Connectivity and impact assessment of land use/cover and benthic cover change by advance remote sensing analysis

摘要

Aside from the effects of coral-bleaching phenomenon and crown-of-thorns starfish (COTS) outbreaks, the coral reef ecosystem is slowly deteriorating due to stress brought about by water pollution from surrounding nearby sources. Sediment and nutrient discharge, as a result of anthropogenic impacts on land, may hold the greatest influence in the condition of the coral reef. To effectively manage the coral reef system, it is worthwhile to understand the relationship between the coral reef and the land use activities in the surrounding watersheds. This paper aims to establish the connectivity between the terrestrial and the coastal waters through examination of the historical change pattern between the land and benthic covers by remote sensing analysis and to correlate the impact of the sediment discharge to the benthic cover. Analyses were done for some of its zones and for some local coral reef areas near river mouths in the Sekisei Lagoon, Japan. Results show that local coral reef areas are more vulnerable to impact from sediment discharge, while the wider coverage zones in the Sekisei Lagoon receives more impact from COTS and coral-bleaching events. Proximity from the sediment source and hydrodynamic circulation may have increased or decreased the impact of various threats in some areas of the Sekisei Lagoon.