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After a quick spread over 100 miles of Florida's west coast, red tide has receded and it would seem the colder temperatures may be the reason why.

Between Nov. 6 and Nov. 12 the Florida Fish and Wildlife Conservation Commission found the phytoplankton responsible for red tide, known as karenia brevis, was highly prevalent off the coasts of Pinellas, Lee, Charlotte and Collier counties. Samples of red tide were also found in Manatee and Sarasota counties.

December data indicate red tide fell drastically after the large bloom between October and November.

Red tide samples were observed in low concentrations in Sarasota County and in medium concentrations in Charlotte, Lee, Monroe and Collier.

Natural factors that contribute to red tide's growth are stagnant waters, ample summer sunlight and warm waters, according to the FWC.

Temperatures in October off Sarasota reached a mean of 82 degrees and an average high of 90 degrees, according to the National Weather Service.

However temperatures began to shift from October's unusual warmth and into a more fall familiar climate. The maximum high in November was 91 degrees, which was observed on the 7th, but as the month began to wind down, temperatures dropped down as well; the mean temperature was 71 degrees with the lowest reaching 51 degrees.

Red tide is a naturally occurring phenomenon, but massive blooms of the algae can lead to respiratory irritation for humans, water discoloration and marine life deaths because of the lack of oxygen in the water.

Respiratory irritation was reported over the past week in Southwest Florida in Lee and Collier counties.

Over 130 fish kill reports were cataloged between Sept. 1 and Nov. 20 with red tide listed as the cause of death, according to the FWC's fish kill data base. The majority of the fatalities were reported in Collier County around Naples and Marco Island. Fish kills is a general term the FWC uses to describe marine life, and fatalities have included a large amount of mullet and catfish, but also at least one sea turtle, crabs, sea snakes and at least one pelican.

Since the start of December there have been 12 fish kill reports on the west; most of the species were unidentified, but at least two were sharks.

One hundred seventy-four dolphins died between July 2018 and June 20, 2019, in Collier, Lee, Charlotte, Sarasota, Manatee, Hillsborough and Pinellas counties, according to the National Oceanic Atmospheric Administration. The reported deaths were considered an "unusually high mortality rate," and many of the dolphins tested positive for the red tide toxin, NOAA reported.

Between 2017 and 2018, Florida's beaches were ravaged by red tide with over 150 miles of the west coast consumed by it. Florida's east coast also reported samples of the organism, which is unusual due to the cold nature of the Atlantic, according to the FWC.

Explore further Red tide grew drastically along Florida's west coast in less than a month

©2019 The Orlando Sentinel (Orlando, Fla.)

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