Climate Change is Pushing Lake Okeechobee’s Water Levels Higher — And that’s Bad News For Algae Blooms, Flood Risk

More powerful storms. Heavier extreme rainfall events. Storms with higher potential energy. These are the result of a human-forced warming of the Earth’s atmosphere. And South Florida finds itself sandwiched between heavier evaporation flows streaming off the Gulf of Mexico, a more volatilely stormy North Atlantic, and large rivers of moisture streaming in from the Southeast Pacific.

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(Atmospheric water vapor levels over South Florida during late June of 2016. South Florida sits between numerous heavily laden atmospheric moisture flows. As human forced warming increases evaporation, these moisture flows expand, resulting in heavier rainfall potentials during storms over South Florida. This climate change dynamic is increasing over-topping flood risks for Lake Okeechobee even as the added heat and rainfall run-off enhances the potential for toxic algae blooms like the one now afflicting South Florida. Image source: Earth Nullschool).

And as these moisture-enhanced storms of climate change dump heavier and heavier rains over South Florida’s Lake Okeechobee, the choice appears to be one between flood risk or toxic algae blooms.

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Flood Risk Worsens With Climate Change

Lake Okeechobee sits at the heart of South Florida. Covering 730 square miles, the lake is bounded on the north, east, and west by farms. Run-off from these farms streams into the lake, feeding the growth of algae blooms. As the Earth’s atmosphere and ocean warmed due to human greenhouse gas emissions, rainfall events over South Florida have grown more intense. This trend increases run-off from pesticide, phosphorous, and nitrogen rich soils which then swell the lake with these chemicals and compounds — many of which promote the growth of cyanobacteria (or blue-green algae).

The increasingly heavy rains also force lake levels higher. During Winter of 2016, the wettest January in South Florida’s climate record pushed Lake Okeechobee’s water levels to 16.4 feet above sea level by February. November through May is South Florida’s dry season. So abnormally wet conditions during a typically dry period greatly increased flood risk for communities surrounding the lake as South Florida entered its June through October wet season.

Heavy rains have continued through recent months and, in order to mitigate the heightened flood risk, the US Army Corp of Engineers has been pumping large volumes of the run-off enhanced, nutrient-rich waters out of the lake in order to relieve pressure on the Hoover Dike. The Dike, for its part, is a 132 mile system of levees surrounding the lake and preventing its waters from flooding local communities during heavy rainfall events.

Lake Okeechobee Algae laden waters South Florida late June

(Lake Okeechobee [upper right of frame] and the algae-laden coastal waters of South Florida as seen in this June 26 LANCE MODIS satellite shot.)

Paul Gray, a scientist with Audubon Florida and Lake Okeechobee expert recently noted:

“One big storm would be a bad situation, really bad. We are nearing the heart of the tropical season and the corps knows they are one storm away from levels they are not comfortable with.”

To reduce pressure on the Dike, the Corps likes to keep Lake Okeechobee in a range of 12.5 to 15.5 feet above sea level. This creates a buffer zone to allow for the impacts of unexpectedly strong storms — like tropical cyclones — which can alone produce enough rainfall to push lake water levels between 1-4 feet higher.

At around 18.5 to 19.5 feet above sea level, the Hoover Dike system is under high risk of a breach or of over-topping. An event which would flood thousands of homes and businesses with 1-5 feet of water and generate a serious risk of loss of life.

So this year, with the dry season acting like the rainy season and with the rainy season now underway, the US Army Corps of Engineers has been releasing much larger volumes from the Lake in what some could call a frantic effort to keep water levels there in the safe range. These efforts, as of Thursday, July 7 produced a Lake Okeechobee water level of 14.93 feet — which was at the top edge of the safe zone. But the effort came at the cost of flushing nutrient rich waters into South Florida’s rivers and estuaries.

Mitigate Flood Risk and Toxic Algae Blooms Result

During recent years, heavy use of fertilizers has loaded up farmland soils surrounding Lake Okeechobee with phosphorous and nitrogen. As human-forced climate change has produced more extreme rainfall events over lands surrounding the lake, greater runoff of these nutrient-rich soils and chemicals into the lake has resulted.

Phosphorous levels, which government regulators like to keep in the range of 40 parts per billion in lake waters, has risen to 100 to 200 parts per billion. That’s 2.5 to 5 times the safe allowable level. And as the Army Corps of Engineers ramped up lake water outflows into the St. Lucie and Caloosahatchee rivers during recent months, this influx of high nutrient lake waters helped to spur the large algae blooms now afflicting the region.

