Understanding how nuclear power plant thermal effluents influence the phytoplankton community may provide insights into the potential ecological consequences of global warming. In the present study, long-term trends in the phytoplankton community structure under the influence of nuclear power plant thermal effluent in the subtropical Daya Bay (DYB) in China were investigated in the summer season from 1982 to 2005. Water temperature at the outfall station was significantly higher than in the surrounding water, by as much as 5.6°C, and increased by 6.8°C during the 23 yr study period. The contribution of diatoms and dinoflagellates to the total phytoplankton showed significant correlation with temperature (R 2 > 0.65), negative for diatoms, while positive for dinoflagellates. Although dinoflagellate abundance increased over time at both the outfall and adjacent (control) stations, the increase at the outfall station was much more dramatic and accelerated over time. No clear relationship between the phytoplankton shift and stratification was evident. When water temperature reached 35°C or > 3.7°C above that at the control station, dinoflagellates, such as Ceratium furca, C. fusus, C. trichoceros, Dinophysis caudate and Protoperidinium depressum, grew to prominence, accounting for about 50% of the total phytoplankton abundance. On the contrary, the diatom contribution decreased during the study period, from 82.0% in 1982 to 53.1% in 2005. These results suggest that the rise in temperature caused by power plant thermal discharge has imposed strong influences on the phytoplankton community, favoring dinoflagellates over diatoms, with a remarkable diatom to dinoflagellate shift when temperature increases to a threshold level of 35°C or reaches a threshold differential of 3.7°C relative to the normal ambient temperature in DYB.KEY WORDS: Daya Bay · Nuclear power plant · Thermal effluent · Phytoplankton · Ecological effects
Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 424: [75][76][77][78][79][80][81][82][83][84][85] 2011 perature can be indirect, via a decrease in the resupply of nutrients for phytoplankton production resulting from the intensification of water stratification (Margalef 1978, Jones & Gowen 1990. Since phytoplankton have short generation times, they can rapidly respond to temperature increases, and, because they are at the base of the aquatic food web, observations of their responses could provide useful insights into how temperature increases may induce ecosystem changes (Niemi & McDonald 2004). Phytoplankton community structure and abundance have been found to be changing as a result of global warming in many areas (Richardson & Schoeman 2004). For example, the changes in phytoplankton communities have been used as indicators of global warming in the North Sea (Edwards & Richardson 2004) and to monitor nonnative, warm-water species in the Mediterranean and the North Seas (Walther et al. 2002). Because organisms at different trophic levels m...