NOAA's HAB-OFS provides information and operational forecasts regarding the potential development, intensification, transport and associated impacts of harmful algal blooms of Karenia brevis (commonly known as red tide) in the Gulf of Mexico (Florida and Texas).

The forecasts are communicated through two main products: the HAB-OFS Conditions Reports and the Bulletins. The conditions report includes a forecast of the potential levels of respiratory irritation associated with a K. brevis bloom over the next 3-4 days, and is posted to this website at least twice a week after confirmation of a HAB. Additional bloom analysis is included in the HAB Bulletin that is emailed to a subscriber list of state and local coastal resource managers, public health officials and research scientists.

The HAB-OFS relies on satellite imagery, field observations, models, public health reports and buoy data to provide the large spatial scale and high frequency of observations required to support operational forecasts. The HAB-OFS is an ongoing project that depends on the dedication, energy, and feedback of individuals from partner agencies and numerous other organizations working on this issue in the Gulf of Mexico. For more information, please visit the Contributors & Data Providers webpage.

The data sources used in HAB monitoring and forecasting in the Gulf of Mexico include ocean color satellite imagery, observed and forecasted wind data from NOAA's National Weather Service and National Data Buoy Center, K. brevis cell concentration data from the states of Florida and Texas, modeled and observed currents from the Texas General Land Office's (TGLO) Texas Automated Buoy System (TX only), water optical properties from Mote Marine Lab and Texas A&M University and respiratory irritation observations from Mote Marine Lab (FL only) and the state of Texas. See our Contributors & Data Providers page for more detail.

The daily satellite imagery is colored to indicate chlorophyll concentrations. High chlorophyll concentrations can indicate the presence of K. brevis. However many algal blooms (toxic and non-toxic) routinely produce high chlorophyll concentrations, so chlorophyll alone is not a reliable indicator of the presence of a K. brevis bloom. Analysts compare locations of high chlorophyll with water sample data to verify the presence of K. brevis.

To highlight possible K. brevis blooms in imagery, an algorithm is applied to daily chlorophyll imagery that flags areas of anomalously high chlorophyll which may be the result of rapid increases in chlorophyll, usually due to growth, aggregation, or resuspension (stirred up sediments). Since the surface waters along the Texas coast are prone to resuspension events, a revised chlorophyll anomaly algorithm is used for the Texas bulletins that subtracts an estimate of the resuspended chlorophyll from the chlorophyll anomaly.

To further refine K. brevis detection, an ensemble approach, recommended by Tomlinson et al. (2009) is used that combines the chlorophyll anomaly with algorithms that target specific light-deflecting and light-reflecting properties of K. brevis blooms. One of the algorithms in the ensemble accounts for the relative particulate backscatter of blooms and the other looks at how K. brevis blooms change the spectral shape characteristics in the blue wavelengths (at 490 nm).

If you are involved in HAB event response or research and are interested in subscribing to our bulletins, please click here.

Levels of potential respiratory irritation are forecast once water samples indicate concentrations of Karenia brevis along the coast (within 1 mile of shore). The forecasts may also be based on the level of respiratory irritation observed at the coast, as long as it is confirmed to be associated with K. brevis.

Respiratory irritation forecasts are provided in the HAB-OFS Conditions Reports and are issued by region for each state. See below for links to the respiratory irritation forecast region maps.

Respiratory irritation impacts are forecasted in levels ranging from "very low" to "high" (in addition to "none" or "not expected") based on wind direction and speed, as well as the nearby algal cell concentrations identified in water samples. The "very low" respiratory irritation level affects only people with severe or chronic respiratory conditions. Similarly, the "low" respiratory irritation level affects people who are otherwise healthy, but are more sensitive to Karenia brevis aerosols. The "moderate" respiratory irritation level indicates that the general public may potentially notice mild respiratory symptoms, while the "high" respiratory irritation level is likely to affect most of the general public with adverse respiratory symptoms (NOAA, 2013). Refer to the table below for more information about the respiratory impact levels. Due to limited spatial and temporal observations, these forecasts are made for each half-county (~30-60 km) and only for coastal regions because respiratory irritation impact levels are not well understood in open water regions (Stumpf, et al., 2009). See below for forecast region maps.

