Effect of the water column on submerged coral reef hyperspectral response

Abstract

Monitoring coral reef ecosystems systematically and repetitively using remote sensing technology will help document the scale, extent and duration of ecosystem changes. A satellite or airborne image could be used to create a thematic map delineating areas where corals are under stress and would enable change detection studies to determine the extent and rate of coral health decline or recovery. One limitation to the accuracy of interpreting uncorrected images of submerged ecosystems is that the water column over a submerged coral reef modifies the remotely sensed signal within the visible spectrum. Furthermore, the effect has been observed as depth, bottom-type, and wavelength dependent; such complex modifications limit the accuracy of remote identification of submerged coral reef features. In an attempt to resolve this problem, in situ hyperspectral reflectance measurements were collected in the U.S. Virgin Islands at various depths, over different substrate types in water of consistent quality. A comparison is made between top and bottom of the water column hyperspectral reflectance in different water depths over different substrate types.