Physicochemical characteristic, nutrient, and fish production in different types of mangrove forest in North Sumatra and Aceh Provinces of Indonesia

Mangrove forests are highly productive ecosystems that sustain marine life, including fish communities. This study aimed to analyse mangrove characteristics, physicochemical parameters, nutrient and primary production derived from mangrove litter and estimate the fish production. The study was conducted at five mangrove sites in North Sumatra and the Aceh Provinces, Indonesia. Two sites represented natural forest at North Sumatra and Aceh (Jaring Halus and Langsa). In comparison, two sites were mangroves converted into oil palm plantations (Pulau Sembilan and Pulau Kampai, North Sumatra). The fifth site was a mangrove forest converted into aquacultural ponds (Percut Sei Tuan, North Sumatra). The study displays the dissemination of mangrove species in five different mangrove sites showing diversity. Avicennia spp found in estuarine near a coastal area, Rhizophora spp spread across the sites, and Sonneratia spp were more likely to occur in the mouth of the upstream river. Litter production at the present study site was dominated by Rhizophora spp., followed by Avicennia spp. This finding was very closely related to the nutrients resulting from litter decomposition in the mangrove ecosystem. The primary production value of 870-1,747 g C m^-2 year had a significant role as the beginning of the estuary food chain. Our results show a close association between fish productivity and mangrove management, and conservation status. The highest fish production was found in the well-preserved forests (Jaring Halus and Langsa), followed by the sites converted to palm oil plantations (Pulau Sembilan and Pulau Kampai). At the same time, the least fishing productivity was identified at the fishing ponds (Percut Sei Tuan). The present study provides further evidence of the significant role of mangrove ecosystems for fisheries and calls for effective restoration programs to support local food security along the coast of Indonesia.