摘要
In the high mountain oligotrophic Seven Rila Lakes (2 095–2 535 m a.s.l.) bacterial abundance was recorded in July and September 2006. In July, bacterial abundance (average (3.32±2.5)×105 cell/ml) in the lakes correlated negatively with elevation, while in September (average (26.39±7.1)×105 cell/ml) this pattern was altered and the greatest abundance of bacteria occurred at the highest ((39.05±1.5)×105 cell/ml) and the lowest ((30.63±6.0)×105 cell/ml) elevated lakes. Regression analyses suggested that the principal factor controlling bacterial abundance, in both July and September, was inorganic nitrogen (NO3-N and NH4-N; R2=0.70, P<0.05). Other major regulating factors were temperature (R2=0.66, P<0.03) in July and filter-feeding zooplankton (R2=0.95, P<0.01) in September. All factors, except NO3-N, had a positive effect on bacterial abundance.
In the high mountain oligotrophic Seven Rila Lakes （2 095-2 535 m a.s.l.） bacterial abundance was recorded in July and September 2006. In July, bacterial abundance （average （3.32±2.5）×10^5 cell/ml） in the lakes correlated negatively with elevation, while in September （average （26.39±7.1）×10^5 cell/ml） this pattern was altered and the greatest abundance of bacteria occurred at the highest （（39.05±1.5）×10^5 cell/ml） and the lowest （（30.63±6.0）×10^5 cell/ml） elevated lakes. Regression analyses suggested that the principal factor controlling bacterial abundance, in both July and September, was inorganic nitrogen （NO3-N and NH4-N; R^2=0.70, P〈0.05）. Other major regulating factors were temperature （R^2-0.66, P〈0.03） in July and filter-feeding zooplankton （R^2=0.95, P〈0.01） in September. All factors, except NO3-N, had a positive effect on bacterial abundance.
基金
Supported by the Sofia University "St. Kl. Ohridski" fund for scientific research (No. 90/2006)