John Campbell, a spokesperson for the US Army Corps of Engineers recently noted that people often ask:

“‘Why didn’t you release more water?’ Well, this is what releasing more water looks like.”

Due to the increased water outflows from Lake Okeechobee, high nutrient levels hit river systems warmed to bacterial growth enhancing temperatures by climate change. Cyanobacteria (blue-green algae) populations in these river and estuary systems then exploded. Goo painted waterways green, putrescent mats of algae formed in calmer waters, and airs smelling of rotten eggs wafted up from the suffocating rivers. These explosive and toxic bacterial growths prompted a declaration of a state of emergency by Governor Rick Scott as four South Florida counties were heavily impacted by the algae blooms.

Algae bloom Florida

(Toxic algae blooms like this one have resulted in beach closures across South Florida. Human-caused climate change spurs an increasing incidence of such toxic algae blooms by increasing water temperatures, which enhances algae growth, and by spurring more extreme heavy rainfall events — which generates increased nutrient influx into rivers, lakes, and oceans. Image source: Surfrider.)

Directly, cyanobacteria can produce a number of toxins capable of harming animal and human organ systems. Most common toxins are neurotoxins and toxins that impact the gastrointestinal track — particularly the liver. In addition, large blooms can deprive waterways of life-giving oxygen. Such anoxic conditions spur fish kills and mass production of hydrogen-sulfide generating organisms — a powerful toxin which generates the sulfuric rotten eggs smell that many South Florida locations are now reporting.

Indirectly, the blooms are unpleasant, unsightly and result in beach closures. And since the blooms became widespread, South Florida has experienced losses to its tourist industry (see toxic algae chokes business) — one of the biggest revenue producers for the State. Yet one more example of how human-forced warming not only harms the health of the natural world, but also harms human systems that rely on such natural wealth and beauty to function.

(Large algae blooms spurred by rising water outflows from an increasingly flood-stressed Lake Okeechobee resulted in tourism industry losses during the Fourth of July weekend of 2016. However, residents are rightfully concerned over long-term health risks due to the algae blooms. Note that purple water in gaps between the algae as well as reports of ‘rotten eggs’ smell is circumstantial evidence of increasing concentrations of hydrogen sulfide producing bacteria that tends to thrive in the anoxic dead zones produced by the algae. Video Source: CBS Youtube.)

Conditions in Context

The US Army Corps of Engineers is now reducing Lake Okeechobee water outflows in an effort to limit harmful algae blooms over South Florida waterways and estuaries. Outflow levels, as of June 30 were cut by 35 percent. As a result, some of the nutrients feeding algae blooms will be removed from waterways. But it’s questionable if the large algae blooms can be entirely halted by this mitigation.

Warmer than normal temperatures and heavier than normal rains are expected over this region during the coming weeks and months and these conditions will add to bloom promotion even without a larger pulse of water coming from Lake Okeechobee. In addition, reducing water flows from the lake will again push the lake to rise. And that puts South Florida one large storm away from risking an over-topping of the Hoover Levee System.

Climate change, in this context, has therefore put South Florida in a tough bind between worsening algae blooms over its waterways or worsening flood threats from a swelling Lake Okeechobee. A more immediate problem juxtaposed to the longer term risk of sea level rise — a human-forced ocean invasion which could flood the whole of South Florida by or before the end of this Century.

Links:

Why Drain Lake O? One Storm Could Push it Over its Limits.

What is Causing the Toxic Algae Blooms in Florida’s Waterways?

Army Corps to Reduce Lake Outflows Fueling Toxic Algae Blooms

Toxic Algae Chokes Florida Tourist Industry

Earth Nullschool

LANCE MODIS

CBS Youtube

Surfrider

Hat tip to Colorado Bob

Hat tip to DT Lange

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Starving Sea Lion Pups and Liquified Starfish — How We’ve Turned the Eastern Pacific into A Death Trap for Marine Species

As of late January, the news reports were coming in hot and heavy. Baby sea lions were dying in droves. More than 15,000 of the pups were already lost due to starvation. And with each passing week, more than 100 of the emaciated, beleaguered, hopeless animals were washing up on California shores.

The pups staggered across beaches, wandered into vacant lots, or tottered, disoriented, along roadways. Refugees all to some unspeakable disaster. Orphans lost or abandoned by parents unable to provide them with even the most basic of sustenance.

