Wright J F, Gunn R J M, Winder J M, Wiggers R, Vowles K, Clarke R T, Harris I
Centre for Ecology and Hydrology Dorset, Winfrith Technology Centre, Winfrith Newburgh, Dorchester, UK.
Sci Total Environ. 2002 Jan 23;282-283:121-42. doi: 10.1016/s0048-9697(01)00948-2.
In 1974-1976, baseline studies were carried out on the flora and macroinvertebrate fauna of the R. Kennet at two sites downstream of Marlborough (Savernake Upper and Lower) and at one site upstream of Hungerford (Littlecote). Simplified maps of each site, showing the cover of macrophytes, were obtained monthly between April 1974 and April/June 1976, and replicated quantitative samples of the macroinvertebrates were collected on the dominant macrophyte and on gravel in June 1974, and also in June and December 1975. As a consequence of two major droughts and increasing concern over water quality in the Upper Kennet in the 1990s, the studies recommenced in the summer of 1997 using the same sites and methodologies. Maps and macroinvertebrate samples were obtained in early July and December 1997 and in June of both 1998 and 1999. At the Savernake sites, mapping in summer 1997 confirmed what had been apparent for some years. That is, macrophyte cover (both Ranunculus and Schoenoplectus) was much lower than in the 1970s. In contrast, the site downstream at Littlecote retained a relatively high cover of Ranunculus, despite the drought. In late autumn 1997, phosphate stripping commenced at Marlborough Sewage Treatment Works, the drought ended and in addition, the spring of 1998 was unusually wet. Ranunculus recolonised both Savernake sites with remarkable speed by summer 1998 and retained this dominant position in 1999. Quantitative samples of macroinvertebrates collected on gravel and the dominant macrophyte at each of the three study sites indicated that there was no evidence of major loss of family richness between the 1970s and 1990s as a result of the low flows or enrichment. However, at Savernake (but not Littlecote) in summer 1997, the macroinvertebrate assemblage was affected by low flows and/or enrichment. This took the form of changes in the abundance of some families, with lentic forms being favoured in relation to some lotic families. Following the end of the drought, many macroinvertebrate families at Savernake showed a rapid response to the new conditions and the assemblages reverted to those expected in a fast-flowing cretaceous chalk stream. Continued monitoring through the next drought is advisable to provide a greater understanding of the interplay between water quality, the discharge regime, habitat quality (including macrophyte growth) and the response of the macroinvertebrate fauna.
1974年至1976年期间，对马尔伯勒下游的两个地点（上萨弗纳克和下萨弗纳克）以及亨格福德上游的一个地点（利特尔科特）的肯尼特河的植物群和大型无脊椎动物区系进行了基线研究。在1974年4月至1976年4月/6月期间，每月获取每个地点的简化地图，显示大型植物的覆盖情况，并于1974年6月以及1975年6月和12月在优势大型植物和砾石上采集大型无脊椎动物的重复定量样本。由于20世纪90年代的两次重大干旱以及对上肯尼特河水质的日益关注，1997年夏天使用相同的地点和方法重新开展了研究。1997年7月初、12月以及1998年和1999年6月获取了地图和大型无脊椎动物样本。在萨弗纳克地点，1997年夏天的测绘证实了几年来一直明显的情况。也就是说，大型植物覆盖（毛茛属和黑三棱属）比20世纪70年代低得多。相比之下，尽管干旱，利特尔科特下游的地点仍保留了相对较高的毛茛属植物覆盖。1997年秋末，马尔伯勒污水处理厂开始进行磷酸盐去除，干旱结束，此外，1998年春天异常湿润。到1998年夏天，毛茛属植物以惊人的速度重新在两个萨弗纳克地点定殖，并在1999年保持了这一优势地位。在三个研究地点的砾石和优势大型植物上采集的大型无脊椎动物定量样本表明，没有证据表明20世纪70年代至90年代由于低流量或富营养化导致科级丰富度有重大损失。然而，1997年夏天在萨弗纳克（但不是利特尔科特），大型无脊椎动物群落受到低流量和/或富营养化的影响。其表现为一些科的丰度发生变化，相对于一些流水科，静水种类更受青睐。干旱结束后，萨弗纳克许多大型无脊椎动物科对新环境表现出快速反应，群落恢复到快速流动的白垩纪白垩溪流中预期的状态。建议在接下来的干旱期间继续进行监测，以更深入了解水质、排放状况、栖息地质量（包括大型植物生长）和大型无脊椎动物区系反应之间的相互作用。
