Increasing fish taxonomic and functional richness affects ecosystem properties of small headwater prairie streams
Increasing fish taxonomic and functional richness affects ecosystem properties of small headwater prairie streams
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鱼类分类和功能丰富度的增加影响小源头草原溪流的生态系统特性
DOI：
10.1111/fwb.12752
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发表时间：
2016
影响因子：
2.7
通讯作者：
A. Veach
中科院分区：
文献类型：
--
作者：
E. Martin;K. Gido;N. Bello;W. Dodds;A. Veach
总结1。河流鱼类可以通过直接和间接途径调节环境，不同分类和功能丰富度群落对生态系统特性的相对影响可能取决于生境结构。考虑到这种复杂性，关于河流鱼类群落如何影响生态系统的观察性研究显示出不同的结果也就不足为奇了。2. 在本研究中，我们评估了观察到的鱼类分类（0、1、2或3种）和功能（0、1或2类）丰富度梯度对实验河流中生态系统几个关键特性的影响。我们的研究模拟了小的（小于2米宽的）源草原溪流，每个中游环境有三个连续的池-溪流结构（上游、中游和下游）。生态系统响应包括浮游藻垫和底栖藻类的叶绿素a、底栖有机物、大型无脊椎动物（均为单位面积质量）、藻丝长度和溪流代谢（光合作用和呼吸速率）。利用一般线性混合模型分别分析了生态系统的响应。3. 除一个生态系统响应变量外，生境（池和河）相互作用对所有生态系统响应变量都有显著的处理作用（分类和功能丰富度）。在考虑了位置（上游、中游和下游）效应后，与无鱼对照相比，一个或两个食草动物的存在导致池塘中平均藻丝长度更短。这些观察结果表明，食草动物可以在水池中维持短的藻丝，这可能会阻止长丝到达水面。因此，与无鱼对照相比，放牧处理中下游地区的浮藻垫减少了。4. 在全河段尺度上，两种食草动物处理的总初级生产力和呼吸量均高于食虫/食草混合处理或对照处理。5. 因此，河流资源在不同生境类型和河段内的分布可能受到小草原河流鱼类的分类和功能组成的影响。因此，改变这些系统多样性的干扰可能会产生意想不到的生态系统后果。
SUMMARY 1. Stream fish can regulate their environment through direct and indirect pathways, and the relative influence of communities with different taxonomic and functional richness on ecosystem properties likely depends on habitat structure. Given this complexity, it is not surprising that observational studies of how stream fish communities influence ecosystems have shown mixed results. 2. In this study, we evaluated the effect of an observed gradient of taxonomic (zero, one, two or three species) and functional (zero, one or two groups) richness of fishes on several key ecosystem properties in experimental stream mesocosms. Our study simulated small (less than two metres wide) headwater prairie streams with a succession of three pool-riffle structures (upstream, middle and downstream) per mesocosm. Ecosystem responses included chlorophyll a from floating algal mats and benthic algae, benthic organic matter, macroinvertebrates (all as mass per unit area), algal filament length and stream metabolism (photosynthesis and respiration rate). Ecosystem responses were analysed individually using general linear mixed models. 3. Significant treatment (taxonomic and functional richness) by habitat (pools and riffles) interactions were found for all but one ecosystem response variable. After accounting for location (upstream, middle and downstream) effects, the presence of one or two grazers resulted in shorter mean algal filament lengths in pools compared to no-fish controls. These observations suggest grazers can maintain short algal filaments in pools, which may inhibit long filaments from reaching the surface. Accordingly, floating algal mats decreased in mid- and downstream locations in grazer treatment relative to no-fish controls. 4. At the scale of the entire reach, gross primary productivity and respiration were greater in treatments with two grazer species compared to mixed grazer/insectivore or control treatments. 5. The distribution of stream resources across habitat types and locations within a reach can therefore be influenced by the taxonomic and functional composition of fishes in small prairie streams. Thus, disturbances that alter diversity of these systems might have unexpected ecosystemlevel consequences.