Collaborative Red Tide Research on the West Coast of Florida

CIMAS postdoctoral researcher Brendan Turley, Ph.D., is studying the ecosystem effects of red tide along the west coast of Florida.

The Florida west coast is home to annual red tide events caused by the toxic phytoplankton Karenia brevis. This organism can reproduce rapidly, turning the coastal waters reddish-brown—hence the name “red tide.” These red tides can have wide ranging environmental and societal effects. For example, red tides can lead to mass mortality events of marine creatures littering beaches with dead fish and other marine organisms. Red tides can also cause respiratory irritation in humans, as wave crashing breaks open the K. brevis cells, releasing the toxin produced by K. brevis into the air. No humans have been known to have died from exposure; it mostly causes scratchy throat and shortness of breath to beach goers and boaters. However, marine mammals such as manatees have died, showing that mammals are also susceptible. The cause of red tides is primarily due to excess nutrients usually from river runoff or storm drains emptying into coastal waters.

red tide event Dr. Wolf Vogelbein
Areal image of red tide event showing visible reddish-brown streaks of the phytoplankton bloom. Used with permission from photographer Dr. Wolf Vogelbein.

Old problem, renewed attention

Several recent severe red tides events have led to more interest in these phenomena by fisheries researchers. In 2005, a severe red tide occurred that significantly impacted the red grouper fishery, which is an important commercial and recreational fishery on the west coast of Florida. Fishery managers estimated that almost 3 out of 10 red groupers were killed as a result of the red tide that year (SEDAR 61); this event also resulted massive fish kills on the beach and respiratory problems for beach goers.

Almost a decade later, in 2014, another red tide, while not as bad for beachgoers as 2005, caused many fishermen to switch tactics or move south further away from the affected area. More recently, 2017–2019 saw one of the longest and most widespread red tide event in modern memory. The event started late in 2017 around Charlotte Harbor and spread to the panhandle and even to the east coast just south of Cape Canaveral. The red tide did not disappear until early 2019. These events have led to ongoing collaboration between fishermen, NOAA (National Oceanographic and Atmospheric Administration) scientists, and CIMAS researchers.

Collaboration for the future

During the summer of 2018, a team of scientists from both NOAA and CIMAS conducted a series of workshops and interviews with local fishers (the term “fisher” is more inclusive than “fishermen,” as not all are men!). The goals of these workshops were to better understand the issues that the fishers found most pressing, and, more importantly, to build trust and lines of communication between the people who make a living on the water and people who have dedicated their careers to studying the ocean. Not surprisingly (remember, this was in the middle of a severe red tide), the dominant themes that arose from the fishers who participated were concerns about water quality, pollution, and red tide.

water sampling FL Commercial Waterman's Conservation
Fisher collecting water samples to analyze for red tide off Ft. Myers, FL. Image used with permission from Florida Commercial Waterman’s Conservation.

Out of those workshops, a group of fishers formed a non-profit called the Florida Commercial Watermen’s Conservation ( This group collects data and sends it to NOAA and CIMAS scientists who then analyze it and produce bulletins of current conditions. This arrangement is a benefit to both partners, because the fishers are always on the water and it is easy to collect the data, whereas a research cruise can be expensive to operate. Unfortunately, the COVID-19 pandemic has hit fishers hard, as the market for fresh fish has decreased with the sharp decline in tourism. Since the fishers are not going out as much, the data are not being regularly collected. It is hoped that more data will be collected as things begin to return to some normalcy with widespread vaccination on the horizon. The overall goal of the collaboration is to provide the people that live on the water information to plan for extreme red tide events, and to give NOAA and CIMAS scientists data to better understand red tide on local scales.

January 25, 2021