Davis Stephanie, Golladay Stephen W, Vellidis George, Pringle Catherine M
J.W. Jones Ecological Research Center, Route 2, Box 2324, Newton, GA 31770, USA.
J Environ Qual. 2003 May-Jun;32(3):1036-43. doi: 10.2134/jeq2003.1036.
Little attention has been given to the ecology of intermittent coastal plain streams in the southeastern United States, and it is not known whether available macroinvertebrate biomonitoring methods reliably detect degradation in these streams. This study compared differences in biomonitoring metrics between reference and agricultural streams, and between the flow period (January-April) and the intermittent flow period (May-December). Percentages of crustaceans, isopods, and Ephemeroptera-Plecoptera-Trichoptera (EPT) were significantly higher at the reference site than the two most impacted sites during the flow period, probably resulting from the abundance of leaf litter and lower temperatures. During this same period, the agriculturally impacted sites had a significantly higher percentage of dipterans--a group that thrives in the silty, nutrient-rich waters. Four metrics (percent Crustacea, Isopoda, Diptera, and EPT) had no overlap between values for the most impacted and the least impacted sites during the flow period, but no metrics were able to detect more discrete differences among sites. Sites were physically and biologically similar during the intermittent period when natural stresses (i.e., stagnant water, high temperatures, low dissolved oxygen) were high, with many metrics, such as percentages of dominant family, burrowers, chironomids, and dipterans becoming similar at all sites. Our findings indicate that development of a better understanding of invertebrate fauna in reference conditions and of the natural variation in intermittent streams is necessary to develop effective biomonitoring programs for these systems.
美国东南部间歇性沿海平原溪流的生态学研究较少，目前尚不清楚现有的大型无脊椎动物生物监测方法能否可靠地检测出这些溪流的退化情况。本研究比较了参考溪流和农业溪流之间以及流动期（1月至4月）和间歇性流动期（5月至12月）生物监测指标的差异。在流动期，参考站点的甲壳类动物、等足类动物和蜉蝣-襀翅目-毛翅目（EPT）的百分比显著高于两个受影响最大的站点，这可能是由于落叶丰富和温度较低所致。在同一时期，受农业影响的站点双翅目昆虫的百分比显著更高，双翅目昆虫在粉质、营养丰富的水域中大量繁殖。在流动期，四个指标（甲壳纲、等足目、双翅目和EPT的百分比）在受影响最大和最小的站点之间没有重叠，但没有一个指标能够检测出站点之间更明显的差异。在间歇性流动期，当自然压力（即死水、高温、低溶解氧）较高时，各站点在物理和生物学上相似，许多指标，如优势科、穴居动物、摇蚊和双翅目的百分比在所有站点都变得相似。我们的研究结果表明，有必要更好地了解参考条件下的无脊椎动物区系以及间歇性溪流的自然变化，以便为这些系统制定有效的生物监测计划。
