Macroinvertebrate Responses to Constructed Riffles in the Cache River,Illinois, USA

Stream restoration practices are becoming increasingly common, but biological assessments of these improvements are still limited. Rock weirs, a type of constructed riffle, were implemented in the upper Cache River in southern Illinois, USA, in 2001 and 2003–2004 to control channel incision and protect high quality riparian wetlands as part of an extensive watershed-level restoration. Construction of the rock weirs provided an opportunity to examine biological responses to a common in-stream restoration technique. We compared macroinvertebrate assemblages on previously constructed rock weirs and newly constructed weirs to those on snags and scoured clay streambed, the two dominant substrates in the unrestored reaches of the river. We quantitatively sampled macroinvertebrates on these substrates on seven occasions during 2003 and 2004. Ephemeroptera, Plecoptera, and Trichoptera (EPT) biomass and aquatic insect biomass were significantly higher on rock weirs than the streambed for most sample periods. Snags supported intermediate EPT and aquatic insect biomass compared to rock weirs and the streambed. Nonmetric multidimensional scaling (NMDS) ordinations for 2003 and 2004 revealed distinct assemblage groups for rock weirs, snags, and the streambed. Analysis of similarity supported visual interpretation of NMDS plots. All pair-wise substrate comparisons differed significantly, except recently constructed weirs versus older weirs. Results indicate positive responses by macroinvertebrate assemblages to in-stream restoration in the Cache River. Moreover, these responses were not evident with more common measures of total density, biomass, and diversity.     

Understanding Stream Geomorphic State in Relation to Ecological Integrity: Evidence Using Habitat Assessments and Macroinvertebrates

Scientists have long assumed that the physical structure and condition of stream and river channels have pervasive effects on biological communities and processes, but specific tests are few. To investigate the influence of the stream-reach geomorphic state on in-stream habitat and aquatic macroinvertebrate communities, we compared measures of habitat conditions and macroinvertebrate community composition between stable and unstable stream reaches in a paired-study design. We also explored potential associations between these ecological measures and individual geomorphic characteristics and channel adjustment processes (degradation, aggradation, overwidening, and change in planform). We found that habitat quality and heterogeneity were closely tied to stream stability, with geomorphically stable reaches supporting better habitat than unstable reaches. Geomorphic and habitat assessment scores were highly correlated (r = 0.624, P < 0.006, n = 18). Stable reaches did not support significantly greater macroinvertebrate densities than unstable reaches (t = −0.415, P > 0.689, df = 8). However, the percent of the macroinvertebrate community in the Ephemeroptera, Plecoptera, and Trichoptera (EPT) taxa was significantly correlated with the overall habitat assessment scores as well as with individual measures of geomorphic condition and habitat quality. While there is a clear need for more work in classifying and quantifying the responses of aquatic and aquatic-dependent biota to various geomorphic states and processes, this study provides solid preliminary evidence that macroinvertebrate communities are affected by the geomorphic condition of the stream reaches they inhabit and that geomorphic assessment approaches can be used as a tool for evaluating ecological integrity.     

太子河流域不同水生态区EPT群落时空分布特征

为了解同一流域不同水生态区EPT〔蜉蝣目(Ephemeroptera)、襀翅目(Plecoptera)、毛翅目(Trichoptera)〕这一敏感类群的时空分布差异及其影响因素,于2009年枯水期(5月)和丰水期(8月)分别对太子河流域3个水生态区进行了野外调查. 结果表明:太子河流域上游区域的水生态Ⅰ区EPT物种数(64种)显著高于中下游区域的水生态Ⅱ区和Ⅲ区,其中,仅毛翅目物种数在丰水期显著高于枯水期. 典范对应分析(canonical correspondence analysis,CCA)结果显示,水生态Ⅰ区影响EPT群落分布的环境要素为电导率和水温,而水生态Ⅱ区、Ⅲ区则为电导率、φ(细沙)、ρ(BOD₅)、ρ(TP)和ρ(NH₃-N). 枯水期影响EPT群落分布的因素为电导率、建设用地面积所占比例和ρ(BOD₅),丰水期为电导率、ρ(SS)、耕地面积所占比例和水温. 偏线性回归(partial linear regression,PLR)分析显示,水生态Ⅱ区物种和环境要素的模型总解释率最高(均约为0.60),其他2个区次之(水生态Ⅰ区、Ⅲ区总解释率分别为0.13~0.43、0.13~0.53),丰水期模型的总解释率为0.33~0.78,而枯水期模型的总解释率为0.43~0.71. 相对于单一环境要素模型,不同类型环境要素的联合模型对太子河流域EPT群落空间变异具有更好的解释效力.      

固体废弃物浸出毒性特性及美国EPA的实验室测定(待续)

围绕固体废弃物浸出毒性特性这个中心,综述了它在有害废弃物的鉴别和管理,在执行陆地处置限制法规过程中的重要作用。以及在保护水资源、特别是地下水资源方面的重要意义。并简要介绍和评论了美国固体废弃物浸出毒性的实验室测定方法EPT和TCLP。     

固体废弃物浸出毒性特性及美国EPA的实验室测定(续完)

围绕固体废弃物浸出毒性特性这个中心，综述了它在有害废弃物的鉴别和管理，在执行陆地处置限制法规过程中的重要作用。以及在保护水资源，特别是地下水资源方面的重要意义，并简要介绍和评论了美国固体废弃物浸出毒性的实验室测定方法ETP和TCLP。