The Remote Sensing Working Group is developing and testing a wide range of remote sensing tools, including satellite, airborne, acoustic and in-field methods. The Group will quantify the limitations of coral reef remote sensing by combining modelling and field experiments.

The Group is focussed on four key areas:

• Creation of decision-support and analysis software for monitoring the health of coral reefs using remote sensing
• Development of methods to detect changes in coastal environment
• Application of remote sensing to the inventory, monitoring and management of biodiversity
• Creation of an Ocean Atlas and tools to manage coral bleaching

Decision-support and analysis software for monitoring

The Remote Sensing Working Group is quantifying the limitations of coral reef remote sensing by combining modelling and field experiments. Models predict the ability of a given remote sensing instrument to detect the subtleties of bottom reflectance that distinguish reef habitats or the cover of corals and macroalgae within habitats.

While the passage of light through the water column is relatively well understood, the interaction of light between reef organisms, many of which have complex structures, presents a research challenge.

This problem is being addressed using radiosity methods which were originally developed in the computer graphics industry. Coral structures are divided into thousands of individual patches, each of which behaves as a reflecting surface. On reaching the reef, sunlight is reflected and scattered in predictable directions from which we can calculate the net light recorded by the sensor once it has passed back through the water and atmosphere.

Computer models will be refined and tested in the laboratory and then tested under field conditions in a unique, large-scale remote sensing experiment.

Methods to detect changes in the coastal environment

Remote sensing is needed to identify the habitat type and possibly predict the cover of corals and algae on a reef. The Remote Sensing Working Group is undertaking a number of activities to improve the way in which changes in reef condition can be predicted indirectly using remote sensing. These methods will highlight which areas of the coast have undergone the greatest change and help managers quantify the rate of change in reef habitat.
Inventory, monitoring and management of biodiversity

Recent remote sensing research has improved the detail of reef habitat maps but there is not necessarily a good understanding by management of the interpretation and uses of these products. Specifically, what do habitat maps mean in terms of biodiversity and reef function, and how should they be used for conservation planning?

Within the Centers of Excellence, there is an excellent opportunity to quantify the ecological basis of habitat maps. Through the work of the Remote Sensing Working Group, the species composition of habitats is being surveyed in Belize and Mexico and compared and assessed at a Caribbean-wide scale using comparable data from the Bahamas. Comparable surveys will take place in Palau and the Philippines but with less reliance on species-level identification.

A second biodiversity activity is quantifying the relationship between the topographic complexity of reef habitats (called rugosity) and the relative density of reef fish.

Creation of an Ocean Atlas and tools to manage coral bleaching

A wide variety of oceanographic and atmospheric remote sensing products is available for reef-relevant management but many are not user-friendly and found in disparate locations. Some US government agencies are establishing a national Ocean Atlas to collate data sets relevant to coastal management within a single website.

The Remote Sensing Working Group will extend this initiative to create an international Ocean Atlas for coral reef environments. The website will display a number of standard environmental products (e.g. wind speeds, wave heights, solar radiation) and will also develop and test new products which are especially relevant to coral bleaching. The Ocean Atlas will also be used by managers, scientists and students interested in many other ecosystems around the world.