Featured Research

from universities, journals, and other organizations

Health Of Coral Reefs Detected From Orbit

Date:
October 5, 2005
Source:
European Space Agency
Summary:
Australian researchers have found Envisat's MERIS sensor can detect coral bleaching down to ten metres deep. This means Envisat could potentially monitor impacted coral reefs worldwide on a twice-weekly basis. Coral bleaching happens when symbiotic algae living in symbiosis with living coral polyps (and providing them their distinctive colours) are expelled. The whitening coral may die with subsequent impacts on the reef ecosystem, and thus fisheries, regional tourism and coastal protection.

An Envisat MERIS image of the Great Barrier Reef off Australia's Queensland coast, centred on Cape York Peninsula. Taken on 19 August 2004, this MERIS Full Resolution mode images has a spatial resolution of 300 metres.
Credit: ESA

"An increase in frequency of coral bleaching may be oneof the first tangible environmental effects of global warming," statesDr. Arnold Dekker of Australia's Commonwealth Scientific and IndustrialResearch Organisation’s (CSIRO) Wealth from Oceans Flagshipprogram."The concern is that coral reefs might pass a criticalbleaching threshold beyond which they are unable to regenerate."

Aerialor boat-based observation is the current method of detecting bleaching,but many reefs are either inaccessible or simply too large (the GreatBarrier Reef has an area of 350 000 square kilometres) for an eventthat happens within a fortnight. Bleached corals may rapidly becolonised by blue-green to brown algae, more difficult to distinguishfrom live coral.

Repetitive, objective and broad-scale satellitecoverage is the alternative. At this week's MERIS/AATSR Workshop inFrascati, Italy, the CSIRO team presented initial results usingEnvisat's Medium Resolution Imaging Spectrometer (MERIS). MERISacquires images in 15 different spectral bands at 300 m resolution.

"Coralbleaching needs to be mapped at the global scale," Dekker adds."High-spatial resolution satellites can only do it on a few reefs dueto cost and coverage constraints. We need a system that has appropriatecoverage and revisit frequency, with a sufficient amount of spectralbands and sensitivity. There is no more suitable system than MERIS."

Theteam studied Heron Island reef at the southern end of the Great BarrierReef, site of a University of Queensland research station. ValidatingMERIS Full Resolution mode results, they found that observed changes inlive coral cover were correlated to an existing bleaching event.

Theoreticalstudies indicate that for each complete 300-metre pixel of coral underone metre of water it is possible to detect a 2% bleaching of livecoral. MERIS should remain sensitive to detecting from 7-8% bleachedcoral even under ten metres of water.

"MERIS Full Resolutioncovers the world every three days, a bottleneck for global monitoringcould be data processing," Dekker concludes. "However satellite sensorsmeasuring sea surface temperature such as Envisat's Advanced AlongTrack Scanning Radiometer (AATSR) can be applied to prioritise reefsthat are subject to sea temperature heating anomalies-thus focusing theMERIS based bleaching detection.

Australia's Great Barrier ReefMarine Park Authority has expressed interest in the project. Australianscientists plan to progress to perform MERIS monitoring of bleachingevents up to the scale of the whole Great Barrier Reef.



Story Source:

The above story is based on materials provided by European Space Agency. Note: Materials may be edited for content and length.


Cite This Page:

European Space Agency. "Health Of Coral Reefs Detected From Orbit." ScienceDaily. ScienceDaily, 5 October 2005. <www.sciencedaily.com/releases/2005/10/051005075206.htm>.
European Space Agency. (2005, October 5). Health Of Coral Reefs Detected From Orbit. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2005/10/051005075206.htm
European Space Agency. "Health Of Coral Reefs Detected From Orbit." ScienceDaily. www.sciencedaily.com/releases/2005/10/051005075206.htm (accessed July 28, 2014).

Share This




More Earth & Climate News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

The Carbon Trap: US Exports Global Warming

The Carbon Trap: US Exports Global Warming

AP (July 28, 2014) AP Investigation: As the Obama administration weans the country off dirty fuels, energy companies are ramping-up overseas coal exports at a heavy price. (July 28) Video provided by AP
Powered by NewsLook.com
Raw: Sea Turtle Hatchlings Emerge from Nest

Raw: Sea Turtle Hatchlings Emerge from Nest

AP (July 27, 2014) A live-streaming webcam catches loggerhead sea turtle hatchlings emerging from a nest in the Florida Keys. (July 27) Video provided by AP
Powered by NewsLook.com
Trees Could Save More Than 850 Lives Each Year

Trees Could Save More Than 850 Lives Each Year

Newsy (July 27, 2014) A national study conducted by the USDA Forest Service found that trees collectively save more than 850 lives on an annual basis. Video provided by Newsy
Powered by NewsLook.com
Phoenix Thunderstorm Creates Giant Wall of Dust

Phoenix Thunderstorm Creates Giant Wall of Dust

Reuters - US Online Video (July 26, 2014) A giant wall of dust slowly moves north over the Phoenix area after a summer monsoon thunderstorm. Mana Rabiee reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins