Aquatic Biodiversity as an Impact of Mangrove Restoration in Lubuk Kertang, North Sumatra

Mangrove restoration is widely promoted as a nature-based solution to reverse coastal wetland degradation while sustaining fisheries productivity and other ecosystem services. This study evaluated whether a mangrove restoration program in Lubuk Kertang (North Sumatra, Indonesia) is associated with enhanced aquatic biodiversity and supporting water-quality conditions. Mangrove vegetation structure was assessed across restoration ages (2009–2013 plantings; 7–11 years old at the time of survey), and fish assemblages and water quality were sampled in June, August, and December 2021. We recorded 828 individual fishes representing 44 species, 27 families, and 17 orders. Fish diversity was moderate (mean Shannon–Wiener H′ = 2.15; evenness = 0.83; dominance = 0.17), with Engraulidae contributing the highest abundance. Water quality conditions were within ranges typical for estuarine mangrove habitats (DO 3.5–5.15 mg L⁻¹; pH 6.6–7.85; salinity 17.5–28.5; temperature 28.3–31.55 °C). Mangrove vegetation diversity indices were low to moderate (0.05–1.12) across restoration ages. These findings indicate that restored mangrove stands can function as aquatic habitat supporting diverse fish assemblages while maintaining basic water-quality conditions, reinforcing the role of mangrove restoration in sustainable coastal development and the Sustainable Development Goals (SDGs).