Understanding of three decade temporal dataset of mangrove distribution on shoreline expansion in Subang Northern Coastal Area, Indonesia

• Mangroves in the Subang Regency area have experienced dynamic land use for aquaculture ponds. • Over 35 years, the area of mangroves has decreased from 639 ha to 261 ha. • The shoreline change in the northern part has reached 46 meters year -1 and formed accretion due to sediment accumulation at a rate of 23 ha year -1 . • The silvofishery system in the pond landscape is a solution in the mangrove rehabilitation program in this region. Mangroves are vital ecosystems with temporal dynamics influenced by tidal fluctuations and anthropogenic coastal activities that cause high erosion of river estuary landscapes, thereby creating new space for mangroves to expand. Unfortunately, the temporal dynamics of coastal morphology and its relationship with mangroves have been understudied in Indonesia. Therefore, this study aims to examine the dynamics of mangrove cover in changing shoreline areas in Subang Regency, using Landsat spatial data. The Random Forest algorithm through the GEE platform plays a role in classifying mangroves annually from 1990 to 2025, obtaining an existing mangrove area of 261 ha in 2025. This area has decreased significantly compared to 1992, which reached 639 ha (Rsquared 0.63 and p-value < 0.001). The Avicennia marina silvofishery system dominates the anthropogenic intervention area in the critical coastal landscape, following mangrove expansion. The shoreline change reached 46 meters year -1 and accretion formed due to sediment accumulation at an accretion rate of 23 ha year -1 , resulting in additional mangrove cover. However, the rate of aquaculture intervention in coastal areas was not proportional to mangrove succession in the accretion area, resulting in discrimination of mangrove areas up to the shoreline. In mangrove conservation efforts, regional and national policy support is urgently needed to regulate anthropogenic activities through the implementation of a mangrove silvofishery system. These efforts are being undertaken in response to the critical condition of mangroves on the northern coast of Java Island, with the aim of preserving their ecological benefits to support the national FOLU Net Sink 2030 target and annual NDC reporting.