Spectral Reflectance Characteristics of Seagrass and Brown Algae (Phaeophyceae) in Barrang Lompo Island, Sangkarrang District, Makassar, South Sulawesi Danil
Hasanuddin Universirty
Abstract
Seagrass and algae are key components of coastal ecosystems, functioning as habitats, primary producers, and indicators of marine environmental conditions. This study aimed to characterize the spectral reflectance of several seagrass and algae species in the waters around Barrang Lompo Island and to identify differences in their spectral characteristics using an underwater spectroradiometry approach. Data were collected in situ on May 17, 2025, from five seagrass species, three algae species, and one seagrass specimen covered with epiphytic algae. Reflectance was measured using a LOT-2 Spectra Corp spectroradiometer across wavelengths of 400-750 nm with a 3 nm interval. The data were then analyzed through spectral curve visualization, clustering, and Linear Discriminant Analysis (LDA). The results showed that seagrass had peak reflectance in the green-yellow range (500-585 nm), while algae reflected more strongly in the yellow-red range (585-700 nm). Additionally, seagrass leaves covered with algae exhibited higher reflectance values than clean leaves, especially in the red and red-edge bands. Cluster analysis grouped the vegetation into four main clusters, reflecting spectral similarities based on leaf structure and pigment content. LDA successfully differentiated seagrass and algae with high accuracy, particularly in the 550-585 nm range, which was found to be the most discriminative. These findings suggest that spectral reflectance data can serve as a foundation for developing remote sensing-based classification systems for marine vegetation.
