Plate 5 FIELD SURVEY TECHNIQUES

Preparing to survey a deeper reef site (> 5 m depth) near Long Cay on the Caicos Bank using a one-metre quadrat to record percentage cover of different biota and substrate types. [Photograph: P. Mumby]

Underwater survey of reef at about 10 m depth. These surveys were used to construct a classification scheme appropriate for the area and guide supervised classification. [Photograph: E. Green]

Carrying out accuracy assessment from a boat in shallow water using a glass-bottom viewer to determine habitat categories for a stratified random sample of sites. [Photograph: P. Mumby]

A white tarpaulin (2 x 2 m) is secured to the sea bed at a known point (fixed with a differential GPS) prior to a survey flight to provide a ground control point (GCP) for the geometric correction of airborne imagery. [Photograph: P. Mumby]

Measuring attenuation of irradiance of a given wavelength at different depths using a light sensor lowered through the water column. [Photograph: E. Green]   

Measuring the spectrum of a coral (Porites sp.) using a spectroradiometer. An identical instrument is placed over a uniform reflecting surface (white card) above the water surface. The ratio of the measured spectra gives the reflectance spectrum of the coral. [Photograph: P. Mumby]