[Coral-List] NOAA CRW Coral Bleaching Analysis and Outlook Message (Sept 2010)

Coral Reef Watch coralreefwatch at noaa.gov
Fri Sep 10 13:38:55 EDT 2010

Analysis of September 2010 Thermal Stress and Seasonal Guidance Through 
December 2010


The NOAA Coral Reef Watch (CRW) satellite coral bleaching monitoring 
shows sea surface temperatures (SSTs) continue to remain above average 
throughout the wider Caribbean region. Large areas of the southeastern 
Caribbean Sea are experiencing thermal stress capable of causing coral 
bleaching. The western Gulf of Mexico and the southern portion of the 
Bahamas have also experienced significant bleaching thermal stress. The 
CRW Coral Bleaching Thermal Stress Outlook indicates that the high 
stress should continue to develop in the southern and southeast 
Caribbean until mid-October. Bleaching stress in the western Gulf of 
Mexico and southern Bahamas should dissipate quickly in the next couple 
of weeks.

According to the CRW HotSpots, there is currently bleaching-level 
thermal stress around a large region in the northwestern Pacific, but 
except for the eastern coast of Japan, the high-stress areas are outside 
of areas where corals occur. The high thermal stress previously centered 
on the Philippines has mostly dissipated. Some areas around the 
Northwestern Hawaiian Islands, the Philippines, and Palau continue in a 
Bleaching Watch status. The outlook shows that the thermal stress in the 
northwestern Pacific is expected to shift south starting in October as 
the northern hemisphere summer ends. There is a potential for 
bleaching-level stress through November in a region centered to the 
south of Guam and extending from Palau to Chuuk. We will continue to 
watch the potential for thermal stress around Papua-New Guinea later in 
the year.

Most of the southern hemisphere and the entire Indian Ocean basin are 
expected to remain free from significant bleaching thermal stress 
through December 2010.

(See full alert message for details at

(Watch the recording of Reef Resilience Webinar: Bleaching Outlook for 
September through December 2010, with Dr. Mark Eakin of the NOAA Coral 
Reef Watch Program at

Analysis and Outlook for Caribbean, Gulf of Mexico and Bahamas

Current conditions:

The CRW satellite monitoring shows that thermal stress levels capable of 
causing belaching have continued to develop in the southeastern 
Caribbean since July, bearing a similar signature to the thermal stress 
observed at the same time period in 2005, the year of a record mass 
coral bleaching event. The highest thermal stress currently spans the 
entire Lesser Antilles, from Montserrat to Tobago. Lower levels of 
stress extend westward across the northern coast of Venezuela, and high 
stress is also found on the Caribbean coast of Panama and Costa Rica.

The bleaching stresses in the western Gulf of Mexico and southern 
Bahamas are still lingering. Earlier stress in Florida, northern 
Bahamas, and the Greater Antilles has eased, partly due to recent 
tropical weather. Hurricane Earl left a clear track of cooler water 
north of the region including reports of cool water at depth in the US 
Virgin Islands, and other weather disturbances have cooled temperatures 
from Texas to the Virgin Islands. Mixing and cooling from a hurricane 
can reduce thermal stress to a reef and prevent severe bleaching 
(Manzello et al., 2007). Bleaching has been reported in Tobago to the 
south and mild bleaching in the US Virgin Islands to the north.

Bleaching outlook:

The CRW Coral Bleaching Thermal Stress Outlook continues to indicate a 
high potential for thermal stress capable of causing significant coral 
bleaching in the southern Caribbean in 2010. The region at greatest risk 
fills the region east from Nicaragua past the island of Hispaniola to 
Puerto Rico and the Lesser Antilles, and south along the Caribbean 
coasts of Panama and South America. The intensity of the potential 
thermal stress is predicted to increase through October. The Caribbean 
typically experiences elevated temperature during the second year of an 
El Niño event, with the 2009-2010 El Niño ending in May 2010. The region 
described here as having the highest potential to experience 
bleaching-levels of thermal stress is the same region that has been 
anomalously warm throughout 2010. The model is only slightly 
over-predicting the strength of the current thermal stress, adding to 
our confidence that this may be a severe bleaching event.

The lingering bleaching stress in the western Gulf of Mexico and 
southern Bahamas is expected to dissipate quickly in the next couple of 

Analysis and Outlook for western Pacific:

Current conditions:

The thermal stress that caused bleaching in Southeast Asia and the 
Philippines has abated, but temperatures across much of the western 
tropical Pacific remain above normal at the moment. Some thermal stress 
has accumulated in the Northwestern Hawaiian Islands, and temperatures 
remain near the bleaching threshold in that region.

As the summer comes to an end in the northern hemisphere, our outlook 
shows that the thermal stress in the northwestern Pacific is expected to 
shift south starting in October. The outlook indicates that there is a 
potential for thermal stress capable of causing bleaching through 
November in the region south from the Northern Mariana Islands and Guam 
to the Federated States of Micronesia (FSM), extending from Palau to 
Chuuk. This may move to include the northern coast of Papua-New Guinea 
in December. However, unlike conditions in the Caribbean, most of this 
western Pacific region has not yet warmed to bleaching levels. The model 
is over-predicting warming at this time, leading to a hope that 
bleaching will not be severe.

[Note: The Coral Reef Watch Bleaching Outlook is an experimental product 
and should be used as an indicator of potential general patterns rather 
than a precise predictor of thermal stress at any location. Actual 
conditions may vary due to model uncertainty, subsequent changes in 
climatic conditions, extreme localized variability, or weather patterns.]

Current HotSpot and Degree Heating Week charts and data formatted for
HDF and Google Earth can be found at:

Time series graphics for index sites can be found at:

You can sign up for automated bleaching alerts at:

Please report bleaching events (or non-events) at:

NOAA Coral Reef Watch
coralreefwatch at noaa.gov

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