12.2.4 Application to Reef Management
Coral bleaching results from the stress and loss of symbiotic algae, known as
zooxanthellae, from coral tissues during times of stress, often due to temperatures
higher than the tolerance level of the coral colony (Glynn 1993). Monitoring of
SST at global scales provides researchers and stakeholders with tools to understand and better manage the complex interactions leading to coral bleaching. When
bleaching conditions occur, these tools can be used to trigger bleaching response
plans and support appropriate management decisions (Beggs 2010).
NOAA’s Coral Reef Watch (CRW; www.coralreefwatch.noaa.gov) provides
current reef environmental conditions to identify areas at risk for coral bleaching.
CRW uses the operational NOAA/NESDIS 0.5° (*50 km), twice weekly, nighttime, AVHRR SST composites for near real-time monitoring of thermal stress that
can cause coral bleaching (Liu et al. 2009). This product suite includes both data
and global maps of SST and SST anomalies, as well as the coral-specific products
HotSpot (positive anomaly from the warmest month climatology) and Degree
Heating Weeks (DHW; accumulated thermal stress as given by HotSpot). A full
description of these products is given by Skirving et al. (2006). More recently,
additional management products have been added. The Bleaching Area Alert
Product consolidates the HotSpot and DHW data to provide maps of the current
status of thermal stress as it pertains to coral bleaching. Automated emails, through
the Satellite Bleaching Alert system, summarize the bleaching risk at a usernominated subset of (currently) 227 coral reef locations and inform stakeholders of
status level changes at selected reefs.
In addition to NOAA’s products, Australia’s Great Barrier Reef Marine Park
Authority (GBRMPA) uses ReefTemp (Maynard et al. 2008), a regionally-specific,
higher resolution mapping product that provides information on bleaching risk in
near real-time based on a combination of SST and other measures of temperature
stress (www.cmar.csiro.au/remotesensing/reeftemp). ReefTemp builds upon the
work by the NOAA CRW in that it ‘nowcasts’ bleaching risk daily at 0.018°
(*2 km) resolution. Images of SST and associated measures of temperature stress
produced by ReefTemp are based on comparing data from a 10 day composite of
AVHRR SST to monthly average temperatures calculated from 1992 to 2002
(Griffin et al. 2004). Where the SST cannot be calculated due to cloud cover, the
most recent SST is maintained for that location up to 10 days (for most locations
SST values are typically updated every 1–4 days). The legend used to describe
temperature stress is calibrated to in situ observations of bleaching stress from
around Australia. ReefTemp is an important component of the GBRMPA’s Coral
Bleaching Response Plan (www.gbrmpa.gov.au/corp_site/key_issues/climate_
change/management_responses) as it forms part of the early warning system, targeting assessment and monitoring plan for sites that experience stress levels conducive to bleaching.
Seasonal forecasting of potential thermal conditions leading to mass coral
bleaching is performed by NOAA CRW, using output from SST forecast models,
324
S. J. Weeks et al.
Coral bleaching results from the stress and loss of symbiotic algae, known as
zooxanthellae, from coral tissues during times of stress, often due to temperatures
higher than the tolerance level of the coral colony (Glynn 1993). Monitoring of
SST at global scales provides researchers and stakeholders with tools to understand and better manage the complex interactions leading to coral bleaching. When
bleaching conditions occur, these tools can be used to trigger bleaching response
plans and support appropriate management decisions (Beggs 2010).
NOAA’s Coral Reef Watch (CRW; www.coralreefwatch.noaa.gov) provides
current reef environmental conditions to identify areas at risk for coral bleaching.
CRW uses the operational NOAA/NESDIS 0.5° (*50 km), twice weekly, nighttime, AVHRR SST composites for near real-time monitoring of thermal stress that
can cause coral bleaching (Liu et al. 2009). This product suite includes both data
and global maps of SST and SST anomalies, as well as the coral-specific products
HotSpot (positive anomaly from the warmest month climatology) and Degree
Heating Weeks (DHW; accumulated thermal stress as given by HotSpot). A full
description of these products is given by Skirving et al. (2006). More recently,
additional management products have been added. The Bleaching Area Alert
Product consolidates the HotSpot and DHW data to provide maps of the current
status of thermal stress as it pertains to coral bleaching. Automated emails, through
the Satellite Bleaching Alert system, summarize the bleaching risk at a usernominated subset of (currently) 227 coral reef locations and inform stakeholders of
status level changes at selected reefs.
In addition to NOAA’s products, Australia’s Great Barrier Reef Marine Park
Authority (GBRMPA) uses ReefTemp (Maynard et al. 2008), a regionally-specific,
higher resolution mapping product that provides information on bleaching risk in
near real-time based on a combination of SST and other measures of temperature
stress (www.cmar.csiro.au/remotesensing/reeftemp). ReefTemp builds upon the
work by the NOAA CRW in that it ‘nowcasts’ bleaching risk daily at 0.018°
(*2 km) resolution. Images of SST and associated measures of temperature stress
produced by ReefTemp are based on comparing data from a 10 day composite of
AVHRR SST to monthly average temperatures calculated from 1992 to 2002
(Griffin et al. 2004). Where the SST cannot be calculated due to cloud cover, the
most recent SST is maintained for that location up to 10 days (for most locations
SST values are typically updated every 1–4 days). The legend used to describe
temperature stress is calibrated to in situ observations of bleaching stress from
around Australia. ReefTemp is an important component of the GBRMPA’s Coral
Bleaching Response Plan (www.gbrmpa.gov.au/corp_site/key_issues/climate_
change/management_responses) as it forms part of the early warning system, targeting assessment and monitoring plan for sites that experience stress levels conducive to bleaching.
Seasonal forecasting of potential thermal conditions leading to mass coral
bleaching is performed by NOAA CRW, using output from SST forecast models,
324
S. J. Weeks et al.