Airborne hyperspectral detection of microbial mat pigmentation in Rangiroa atoll (French Polynesia)

The pigmentation of a cyanobacterial mat located in Rangiroa atoll (French Polynesia) was characterized using low-altitude (500 m) Compact Airborne Spectrometer Imager hyperspectral measurements. Peaks in second and fourth derivatives of the reflective absorptance can be explained by chlorophyll and carotenoid pigments, which were independently identified by high-pressure liquid chromatography. Phycobilin pigments were also detected from airborne measurements. The study confirms the extensibility of derivative spectroscopy from in vivo to highresolution remote sensing measurements for biology and geochemistry investigations in marine communities. Microbial mats are peculiar microecosystems encountered worldwide in various coastal environments. They are abundant in many atoll lagoons of the Pacific Ocean, particularly along atoll rims in the Tuamotu Archipelago (French Polynesia) at the lagoon/land interface and in large ponds inside islets (Défarge et al. 1994a). In Polynesian islands, these microbial mats are called ‘‘kopara.’’ They are gelatinous deposits a few tens of centimeters thick, typically with a vivid orange to red color that can shift to dark green or black with local development of the cyanobacterium Scytonema. Kopara mats persist under contrasting environmental situations, 1 Corresponding author ([email protected]).