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´┐Żo 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:6/22/2016)... , June 22, 2016  The American College of Medical ... Show Executive Magazine as one of the fastest-growing trade ... 25-27 at the Bellagio in Las Vegas ... highest percentage of growth in each of the following categories: ... companies and number of attendees. The 2015 ACMG Annual Meeting ...
(Date:6/21/2016)... June 21, 2016 NuData Security announced today ... role of principal product architect and that ... of customer development. Both will report directly to ... The moves reflect NuData,s strategic growth in its ... high customer demand and customer focus values. ...
(Date:6/15/2016)... York , June 15, 2016 ... new market report titled "Gesture Recognition Market by Application ... Forecast, 2016 - 2024". According to the report, the  ... 11.60 billion in 2015 and is estimated to ... USD 48.56 billion by 2024.  Increasing ...
Breaking Biology News(10 mins):
(Date:6/27/2016)... June 27, 2016  Sequenom, Inc. (NASDAQ: ... healthier lives through the development of innovative products and ... the United States denied its petition ... claims of Sequenom,s U.S. Patent No. 6,258,540 (",540 Patent") ... established by the Supreme Court,s Mayo Collaborative Services v. ...
(Date:6/27/2016)...  Liquid Biotech USA , ... Sponsored Research Agreement with The University of Pennsylvania ... cancer patients.  The funding will be used to ... clinical outcomes in cancer patients undergoing a variety ... employed to support the design of a therapeutic, ...
(Date:6/24/2016)... Raleigh, NC (PRWEB) , ... June 24, 2016 , ... ... find the most commonly-identified miRNAs in people with peritoneal or pleural mesothelioma. Their findings ... here to read it now. , Diagnostic biomarkers are signposts in the blood, ...
(Date:6/23/2016)... SPRING, Md. , June 23, 2016 A ... collected from the crime scene to track the criminal down. ... and the U.S. Food and Drug Administration (FDA) uses DNA ... Sound far-fetched? It,s not. The ... genome sequencing to support investigations of foodborne illnesses. Put as ...
Breaking Biology Technology: