Southwest Florida scientists tracking changes in red tide algae counts

Mote Marine Laboratory scientists in Southwest Florida and others along Florida's Gulf Coast are closely monitoring counts of red tide algae, after noting low-level increases of these algae cells in multiple seawater samples during the past two weeks.

K. brevis, the single-celled, harmful algae that causes Florida red tide, occurs naturally in background concentrations in the Gulf. Recently, some samples in Southwest Florida and the Panhandle have revealed “low” or “very low” counts of K. brevis, which are greater than the normal “background” levels.  (See below).

Algae are a valuable part of marine ecosystems, producing half of the oxygen we breathe and providing food for marine wildlife. However, harmful algae can be a nuisance or even a health concern.

When K. brevis algae cells accumulate in high abundances, their toxins may affect marine life and people. These toxins can enter the air and cause respiratory irritation among beachgoers, such as coughing, sneezing or a scratchy throat. These symptoms are temporary and often considered an annoyance, but people with asthma, COPD or other chronic respiratory conditions should avoid areas with red tide algae, since the toxins can trigger their symptoms. Low or very low concentrations of the organism may cause respiratory irritation, particularly if winds blow onshore. Low concentrations also can kill fish. Many factors, including algae distribution, currents and winds, can determine whether the effects are noticeable.

Recent monitoring results are summarized below. Links to updates for the public at the bottom.
Visit the Florida Fish and Wildlife Conservation Commission’s (FWC’s) red tide status page for the statewide red tide status each Friday. Status updates include tables, static maps and interactive Google Earth maps. Mid-week updates are also provided each Wednesday during red tides. Results from the FWC-Mote Red Tide Cooperative Program are included in these updates.
In Sarasota County, beach water is sampled weekly at 16 locations by the Sarasota Healthy Beaches program of the Florida Department of Health and analyzed for K. brevis cells by Mote. Mote scientists partner with FWC through the FWC-Mote Red Tide Cooperative Program to monitor and study K. brevis. In addition, Mote operates the Beach Conditions Reporting System, which provides daily updates of beach conditions for multiple Gulf Coast beaches.

Recent monitoring results

Sept. 28 (Southwest Florida – many areas pending)
Water samples collected Monday, Sept. 28, along Sarasota County and analyzed by Mote showed K. brevis cell counts elevated to low in New Pass (adjacent to City Island) and along Siesta Beach and Turtle Beach on Siesta Key. In addition, very low counts were found that day in samples along Longboat Key and the Ringling Causeway, three sampling sites along Lido Key, near North Jetty in Nokomis, at five sampling sites along Venice and at Manasota Beach.

Samples collected on Sept. 28 along Collier, Hernando and Pinellas counties did not contain red tide, according to FWC, which is still awaiting the latest samples from other areas.
As of Tuesday evening, Sept. 29, Mote’s Beach Conditions Reporting System was NOT showing respiratory irritation among beachgoers and was NOT showing dead fish along monitored beaches in Sarasota or Manatee counties, or any other participating areas.

Sept. 25 (latest statewide FWC report)

Red tide monitoring in Florida is accomplished through a unique collaboration between FWC’s Fish and Wildlife Research Institute, the Florida Department of Agriculture and Consumer Services (FDACS), Mote Marine Laboratory, the University of South Florida, county agencies, other private non-profit agencies and citizen volunteers (i.e., the Red Tide Offshore Monitoring Program). The Sept. 25 statewide report from FWC includes the water samples collected and/or analyzed by these partners around Florida last week. A brief update will be available Wednesday, Sept. 30, followed by a full report on Friday, Oct. 2 at

Last Monday Sept. 21, one water sample collected along Nokomis Beach in Sarasota County showed a very low concentration of Karenia brevis. The 15 other Sarasota County stations sampled Monday contained background or no K. brevis cells.

On Sept. 22, Mote and FWC collected water samples by boat offshore between Tampa Bay and San Carlos Bay. Most of those samples had no K. brevis cells, some had background levels and one sample 12 miles west of Anna Maria Island was elevated to very low. Additional offshore sampling is scheduled in the coming weeks.

In Northwest Florida, samples collected on Sept. 23 showed very low or low concentrations along parts of Gulf County.

One sample from Sept. 23 from Englewood Beach in Charlotte County also showed very low levels of K. brevis cells.

Any counts of K. brevis algae above background are a good reason for scientists to watch closely and for the public to get familiar with the sources of updates on harmful algae.

Algae updates and resources

FWC’s statewide red tide status reports (on abundance of K. brevis algae) are updated every Friday afternoon
Based on statewide results, the National Oceanic and Atmospheric Administration provides forecasts of potential respiratory irritation
Mote’s Beach Conditions Reporting System provides shoreline observations as often as twice daily
Red tide background info from Mote and FWC (including FAQs)
Red tide and human health – information and multi-lingual rack cards from Florida Department of Health
FWC’s red tide offshore monitoring program – a way for volunteers to help
FWC-Mote Facebook page, Florida Red Tide and Other Harmful Algal Blooms
Trichodesmium (a benign algae that also occurs along the Gulf Coast) information from Mote