Groundwater and subsurface water have important roles in river ecosystems: e.g., stabilizing flow regime and water temperature, supplying nutrients, and increasing biodiversity. However, detection of springs and quantitative estimation of groundwater contribution to the surface water ecosystems are not easy in the field. Although some indirect measurements combing simulations and models have been widely used to estimate the groundwater flow, they require certain assumptions, thus it is rather difficult to estimate the discharge of groundwater on a local scale. Direct field-scale measurement of groundwater flow is also difficult particularly for researches of ecology and environmental science.

In this study, we present biological indicators of benthic invertebrates to evaluate the contribution of groundwater to surface water bodies. Because the benthic invertebrates show distribution patterns reflecting habitat scale environmental conditions in a sensitive manner, they are expected to serve as a biological indicator of groundwater spring sites. We collected data of benthic invertebrates from literature in a global scale and additional field research in Japan. By analyzing their taxonomic features and biological habits, we identified spring indicator taxa of benthic invertebrates based on the degree of dependency to groundwater environment.

A total of 1,448 aquatic invertebrate species representing 58 orders were found from 249 research sites. The spring indicators were identified as spring dependent species including groundwater species (Stygobites and Stygophiles), cave species (Troglobites and Troglophile), and stenothermal species. Considering the geographical distribution patterns of the spring indicator taxa, stenothermal species were classified into "cold stenothermal species" which evolutionarily originate in more boreal regions and "warm stenothermal species" derived from more tropical regions. Ecological interpretation of these stenothermal species was discussed in relation to climatic zones and altitude of the basin concerned. Based on the variations of spring contribution into river ecosystems suggested by the spring indicator species, we proposed an application procedure of the spring indicators for environmental assessment and nature conservation works in river management.

地下水和地下水在河流生态系统中具有重要作用：例如，稳定水流和水温，提供营养和增加生物多样性。然而，在野外，对泉水的检测和地下水对地表水生态系统贡献的定量估算并不容易。尽管一些将模拟和模型结合起来的间接测量已广泛用于估算地下水流量，但它们需要一定的假设，因此，很难在局部范围内估算地下水的排放量。尤其是对于生态学和环境科学研究而言，直接对地下水流量进行现场规模测量也很困难。

在这项研究中，我们介绍了底栖无脊椎动物的生物学指标，以评估地下水对地表水体的贡献。由于底栖无脊椎动物以敏感的方式显示出反映栖息地规模环境条件的分布模式，因此有望作为地下水泉水位点的生物学指标。我们从全球范围内的文献中收集了底栖无脊椎动物的数据，并在日本进行了其他野外研究。通过分析它们的分类学特征和生物学习性，我们根据对地下水环境的依赖程度确定了底栖无脊椎动物的春季指标分类。

从249个研究地点中发现了总计58种的1,448种无脊椎动物。春季指标被确定为依赖春季的物种，包括地下水物种（肉食动物和嗜火菌），洞穴物种（三叶虫和嗜热菌）和嗜热物种。考虑到春季指示物类群的地理分布模式，将热热种类分为“冷热热种类”，其进化起源于更多的北方地区，而“热热热种类”则来源于更多的热带地区。讨论了与这些盆地的气候区和海拔有关的这些热液种类的生态学解释。根据春季指示物种类建议的春季对河流生态系统的贡献变化，