Documenting flow regimes and the ecology of source headwater streams has gained considerable attention for scientific and regulatory purposes. These streams do not appear on standard maps, and local physiographic and climatologic conditions can control their origins. We investigated macroinvertebrate assemblages seasonally and in relation to flow duration, catchment and habitat variables within 14 source headwaters (< 1 ha) in the Western Allegheny Plateau over a 19-month period. We classified 6 perennial (P) and 8 intermittent (I) streams directly with continuous flow data loggers. Several biological and trait-based metrics could distinguish flow class, but few instream physical measures could. Macroinvertebrate metrics and assemblage dispersion varied seasonally and responded significantly along a gradient of total flow duration. Separate indicator species analyses generated 22 genera and 15 families with significant affinities to P streams. Richness of P-indicator taxa was also strongly correlated with flow duration gradients, and we estimated a total flow duration changepoint at 77% (3 indicator families) followed by a sharp increase in richness. Two rapid field-based flow duration methods (NC Stream Identification index and OH Headwater Habitat Evaluation index) could distinguish upstream ephemeral reaches from P and I reaches, but misclassified P as I more frequently. Our findings highlight that diverse coldwater macroinvertebrate assemblages inhabited extremely small, low-discharge springs in the region, and responded with flow duration. These source headwater habitats are susceptible to human disturbance and should be monitored as is routinely done in larger lotic systems.

出于科学和监管目的，记录源头水流的流态和生态已经引起了相当大的关注。这些溪流不会出现在标准地图上，当地的自然地理和气候条件可以控制它们的起源。我们在 19 个月的时间里对西阿勒格尼高原 14 个源头水源（< 1 公顷）内的大型无脊椎动物组合进行了季节性调查，并与流量持续时间、集水区和栖息地变量相关。我们将 6 个多年生 ( P ) 和 8 个间歇性 ( I) 流直接与连续流数据记录器。几个基于生物和特征的指标可以区分流量类别，但很少有内流物理措施可以区分。大型无脊椎动物指标和组合散布季节性变化，并沿着总流动持续时间的梯度显着响应。单独的指示物种分析产生了对P流具有显着亲和力的 22 个属和 15 个科。P-的丰富度指标类群也与流动持续时间梯度密切相关，我们估计总流动持续时间变化点为 77%（3 个指标族），随后丰富度急剧增加。两种基于现场的快速流动持续时间方法（NC 溪流识别指数和 OH 源头栖息地评估指数）可以区分上游临时河段与P和I河段，但更频繁地将P错误分类为I。我们的研究结果强调，不同的冷水大型无脊椎动物组合栖息在该地区的极小、低流量的泉水中，并随着水流持续时间做出反应。这些源头水源栖息地容易受到人为干扰，应该像在大型水流系统中常规进行的那样进行监测。