Respiratory irritation forecasts are included within the HAB-OFS Conditions Reports. The NOAA HAB-OFS Conditions Report identifies whether or not there are Karenia brevis cell concentrations. When K. brevis cell concentrations are present, the report indicates the general location and provides forecasts of the highest potential level of associated respiratory irritation.

A "red tide" is a common term used for a harmful algal bloom. Read more from the National Ocean Service Ocean Facts here.

To learn more about why harmful algal blooms occur and the research that is being done, visit the National Ocean Service Ocean Facts here.

Harmful algal blooms of Karenia brevis (red tide) are common in the Gulf of Mexico, occurring nearly every year along the Gulf Coast of Florida and with increasing frequency along the coast of Texas. The blooms occur more often late in the year, typically starting between August and October and ending between December and February. The presence and duration of blooms, their intensity, and the extent of the area impacted by the bloom varies significantly from year to year. Blooms can last a few weeks, months and sometimes over a year. Typically a harmful algal bloom only affects small portions of the coast for short periods of time.

In Florida, blooms more frequently form offshore of the southwest coast of Florida between Tampa Bay and Naples. Occasionally a harmful algal bloom that formed offshore the west coast of Florida is transported to the east coast by ocean currents. Every few years blooms may also form offshore the Florida Panhandle. In Texas, blooms are most frequently reported in the Port Aransas and South Padre Island regions.

For information about historical bloom records in Florida, visit the Fish and Wildlife Research Institute's HAB Monitoring Database webpage, which includes a table of the years and months with confirmed and suspected red tide along the west coast of Florida from 1844 through present.

Not all areas of the coast are equally affected during a red tide. HABs are generally isolated patches that are transported by winds and currents. The blooms are patchy in nature and the impacts vary by location and throughout the day depending on nearby bloom concentrations, ocean currents, surf conditions, and wind speed and direction. Check NOAA's forecasts for help finding an unaffected coastal area.

The HAB-OFS Conditions Report includes a forecast of the potential levels of respiratory irritation associated with a Karenia brevis bloom over the next 3-4 days, and is posted twice a week after confirmation of a HAB and once weekly during the inactive HAB season. Forecasts for potential bloom development at the coast (Florida only), transport (Florida and Texas), and intensification (Florida only) are available in the HAB Bulletin.

the duration of blooms, their intensity, and the extent of the area impacted by the bloom varies significantly from year to year, and it is currently not possible to make long-term forecasts about bloom development, frequency, or intensity. Additionally, because conditions vary with winds and ocean currents, it is not possible to forecast harmful algal bloom ("red tide") conditions more than three to four days in advance. To request bulletin subscription, click here.

In the Gulf of Mexico, one of the most common HABs is the phytoplankton species Karenia brevis. Commonly known as red tide, this organism produces a toxin called brevetoxin that can cause respiratory irritation in humans, contaminate some shellfish, and affect the central nervous system of fish , marine mammals, and birds, potentially causing fish kills and marine mammal death.

When Karenia brevis cells near the ocean surface are broken up by surf at the shore or by breaking waves offshore, the toxin produced by K. brevis can become airborne and incorporated into the marine aerosol, or sea spray. (Find out more about "sea foam"). Onshore winds can blow the airborne toxins onto the beach, potentially causing eye and respiratory irritation (coughing, sneezing, tearing, and itching) to beachgoers. Onshore winds and currents can also transport fish killed by exposure to the toxin onto the beach. Respiratory irritation in humans is significantly reduced when the winds are blowing offshore. Any effects usually decline when a person is no longer exposed, and wearing a particle mask can reduce irritation for some people. People with severe or persistent respiratory conditions (such as chronic lung disease or asthma) may experience stronger adverse reactions and should avoid red tide areas.

State authorities monitor the levels of K. brevis and when cell concentrations reach a predetermined level, are required to put a shellfish ban in effect stating that it is not safe to harvest mollusks (e.g., clams and oysters) and gastropods that feed on bivalves (e.g., whelks). These notices are available from the Florida Department of Agriculture and Consumer Services and the Texas Department of State Health Services. More information about shellfish harvesting and consumption during a red tide is provided below.

