An early warning network for coral bleaching in southeast Florida
SEAFAN BleachWatch helps to detect and monitor coral bleaching events in southeast Florida
and improve scientific understanding by:
Tracking weather conditions and sea surface temperatures for conditions favorable for
Collecting field observations on the condition of the reef from trained observers;
Summarizing data and producing reports on the current conditions in the region.
Recreational, commercial and scientific divers are
encouraged to become part of the BleachWatch Observer
Network by participating in a training session. These
1.5 hour sessions include an introduction to SEAFAN, a
short lesson on coral biology/bleaching, a description
of the BleachWatch Early Warning Program, and an
overview of how to properly assess coral condition,
record observations, and submit reports. All
participants will be provided with a BleachWatch Kit,
which includes a program overview, coral bleaching fact
sheet, data sheets, data sheet instructions, dive
whistle, and coral ID and bleaching example cards to use
as a reference below and above the water.
BleachWatch Observers - Don't forget to report your observations!
Remember, reports of 'no bleaching' are just as important as 'bleaching'
SEAFAN BleachWatch training materials
Interested in becoming part of the SEAFAN BleachWatch Observer Network?
Contact Karen Bohnsack at 305-795-1204 or
about participating in a
training session, which are held periodically during the
spring and summer. With enough interest from a group of people, efforts will be made
to arrange additional training opportunities.
While localized, colony specific bleaching has been recorded for over 100 years,
there is an indication that coral bleaching has increased in frequency and severity
along the Florida Reef Tract since the 1980s. Increasing public, media, and
scientific concern for the reef highlighted the need for a program to monitor bleaching
before, during, and after each incident to help improve scientific understanding. In
2005, modeled after the Great Barrier Reef's BleachWatch Program, the Florida Keys
National Marine Sanctuary and Mote Marine Laboratory created the Florida Keys
BleachWatch Program to act as an early warning network for coral bleaching. In 2013,
the Florida Department of Environmental Protection (DEP) created SEAFAN BleachWatch,
an extension of this early warning network along the northern portion of the Florida
Reef Tract, located off of mainland southeast Florida from the northern border of
Biscayne National Park in Miami-Dade County to the St. Lucie Inlet in Martin County.
There are many questions about coral bleaching that must be answered in order to fully assess
the environmental impact of bleaching events. Where and when is bleaching taking place? What
species are more vulnerable? What is the duration and severity of the bleaching event? And
finally, what is the recovery and resilience potential of the southeast Florida coral reef
ecosystem? The SEAFAN BleachWatch program was designed to help answer some of these questions
by providing valuable information about the condition of southeast Florida's coral reefs.
The BleachWatch Program combines climate and sea surface temperature data with field observations
on the condition of coral reefs from a trained Observer Network in order to detect the potential
onset of mass bleaching events. The environmental monitoring data will be combined with Observer
Network reports to produce a comprehensive overview of current conditions in the region.
Comparison of healthy (left), paling (middle), and bleached (right) brain coral,
Image: Mote Marine Laboratory
Weather conditions such as calm winds and clear sunny days can lead to an increase in sea temperatures,
and are generally associated with mass bleaching events. Seasonal climate predictions and local weather
forecasts will be monitored for periods of light winds and decreased cloud cover, which may intensify
coral stress during summer months when sea surface temperature is elevated.
Sea surface temperature is monitored by NOAA's Coral Reef Watch
program which provides a variety of internet-based satellite imagery products that summarize
temperature data and can be used to predict if conditions are conducive to coral bleaching. Small
increases in sea temperatures over several weeks or large increases over a few days stress coral and,
if these conditions persist, could lead to mass bleaching. The Coral Reef Watch products will be used
to assess thermal stress and determine if there is a significant risk of coral bleaching in southeast
Florida. If available data indicates the presence of environmental conditions favorable for bleaching,
an alert will be sent out to the BleachWatch Observer Network to submit field observations on the
condition of coral reefs throughout the region.
