Week 25-31st Jan
If 33-50 per cent of the world’s coral reefs have already been degraded or lost due to climate change and human impacts, most of the functioning reef ecosystems may well disappear by mid-century, say reef scientists.
• As a first step to estimate the extent of damage to coral reefs, NASA has embarked on an air-borne three-year field experiment called The COral Reef Airborne Laboratory (CORAL), which aims to survey the conditions of the major reefs of the world through remote-sensing.
• Dr. Erich Hochberg’s team will survey the condition of entire reef systems in Hawaii, Palau, the Mariana Islands and Australia. The regions were chosen because they represent a wide range of reef types (fringing, barrier, atoll, oceanic and continental) and a wide range of environmental conditions (from pristine to heavily impacted).
• CORAL will involve the aerial deployment of a spectrometer called PRISM (Portable Remote Imaging Spectrometer) developed and managed at NASA’s Jet Propulsion Laboratory in Pasadena, California, which will detect the spectral signature of the various components of a reef such as coral, algae, sand etc. which will enable assessment of the condition of the reef.
• For example, as coral is degraded, it is replaced by algae and hence the ratio of algae to coral is an indicator of reef condition. PRISM records the spectrum (all the different colours) of incoming light from the ocean below, across the ultraviolet, through the visible region and up to the near infrared. The CORAL data processing takes into account the complex interactions of sunlight with the atmosphere, ocean, and reef.
• The signatures are used for identifying reef areas that are coral, algae, etc. CORAL also uses those signatures to model photosynthesis.
• Measuring the oxygen concentration is very important as productivity is indicated by the change in oxygen over time for a given area of the reef. A more productive reef releases more oxygen.
• Coral reefs are home to a quarter of all ocean fish species. They protect shorelines from storms and provide food for millions of people, yet very little of the world’s reef area has been studied scientifically. Virtually all measurements have been made by expensive, labour-intensive diving expeditions. Many reefs have never been surveyed, and those reefs that have been studied were measured only at a few dive sites.