For more information regarding red tides and their impacts in the Gulf, refer to the HAB-OFS Health Information, Florida Department of Health Aquatic Toxins, and Texas Department of State Health Services webpages and the references listed below.

Although some people can experience skin irritation and burning eyes, swimming during a red tide is safe for most people. However, never swim among dead fish because they can be associated with harmful bacteria. If you experience adverse symptoms, get out of the water and thoroughly wash off with fresh water. For more information about being in and around a red tide, visit the Florida Department of Health and Texas Department of State Health Services websites.

Commercial seafood available from local restaurants and seafood dealers are strictly regulated and regularly tested for safety.

Always check on the status of shellfish (clams, oysters, mussels) harvesting areas before engaging in recreational shellfish harvesting or consuming shellfish that were harvested recreationally. Cooking and/or freezing does not destroy the red tide toxin.

According to the Texas Department of State Health Services and Florida Fish and Wildlife Research Institute, it is usually okay to eat fish, crabs, lobsters, and shrimp during a red tide bloom because the toxin is not absorbed into the fleshy tissues of these animals. This advice is based on the assumption that only the "edible" portions are being consumed (the fillet or muscle). Scallops are also safe to eat as long as you only eat the muscle of the scallop and not the whole animal.

Oysters and other shellfish, such as clams, mussels, and whelks, can accumulate red tide toxins in their tissues. People that eat oysters or other shellfish containing red tide toxins (brevetoxins) may become seriously ill with neurotoxic shellfish poisoning (NSP). Once a red tide appears to be over, toxins can remain in the oysters for weeks or months. Toxins are heat resistant, so cooking infected shellfish will not remove or deactivate the toxins.

For more information on red tides and their impacts in the Gulf, refer to the HAB-OFS Health Information webpage. For additional Health and Safety information, visit the FWRI and Texas Parks and Wildlife Department (TPWD) Health Information FAQs.

The HAB-OFS forecasts impacts only for potential respiratory irritation. Respiratory irritation impacts addressed in the Condition Report refer to the impacts on humans caused by the toxic aerosols produced by Karenia brevis.

The respiratory irritation impact levels are based on studies reported in the scientific literature (see Kirkpatrick and others 2004, referenced below). The criteria used are the direction and strength of the nearshore winds and the intensity of the Karenia brevis HAB (red tide), which is determined by the concentration of K. brevis cells in the water.

Studies (e.g. Kirkpatrick and others, 2004, referenced below) have shown that onshore winds and breaking surf result in the release of toxins as aerosols. Wind speeds of greater than 7 miles per hour or 3 meters per second are an approximate threshold for the onset of breaking waves. When winds of this speed or greater are onshore, toxic aerosols may be present at the beach. Present wind conditions and wind forecasts are provided by the NOAA National Weather Service's National Data Buoy Center and models run by the National Weather Service's National Centers for Environmental Prediction.

Cell concentration categories used to determine red tide impacts are defined by the Florida Fish and Wildlife Research Institute and have been reported in several peer-reviewed journal articles (see below). In general, higher cell concentrations can produce more aerosols and potentially create a more serious impact.

For the HAB-OFS, the impact levels are defined as follows:

1. See Kirkpatrick and others, 2004, referenced below. Health studies associated with Karenia brevis are also available from the Centers for Disease Control and Prevention (CDC) at http://www.cdc.gov/nceh/hsb/hab/default.htm.
2. The public information on red tide conditions includes information on the impacts of confirmed fish kills caused by red tides during recent days. Since there are many factors that can cause fish kills, the Conditions Report does not attempt to predict the potential for dead fish to reach the beach. For more information on the effect of red tides on various marine animals, refer to Landsberg and others (2002) referenced below and the Florida Fish and Wildlife Research Institute Web site at http://research.myfwc.com/.

For shellfish closures, refer to the Florida Department of Agriculture and Consumer Services Division of Aquaculture and Texas Department of State Health Services.

