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Algae are microscopic organisms that can have big effects on the Gulf Coast of Florida and elsewhere along coastlines worldwide. Over the years, there has been a number of events where large blooms (sudden increased growth) of algae in the waters have created problems for residents, business, fisheries and visitors to the coast. Happily there have been no significant blooms of red algae or red tide since early 2007.
Two main forms of algae blooms have affected the west coast of Florida over the years:
This is a microscopic algae that can you cannot see directly in low concentrations, but can be seen by plane and satellite as a red-brown stain on the water and has a nasty odor when present in medium to high concentrations. Some people are affected by airborne particles that can irritate the eyes, sinuses and can cause breathing difficulties or trigger asthma attacks. The higher the concentration in the nearby water the greater the likelihood of having a reaction. The effects are also more likely near areas with pounding surf or high waves as this creates more airborne particles. Moving inland away from the beach usually relieves the symptoms. Entering red tide contaminated water may also cause skin rashes.
Red tide's biggest impact is fish kills: when there is a widespread bloom or medium to high concentration of the organism near or off the shore, there can be hundreds or thousands of dead fish that can wash up onto the beaches and into bayside marinas. The subsequent decay of these fish forms what one would expect - a very foul odor until the fish are washed away by subsequent tides (that are hopefully red tide free).
Important Note: Any shellfish harvested from contaminated waters can develop a toxin that can be deadly to humans. Buy your shellfish at markets and in restaurants.
Red Tide is more common in summer months but can occur anytime. It can affect anywhere along the gulf coast of Florida. Sanibel is therefore not more nor less likely to suffer from it than anywhere from Tampa to Marco Island. When it does, it often only affects parts of the island while other areas can remain clear. When and where it will be cannot be forecast, however recent past history on Sanibel suggests that the higher likelihood runs from July though late October.
Red Drift Algae
This is a different form of algae that looks like red-brown seaweed and is often washed up on shore in small amounts. On occasion, there are very large blooms and if the currents and tides are favorable it washes up on the shore in huge quantities. While not toxic or dangerous, the piles of algae will decay after a few days and emit a "fishy" or "rotten egg" odor until removed or washed away.
There can also be small fish and shellfish that get caught in the seaweed and die and as such there could be a problem with bacterial contamination from these. Although walking on the seaweed is probably OK, you should be careful because imbedded sharp shell fragments could cause injury and infection. Likewise it would be wise not to touch the seaweed with your hands and then touch food or your mouth, so small children should be watched carefully.
It does decay in the water as well and on rare occassions the City of Sanibel posts DO NOT Swim warnings on affected beach areas when the water has too much bacteria.
Blooms are sporadic and unpredictable. Unlike red tide, there does not seem to be a season where the incidence is higher. There certainly have been more frequent and severe events in the past three years since Hurricane Charley and other storms hit Florida, however whether these increased blooms of either algae represent a future trend or are temporary flucuations remains unknown at present. Overall, this past year has been an improvement over the prior two, possibly due to the drier-than-normal conditions whcih have affected southern Florida and have therefore greatly reduced the amount of run-off entering the coastal waters.
There can be large deposits of red drift algae one day and then it is completely gone the next morning. Sometimes a heavy deposit can last over a week before the tides wash it away. Additionally, the conditions can also be drastically different within a few hundred feet. When the blooms are bad, it usually seems to affect one part of the island and leaves the other parts only lightly affected. Captiva has for the most past not been affect by much seaweed. So there will almost always be a number of beaches you can visit in the event that the beach in fornt of your accommodation is affected.
What causes these blooms? No one knows for sure, but many point to nutrient-rich polluted runoff that collects in the rivers that drain into the Gulf. In addition, the multiple hurricanes that hit Florida in 2004 and 2005 caused the levels of Lake Okeechobee to rise too high; the authorities then released tremendous amounts of water into the rivers to lower the lake. To make things worse, all the turbulance caused by the storms stirred up the lake and toxins and nutrients that usually lie dormantly near the lake floor mixed into the water throughout the lake which in turn ended up going into the rivers. These pollutants and the accompanying massive amounts of fresh water upset the delicate balance of the estuaries and bays.
On a positive note, the drought of 2007 greatly reduced water levels in Lake Okeechobee to the point where large expanses of the lake bottom are exposed. This is allowing a massive cleanup of the "muck" and should help further reduce pollutants from entering the waterways in the future.
Will there be any problems when you visit Sanibel? While no one can say for sure, the chances are that at any particular beach at any given time you will not notice a significant problem while on Sanibel Island.
It should be remembered that Sanibel beaches have always been kept in "natural" condition- which does not mean clean; small to moderate amounts of seaweed along with shells are a part of normal beach ecology and Sanibel leaves the beach in its natural state.
Until recently, as a nature-conscious community, the City of Sanibel did not allow any clearing or grooming of the beaches even if heavy amounts of red drift algae were present. As a result of massive community input, the City has begun to recognise that severe algae overgrowth is itself a sign of an environmental inbalance and has now become more active in seeking environmentally acceptable ways to remove excess seaweed from the beaches including mechanical methods that are currently used in Maui. The lack of algae has prevented any testing of the proposed solutions.
Additionally, the State of Florida has begun the process of finding alternatives to releasing large amounts of water from Lake O. This should help reduce the frequency and duration of future blooms.
If you want to help, residents and other concerned individuals can find out more information about the Sanibel Captiva Conservation Foundation and on Florida Fish and Wildlife Research Institute The Fish and Wildlife Research Institute also posts updates on red tide readings every Friday when blooms are present anywhere along the Florida coast.
If you are concerned about whether an algae bloom is present or will affect you or your plans, it is a good idea to follow the updates in the Sanibel forums, check the web sites above and also contact the management at your accommodation. Most individuals are concerned about Sanibel-Captiva and the health and goodwill of their guests and will give you accurate information. (However, some people are better informed than others, and even the best-intentioned host may not truly understanding the current conditions.)