Ocean Sentry
A red tide – bloom of harmful algae – is a natural phenomenon in saline waters caused by a higher than normal concentration of microscopic algae.
These toxic algal blooms are not unusual. Red tides appear off the state’s coast almost every year, usually in late summer or early fall. These algae, more specifically phytoplankton, are microscopic, single-celled protists, plant-like organisms that can form dense, visible patches near the water’s surface.
Certain species of phytoplankton contain photosynthetic pigments that vary in color. When the algae is present in high concentrations, the bloom turns coastal waters reddish-brown.
There are three types of algae associated with red tides. Karenia brevis (K.brevis), especially prevalent along the west coast of Florida and Texas, is found in the Gulf of Mexico. A low concentration of the Karenia brevis organism is considered to be 10 cells per liter of water, while a high concentration — which has the ability to kill fish — typically starts at 500,000 cells per liter.
When the cells break, they release a powerful neurotoxins called brevetoxins which kill marine life and affect humans in case of consumption of contaminated fish or shellfish.
Scientists say that red tides, which occur in Florida since before the first human settlements, develop far from the coasts (about 10 – 40 miles) and therefore far from sources of nutrients of anthropogenic origin (runoffs) that usually occur on the coasts.
However, these toxic tides may end up getting closer to the coast pushed by winds and currents. This particular red tide began in November and to date has already affected 150 miles of beaches.
What it is hardly discussed is the toxic freshwater blue-green slime blooming every summer in Lake Okeechobee – one of the largest lakes in Florida and the seventh largest in the country – and that has been propagated to rivers and canals. This blooming of harmful blue-green algae (Microcystis cyanobacteria), which only proliferates in freshwater (lakes and rivers), is leaving images like these:
Lake Okeechobee has been severely contaminated with phosphorus and nitrates after a century of intense agricultural practices and urban development.
Under normal circumstances, during the rainy season, the lake would overflow and the water would move to the south, through what is known as “River of grass” to give life to the iconic Everglades.
However, since 1910 a series of containment dikes began to be constructed to drain the water and convert the soil into agricultural land. This dyke system, called Herbert Hoove Dam, consists of about 143 dams. Two companies – U.S Sugar and Florida Crystals, collectively called ‘Big Sugar’ and located just south of the lake and owning much of the Everglades Agricultural Area (EAA) – are hampering this natural flow and are the powerful group of pressure against the restoration of the Everglades.
Once the natural flow is contained, water accumulates in the lake during periods of heavy rainfall while receiving discharges from urban runoff, cattle ranching and the enormous toxic runoffs from giant Big Sugar and Mosaic Company, a leading producer of concentrated phosphate.
To protect the EAA from flooding and relieve pressure on the levee during the heavy rainfall season, the US Army Corps of Engineers regularly discharges huge quantities of this contaminated water to the east (St. Lucie Estuary) and to the west ( Caloosahatchee Estuary) – two estuaries artificially connected to Lake Okeechobee. These discharges cause serious affectations to the organisms of both estuaries and increase the flowering of algae and other bacteria in the water (during Hurricane Irma, up to 20 million gallons of freshwater were discharged to both estuaries).
Heavy rains this year have forced more of the freshwater algae to be flushed from Lake Okeechobee into the estuaries. Fertilizer pollution from sugar farms and other sources feed the algae.
Environmentalists have long been calling on the state of Florida to buy these lands to restore the natural flow of water. However, the project does not succeed.
Residents and conservationists believe that dumping thousands of gallons of contaminated freshwater from Lake Okeechobee has aggravated this year’s red tide. While red tides are natural phenomena, they can increase in strenght and duration because of antrophogenic sources.
This ecological disaster is intensifying as the days go by and the ravages of marine life, both in rivers and channels and in the sea, are still to be determined, but they count in tons of marine life, reaching unprecedented numbers.
20 dead dolphins have been found dead in the Sarasota county over the last two weeks – the number of deaths that usually occur throughout the year.
A well-known dolphin called Speck was the first dolphin from the Sarasota Bay dolphin community to die during the current severe red tide. Speck was sighted more than 340 times since his birth in 2006 by researchers who monitor the generations of dolphins in the bay.
The Florida manatee, a threatened species with only 6,131 individuals left, is among the species most at risk. So far 540 have died throughout the state due to several causes, including ship propellers, cold stress and algae blooms.
On July 20, the carcass of an adult whale shark washed up on a Sanibel beach. Biologists took tissue samples of the shark to help determine if red tide is, in fact, what caused the animal’s death.
Sea turtles found dead amounted to hundreds. The figure stands at the moment in more than 400.
However, it was not until last Monday that Florida Gov. Rick Scott was forced to declare a state of emergency, without even mentioning the blue-green slime blooming. Why? Maybe because Rick Scott habitually sides with the biggest polluter.
In addition to its toxicity, these algae blooms (green and red) deplete the water of oxygen during its decomposition process, killing everything in its path.
In the sea, the most affected marine life are corals as well as very territorial marine creatures, which means that they will not abandon their territory to flee to a more secure one, or creatures that are slow swimmers, such as seahorses.
