Coral reef science enters the space age
Coral reefs are home to a quarter of the fish species in the ocean, they protect our shores from battering storms and provide food for millions of people. Yet what we know about them is just a drop in the ocean.
All that is set to change this October when new technology created by NASA links in with CSIRO’s knowledge of the Great Barrier Reef, to collect and review reef information that will be more complete and relevant than ever before.
The COral Reef Airborne Laboratory (CORAL) mission will be supported by CSIRO field crews to map six sections of the Great Barrier Reef and some Coral Sea reserves. The CORAL mission will deploy one of the most advanced imaging sensors in the world; a hyperspectral imager called the portable remote imaging spectrometer, or PRISM. PRISM measures reflected sunlight in hundreds of narrow bands.
“PRISM is a unique instrument developed in NASA’s Jet Propulsion Laboratory,” explains Arnold Dekker, Earth Observation Informatics Future Science Platform Leader and one of the key collaborators on the project. “It will use colour sensors to collect data on the state of the corals from an aeroplane flying over the reef.”
Healthy corals, with their symbiotic algae, produce many colours, while stressed or dying corals lose their algae and become bleached – this is the basis for the assessment.
A main objective of the CORAL expedition is to build a better understanding of coral reef health and anthropogenic influences, while arming scientists with the tools to accurately model these impacts and mitigate against changes.
The expedition will inform on key marine health indicators such as benthic cover of coral, algae and sand cover, bio-optical properties of the water, primary productivity and calcification.
Significant scientific methodology has already gone into creating models that show what is happening in the reef ecosystem, and how it is changing. The CORAL mission will provide the data needed to calibrate these models.
NASA will collaborate with CSIRO scientists, to collect field data at the same time the images are acquired, to develop and test the new mapping algorithms. These algorithms will take the values measured in the image and transform them to measures of productivity in the corals.
“The project teams will be working at sea level, carrying out surveys of the species present, measuring water quality, and examining carbon chemistry and calcification of the reefs, at the same time that the PRISM is collecting the remote data,” explains Janet Anstee of CSIRO’s Coastal Development and Management Program. “When we combine and analyse the datasets we’ll get a more detailed analysis of the condition of the corals.”
The resulting data will not only vastly increase understanding of the state of reefs but, it is hoped, will also lead to continual monitoring of coral reefs from space.
An Earth Venture
This mission is called an ‘Earth Venture Suborbital’, which is essentially a trial run for technology that occurs closer to the planet’s surface, before potentially being launched into space.
The first phase of CORAL will investigate large areas of reef in Hawai’i, Palau and the Mariana Islands, Florida as well as the Great Barrier Reef. Reef survey missions will be conducted for the next three years.
The initial project will provide proof of concept and validation of the mapping algorithms which could be applied to future airborne and satellite missions. If CORAL is successful, future assessments could use data from satellite-mounted instruments.
A leap for coral reef science
Globally, coral reefs have been recognised as being under threat from human activities and the physical and biological impacts of our changing climate; including a changing chemistry of seawater. This mission comes at a critical time for the world’s coral reefs as it will provide an essential capability for mapping and monitoring reefs that we don’t currently have.
“The CORAL mission will push the science forward, and the time is absolutely right for that,” says Stuart Phinn, project collaborator at the University of Queensland (UQ). “Chris Roelfsema and I been working at these sites (on the GBR) for over 16 years. The challenge now is to scale up our knowledge to much larger areas and this approach will provide one of the tools we need.”
UQ and CSIRO teams will be giving vital support to the American project, providing access to long-studied sites and long-term datasets. Data will be freely shared between the groups, and also made publicly available.
The current project will assess about 4% of the world’s reefs, but much more is needed. If the next phase gets the go-ahead, satellite-mounted equipment will vastly increase coverage as well as providing regular monitoring.