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:4/17/2017)... , April 17, 2017 NXT-ID, Inc. ... company, announces the filing of its 2016 Annual Report on Form ... Exchange Commission. ... Form 10-K is available in the Investor Relations section of the ... on the SEC,s website at http://www.sec.gov . 2016 ...
(Date:4/11/2017)... Research and Markets has announced the addition of the ... ... to grow at a CAGR of 30.37% during the period 2017-2021. ... been prepared based on an in-depth market analysis with inputs from ... prospects over the coming years. The report also includes a discussion ...
(Date:4/5/2017)... , April 5, 2017  The Allen Institute ... Allen Cell Explorer: a one-of-a-kind portal and dynamic digital ... 3D imaging data, the first application of deep learning ... human stem cell lines and a growing suite of ... platform for these and future publicly available resources created ...
Breaking Biology News(10 mins):
(Date:10/11/2017)... ... October 11, 2017 , ... Singh Biotechnology today announced ... to SBT-100, its novel anti-STAT3 (Signal Transducer and Activator of Transcription 3) B ... to cross the cell membrane and bind intracellular STAT3 and inhibit its function. ...
(Date:10/10/2017)... International research firm Parks Associates announced today that ... TMA 2017 Annual Meeting , October 11 in Scottsdale, ... security market and how smart safety and security products impact the competitive ... Parks Associates: Smart Home Devices: Main ... "The residential security market has experienced continued ...
(Date:10/9/2017)... ... October 09, 2017 , ... The award-winning American Farmer television series will feature ... Farmer airs Tuesdays at 8:30aET on RFD-TV. , With global population estimates nearing ... how to continue to feed a growing nation. At the same time, many of ...
(Date:10/7/2017)... ... October 06, 2017 , ... ... Hi-C-based genomic technologies, launched its ProxiMeta™ Hi-C metagenome deconvolution product, featuring the ... and accompanying cloud-based bioinformatics software to perform Hi-C metagenome deconvolution using their ...
Breaking Biology Technology: