水体及沉积物氮磷水平对附植藻类的影响

为了探讨湖泊富营养化过程中沉积物及水体氮、磷浓度对附植藻类的影响,通过室内模拟实验,研究了水体及沉积物氮、磷升高对苦草(Vallisnerianatans(Lour.) Hara)上附植藻类生长、群落组成及其体内氮、磷含量的影响.结果表明,在实验条件下,随着水中氮、磷含量升高,附植藻类生物量及附植藻类氮、磷含量均呈极显著增加(p0.01).随着水体可获得的氮、磷浓度升高,附植藻类的相对丰度有所变化,舟形藻(Navicula)、小球藻(Chlorella)及微囊藻(Microcystis)相对丰度随着氮、磷水平的升高而下降,直链藻(Melosira)则相反,但舟形藻、直链藻、微囊藻、小环藻(Cyclotella)和小球藻均为群落的优势属种.沉积物氮、磷含量升高对附植藻类生物量、优势种丰度及群落氮、磷含量影响较小,均未达到显著水平(p0.05).在实验条件下,沉积物氮、磷含量对附植藻类影响不大,而水体氮、磷浓度升高显著地促进了附植藻类生长.研究结果也为解释富营养化湖泊沉水植物衰退及消亡提供了一定的科学依据.

Effects of nitrogen and phosphorus availability on epiphytic algae attaching to the macrophyte Vallisneria natans

To investigate the effect of nitrogen and phosphorus availability on epiphytic algae in the process of lake eutrophication, the epiphytic algal biomass, community composition and contents of nitrogen and phosphorus were measured under different levels of nitrogen and phosphorus both in sediment and water column by indoor simulation experiment. The results show that with increasing nutrient availability in the water column, the biomass and the nutrient contents of epiphytic algae increased (p<0.01), and Navicula, Melosira, Microcystis,Cyclotella and Chlorella were the dominant population., while the relative population abundance of epiphytic algae changed with the increase of nitrogen and phosphorus levels, and the relative abundances of Navicula, Chlorella and Microcystis decreased but Melosira increased. The concentrations of nitrogen and phosphorushad little effect on the biomass, dominant species and nutrient contents of epiphytic algae in sediments (p<0.05). This result could account for the decline of submerged macrophytes in eutrophic lakes.