to the southern area. High concentrations of red tide were documented in both surface and bottom waters sampled in the nearshore region, and high concentrations of red tide were found in surface waters offshore of the affection region. A strong thermocline was observed throughout the region sampled during the cruise.
"Researchers conducted dives at eight sites during the cruise and observed variable effects from site to site. Sites that were affected had high hydrogen sulfide levels and low visibility. Unaffected sites looked like typical live, soft bottom Gulf of Mexico habitats and were located on the western fringes of the hypoxic region."
A similar dead zone, also apparently caused in part by red tide, occurred in 1971 across "only" about 500 square miles of the Gulf. Bottom life returned in about two years.
What does it mean?
Well, the offshore dead zone probably means that offshore recreational fishing is severely hamstrung for a while. If preliminary reports are accurate, the zone stretches out to 30 miles from shore from Sarasota north to Hernando County.
Anybody hoping to do any bottom fishing closer than about 40 miles from shore could be out of luck. Ditto sport diving.
Impacts on the stone crab fishery, which opens Oct. 15, are still up in the air. Remember that most of the stone crabs move from the deep Gulf to nearshore waters - they've got to crawl through the dead zone to get here, and they're bottom feeders.
Sea turtle strandings have tapered off in the past week, so an argument could be made that the unprecedented number of dead turtles that washed ashore were those that were caught in the zone when it was created.
But the underlying mystery of the cause of red tide remains. What causes the algae to suddenly start to bloom?
Scientists have for years argued that phosphate and nitrogen found on land-based stormwater runoff had little impact in red tide bloom. However, in the past few years, there have been a few lone voices which have argued that the nitrogen loadings and red tide blooms are linked.
And it's an awfully odd coincidence that, since early 2003, there have been upwards of a million gallons a week of treated effluent from a defunct phosphate plant running into the Gulf to the north of us, and now we've had nine months of red tide off our coast.
Scientific data indicates the Piney Point discharge isn't playing a part in the red tide outbreak, but the coincidence of the two events sure seems suspicious.
More studies are in the works, Gov. Jeb Bush is apparently considering declaring the area a natural disaster which would open up federal assistance, and the whole matter will be reviewed at length.
As they say, stay tuned.
Bringing things into a perspective that we can all understand is the hallmark of an expert, and land use planner Tony Arrant has proven that he does indeed know of which he speaks.
Arrant has offered the following regarding shrinking data down to anyone's level of comprehension:
If we could shrink the Earth's population to a village of precisely 100 people, with all existing human ratios remaining the same, it would look like this:
There would be 57 Asians, 21 Europeans, 14 from the Western Hemisphere, including North and South America, and eight from Africa.
- Fifty-one would be female, and 49 would be male.
- Seventy would be non-white, while 30 would be white.
- Sixty-six would be non-Christian.
- Eighty would live in substandard housing.
- Seventy would be unable to read.
- Half would suffer from malnutrition.
- One would be near death, and one would be near birth.
- Only one would have a college education.
- One would have a computer.
- Two-thirds of the entire village's wealth would be in the hands of only six people, and all six would be citizens of the United States.