向挪威南部艾于德纳河中施加石灰:底栖无脊椎动物恢复的大规模试验

本研究描述了1985年向艾于德纳河溯河鱼类所在部分施加石灰后敏感的无脊椎动物的恢复情况.这条河流在1960～1970年间丧失了它的大马哈鱼种群.施加石灰的目的是产生pH＞6.0和ANC＞20μg/L的水质,并减少不稳定铝的含量.施加石灰前,在这条河中找不到像蜉蝣类的Baetis rhodanf等高度敏感的无脊椎动物.施加石灰2年后,一些敏感的无脊椎物种产生了积极的回应.河流下游有两处地点发现了B.rhodanf.在随后的5年里,一些敏感的无脊椎物种开始在施加石灰的整个河段聚集,并且数量越来越大.在向河流施加石灰10年后,出现了蜗牛Lymnaeaperegra.这个物种的扩散也非常迅速,5年后它可以在40km范围内施以石灰的的主要河流的所有调查地点被发现.在这一区域减少硫的沉降也引起了艾于德纳河未施加石灰的各支流水质的提高.施加石灰与未施加石灰的地点的比较说明了水质和敏感物种的临界限制是决定艾于德纳河动物组成的主要因素,而与水质变化的原因无关.     

Recovery from acidification in European surface waters: a view to the future

There is now overwhelming documentation of large-scale chemical recovery from surface water acidification in Europe, but to date there has been little documentation of biological recovery. Modelling studies based on current emission reduction plans in Europe indicate that there will be further chemical recovery. The uncertainties in these scenarios mainly relate to the future behavior of nitrogen in the ecosystem and the effects of climate change. Four major climate-related confounding factors that may influence the chemical and biological recovery process are: i) increased frequency and severity of sea-salt episodes; ii) increased frequency and severity of drought; iii) increased turnover of organic carbon; iv) increased mineralization of nitrogen. International cooperative work to abate acidification has so far been very successful, but there is still a long way to go, and many potential setbacks. It is essential that future development of water chemistry and aquatic biota in acidified waterbodies continue to be monitored in relation to further emission reductions of S and N and future effects of climate change.     

酸化湖泊水生生物恢复的理论框架构建

在欧洲和北美广大地区,随着大气硫沉降的减少,地表水体酸度正在逐渐降低,但是对水质改善的生态响应过程却依然扑朔迷离.有些湖泊和河流的生物正在恢复,有些水体的生物并没有得到恢复.为理解这些生物响应的差异,有利于酸雨问题的有效管理,我们需要对下面2个问题有清晰的认识:①生物群落恢复所必须经历的生态步骤;②倘若恢复受阻,从哪里着手对恢复进程实施干预,如何干预.本文通过构建一套理论框架来回答上述问题.第一层框架是基于生态学考虑而构建的,通过决策树来反映生态恢复进程中必须经历的若干步骤,步骤之间则通过管理工具或对瓶颈的响应来连接.水质不佳,移生生物供给不足以建群,以及群落水平上对恢复动态变化的阻碍等等都可能成为恢复的瓶颈所在.第二层框架则是基于管理层次来构建的,为了克服瓶颈,框架指明从哪里着手对恢复进程实施干预,为建模来进一步将框架具体化,需要做哪些研究.一旦我们可以用模型来预测酸化水体生态恢复的速率和程度,对硫排放减少带来的效益评价就变得简单起来.而这些模型的构建需要充分认识恢复进程中的生态步骤.本文提出的理论框架将有助于我们朝这个目标迈进.     

欧洲地表酸化水体恢复--未来展望

到目前为止,有关欧洲地表酸化水体大范围化学恢复的文献层出不穷,而有关生物恢复的报道并不多见.建立在现今欧洲排放减少计划之上的模型研究表明,化学恢复仍将继续.而影响恢复进程的诸多不确定性因素主要包括:未来生态系统内氮的可能行为和气候变化的影响.下列4个与气候变化相关的因子可能对未来恢复进程产生影响:①海水盐分入侵事件爆发频率和强度增加;②干旱发生频率和强度上升;③有机碳交换周期加快;④硝化作用增强.目前降低水体酸化程度的国际性协作是成功的,但是未来还有大量问题需要解决,也会遇到许多困难.对未来硫、氮排放减少后以及气候变化背景下酸化地表水体的水化学和水生生物变化需要继续监测.     

