CORAL will collect and synthesize a range of data to meet two specific science objectives:

  1. Measure the conditions of representative coral reefs across a range of biogeophysical values (e.g., different water temperatures, light conditions, etc.)
  2. Establish models of the relationship between reef condition and biogeophysical parameters

Coral reef condition can be reduced to the quantitative measure of the distributions of coral, algae and sand (i.e., benthic cover), as well as primary production and calcification.

Natural, balanced reefs are mosaics of coral, algae and sand. Together, these benthic types drive the function and structure of the reef ecosystem. However, when corals die, algae rapidly colonize their skeletons. Healthy reefs usually increase coral coverage during recovery from stress, with coral often returning to the pre disturbance level. In contrast, algae and rubble gradually dominate degraded reefs with little or no recovery of coral. With the loss of reef-builders, the carbonate skeleton erodes, ultimately becoming a flat bottom with shifting rubble and sand. This phenomenon is called a “phase shift” in the ecosystem and represents a radical change in the character of the reef. Thus, a key parameter in assessing the condition of a reef is to measure the proportional covers of coral, algae and sand.


Fortunately, coral, algae and sand each have unique spectral signatures–that is, how much light is reflected as a function of wavelength. CORAL’s approach to determining benthic composition is to measure the spectra of light reflected from reefs, using the PRISM instrument, then to decipher those signals to map coral, algae and sand. CORAL will also conduct intensive in-water surveys to validate the airborne observations.


Graph of bottom reflectance

A graph showing the spectral signatures of a variety of benthic types


In addition to the airborne and validation data, ten primary biogeophysical parameters have been selected for inclusion in CORAL algorithms based on their recognized influence on reef systems. Data sets describing these parameters will be obtained through a variety of sources, including NASA, NOAA, the Australian Institute of Marine Science and the World Resources Institute. Including these data will help ensure more accurate models relating reef condition to the environment.


Biogeophysical Parameters

Example data sets of the ten biogeophysical parameters to be used in CORAL models