Habitat size influences food web structure in drying streams
Habitat size influences food web structure in drying streams
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DOI：
10.1111/ecog.01193
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发表时间：
2015-07-01
期刊：
影响因子：
5.9
通讯作者：
McIntosh, Angus R.
中科院分区：
文献类型：
--
作者：
McHugh, Peter A.;Thompson, Ross M.;McIntosh, Angus R.
由于全球气候变化和人类对淡水资源的需求不断增加，导致水流极端低流量的严重性和发生率增加，从而威胁到流动沃茨的生物多样性。虽然它是未知的，以及在何种程度上，沿河社区将在面对这些威胁的变化，相当大的洞察力将获得的努力，旨在量化栖息地的大小相关的控制，在经历极端流量损失的流类群之间的营养关系。在这里，我们报告了一个详细的时空调查复制流食物网采样沿着常年干燥连续在每一个不同的间歇性南岛，新西兰流。我们量化了58个站点的食物网的几个结构属性，包括两个基于分类学的指标（网络大小，捕食者：猎物比）和三个基于稳定同位素的指标（食物链长度[FCL]，营养区，C-13范围）;我们还量化了每个站点的栖息地大小，干扰和资源相关协变量。食物网的结构变化很大，在整个研究流和大部分的这种变化的样本网站解释栖息地的大小。与我们的预测一致，我们发现食物网变得更小（约30至约15个分类群，基于稳定同位素的营养区域减少约20倍）和更短（最大营养位置[FCL]从4.1到2.0，减少25%捕食者：猎物比率）随着我们从最大的栖息地转移到更小的栖息地。这些结果，并比较我们的研究结果与那些从一个类似的评估进行常年流，表明有扰动阈值，可能会引发食物网崩溃时，超过，并进一步暗示，食物网可能最终的大小“最小流量，而不是平均流量条件。我们的工作提供了一个基础，使一般的预测栖息地收缩，特别是流量损失，可能会影响社区，并提供了进一步关注的机制的见解。
Biodiversity in running waters is threatened by an increased severity and incidence of low-flow extremes resulting from global climate change and a growing human demand for freshwater resources. Although it is unknown how and to what extent riverine communities will change in the face of these threats, considerable insight will be gained from efforts aimed at quantifying habitat size-related controls on the trophic relationships among taxa in streams experiencing extreme flow loss. Here we report on a detailed space-for-time survey of replicate stream food webs sampled along the perennial- to-drying continuum in each of fourteen different intermittent South Island, New Zealand streams. We quantified several structural attributes of food webs at fifty-eight sites, including two taxonomically-based metrics (web size, predator:prey ratio) and three stable isotope-based metrics (food chain length [FCL], trophic area, C-13 range); we also quantified habitat size-, disturbance-, and resource-related covariates at each site. Food web structure varied widely across sample sites within and across study streams and much of this variation was explained by habitat size. Consistent with our predictions, we found that food webs became smaller (ca 30 to ca 15 taxa, ca 20-fold reduction in stable isotope-based trophic area) and shorter (maximum trophic position [FCL] from 4.1 to 2.0, 25% reduction in predator:prey ratio) as we moved from the largest to smaller habitats. These results, and a comparison of our findings with those from a similar assessment conducted in perennial streams, suggest that there are perturbation thresholds which may trigger food web collapse when exceeded, and further imply that food webs may ultimately be sized' to minimum flows rather than average flow conditions. Our work provides a basis for making general predictions about how habitat contraction, and flow loss in particular, may affect communities and additionally provides insight on mechanisms warranting further attention.