MICROPLANKTON COMMUNITY DYNAMICS DURING THE ALGAE REMOVAL PROCESS FOR NUTRIENT CONTROL

In order to explore the possible impact of nutrient decrease on microplankton community under high eutrophication stress, rotifer, protozoa and algae samples were collected during a nutrient control from July to August, 2008 in Taihu Lake in China, and examined by both species and phylogenetic patterns. A total of 10 rotifer, 40 protozoal and 24 algal taxa were detected before the nutrient control in July, 2008. After the nutrient control (August, 2008), a total of 23, 16 and 9 taxa were detected for rotifer, protozoa and algae, respectively. By comparing samples to those before the control, the average Shannon-Wiener indexes, Simpson indexes and Pielou evenness indexes increased 197%, 101% and 73%, respectively. The average phylogenetic species variability (PSV) and phylogenetic species evenness (PSE) decreased 63% and 1%, respectively. Canonical correspondence analysis (CCA) of interactions between environmental variables and microplankton communities indicated that most of the microplankton species found in August were negatively correlated with nutrient level (e.g. total nitrogen, ammonia nitrogen, total phosphorus and orthophosphate), with both species and phylogenetic patterns. This study showed that the lower diversity and closer species relatedness of microplankton under high eutrophication stress could get mended when the nutrient got down. In addition, the results revealed that phylogenetic diversity patterns could effectively help community research when predicting community and species responses to disturbance.In order to explore the possible impact of nutrient decrease on microplankton community under high eutrophication stress, rotifer, protozoa and algae samples were collected during a nutrient control from July to August, 2008 in Taihu Lake in China, and examined by both species and phylogenetic patterns. A total of 10 rotifer, 40 protozoal and 24 algal taxa were detected before the nutrient control in July, 2008. After the nutrient control (August, 2008), a total of 23, 16 and 9 taxa were detected for rotifer, protozoa and algae, respectively. By comparing samples to those before the control, the average Shannon-Wiener indexes, Simpson indexes and Pielou evenness indexes increased 197%, 101% and 73%, respectively. The average phylogenetic species variability (PSV) and phylogenetic species evenness (PSE) decreased 63% and 1%, respectively. Canonical correspondence analysis (CCA) of interactions between environmental variables and microplankton communities indicated that most of the microplankton species found in August were negatively correlated with nutrient level (e.g. total nitrogen, ammonia nitrogen, total phosphorus and orthophosphate), with both species and phylogenetic patterns. This study showed that the lower diversity and closer species relatedness of microplankton under high eutrophication stress could get mended when the nutrient got down. In addition, the results revealed that phylogenetic diversity patterns could effectively help community research when predicting community and species responses to disturbance