Starving Sea Lion Pups

(Starving sea lion pups taken in by the Marine Mammal Center in San Francisco. Image source: WTSP.)

Marine rescue centers, volunteer centers, and even animal shelters were inundated by a flood of desperate, dying animals. Their organs were shutting down. They could barely breathe or walk. The future generation of the more than 300,000 sea lions living along the US West Coast taking a severe blow from a deadly killer lurking in West Coast waters.

By late February more than 1000 sea lion pups had flooded the California Marine Mammal Center. Hundreds more found their way into local and ad-hoc shelters. The number was so great that all support systems for the animals were overwhelmed. Persons finding and seeking help for the dying pups were, more often than not, turned away due to lack of support and rescue resources.

It was like the scene out of some heart-wrenching sci-fi disaster movie. And everyone kept asking the same question — what could cause this?

Mass Sea Lion Deaths for Three Years Running

This most recent spate of sea lion pup deaths and strandings comes after years of the same. News media currently reports the event in isolation — as if 2015 were the only year for such a thing to happen. But the truth is that this crisis has been ongoing now since at least 2013, with an earlier episode in 2009-2010 preceding the current chain of related events.

The 2013 event was so severe that in the end 70 percent of the 50,000 sea lion pups born that year had died. The 2014 event was rather less severe, accounting for ‘only’ twice the normal loss rate. But 2015 has so far been so deadly that even 2013’s staggering number of sea lion pup losses could be exceeded.

The multi-year event represents such a heavy blow to sea lions that marine organizations have declared the entire current young generation under threat of being wiped out.

Adult Sea Lions, Otters, Starfish, Birds and other Marine Creatures Involved

But the story doesn’t stop at young sea lion deaths alone. From May through August of last summer, reports were flooding in of mass adult sea lion, otter, and bird deaths due to what appeared to be exposure to some form of toxin.

The animals would wash up on the beach or drop out of the sky. They would show signs of convulsions. Autopsies of the deceased animals revealed shrunken hippocampus, brain and heart lesions.

The same marine mammal center that is now taking in over 1,000 baby sea lion pups this summer took in 751 adults suffering from these signs of toxic poisoning. Simply put, the adults died this past summer and now the pups are starving.

Further down the food chain, creatures living in bottom water zones were also suffering and dying. Fishermen off Oregon had to go further and further afield to fill nets. Near shore fishing lines came up empty except for crabs scurrying up the lines as if in an attempt to escape from danger below.

And in 2013, thousands upon thousands of starfish began to turn to white clumps. A freakish instance of mass star fish death that continued inexorably through 2015.

A Victim of Sea Star Wasting Syndrome

(A victim of Sea Star Wasting Syndrome. Image source: Crosscut.)

The star fish would succumb to a strange wasting illness. An illness that would ultimately waste whole swaths of multiple starfish species (20 separate starfish species and millions of animals are now thought to be involved). Entire regions saw their starfish populations dwindle to zero. As with the mass sea lion deaths, marine researchers were both stunned and befuddled.

Perhaps even more disturbing is that the various species deaths just keep on coming — with no apparent end in sight.

A Hothouse Serial Killer

Just off shore, a warm wind runs from south to north over the increasingly wasted waters. Warm airs born of warm waters, providing us with clues for the cause of this ongoing mass death event. For the seas off the US West Coast have reached record levels of warmth — a level of ocean surface heat that flared with the most recent El Nino in 2009 and 2010. A warming that has been building steadily ever since mortality events began their incessant march in 2013.

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(Sea surface temperature anomaly map for February 27, 2015 depicting very large swath of much warmer than average sea surface temperatures running along the West Coast of North America through to the Bering Sea. Such widespread surface warming contributes to numerous detrimental changes to ocean health. Image source: Earth Nullschool. Data Source: Global Forecast System Model.)

Now a broad swath of surface water ranging from 2-5 C above average blankets an entire oceanic zone from Alaska to Mexico.

Such excess heat may seem innocuous at first blush. A little extra warm water may seem pleasant to the casual observer. But what seems pleasant actually conceals a deadly threat.

