11th ICRS Abstract book - Nova Southeastern University

Oral Mini-Symposium 17: Emerging Techniques in Remote Sensing and Geospatial Analysis
17-13
Comparison Of in Situ Temperature Data From The Southern Seychelles With Sst
Data: Can Satellite Data Alone Be Used To Predict Coral Bleaching Events?
Ben STOBART* 1 , Nigel DOWNING 2 , Raymond BUCKLEY 3 , Kristian TELEKI 4
1 Marine Reserves, Spanish Institute of Oceanography, Palma de Mallorca, Spain,
2 Cambridge University Coastal Research Unit, Cambridge University, Cambridge,
United Kingdom, 3 College of Ocean and Fishery Sciences, University of Washington,
Seattle, WA, 4 International Coral Reef Action Network (ICRAN), Cambridge, United
Kingdom
Degree-heating-weeks data derived from satellite sea surface temperature (SST) readings
are increasingly being used to predict where bleaching is likely to occur, though
predictions have not always been calibrated and corroborated by field observations.
While SST can provide a good indication of water temperature, local oceanographic
conditions will determine the depth to which satellite SST readings are representative. In
2003 the Aldabra Marine Programme initiated a temperature monitoring network,
currently involving 40 temperature data loggers, in the southern Seychelles at Aldabra,
Assomption, Astove and St. Pierre The annual temperature cycle in the region involves a
shorter period of winter lows (min 23 ºC) between June and October, and extended high
summer temperatures (max 30 ºC) between December and April. We compare SST
temperature data from the four locations with in situ temperature measurements at 6m,
10m and 20m depth. In situ data is most similar to satellite SST during the winter period
(typically not more than 1 ºC difference), and differs most during the summer period (up
to 4 ºC difference). This seasonal difference is due to water column stratification during
the summer, which is typified by calm weather with weak winds (though remaining a
period of occasional cyclone activity). While during the winter rough weather fuelled by
strong southeasterly winds reduces stratification. During the period of stratification in
situ water temperatures are most similar to satellite data at 6m, followed less so by 10m
and 20m depth. A combination of greater stratification during the summer period, along
with periods of cool water upwelling, may in some cases reduce the reliability of satellite
derived SST data for predicting bleaching events. We propose that during bleaching
events exposure of coral communities at Astove, St Pierre and select sites at Aldabra to
thermal stress may be reduced by local oceanographic conditions.
17-14
New Ecological Insights From A 21-Year Coral Reef Temperature Anomaly
Database
Kenneth CASEY* 1 , Elizabeth SELIG 2 , John BRUNO 3
1 National Oceanographic Data Center, NOAA, Silver Spring, MD, 2 Curriculum in
Ecology, University of North Carolina - Chapel Hill, Chapel Hill, NC, 3 Department of
Marine Science, University of North Carolina - Chapel Hill, Chapel Hill, NC
A wide range of new ecological insights has been enabled by advances in satellite remote
sensing of the physical characteristics of the ocean. Dramatically improved algorithms
coupled with advances in computational capabilities have resulted in new products with
finer resolution, longer temporal coverage, greater accuracy, and better consistency. The
Coral Reef Temperature Anomaly Database (CoRTAD), based on 21 years of AVHRR
Pathfinder sea surface temperatures, is one such product that is yielding insights into the
spatial and temporal characteristics of thermal stress and its influence on coral bleaching
and disease. The development of the CoRTAD will be presented along with selected
research highlights from its application to understanding thermal stress patterns, coral
disease, and marine protected area design and effectiveness. In addition, information on
how the extensive collection of information in the CoRTAD can be accessed and applied
to global, regional, and local coral studies will be provided.
17-15
A Methodology For Using Satellite-Based Temperature And Light Measurements For
Predicting Coral Bleaching Severity And Mortality
William SKIRVING* 1 , Roberto IGLESIAS-PREITO 2 , Susana ENRIQUEZ 2 , Tyler
CHRISTENSEN 1 , John HEDLEY 3 , Mark EAKIN 1 , Ove HOEGH-GULDBERG 4 , Sophie
DOVE 4 , Scott HERON 1 , Peter MUMBY 3 , Alan STRONG 1 , Gang LIU 1 , Jessica MORGAN 1 ,
Dwight GLEDHILL 1
1 NOAA Coral Reef Watch, Silver Spring, MD, 2 Universidad Nacional Autonoma de, Puerto
Morelos, Mexico, 3 University of Exeter, Exeter, United Kingdom, 4 University of Queensland,
St Lucia, Australia
The current NOAA Coral Reef Watch (CRW) suite of satellite products is designed to help
coral reef managers monitor heat stress to better understand and predict mass coral bleaching.
Although these products perform well when used to describe the onset of coral bleaching, they
are not as accurate in describing the severity and mortality associated with mass coral bleaching
events. The coral bleaching HotSpot and Degree Heating Week products are based purely on
sea surface temperature (SST), yet coral bleaching is a physiological response that results from
a combination of temperature and light. Here, we describe a potential major evolution of the
NOAA CRW satellite products. A new methodology under development combines satellitederived
SST data with a new satellite-derived solar radiation product to better predict the
severity and mortality of mass coral bleaching events. This new methodology is novel in that it
goes beyond just examining the thermal stress, but actually combines thermal stress
measurements of the existing CRW suite with light measurements from the Geostationary
Environmental Satellites to provide a measure of the total photo-thermal damage.
17-16
Producing A Satellite Sst Climatology – How Long Is A Piece Of String?
Scott F. HERON* 1 , William J. SKIRVING 1 , Gang LIU 2 , Tyler R.L. CHRISTENSEN 2 , C.
Mark EAKIN 1 , Jessica A. MORGAN 2 , Dwight K. GLEDHILL 2 , Alan E. STRONG 1
1 NOAA Coral Reef Watch, Silver Spring, MD, 2 IMSG at NOAA Coral Reef Watch, Silver
Spring, MD
Coral reef ecosystem stress often occurs in response to abnormal environmental conditions
(e.g., temperature, salinity, and light) rather than the absolute level of these. For example,
corals in the Persian Gulf are accustomed to warmer summer conditions than corals off the
coast of Brazil; as such, ocean temperatures of 30°C would be “comfortable” for the former but
stressful for the latter. Identifying anomalous conditions requires good knowledge of the
baseline of usual (“normal”) conditions. Here we discuss whether the existing 22-year satellite
sea surface temperature (SST) record is of sufficient length to calculate a long-term average
(climatology) that can sensibly be used as a baseline for monitoring the health of corals. We
also discuss issues related to global warming in determining this baseline and the relevance of
adaptation by corals. At present, NOAA Coral Reef Watch uses near-real-time satellite
temperatures to determine regions that experience thermal anomalies that have been linked to
coral bleaching events. Inherent within the present operational process is a SST climatology
that was defined using satellite SST data and which underpins the satellite-monitoring success.
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