Diversity and spectral response of microbial communities on fossiliferous limestone platforms in moorea

Extremophiles are organisms that survive extreme environmental differentials. Cyanobacterial mats on fossiliferous limestone platforms in the intertidal zone of oceanic islands are subject to wave stress and intense UV radiation. The distribution of each mat was studied to infer causal factors of zonation. Line transects delineated zonation in visibly distinct cyanobacterial mats. Spectrometry determined spectral transmittance of a mat and an inhabited rock. Six distinct mat types, coralline algae and Littorina coccinea snails were quantified. For a 20 meter platform, mats with yellow-green, black-green moss-like and brown morphologies were most abundant (over 50% cover) closest to the lagoon (up to 2 meters from the lagoon), the middle of the platform (from 1 meter to 14 meters from the lagoon), and closest to the beach (from 6 meters to 20 meters from the lagoon) respectively. L. coccinea were found closest to the beach (between 6 meters from the lagoon and the beach). Spectrum of a black-green moss-like slice shows the mat type blocks 90% of low visible wavelength light. Future studies will be done on identifying the microbial communities of each mat and desiccation tolerances as possible causes of community stratification.