Environment shapes invertebrate assemblage structure differences between volcanic spring-fed and runoff rivers in northern California
Environment shapes invertebrate assemblage structure differences between volcanic spring-fed and runoff rivers in northern California
复制标题
环境塑造了北加州火山泉水和径流河流之间无脊椎动物群落结构的差异
DOI：
10.1086/687114
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发表时间：
2016
影响因子：
1.8
通讯作者：
R. Dahlgren
中科院分区：
文献类型：
--
作者：
Robert A. Lusardi;M. Bogan;P. Moyle;R. Dahlgren
流变率在构建湖泊群落中起着重要的作用，但相对知之甚少的过程中，控制组合动态的河流生态系统与稳定的环境条件，如泉水喂养的河流。火山泉水河流（以下简称泉水河流）出现在美国西部和地球仪周围地质活跃的景观中。我们采样无脊椎动物组合和量化的初级生产力和栖息地的春季喂养和径流河流在北方加州超过4个赛季的特点。我们预测，非生物因素将更加稳定，养分供应更大，无脊椎动物的密度将更大，多样性较低，在春季喂养比径流河流。径流河流表现出很高的流量和温度的变化，而春季喂养的河流相对稳定，自然发生的营养水平高。平均而言，泉水中NO3−和PO43−的浓度是径流河流的40倍。根据季节的不同，春季河流支持的无脊椎动物密度比径流系统高出近7至16倍。然而，无脊椎动物物种丰富度更大的径流河流在所有季节。春季喂养的河流无脊椎动物组合与营养盐浓度升高和基础C源，而径流组合与排放变异性和中值基质大小有很强的相关性。我们认为，强烈的差异，在非生物的变化之间的泉水喂养和径流河流在确定无脊椎动物组合结构中发挥了重要作用。由于春季喂养的河流表现出更稳定的温度，全年和较低的温度在夏季比径流河流，他们可能会提供必要的避难所冷水类群在气候变暖。
Flow variability plays an important role in structuring lotic communities, yet comparatively little is known about processes governing assemblage dynamics in stream ecosystems with stable environmental conditions, such as spring-fed rivers. Volcanic spring-fed rivers (hereafter spring-fed rivers) occur in geologically active landscapes of the western USA and around the globe. We sampled invertebrate assemblages and quantified primary productivity and habitat characteristics of spring-fed and runoff rivers in northern California over 4 seasons. We predicted that abiotic factors would be more stable and nutrient availability greater and that invertebrate density would be greater and diversity lower in spring-fed than in runoff rivers. Runoff rivers exhibited high variability in discharge and temperature, whereas spring-fed rivers were relatively stable with high naturally occurring nutrient levels. On average, NO3− and PO43− concentrations were 40× greater in spring-fed than in runoff rivers. Spring-fed rivers supported nearly 7 to 16× greater densities of invertebrates than runoff systems, depending on season. However, invertebrate species richness was greater in runoff rivers in all seasons. Spring-fed river invertebrate assemblages were strongly correlated with elevated nutrient concentrations and basal C sources, whereas runoff assemblages were associated with discharge variability and median substrate size. We suggest that strong differences in abiotic variability between spring-fed and runoff rivers play an important role in determining invertebrate assemblage structure. Because spring-fed rivers exhibit more stable temperatures throughout the year and lower temperatures during the summer than runoff rivers, they may provide essential refugia for coldwater taxa in a warming climate.