Click on the links below to access the forecast region maps. Links to the maps are also available on our webpage here, next to the corresponding conditions report.

Southwest Florida

Northwest Florida to Louisiana

Texas

To Report Suspected Illness Related to Aquatic Toxic Exposures or Harmful Algae:
Poison Control Center: (800) 222-1222

Florida

To Report Red Tide Symptoms:
Collier County Natural Resources Department: (239) 252-2502

For Red Tide Status Updates:
Fish and Wildlife Research Institute: (866) 300-9399; callers from outside Florida dial (727)552-2448
Collier County Red Tide Hotline: (239) 252-2591

To Report Dead Fish:
Fish and Wildlife Research Institute (FWRI) fish kill hotline: (800) 636-0511; submit a fish kill report online here.
Collier County Natural Resources Department: (239) 252-2502

Additional Resources:
Florida Department of Health: (850) 245-4299
Florida Department of Health, Public Health Toxicology Section: (850) 245-4401

Texas

For Red Tide Status Updates
Texas Parks and Wildlife (TPWD) hotline: (800) 792-1112, select "fishing" and then "red tide"

For Current Information about Shellfish Closures:
Texas Department of State Health Services Seafood Safety Division: (800) 685-0361

To Report Fish Kills and Discolored Water:
During normal business hours, call your local TPWD office or (361) 825-3244; outside of normal business hours, call TPWD's 24-hour communications centers at (512) 389-4848 (Austin) or (281) 842-8100 (Houston)

HAB-OFS > Health Information
National Ocean Service: Explore > Harmful Algal Blooms
National Centers for Coastal Ocean Science

Kirkpatrick, B., L.E. Fleming, D. Squicciarini, L.C. Backer, R. Clark, W. Abraham, J. Benson, Y.S. Cheng, D. Johnson, R. Pierce, J. Zaias, G.D. Bossart, and D.G. Baden. 2004. "Literature Review of Florida Red Tide: Implications for Human Health Effects." Harmful Algae. Volume 3. Pages 99 to 115.

Kusek, K.M., G. Vargo, and K. Steidinger. 1999. "Gymnodinium Breve in the Field, in the Lab, and in the Newspaper - A Scientific and Journalistic Analysis of Florida Red Tides." Contributions in Marine Science. Volume 34. 229 pages.

Lansberg, J.H. 2002. "The Effects of Harmful Algal Blooms on Aquatic Organisms." Reviews in Fisheries Science. Volume 10, Number 2. Pages 113 to 390.

NOAA. (2013). NOAA Harmful Algal Bloom Operational Forecast System (HAB-OFS). Retrieved February 8, 2013, from CO-OPS HAB-OFS.

Steidinger, K.A., G.A. Vargo, P.A. Tester, and C.R. Tomas. 1998. "Bloom Dynamics and Physiology of Gymnodinium breve with Emphasis on the Gulf of Mexico." In Physiological Ecology of Harmful Algal Blooms. Editors D.M Anderson, A.D. Cembella, and G.M. Hallegraeff.

Stumpf, R.P., M.E. Culver, P.A. Tester, M. Tomlinson, G.J. Kirkpatrick, B.A. Pederson, E. Truby, V. Ransibrahmanukul, and M. Soracco. 2003. "Monitoring Karenia brevis Blooms in the Gulf of Mexico Using Satellite Ocean Color Imagery and Other Data." Harmful Algae. Volume 2. Pages 147 to 160.

Stumpf, R., Tomlinson, M., Calkins, J., Kirkpatrick, B., Fisher,K., Nierenberg, K., Wynne, T. (2009). Skill assessment for an operational algal bloom forecast system. Journal of Marine Systems, Pages 151-161.

Tomlinson, M.C., R.P. Stumpf, V. Ransibrahmanakul, E.W. Truby, G.J. Kirkpatrick, B.A. Pederson, G.A. Vargo, and C.A. Heil. 2004. "Evaluation of the Use of SeaWiFS Imagery for Detecting Karenia brevis Harmful Algal Blooms in the Eastern Gulf of Mexico." Remote Sensing of Environment. Volume 91. Pages 293 to 303.