Assessment of mangrove ecosystem conditions in Sepulu District, Bangkalan

Abstract

The mangrove ecosystem is one of the many coastal and marine natural resources. This ecosystem has many benefits, both for society and the environment. The purpose of this study was to assess the state of the mangrove ecosystem in Sepulu District, Bangkalan. Sentinel-2A image data of 2021 downloaded from https://scihub.copernicus.eu and in situ data were used in this study. Three villages were used as data collection locations and in each village there are 6 - 15 transect plots. The structure of the mangrove ecosystem was studied using quadrat transects (10 x 10 m), hemispherical photography (4 - 9 photos for each plots) and the Normalized Difference Vegetation Index (NDVI) for calculating the density of mangrove. The mangrove canopy cover was analyzed using Image J software. The findings included Sonneratia alba, Rhizopora mucronata, Rhizophora stylosa, Avicennia alba, Avicennia marina, Rhizophora apiculata, and Bruguera gymnorrhiza. In general, the Sonneratia alba (147.07) had the greatest important value index (IVI), followed by the Rhizophora mucronata (96.71). Mangroves with a high IVI indicate the magnitude of the mangrove's influence in a location. Canopy cover and density were used to measure mangrove conditions. The results revealed that the overall canopy cover was 64.55 ± 9.31 (%) and the density was 2289 ± 1131 (ind/ha). Furthermore, the result indicated the average of NDVI (0.62) with dense conditions. Overall, the findings suggest that the Sepulu District mangrove ecosystem was in good/healthy condition and need potential action for improvement in mangrove conservation and management in Sepulu District.