Effects of Nutrient Replacement on Benthic Macroinvertebrates in an Ultraoligotrophic Reach of the Kootenai River, 2003–2010
Effects of Nutrient Replacement on Benthic Macroinvertebrates in an Ultraoligotrophic Reach of the Kootenai River, 2003–2010
复制标题
2003-2010 年库特奈河超贫营养河段养分替代对底栖大型无脊椎动物的影响
DOI：
10.1086/677900
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发表时间：
2014
期刊：
影响因子：
4.8
通讯作者：
Pat Barrett
中科院分区：
文献类型：
--
作者：
G. Minshall;Bahman Shafii;W. Price;Charlie Holderman;P. Anders;G. Lester;Pat Barrett
摘要：
大型蓄水池从河流中清除大量沉积物和养分，并且常常限制下游初级生产者和次级消费者的生产。 1972 年利比大坝建成后，爱达荷州和蒙大拿州库特奈河下游（第七级，平均年流量 = 454 立方米/秒）的营养水平、大型无脊椎动物和鱼类丰度急剧下降。随后的一项研究表明，超寡营养条件（总溶解 P [TDP] ≤ 2 µg/L TDP）是主要致病因素，并促使一项正在进行的实验性营养添加计划利比大坝下游的库特奈河，在爱达荷州和蒙大拿州边境进行给药。预处理监测从2003年开始，2006年至2010年生长季每年添加液体聚磷酸铵肥料（10-34-0），目标TDP浓度为3μg/L，TN:TP接近20:1。我们研究了底栖大型无脊椎动物对实验添加的反应，并假设无脊椎动物的丰富度、丰度和生物量适度增加，而组合结构几乎没有变化。我们采用前后对照影响 BACI 设计，对 2003 年 7 月至 2010 年 11 月上旬从受精和未受精河段收集的大型无脊椎动物样本进行处理。处理后，平均修饰（少毛类和摇蚊亚类除外）总丰度增加了 72%，平均总丰度增加了 69%，平均生物量增加了 48%。研究区主要昆虫目蜉蝣目的丰度增加了 66%。滤食动物丰度也增加，表明除了其他底栖大型无脊椎动物消耗的附着形式之外，悬浮有机物也增加。前 5 年的实验处理增加了本地鱼类的食物资源，而大型无脊椎动物群落结构或营养途径没有发生重大改变。
Abstract:
Large impoundments remove substantial amounts of sediment and nutrients from rivers and often limit production by downstream primary producers and secondary consumers. Nutrient levels and macroinvertebrate and fish abundance in the lower Kootenai River (7th order, mean annual discharge = 454 m3/s) in Idaho and Montana declined dramatically after Libby Dam was built in 1972. A subsequent study implicated ultraoligotrophic conditions (total dissolved P [TDP] ≤ 2 µg/L TDP) as a principal causative agent and prompted an on-going experimental nutrient-addition program for the Kootenai River downstream from Libby Dam, with dosing at the Idaho—Montana border. Pre-treatment monitoring began in 2003 and liquid ammonium polyphosphate fertilizer (10-34-0) was added each year during the growing season from 2006 through 2010 with a target TDP concentration of 3 µg/L and TN:TP near 20:1. We studied benthic macroinvertebrate responses to the experimental addition and hypothesized moderate increases in invertebrate richness, abundance, and biomass with little change in assemblage structure. We used a before—after control—impact BACI design with macroinvertebrate samples collected pre- and post-treatment from July to early November 2003–2010 from fertilized and unfertilized reaches. After treatment, mean modified (Oligochaeta and Chironomidae subtaxa excluded) total abundance increased 72%, mean total abundance increased 69%, and mean biomass increased 48%. Abundance of Ephemeroptera, the principal insect order in the study area increased 66%. Filter-feeder abundance also increased, indicating increased suspended organic matter in addition to the attached forms consumed by other benthic macroinvertebrates. The first 5 y of experimental treatment resulted in increased food resources for resident native fishes with no major alteration of macroinvertebrate community structure or trophic pathways.