Department of Bioscience and Biotechnology, Chungnam National University, Daejeon 34134, Korea.
Int J Environ Res Public Health. 2022 Jul 29;19(15):9305. doi: 10.3390/ijerph19159305.
This study was performed to determine the ecological health of a temperate river over nine years (2011−2019); it also analyzed the trophic structure and linkage of nutrients (nitrogen [N] and phosphorus [P]), sestonic chlorophyll-a (CHL-a), and the top trophic fish in the Asian monsoon region. Water chemistry, trophic indicators, and tolerance guilds were primarily influenced by land use and land cover (LULC); the magnitude of variation was also related to geographic elevation, artificial physical barriers (weirs), and point sources. Levels of nutrients, organic matter, and CHL-a largely influenced by the intensity of the monsoon seasonality for a particular LULC and stream order. Mann−Kendall tests based on a long-term annual dataset showed that annual organic matter and CHL-a increased over time because of longer hydraulic residence time after weir construction. The results of empirical nutrient models suggested that P was the key determinant for algal growth (CHL-a); the strong P-limitation was supported by N:P ratios > 17 in ambient waters. Linear regression models and canonical correspondence analysis (CCA) were used to determine the influences of LULC and water quality on the trophic/tolerance linkages, fish community compositions and structures, and river health. Tolerant species had a positive functional relationship with nutrient enrichment through total phosphorus (TP) (R2 = 0.55, p < 0.05) and total nitrogen (TN) (R2 = 0.57, p < 0.05), organic pollution in terms of biological oxygen demand (BOD) (R2 = 0.41, p < 0.05) and chemical oxygen demand (COD) (R2 = 0.49, p < 0.05), and algal growth (R2 = 0.47, p < 0.05); sensitive species exhibited the opposite pattern. The degradation of river health, based on the multi-metric index of biotic integrity (IBI) model, was evident in the downriver region (“fair−poor” condition) and was supported by the quantitative fish community index (QFCI) model. The outcomes suggested that the degradation and variation of ecological river health, trophic linkages of water chemistry (N, P)-algal biomass-fish, were largely controlled by the land use pattern and construction of physical barriers in relation to the Asian monsoon.
本研究旨在确定九年来（2011-2019 年）一条温带河流的生态健康状况；分析营养物质（氮[N]和磷[P]）、悬浮叶绿素-a（CHL-a）和亚洲季风区顶级掠食性鱼类的营养结构和联系。水化学、营养指标和耐受力等级主要受土地利用和土地覆盖（LULC）的影响；变化的幅度也与地理海拔、人工物理障碍（堰坝）和点源有关。营养物、有机物和 CHL-a 的水平主要受到特定 LULC 和溪流等级的季风季节性强度的影响。基于长期年度数据集的 Mann-Kendall 检验表明，由于堰坝建设后水力停留时间延长，年度有机物和 CHL-a 随着时间的推移而增加。经验营养模型的结果表明，P 是藻类生长（CHL-a）的关键决定因素；在环境水中 N:P 比>17 支持强烈的 P 限制。线性回归模型和典范对应分析（CCA）用于确定土地利用和水质对营养/耐受力联系、鱼类群落组成和结构以及河流健康的影响。通过总磷（TP）（R2=0.55，p<0.05）和总氮（TN）（R2=0.57，p<0.05）、生物需氧量（BOD）（R2=0.41，p<0.05）和化学需氧量（COD）（R2=0.49，p<0.05）表示的有机污染，以及藻类生长（R2=0.47，p<0.05），耐受物种与营养富集呈正功能关系；敏感物种则表现出相反的模式。基于生物完整性多指标指数（IBI）模型的河流健康退化在下游地区（“一般较差”状况）明显，并得到定量鱼类群落指数（QFCI）模型的支持。结果表明，生态河流健康的退化和变化，水化学营养物质（N，P）-藻类生物量-鱼类的营养联系，主要受与亚洲季风相关的土地利用模式和物理障碍建设的控制。
