Combining Landsat ETM+ and Reef Check classifications for mapping coral reefs: a critical assessment from the southern Great Barrier Reef, Australia

摘要

While the remote-sensing community attempts to find measures of reef health able to be detected and mapped using satellite image data, internationally recognized field assessments are already in place to document benthic cover, among other parameters, as an indicator of coral reef status. Reef Check is one such program, designed in 1996 as a globally applicable, rapid, field-survey protocol for coral reef health monitoring by volunteer divers (Hodgson 1999). The protocol is designed to provide a measure of reef health based on indicator species or families for fish, invertebrates, and substrates. Data collected contribute to a global-scale database on coral reef status for use in management plans (Hodgson 1999). Today, over 5,000 trained volunteer divers are led by more than 160 scientists in surveys of 1,500 reefs in 60 countries. During the survey, they record substrate type directly under a measuring tape at 0.5-m intervals on 4*20 m consecutive transects between 3- and 10-m depth (Hodgson and Liebler 2002). The Reef Check substrate classification scheme provides information on benthic habitats such as hard coral, dead coral, soft coral, fleshy algae, rock, rubble, sand, silt, sponge, and other. This is the same type of information that remote-sensing scientists are often asked to extract from image data by coral reef scientists and managers.