Sarasota Bay Estuary Program executive director provides more in-depth reporting on Hurricane Ian’s effects on red tide
In its most recent advisories on red tide in the region, the Florida Fish and Wildlife Conservation Commission (FWC) has continued to report higher numbers of “bloom concentration” water samples from Sarasota County than from most of the surrounding coastal counties.
In its Dec. 14 update, FWC noted that bloom concentrations — those with more than 100,000 cells of the red tide algae, Karenia brevis, per liter of water — were found in 10 samples from Sarasota County over the past week. The only county with a higher level was Pinellas, with 17 samples. Four Manatee County samples showed bloom concentrations, FWC added.
Over the seven days prior to the Dec. 14 report, FWC said, Karenia brevis was found in “background to high concentrations in and offshore of Sarasota County.” For Pinellas, the agency noted, “background to high concentrations in and offshore,” as well.
High concentrations were found in Hillsborough County, FWC continued, and “background to medium concentrations [showed up in samples taken] in and offshore of Manatee County.”
Further, Sarasota was included in the FWC lists of counties where reports of fish kills and respiratory irritation were suspected to have been related to red tide. The other counties on that list in the Dec. 14 update were Manatee, Lee, Pinellas and Collier.
In its Dec. 9 update, FWC reported 19 water samples collected in Sarasota County showed bloom concentrations of Karenia brevis over the preceding seven days. In fact, Sarasota County was the source for almost two-thirds of the 29 bloom concentration samples collected during that period, the agency pointed out.
Two samples from Manatee County had bloom concentration levels, FWC noted.
The Dec. 9 update also said that Karenia brevis was found in “background to high concentrations in Sarasota County,” with reports of fish kills and respiratory irritation in the county suspected to be related to red tide.
Also on Dec. 9, the Sarasota Bay Estuary Program (SBEP) released its Winter 2022 Bay Reflections newsletter, which included a report on how Hurricane Ian affected the bays in the area.
That section explained, “Stormwater runoff adds nutrients to the bay, which can feed or worsen existing algal blooms.
Hurricane Ian also caused an upwelling of deeper water that has a natural nutrient content higher than most surface waters. A big part of managing Sarasota Bay is focused on reducing the amount of algae in our bay. Microscopic floating algae can give the water a greenish tint, reduce water clarity, and result in the loss of seagrass meadows due to light limitation.”
That part of the newsletter added that satellite imagery “suggests a phytoplankton bloom in excess of 100 miles offshore, from southern Sarasota Bay down to Boca Grande. [FWC] maps … also show high levels of Karenia brevis, or red tide, in the same general areas as the satellite imagery shows the algal blooms. What does this all mean? We don’t yet know. But we do know algal blooms that originate way offshore in the Gulf of Mexico (like red tide) can be made worse if they are transported to our coast by prevailing winds and currents and then fed by land-based nutrients.”
An earlier SBEP report — which David Tomasko, executive director of the nonprofit, issued on Nov. 29 — explained, “Karenia brevis is pretty much always around to some degree.” When the organisms reach the level of bloom concentrations, or higher, Tomasko continued, “they can kill fish, and once they start killing fish, they can start to make their own ‘fertilizer’ via the decomposing fish.”
He included in that report a satellite image taken on Sept. 21, a week before Ian’s landfall. Low levels of phytoplankton were visible in Charlotte Harbor and offshore of Boca Grande Pass that day, Tomasko noted, “but not much [was] going on along our coast.”
Then, on Oct. 5, he wrote, “[W]e had a massive algal bloom in the nearshore waters of the eastern Gulf of Mexico, mostly coinciding with the same areas where other satellite imagery showed plumes of freshwater runoff extending miles into the eastern Gulf.”
Tomasko explained in the Dec. 9 newsletter, “Because of the way our cities are designed, much of the rain [from a storm] becomes stormwater and heads towards the nearest drain, canal, or creek and out to body of water. This means our bays and estuaries receive a large pulse of freshwater.”
He added, “Flipped over porta potties, failed septic tanks, wastewater overflows, dead animals, pet waste, and decaying plant material greatly affect water quality after storm events. Sarasota and Manatee counties had more than 18 million gallons of wastewater overflows as a result of Ian.”
In his Nov. 29 report, Tomasko wrote that satellite imagery provided by the National Oceanic and Atmospheric Administration (NOAA) “and concurrent field sampling suggested that most of the [algal bloom in the nearshore waters of the eastern Gulf] was red tide, at levels up to and in excess of 1 million cells per liter. So how big was this bloom, a week after Ian?” he continued. “Well, the combination of Charlotte Harbor and Pine Island Sound” comprises about 350 square miles. The red tide one week after Ian’s landfall, he added, “was likely more than 300 square miles in size.”
On Nov. 28 — the day before he released that report — Tomasko noted that the red tide “was much reduced in size, but it had shifted to become centered just offshore of [the Sarasota County] coast, and down to Manasota Key.”
Tomasko also pointed out, “We now have red tide at fish-killing concentrations in the Gulf of Mexico and within parts of our bay.” He added, “There are dead fish along the beaches along much of our shoreline …”
A Sarasota News Leader spot check of county beach conditions this week, using Mote Marine Laboratory’s reporting system, found that, early in the afternoon of Dec. 14, no respiratory irritation was reported on Lido Key Beach, but some dead fish were on the shoreline. The water color was classified as “Moderate.”
The previous day, “Slight” respiratory irritation was noted, and, again, “Some” dead fish were on the beach.
About midafternoon on Dec. 14 on Siesta Key Beach, that report showed no respiratory irritation or dead fish, and the beach was crowded. The water color was listed as “Moderate,” however.
Just before 10 a.m. on Dec. 12 on Siesta, that Mote report said, the water color was “Clear,” and no beach debris or respiratory irritation was cited.
On Dec. 13 on Venice North Jetty Beach in Nokomis, Mote reported no respiratory irritation or dead fish, but the water color was “Moderate.”
Just after 10 a.m. on Dec. 14 on Manasota Key Beach, near Englewood, Mote said that the water color was “Clear,” with no respiratory irritation or dead fish.
“For recent and current information at individual beaches,” FWC says, visit https://visitbeaches.org and for forecasts that use FWC and partner data, please visit https://habforecast.gcoos.org/?utm_content=&utm_medium=email&utm_name=&utm_source=govdelivery&utm_term=campaign.