Diversity of Fishes in the Estuarine Areas of the Mekong River

Estuarine areas are ecologically and sustainablty important for fisheries development. However, they have faced numerous threats causing habitat degradation. Urgent actions to conserve the estuarine ecosystem are needed. In the present study, the Simpson index, Jarccard coefficient, and Bray-Curtis were employed to evaluate fish composition in four estuaries (i.e., Dinh An, Tran De, Cua Lon and Bay Hap) of the Mekong River. Data on environmental parameters, including surface and bottom salinity, transparency, pH, and temperature, were gathered. A total of 162 species were identified, with a number of species varying from 84 to 94 among the four estuaries. Relative abundances were similar among the estuaries and seasons, whereas diversity indices went considerably. The high Simpson indices were found in Tran De (9.2), Cua Lon (8.0), and Dinh An (6.8) in the dry season, whereas the lowest values were in Dinh An (3.2), Cua Lon (3.6), and Bai Hap (4.3) in the rainy season. The distinctiveness and cluster analyses showed that fish composition was classified into two groups, i.e., the estuaries in the east (Dinh An, Tran De) and the west (Cua Lon, Bay Hap) of the Mekong Delta. Fish composition in the east coast estuaries was further classified into rainy and dry seasons. Environmental factors could explain the spatiotemporal variations in fish composition. The ecological role of the estuaries was also discussed. Findings from the study could be helpful for fisheries management of the Mekong River.