Sanibel Red Tide Bloom- What is it?
As of Monday August 5th, conditions appear to be improving on the beaches of Sanibel, after a significant outbreak of red tide last week. For those not familiar with red tide, it is a colloquial name for a naturally occurring growth of red algae know as Karenia Brevis. Many types of algae naturally occur in the southeastern United States. Karenia brevis is a dinoflagellate found in the Gulf of Mexico, along the coasts of Texas, Louisiana, Florida, and North Carolina. They are photosynthetic. Because they require light, they cannot live at depths below 200 feet. Karenia brevis has a temperature range between 4 and 33 degrees Celsius. However, their optimal range is 22-28 degrees Celsius. In addition, this organism can live in a salinity of between 25-45 ppt.
What Causes Algal Blooms?
Algal blooms can occur when there is a change in chemical levels in the water. A chemical change in the water can take place for multiple reasons. The most common is when chemicals are dumped in the water from local run-off zones. These chemicals can come from fertilizers used for agricultural growth near a coastal run-off zone. If chemical levels such as nitrogen increases past normal levels, the algae will use this for nitrogen fixation and reproduce rapidly. This is what we call the “algal bloom”, and these blooms can deplete the oxygen in the water and create a shade from the sun, preventing organisms that need sunlight from obtaining it. K. Brevis produces harmful algal blooms that cause red tides. When red tides occur, toxins are let out in the oceans and may kill or harm marine animals, as well as cause several human illnesses that can arise from eating seafood that have retained levels of these toxins.
Recent Events (bloom timeline, etc.)
For several weeks certain areas of the west coast of Florida have been plagued by red tide blooms, but Sanibel had been relatively unaffected. Our team at Select Vacation Properties has been out monitoring conditions, as well as using local, regional and online resources to keep abreast of the situation. From a personal perspective, Just two weeks ago I took my own summer beach vacation at the east end of the island with my wife and 8 year old daughter, and the waters were fine, and we had a great stay. Last week, our team at SVP was going out to the beach every day to personally check on conditions, and we did not observe any negative impacts to the local environs. We did continue to add information to our website with info, suggestions and links to great resources to keep our guests informed. As recently as Friday, July 27th, I was taking pictures on Sanibel beaches of happy people and children swimming in the Gulf. I interviewed 3 or 4 different groups and families, inquiring whether they had seen any dead fish or had difficulty breathing. No one I spoke to reported anything extraordinary or unusual. Then on my way across the causeway on Monday, July 30th, everything had changed; dead fish and sea life all along the beaches, discolored waters and of course the smell. By all accounts this began sometime Saturday, July 28th. City of Sanibel weekly beach conditions reports for the week of July 23rd to July 30th bear this out, with all beaches having good ratings and green flags for that period. The City of Sanibel now has advisories with progress reports being provided daily as to clean up efforts. The worst period for this bloom appears to have occurred between July 30th and August 2nd 2018 as of this writing. The City of Sanibel began unprecedented clean up efforts starting August 2nd, which are now bearing fruit. I was out inspecting beaches this morning (August 6th), and conditions have improved night and day from last Monday to today. Visit our facebook page to see the live videos I shot this morning illustrating current conditions, and well as prior videos. I will continue to upload content, and provide updates as the situation evolves.