Comparison of Fish Assemblages in Two Adjacent Macrotidal Estuaries Altered by Diking

Abstract

This study characterized fish species composition and assemblage structure of two adjacent macrotidal estuaries that had been altered by diking. From February to December 2004, monthly fish samples were collected from the Geum River and Mangyeong River estuaries using stow nets. Coastal migrant fish and brackish-water fish represented 95.5% of species. Interestuary species composition similarity was relatively low between estuarine habitats (36.4%). The proportion of brackish-water fish was significantly higher in the Mangyeong River estuary (MRE) than in the Geum River estuary (GRE). This result may reflect the variability in the fish community associated with diking, which may have affected fish migration pathways. In the GRE, the estuary dike might have limited the access of brackish-water fish to brackish water. In contrast, in the MRE, it appears that movement of coastal migrant fish toward brackish waters was restricted by diking the estuary. The present study provides useful information for safeguarding the sustainability of estuarine ecosystems.