Quantifying biomass and canopy cover of submerged aquatic vegetation on an offshore island

Abstract

The coverage and biomass of submerged aquatic vegetation (SAV) are vital characteristics of marine resource management and development. However, using in situ measurements to assess the distribution and biomass of SAV is challenging because SAV distribution varies with biomass, substrate type, and depth, making it difficult to monitor. Satellite remote sensing is an advanced tool that can tackle this problem. In this study, several techniques, such as atmospheric correction, water column correction, and supervised classification, were integrated with Landsat-8 images to map SAV distribution on an offshore island in Viet Nam, Ly Son island. The substrate-classifying result had high accuracy (OA = 92.6%, Ҡ = 0.9 ). The coastal, blue, and green bands of Landsat-8 were used to estimate the SAV biomass using a polynomial regression (RMSE =±1440.6 g fresh m−2, R2=0.71). The results showed that the total fresh biomass of SAV in Ly Son island is 14551.04 tonnes, with a corresponding area of 332.1 hectares, equivalent to an average biomass of 4381.5 ± 1440.6 g fresh m−2. The distribution and biomass maps of SAV produced in this study could be used as input to measure the attributes of SAV biodiversity, contributing more effectively to monitoring marine ecosystems in Viet Nam.