No abstract

In Brazil, the coral reefs are distributed for practically the whole tropical coast. The urbanization of coastal regions and changes of the climate in global scale can occasion negative impacts on this ecosystem, where the identification of the coral reefs from remote sensing is an important initiative to facilitate the management of these areas.  This paper proposes a radiometric/spectral evaluation of three banks in the Complex Coral Reefs of the Abrolhos-BA (Viçosa, Coroa Vermelha and Sebastião Gomes), through graphic sensitivity and Optimum Index Factor (OIF), in satellite images OLI/Landsat-8. The sensitivity of the three banks in coral reefs was similar. The spectral bands B1, B2, B3, B4 showed sensitivity to enhance the coral reef, the sea water, and from the near-infrared region (≥B5) there was no any sensitivity, even for some emerged coral reefs, as demonstrated statistical Test-t (Student), where there was no difference statistics between the digital values of coral reefs and sea water, since the p-Value was greater than the significance level (alpha = 0.05). Of the four spectral bands in the visible region (B1, B2, B3 and B4), only the B1 presented no significant difference. According to OIF the best color composition for visual differentiation of sea water of coral reefs was 1R 2G 4B (5403.3).