Understanding the stressor–response relationship between nutrient levels and algal biomass is a prerequisite for the management of eutrophication in lakes. In this study, a quantile regression(QR) approach was used t...Understanding the stressor–response relationship between nutrient levels and algal biomass is a prerequisite for the management of eutrophication in lakes. In this study, a quantile regression(QR) approach was used to interpret the stressor–response relationships between nutrient(e.g., phosphorus, nitrogen) concentrations and algal biomass as measured by chlorophyll-a(Chl-a) levels. QR results indicated that Lake Dianshan and Lake Changdang,which are both heavily eutrophicated, were P-limited only.In contrast, Lake Kuilei, which has significantly lower nutrient levels and algal biomass than the other two lakes,was P- and N-limited. Moreover, in Lake Kuilei, N and P levels had significant interaction effects on the algal biomass at the upper quantiles(s [ 0.68). The degree to which the lakes were P-limited increased with rises in the mean total P concentration in the lakes. QR has many advantages over ordinary least squares regression for discriminating limiting factors and, in particular, allows us to estimate changes near the upper extremes of distributions associated with limiting factors. QR is adapted to more specialized risk management problems, such as early warnings of the risk of algal blooms.The probable value-at-risk of harmful algal blooms for Lake Kuilei, Lake Dianshan and Lake Changdang is s = 0.76(Chl-a = 9 mg/m3), s = 0.87(Chl-a = 24 mg/m3) and s = 0.72(Chl-a = 35 mg/m3), respectively. Given the results of the stressor–response relationship analysis, we conclude that reductions in P input represent the most feasible and least costly approach for managing eutrophication in the shallow lakes of the Lake Taihu Basin. To control the magnitude and duration of algal blooms in shallow lakes,reductions in P and N inputs are required. The 95 % CI bounds of slopes indicated that the interactions of nonnutrient factors with nutrients had strong impacts on the algal biomass in lightly eutrophicated Lake Kuilei. It is suggested that, in addition to reductions in nutrient loads,several ecological measures,展开更多
基金supported by the National‘‘11th Five-year Plan’’Water Special Project of Ministry of Science and Technology of China(2009ZX07106-001)
文摘Understanding the stressor–response relationship between nutrient levels and algal biomass is a prerequisite for the management of eutrophication in lakes. In this study, a quantile regression(QR) approach was used to interpret the stressor–response relationships between nutrient(e.g., phosphorus, nitrogen) concentrations and algal biomass as measured by chlorophyll-a(Chl-a) levels. QR results indicated that Lake Dianshan and Lake Changdang,which are both heavily eutrophicated, were P-limited only.In contrast, Lake Kuilei, which has significantly lower nutrient levels and algal biomass than the other two lakes,was P- and N-limited. Moreover, in Lake Kuilei, N and P levels had significant interaction effects on the algal biomass at the upper quantiles(s [ 0.68). The degree to which the lakes were P-limited increased with rises in the mean total P concentration in the lakes. QR has many advantages over ordinary least squares regression for discriminating limiting factors and, in particular, allows us to estimate changes near the upper extremes of distributions associated with limiting factors. QR is adapted to more specialized risk management problems, such as early warnings of the risk of algal blooms.The probable value-at-risk of harmful algal blooms for Lake Kuilei, Lake Dianshan and Lake Changdang is s = 0.76(Chl-a = 9 mg/m3), s = 0.87(Chl-a = 24 mg/m3) and s = 0.72(Chl-a = 35 mg/m3), respectively. Given the results of the stressor–response relationship analysis, we conclude that reductions in P input represent the most feasible and least costly approach for managing eutrophication in the shallow lakes of the Lake Taihu Basin. To control the magnitude and duration of algal blooms in shallow lakes,reductions in P and N inputs are required. The 95 % CI bounds of slopes indicated that the interactions of nonnutrient factors with nutrients had strong impacts on the algal biomass in lightly eutrophicated Lake Kuilei. It is suggested that, in addition to reductions in nutrient loads,several ecological measures,