The onset and severity of mass coral bleaching can vary by species, geographic location, and type of
reef zone, which makes it very difficult to predict where or when it will occur. Similar to the Florida
Keys BleachWatch Program, SEAFAN BleachWatch seeks to create an Observer Network of trained recreational,
commercial, and scientific divers to help identify when and where bleaching is taking place by
monitoring and reporting on the condition of the reefs in southeast Florida.
Divers will be alerted when conditions favorable for bleaching are present, so that field data can be
gathered before, as well as during and after a bleaching event. After each visit to the reef, the divers
complete a data sheet, either printed or online, and send it to the BleachWatch coordinator. Divers are
asked to report whether they see bleaching or not, and are also encouraged to send pictures of their
observations. To help ensure consistency in reported data, the divers attend a formal training session
and are provided with bleaching and coral ID keys to use as a reference below and above the water. While
most involvement in the program will occur during the summer months when the risk of bleaching is
greatest, reports may occasionally be solicited at other times of the year, such as during unusually
"Current Conditions Reports" will be generated throughout the summer to provide a summary of all
available data being collected, including relevant weather information and NOAA Coral Reef Watch
analysis, as well as with BleachWatch Observer Network reports. These reports will provide an overview
of conditions throughout southeast Florida. These will be available online, and produced monthly,
weekly, or biweekly depending on the severity of the climate conditions and extent of coral bleaching
Corals are composed of animals called coral polyps which secrete hard, limestone skeletons. A single
coral colony is made up of numerous individual coral polyps. These polyps receive up to 90% of their
energy requirements from unicellular algae known as zooxanthellae that live within their tissues and
provide them with carbohydrates and oxygen through photosynthesis. The zooxanthellae are usually golden
brown in color and are found at various densities in individual species of corals. Zooxanthellae, along
with the additional pigments that some corals have in their tissues, provide the normal "healthy"
coloration of coral. Stressed corals may lose or expel zooxanthellae, which leaves behind the
transparent tissue and reveals the underlying white skeleton, giving the coral a bleached white
appearance. This process is called coral bleaching.
Bleaching is a stress response that results when the coral-algae relationship breaks down. Coral
bleaching can be caused by a wide range of environmental stressors such as pollution, oil spills,
increased sedimentation, extremes in sea temperatures and salinity, low oxygen, disease, and predation.
Bleached corals are still living, and if the environmental conditions return to normal soon enough,
the corals can regain or regrow their zooxanthellae and survive the bleaching event. If the stressors
are severe or prolonged, however, bleaching can lead to the death of corals. Bleached corals are more
susceptible to disease, predation, and death because they are without their primary energy source.
Great star coral, Montastraea cavernosa, with polyps
Photo: Joe Marino
Localized or colony specific bleaching has been recorded for over 100 years but only in the last 20 years
have we seen mass bleaching events in which a wide range of coral species bleach over a large area of reef.
While the influence of local stressors can explain small scale bleaching events, widespread, mass bleaching
is most commonly attributed to elevated sea temperatures in conjunction with increased ultraviolet radiation
due to calm weather and clear skies. Because most corals live close to their maximum thermal limits, a
temperature increase of only 1-2 degrees Celsius above the long term average can trigger mass bleaching,
particularly when prolonged.
In 1997-1998, a worldwide mass bleaching event caused severe damage to an estimated 16% of the world's reefs.
Additional bleaching events have occurred in some regions since, including the Caribbean and Great Barrier
Reef, and it is likely that both the severity and frequency of such events will increase in the future.
In situations where bleaching causes extensive coral death, recovery is dependent on new coral recruits
settling and growing on the reef. This is a time-consuming process, even on relatively healthy reefs.
Regrowth of reefs that have been severely damaged by bleaching may take decades and the new reef may be
significantly different from that which existed before bleaching. If a recovering reef is affected by
another bleaching event or stress before it has fully recovered, then it may persist in a degraded state
for much longer. In locations suffering from pollution or other chronic pressures, recovery can be
particularly slow or inhibited altogether.
For more information about BleachWatch, contact Karen Bohnsack at 305-795-1204 or