Field Investigation on Biodiversity in the East River (Dongjiang)

A group research project has been initiated to develop an integrated river management strategy and assessment criteria for the East River in Guangdong province. Four field surveys were conducted in 2004 to study the geomorphologic, hydrologic and environmental features of the basin. River bank floral biodiversity was measured on a sandbar at Simeizhou near the Boluo hydrological station. The results suggested that water level had a significant impact on species biodiversity, and that the emergence of dominant species of the Poaceae and Cyperaceae families was evidenced in the wet season. Moreover, regardless of the season, the floral diversity was positively correlated with the distance from the river bank. Epilithic diatom and water samples were collected from four sites in the upper and lower reaches of the river. A total of 23 diatom genera were identified from the study sites during the two sampling periods. The diatom genera Nitzschia represented the most pollutant tolerant epilithic diatoms, comprising over 38% of the overall diatom population in the polluted sites. The correlation between water quality and the Shannon diversity index ( H ), generic index ( GI ), trophic diatom index ( TDI ) and diatom assemblage index to organic pollution ( DAIpo ) were investigated in this study. The results suggested that epilithic diatom may be used as a biological indicator for the integrated environmental health assessment of the East River.