Roles of N:P Ratios on Trophic Structures and Ecological Stream Health in Lotic Ecosystems

Abstract

Abstract:Little is known about the functions of N:P ratios in determining trophic structures and ecological health in lotic ecosystems, even though N:P ratios have been frequently used as a stoichiometric determinant in ambient water for trophic allocation of low-level organisms such as phytoplankton or zooplankton. In this study, nutrients (N, P) and sestonic chlorophyll (CHL) from 40 different streams in the Geum-River watershed were measured from 2008 to 2011. Fish compositions and stream health were also assessed, based on the multi-metric modeling of an index of biological integrity. Land use patterns in these watersheds were a key factor regulating nutrient contents and N:P ratios in ambient water, and also influenced empirical relationships between N:P ratios (or nutrients) and sestonic CHL. Land use patterns in forested, urban and wastewater treatment plant regions were associated with significant differences in stream N:P ratios, and the ratios were mainly determined by phosphorus. Sestonic CHL was significantly correlated with nutrient level (N, P); the ratios had a positive linear relationship with the proportion of omnivores, and a negative relationship with the proportion of insectivores. A similar trend in the N:P ratios was observed in indicator fishes such as N. koreanus and Z. platypus. Overall, the N:P ratio may be a good surrogate variable of ambient concentrations of N or P in assessing trophic linkage and diagnosing the ecological stream health in aquatic ecosystems.

Roles of Nutrient Regime and N:P Ratios on Algal Growth in 182 Korean Agricultural Reservoirs

“…During summer and winter TN:TP was the better forecaster for CHL than TP, while in spring and autumn TP was a better indicator than TN:TP for the CHL concentrations. This strongly supports the idea that TN:TP ratios determined the primary productivity of the waterbody [33]. According to Jung et al (2016), the primary productivity (CHL-a) of the Korean reservoirs is highly dependent on TN:TP ratios, which is in line with the findings of present study [35].…”

“…Quality Parameters TN:TP ratio is a good surrogate variable of ambient nutrient concentrations of the Korean watershed [33]. The TN:TP was highly influenced by water temperature (WT, ºC), biological oxygen demand (BOD, mgL -1 ), chemical oxygen demand (COD, mgL -1 ), dissolved oxygen (DO, mgL -1 ), hydrogen ion concentration (pH), and total suspended solids (TSS, mgL -1 ; Fig.…”

“…The ratio of TN:TP plays a significant role in the growth of algal chlorophyll in American [30,27] , European [31][32], and Asian [33][34] agricultural reservoirs. The nutrient dynamics of the Asian reservoirs -especially in South Korean -are affected by the summer monsoon [28,35], which is an important determinant that controls the limnological characteristics (physical, chemical, and biological condition) of the freshwater ecosystem.…”

Seasonal variations of plankton structure as bioindicators in Zayandehrud Dam Lake, Iran

“…One of them concerns nutrients and their concentration that are essential in the determination of phytoplankton composition and abundance in aquatic systems (Abate et al 2017). NO 3 and PO 4 are among the most important of these nutrients and their ratio (N:P) may be used as an efficient tool for determining of the trophic state of water bodies (Yun and An 2016).…”

Ecological Monitoring, Assessment, and Management in Freshwater Systems

“…Yun and An [22] assessed the influence of land use patterns on nutrient contents and N:P ratios in stream ecosystems, and determined the empirical relationships between N:P ratios and nutrients and sestonic algal biomass. Their results indicated that land use patterns in the study watersheds are a key factor regulating nutrient contents and N:P ratios in ambient water, and influenced empirical relationships between N:P ratios and sestonic chlorophyll.…”