Muenz Tara K, Golladay Stephen W, Vellidis George, Smith Lora L
J.W. Jones Ecological Research Center, Route 2 Box 2324, Newton, GA 39870, USA.
J Environ Qual. 2006 Sep 13;35(5):1924-38. doi: 10.2134/jeq2005.0456. Print 2006 Sep-Oct.
To determine useful metrics for assessing stream water quality in the Southeastern Coastal Plain, we examined differences among two buffered and three unbuffered streams in an agricultural landscape in southwestern Georgia. Potential indicators included amphibian diversity and abundance, aquatic macroinvertebrate populations, riparian vegetative structure, water quality, and stream physical parameters. Variability among sites and treatments (buffered vs. unbuffered) existed, with sites in the same treatment as most similar, and disturbances from a nearby eroding gully strongly affecting one unbuffered site. Of the invertebrate metrics examined, percentages of clingers, Ephemeroptera-Plecoptera-Trichoptera (EPT), Elmidae (Coleoptera), Crustacea (Decapoda and Amphipoda), and dipterans were found to be possible indicators of stream health for perennial streams within this region. Overall, buffered sites showed higher percentages of sensitive invertebrate groups and showed lower and more stable concentrations of nitrate N, suspended solids, and fecal coliforms (FCs). Percent canopy cover was similar among sites; however, riparian vegetative coverage and percent leaf litter were greatest at buffered sites. No differences in amphibian abundance, presence, and absence within the riparian area were apparent between sites; however, instream larval salamanders were more abundant at buffered streams. In this study, stream buffers appeared to decrease nutrient and sediment loads to adjacent streams, enhancing overall water quality. Selected benthic macroinvertebrate metrics and amphibian abundance also appeared sensitive to agricultural influences. Amphibians show potential as indicator candidates, however further information is needed on their responses and tolerances to disturbances from the microhabitat to landscape levels.
为了确定评估东南沿海平原溪流水质的有用指标，我们研究了佐治亚州西南部农业景观中两条有缓冲带和三条无缓冲带溪流之间的差异。潜在指标包括两栖动物的多样性和丰度、水生大型无脊椎动物种群、河岸植被结构、水质以及溪流物理参数。各站点和处理方式（有缓冲带与无缓冲带）之间存在差异，同一处理方式下的站点最为相似，附近一条侵蚀沟壑产生的干扰对一个无缓冲带站点影响很大。在所研究的无脊椎动物指标中，发现附着类、蜉蝣目-襀翅目-毛翅目（EPT）、沼甲科（鞘翅目）、甲壳纲（十足目和端足目）以及双翅目的百分比可能是该地区常年溪流健康状况的指标。总体而言，有缓冲带的站点敏感无脊椎动物类群的百分比更高，硝酸盐氮、悬浮固体和粪大肠菌群（FCs）的浓度更低且更稳定。各站点的树冠覆盖率相似；然而，有缓冲带的站点河岸植被覆盖率和落叶百分比最高。各站点之间河岸区域两栖动物的丰度、存在与否没有明显差异；然而，有缓冲带的溪流中溪流幼虫蝾螈更为丰富。在本研究中，溪流缓冲带似乎减少了相邻溪流的养分和沉积物负荷，提高了整体水质。选定的底栖大型无脊椎动物指标和两栖动物丰度似乎也对农业影响敏感。两栖动物显示出作为指标候选物种的潜力，然而，需要进一步了解它们从微生境到景观层面的干扰响应和耐受性。
