The main problems tropical estuaries face are mangrove deforestation and eutrophication that is a result of land development and agriculture fertilization. While these habitat modifications can significantly reduce the fish diversity and production of mangrove ecosystems, the specific mechanisms are not well understood. It is difficult to quantify the fish production in tropical estuaries, because many fish use estuaries at high tide and migrate to other habitats at low tide. Dr Kusuto Nanjo, based at the Department of Applied Aquabiology, National Fisheries University in Japan, focused on resident fish, which utilize estuaries for a certain period of their life history without tidal migration and account for a large proportion of the fish assemblages, as good indicators in assessing the secondary production of mangrove ecosystems. It is hoped that by elucidating this, his team will be able to establish specific conservation measures that protect biodiversity and life within mangrove ecosystems.