Assessment of the impact of coastal reclamation activities on seagrass meadows in Sungai Pulai estuary, Malaysia, using Landsat data (1994–2017)

Seagrass meadows play a critical role in supporting coastal biodiversity and in providing food and habitats for other marine organisms but are continuously threatened by human activities, such as coastal reclamation in the maritime countries. The Sungai Pulai estuary harbours mangroves, mudflats, and shoals with one of the Malaysia’s largest seagrass meadow (Merambong, Tanjung Adang, and Tanjung Laut) in Johor, Malaysia. This study assessed the environmental impact of coastal reclamation activities based on Landsat imagery (1994–2017) through mapping cover and distribution changes of those seagrass meadows by using a previously developed image enhancement technique with further improvement in the classification scheme (87% overall accuracy). The image-difference maps showed changes in seagrass meadows and mudflat cover with the extension of reclaimed land. Some seagrass meadows experienced large-scale changes, and coastal reclamation activities have been suggested as main factors responsible for habitat degradation, reduction in coverage, and total loss due to physical damage and excessive sedimentation. Sufficient protection of on-site construction materials is essential if coastal areas are to conserve seagrass meadows. This Landsat-based image classification approach should help the coastal manager to map seagrass meadows and to monitor the environmental impact of reclamation activities with a large spatio-temporal scale.