The Cause of Formation and Characteristics of Algal Blooms in Channel-Type Reservoirs

Algal blooms (ABs) in channel-type reservoirs present an increasing problem for ecosystem functioning and human health. This paper presents long-term data of the main eutrophic factors for a tributary of channel-type reservoirs (the Three Gorges Reservoir (TGR), China). The results indicate that all surface water was neutral and alkaline, had high nitrogen and phosphorus concentrations (0.59-27.74 mg/L and 0.005-3.444 mg/L respectively) and suitable air temperatures and water temperatures (19.5 - 40.0℃ and 8.0 - 31.0℃), which these factors can very easily induce ABs in the tributaries of channel-type reservoirs. An increasing number of ABs have been observed in the tributaries of backwater area, which have had several unique characteristics, such as the spatial “migration” of dominant algal species to other areas, the delay of the first spring HAB, and the infrequent occurrence of low-temperature ABs. In addition, with impounding of channel-type reservoirs, ABs in tributaries could more easily occur. It will be worthwhile to give greater consideration to the detrimental effects of ABs caused by sudden increases in nutrients (e.g., N and/or P).

Keywords: Eutrophication; Algal blooms (ABs); Channel-type reservoir; Backwater area; Three gorges reservoir (TGR)