Navigation Links
Health of coral reefs detected from orbit

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. Coral bleaching is linked to sea temperatures above normal summer maxima and to solar radiation. Bleaching may take place on localised and mass scales ?there was an extensive bleaching event in 1998 and 2002 likely linked to El Ni�o events.

"An increase in frequency of coral bleaching may be one of the first tangible environmental effects of global warming," states Dr. Arnold Dekker of Australia's Commonwealth Scientific and Industrial Research Organisation's (CSIRO) Wealth from Oceans Flagship program."The concern is that coral reefs might pass a critical bleaching threshold beyond which they are unable to regenerate."

Aerial or boat-based observation is the current method of detecting bleaching, but many reefs are either inaccessible or simply too large (the Great Barrier Reef has an area of 350 000 square kilometres) for an event that happens within a fortnight. Bleached corals may rapidly be colonised by blue-green to brown algae, more difficult to distinguish from live coral.

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

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

The team studied Heron Island reef at the southern end of the Great Barrier Reef, site of a University of Queensland research station. Validating MERIS Full Resolution mode results, they found that observed changes in live coral cover were correlated to an existing bleaching event.

Theoretical studies indicate that for each complete 300-metre pixel of coral under one metre of water it is possible to detect a 2% bleaching of live coral. MERIS should remain sensitive to detecting from 7-8% bleached coral even under ten metres of water.

"MERIS Full Resolution covers the world every three days, a bottleneck for global monitoring could be data processing," Dekker concludes. "However satellite sensors measuring sea surface temperature such as Envisat's Advanced Along Track Scanning Radiometer (AATSR) can be applied to prioritise reefs that are subject to sea temperature heating anomalies-thus focusing the MERIS based bleaching detection.

Australia's Great Barrier Reef Marine Park Authority has expressed interest in the project. Australian scientists plan to progress to perform MERIS monitoring of bleaching events up to the scale of the whole Great Barrier Reef.


'"/>

Source:European Space Agency


Related biology news :

1. BioMed Central welcomes the new National Institutes of Health public access policy
2. OneWorld Health drug receives Orphan designation from U.S. and European regulatory agencies
3. Health costs soar as 60 million Americans classed as obese
4. Going To Extremes To Improve Human Health
5. Patient-choice C-section rate rises 36%: HealthGrades study
6. Grand Challenges in Global Health initiative funds Yale project
7. Health benefits of a Christmas brandy
8. Health of Acehnese reefs in the wake of the tsunami shows human impacts more harmful
9. Healthy coral reefs of Madagascar resisting damage from climate change
10. Health Canada approves cold and flu medicine
11. Mailman School of Public Health researchers report blood DNA can be early predictor of liver cancer
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:11/3/2018)... ... 01, 2018 , ... As 2018 comes to a close, significant changes to ... quality systems for manufacturers worldwide. To mark World Quality Day this month, ... “While 2020 may sound far off, the May 26 deadline transition deadline that year ...
(Date:10/31/2018)... ... October 30, 2018 , ... Azzur ... Operations. With more than 20 years of antibody purification and management experience, Heidinger ... industry. Heidinger joins Azzur from ImmunoReagents, a company he co-founded and managed for ...
(Date:10/31/2018)... ... 31, 2018 , ... RPS Diagnostics, Inc. (RPS®) today announced ... immediate launch in the European Union and all countries recognizing the CE mark. ... expected to contribute towards a diagnostic solution to the global antibiotic crisis. , ...
Breaking Biology News(10 mins):
(Date:10/31/2018)... ... October 30, 2018 , ... Today, the National Corn Growers ... of this global competition is to find new and innovative uses of field corn. ... farmers produced 14.6 billion bushels of corn and are on pace to produce the ...
(Date:10/24/2018)... Calif. (PRWEB) , ... October 22, 2018 , ... ... events for research scientists, clinicians, and medical experts from around the world, will ... free event will focus on best practices in testing, chromatography, centrifugation, as well ...
(Date:10/17/2018)... ... October 17, 2018 , ... Dr. Richard Amato, ... Dr. Michael Kang, are offering current and new patients the opportunity to enjoy ... the emerging, proven treatment technology known as Piezosurgery® . As long-time believers ...
(Date:10/16/2018)... N.J. (PRWEB) , ... October 15, 2018 , ... ... have characterized tissues through the visualization of histopathology slides by eye wherein key ... the gold standard for diagnosis and research, it is highly limited in that ...
Breaking Biology Technology: