Chapter 2
EXTREME EVENTS AND PERTURBATIONS OF COASTAL ECOSYSTEMS
Sea Surface Temperature Change and Coral Bleaching
WILLIAM SKIRVING
1,2 , ALAN E. STRONG
2
, GAND LIU
2 , FELIPE ARZAYUS
2
,
CHUNYING LIU
2 AND JOHN SAPPER
2
1
Queensland Science and Engineering Consultants, PO Box 806, Aitkenvale,
Queensland, Australia 4814 William.Skirving@noaa.gov
2 Coral Reef Watch, NOAA/NESDIS/ORA, E/RA31, SSMC1, Floor 5, 1335 East-West
Highway, Silver Spring, MD 20910-3226, USA
1. Introduction
Remote Sensing of Aquatic Coastal Ecosystem Processes presents many examples
of remote sensing tools which could be used in an operational sense for the benefit of
management of various aspects of coastal ecosystems. This chapter will present the
World’s first global operational satellite products designed specifically to help coral
reef managers map and monitor anomalous sea surface temperatures (SST) and hence
better understand and predict mass coral bleaching. These products are possibly the
only global suite of operational satellite products currently being used for the
management of any marine ecosystem.
Coral bleaching occurs when there is widespread loss of pigment from coral,
mainly due to the expulsion of symbiotic algae (Yonge and Nicholls, 1931). The algae
are usually expelled in times of stress, often caused by sea surface temperatures which
are higher than the coral colony’s tolerance level. This may be as little as 1 to 2
o C
above the mean monthly summer values (Berkelmans and Willis, 1999; Reaser et al.,
2000).
A number of publications in the early 1990s reported that links had been observed
between significant bleaching and anomalously warm water several weeks earlier (e.g.
Bermuda: Cook et al. 1990; Indonesia: Brown and Suharsono, 1990; Jamaica: Gates,
1990; Andaman Sea: Brown et al., 1996). About the same time a number of journal
articles proposed a mechanism that linked sea surface temperature with mass coral
bleaching (e.g. Lesser et al., 1990; Glynn and D’Croz, 1990). Coles and Jokiel (1977)
and Jokiel and Coles (1990) proposed the existence of a universal critical threshold
temperature for bleaching. They proposed that regardless of location, the threshold
could be defined as a 1
o
C increase over the mean local summer maximum temperature.
As an extension of these ideas, Goreau and Hayes (1994) produced maps of “ocean hot
spots” using monthly global ocean temperature anomaly maps from NOAA Climate
Diagnostic Bulletins (monthly maps derived mostly from in situ data with a small
satellite contribution). These “ocean hot spots” identified areas whose SSTs exceeded
long term averages by more than 1
o
C. Bleaching seemed to be occurring within the
boundaries of the “ocean hot spots” for the warm season in each region.
One of us (Dr. Alan Strong-NOAA/NESDIS) recognized that there was an
opportunity to derive an automated satellite product based on this relationship. As a
result, the HotSpot product was born, which served as the basis of the NOAA Coral
Reef Watch Program. HotSpot was first presented as an experimental product in 1997
(Strong et al., 1997). This proved to be somewhat fortuitist given that we now know
11
and Management Applications, 11-25.
© 2006 Springer. Printed in the Netherlands.
L.L. Richardson and E.F. LeDrew (eds.), Remote Sensing of Aquatic Coastal Ecosystem Processes: Science
EXTREME EVENTS AND PERTURBATIONS OF COASTAL ECOSYSTEMS
Sea Surface Temperature Change and Coral Bleaching
WILLIAM SKIRVING
1,2 , ALAN E. STRONG
2
, GAND LIU
2 , FELIPE ARZAYUS
2
,
CHUNYING LIU
2 AND JOHN SAPPER
2
1
Queensland Science and Engineering Consultants, PO Box 806, Aitkenvale,
Queensland, Australia 4814 William.Skirving@noaa.gov
2 Coral Reef Watch, NOAA/NESDIS/ORA, E/RA31, SSMC1, Floor 5, 1335 East-West
Highway, Silver Spring, MD 20910-3226, USA
1. Introduction
Remote Sensing of Aquatic Coastal Ecosystem Processes presents many examples
of remote sensing tools which could be used in an operational sense for the benefit of
management of various aspects of coastal ecosystems. This chapter will present the
World’s first global operational satellite products designed specifically to help coral
reef managers map and monitor anomalous sea surface temperatures (SST) and hence
better understand and predict mass coral bleaching. These products are possibly the
only global suite of operational satellite products currently being used for the
management of any marine ecosystem.
Coral bleaching occurs when there is widespread loss of pigment from coral,
mainly due to the expulsion of symbiotic algae (Yonge and Nicholls, 1931). The algae
are usually expelled in times of stress, often caused by sea surface temperatures which
are higher than the coral colony’s tolerance level. This may be as little as 1 to 2
o C
above the mean monthly summer values (Berkelmans and Willis, 1999; Reaser et al.,
2000).
A number of publications in the early 1990s reported that links had been observed
between significant bleaching and anomalously warm water several weeks earlier (e.g.
Bermuda: Cook et al. 1990; Indonesia: Brown and Suharsono, 1990; Jamaica: Gates,
1990; Andaman Sea: Brown et al., 1996). About the same time a number of journal
articles proposed a mechanism that linked sea surface temperature with mass coral
bleaching (e.g. Lesser et al., 1990; Glynn and D’Croz, 1990). Coles and Jokiel (1977)
and Jokiel and Coles (1990) proposed the existence of a universal critical threshold
temperature for bleaching. They proposed that regardless of location, the threshold
could be defined as a 1
o
C increase over the mean local summer maximum temperature.
As an extension of these ideas, Goreau and Hayes (1994) produced maps of “ocean hot
spots” using monthly global ocean temperature anomaly maps from NOAA Climate
Diagnostic Bulletins (monthly maps derived mostly from in situ data with a small
satellite contribution). These “ocean hot spots” identified areas whose SSTs exceeded
long term averages by more than 1
o
C. Bleaching seemed to be occurring within the
boundaries of the “ocean hot spots” for the warm season in each region.
One of us (Dr. Alan Strong-NOAA/NESDIS) recognized that there was an
opportunity to derive an automated satellite product based on this relationship. As a
result, the HotSpot product was born, which served as the basis of the NOAA Coral
Reef Watch Program. HotSpot was first presented as an experimental product in 1997
(Strong et al., 1997). This proved to be somewhat fortuitist given that we now know
11
and Management Applications, 11-25.
© 2006 Springer. Printed in the Netherlands.
L.L. Richardson and E.F. LeDrew (eds.), Remote Sensing of Aquatic Coastal Ecosystem Processes: Science