Toxic Algae Blooms, Fish Kills Detected in Gulf: 51 Samples Confirm Red Tide Activity This Week

Photo of a toxic algae bloom danger sign for illustrative purposes

This week, 51 water samples from Florida's Gulf Coast revealed the presence of Karenia brevis, the organism responsible for toxic red tide blooms. While no bloom concentrations exceeding 100,000 cells per liter were detected, satellite imagery from November 4 highlights a massive 165-mile offshore patch of elevated chlorophyll stretching from Pasco to Collier counties. This patch, along with smaller clusters off the Big Bend region, indicates the ongoing presence of algae blooms in the Gulf. However, due to weather, confirmatory offshore sampling was not possible.

In Southwest Florida, low levels of K. brevis were found in Pinellas, Manatee, Sarasota, Charlotte, Lee, and Collier counties. In Northwest Florida, only very low concentrations were detected in Franklin County. Fortunately, no traces of red tide were observed along the Florida East Coast.

The harmful algae have already caused suspected fish kills along parts of Southwest Florida, including Pinellas, Sarasota, Charlotte, Lee, and Collier counties. Respiratory irritation, a common side effect of red tide exposure, was also reported in these regions.

Despite the patch’s significant size, officials suspect that other algal species, including diatoms, are contributing to the chlorophyll detected. Scientists plan further offshore sampling in the coming week to better understand the full extent of these algae blooms and their potential impact.
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The next update on the status of the red tide will be released on Friday, November 8.