ABUNDANCE OF AMMONIA-OXIDIZING ARCHAEA AMONG EIGHT LAKES AND RESERVOIRS AT DIFFERENT TROPHIC STATES.

Ammonia-oxidizing archaea (AOA) play a major role in the ammonia oxidation as the first and limiting step of nitrification. In this research the abundance of AOA in eight small lakes and reservoirs at different trophic states were investigated by amoA gene quantification. Several environmental factors,including temperature, pH, Secchi depth (SD) and total phosphorus (TP), total nitrogen (TN), ammonia nitrogen (NH₄⁺-H) and chlorophyll a (Chl a) contents, total carbon (TC), the classical Carlson index TSI were simultaneously monitored. The results showed that amoA copies ranged from 7.80 × 10⁴ to 1.23 × 10⁶ per liter in water samples and from 1.62 × 10⁵ to 1.30 × 10⁶ per gram in sediment samples. For identify factors that regulate the abundance of AOA in these environments, correlation analysis was performed and the results revealed that the abundance of AOA showed a positive correlation with TN and NH₄⁺-H in both water and sediment samples, while other environmental factors showed no correlation with the abundance of AOA, suggesting that nitrogen is the main factor regulating AOA abundance. [ABSTRACT FROM AUTHOR]