Warm surface waters spreading over the ocean can serve as a kind of lid. The warm water prevents cooler water from upwelling toward the surface, mixing nutrients and refreshing the water’s oxygen levels. This shut down of overturning is a dangerous oceanic condition called stratification. And it can level a severe blow to almost all creatures along the marine food chain. Plankton become less productive. Low oxygen zones expand, killing the slow-moving bottom creatures all while driving the mobile fish to more productive waters. In the warmer waters, toxic algae blooms become more prevalent. Harmful microbes, which are culled during influxes of cold water, thrive and multiply, posing a disease threat to all marine species. Finally, in the deeper reaches off the coasts of Washington and Oregon, the already oxygen-poor zones, zones rife with methane from hydrate venting, begin producing a deadly seep of hydrogen sulfide gas.

The living sea has now become a killer. And all it took was a little extra added heat to lock west coast waters in an expanding zone of warm water and low oxygen marine mortality.

Low Oxygen Ocean Zones

(The signature of ocean stratification expansion — low oxygen zones. Note the large and expanding region of low oxygen in the Eastern Pacific. For reference, high oxygen is shown in greens, blues and purples, low oxygen shown in oranges, reds and black. Image source: AMOP’s Study of Oxygen Minimum Zones. Image date: 2013.)

As a result we have the proliferation of the sea star wasting illness. An illness that would usually be contained by the seasonal influx of cooler waters. So too do we have instances of sea lion adults consuming fish, mullusks, and shellfish contaminated with domoic acid — a toxin produced by algae blooms in warm waters. And lastly, we have the overall stress on the food chain due to low oxygen and productivity which has driven sea lion food sources so far off shore that females are too exhausted after hunting to feed their pups.

More Dangers to Come

The recent mortality events mirror ocean warming episodes which caused similar die-offs at the end of glacial periods. Then, as now, warming robbed waters of oxygen and productive mixing, causing stress to numerous species.

However, the current pace of human warming is much more rapid than the warming periods that occurred at the ends of the ice ages. In addition, under business as usual human carbon emissions, the deadly, low-oxygen ocean zones are expected to expand, eventually covering the majority of the world ocean system. It’s a transition to a stratified ocean that will make the current west-coast die-off look like a minor prelude by comparison.

Hydrogen Sulfide Eruption off Namibian Coast

(Hydrogen sulfide eruption off Namibian coast on February 15, 2015. In Namibia, anoxic bottom waters host hydrogen sulfide producing bacteria. Runoff rich with organic material feeds these bacteria as they produce more toxic hydrogen sulfide gas. During upwelling events, the hydrogen sulfide is brought to the surface where it is visible as a florescent green or black slick. Under stratified and Canfield Oceans, more and more regions are capable of supporting deadly hydrogen sulfide production. Currently, the Baltic Sea, Offshore Namibia, the Chesapeake Bay, and Offshore Oregon are known to host broad regions of hydrogen sulfide producing bacteria in anoxic dead zones. Only in Nambia do these zones occasionally reach the surface waters, so far. Image source: Earth Observatory/NASA.)

Eventually, if CO2e levels exceed 800-1000 parts per million, a transition to an even more deadly state called a Canfield Ocean is increasingly likely. And a Canfield Ocean is a powerful killing machine. Implicated all the previous hothouse extinctions, this killer, during the Permian Extinction, was likely primarily responsible for the deaths of 95 percent of species in the ocean and 70 percent of species on land. For the oceans eventually filled up with deadly toxins (primarily in the form of hydrogen sulfide gas) which then vented into the atmosphere.

It’s a very deadly ocean state we want to avoid at all costs. And we should view these very troubling instances of ocean species mortality along the North American West Coast as a warning to stop warming to oceans as swiftly as possible.

Links:

 Here’s Why Hundreds of Sea Lion Pups are Washing Ashore in California

Researchers Find Warmer Waters Increase Sea Bed Methane Emissions

Surge in Marine Mammal Strandings on US West Coast

On California Coast, Biotoxins Cause of Deadly Sea Lion Siezures, Seafood Scare

Unprecedented Sea Lion Mortality Along California Coast Associated With Anomalous Ocean Conditions

Pelagic Zone: Commons

Global Warming May Boost Dead Zones in Oceans

Eastern Pacific Oxygen Minimum Research

Starving Sea Lion Pup Rescued on San Fransisco Boulevard

Sea Star Wasting Continues: Will King of the Rock Fall?

Pacific Rocky Intertidal Monitoring: Sea Star Wasting Syndrome

When the Stars all Go Out Along the Coast

Hydrogen Sulfide Eruption: Namibia

Earth Nullschool

Global Forecast System Model

Hat Tips:

Colorado Bob

Lief Thurston

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