Prolonged inundation and ecological changes in an Avicennia mangrove : implications for conservation and management

The mangrove around Sungei Pemburongunan in the Brunei-Muara district of Borneo contained the only pure stand of Avicennia marina in Brunei Darussalam. Ecological baseline studies were conducted in early 1990. In mid-October 1990 the mangroves became flooded due to a natural build-up of a sandbar across the mouth of Sungei Pemburongunan. The mangroves remained flooded for 8 weeks before a channel was dug to release the flood water. During this time increasing mortality of the mangrove flora and fauna was observed. Avicennia suffered substantial losses of shrub-sized plants. Seedlings appeared after the flood. Where necrosis of the bark occurred in Avicennia trees, adventitious roots had grown from just bove the necrosed region. Densities of molluscs that colonized the mudflats were reduced. Most common crustaceans which virtually disappeared during the flood reappeared afterwards. During the flood there was increased fishing activity but species composition remained similar throughout. Prolonged flooding could damage Avicennia and its associated flora and fauna.