Mangroves play important roles both economically and ecologically, however mangrove cover has declined significantly lead to habitat fragmentation and biodiversity loss. Mangroves in Thanh Phu have been cleared for shrimp farming. However, information on spatiotemporal changes of mangroves, fragmentation levels, and possible impacts on fish diversity is poorly understood. The aims of this study are to detect spatiotemporal changes, current status of mangroves, and fragmentation changes to understand possible impacts of fragmentation on fish diversity. Landsat images in 1995, 2000, 2009 and 2015 were employed to classify mangrove cover and validated using ground truth data. The Normalized Difference Vegetation Index (NDVI) was used to detect mangrove density. Landscape metrics were employed to examine fragmentation changes. Results show that mangrove cover has declined 49.8%. The overall accuracy was 86% and Kappa coefficient was 0.72. Currently, dense mangroves distribute along the southeast and the northeast coast. The landscape metrics show significant fragmentation of mangroves with the number of patches and edge density increasing 155% and 30.7% respectively. Other important results will be discussed in the full article. The study shows that shrimp farming lead to severe mangrove fragmentation. The research also illustrates the applicability of using Landsat satellite imagery for mangrove fragmentation studies.

Key words: remote sensing, mangrove change, mangrove fragmentation, shrimp aquaculture.