Developing conceptual frameworks for the recovery of aquatic biota from acidification

Surface water acidity is decreasing in large areas of Europe and North America in response to reductions in atmospheric S deposition, but the ecological responses to these water-quality improvements are uncertain. Biota are recovering in some lakes and rivers, as water quality improves, but they are not yet recovering in others. To make sense of these different responses, and to foster effective management of the acid rain problem, we need to understand 2 things: i) the sequence of ecological steps needed for biotic communities to recover; and ii) where and how to intervene in this process should recovery stall. Here our purpose is to develop conceptual frameworks to serve these 2 needs. In the first framework, the primarily ecological one, a decision tree highlights the sequence of processes necessary for ecological recovery, linking them with management tools and responses to bottlenecks in the process. These bottlenecks are inadequate water quality, an inadequate supply of colonists to permit establishment, and community-level impediments to recovery dynamics. A second, more management-oriented framework identifies where we can intervene to overcome these bottlenecks, and what research is needed to build the models to operationalize the framework. Our ability to assess the benefits of S emission reduction would be simplified if we had models to predict the rate and extent of ecological recovery from acidification. To build such models we must identify the ecological steps in the recovery process. The frameworks we present will advance us towards this goal.     

Liming of River Audna,Southern Norway: a large-scale experiment of benthic invertebrate recovery

This study describes the recovery of sensitive invertebrates after liming of the anadromous part of River Audna in 1985. The river lost its salmon population during 1960-1970. The aim of the liming was to produce a water quality with pH > 6.0 and ANC > 20 microg L(-1) and to reduce the content of labile aluminum. Highly sensitive invertebrates like the mayfly Baetis rhodani were not found in the river before liming. Two years after liming, several sensitive invertebrate species showed a positive response. B. rhodani was then recorded at 2 sites in the lower part of the river. In the following 5 years several species of sensitive invertebrates recolonized the whole limed reach of the river and became numerous. Ten years after liming the snail Lymnaea peregra was recorded in the river. The dispersa of this species was also very fast and after 5 years it was found at all investigated sites in the limed main river covering a reach of 40 km. Reduced sulfur deposition in the area also resulted in water-quality improvements in th unlimed stretches of River Audna. Comparisons between limed and unlimed localities indicated that the water quality and the critical limits of sensitive species are the ma factors determining the fauna composition in River Audna independent of the reason for the change in water quality.     

Tracing recovery from acidification in the western Norwegian Nausta watershed

A novel method, redundancy analysis (RDA), has been used to examine whether chemical recovery from acidification in the western Norwegian Nausta watershed produces detectable recovery within the community structure of the macro-zoobenthos. The RDA results have been compared with measures of recovery based on the changes detected using highly specialized and regionally defined biological acidity indices. We found that the beginning of biological recovery in the Nausta watershed was recognizable during the period 1989-1998. Recovery occurred in the upper reaches and in the tributaries. The multivariate approach proved to complement the acidity indices approach, and much biological information can be gained by their combined use. The RDA method is conservative, i.e. does not overestimate biological recovery, and it is not geographically constrained as are the acidity indices. We also found that seasonal climatic factors strongly influence the benthic community, and may confound the detection of the biological recovery process.     

探索挪威西部奈于斯特流域酸化的复原

使用一种新方法-多余度分析(RDA),检查了是否挪威西部奈于斯特流域酸化的化学复原在大型底栖动物群落结构中产生了可测的复原.RDA结果与基于使用高度专门化和区域化界定的生物酸度指数测得的变化的复原测量值作了比较.我们发现,在1989～1998年期间,奈于斯特流域生物复原即开始出现.复原是在奈于斯特河上游及其各支流发生的.多变量方法已证明是酸度指数方法的一种补充,将两者结合使用能够得到大量的生物信息.RDA方法是一种保守的方法,即不会过高地估计生物复原,而且不像酸度指数,从地理上来说不会受到约束.我们还发现,一些季节性气候因素强烈地影响着底栖生物群落,可能引起对生物复原过程检测的混淆.     

Recovery of acid-sensitive species of ephemeroptera, plecoptera and trichoptera in river audna after liming

River Audna has been continuously limed on a full scale basis since 1985. Monitoring of benthic invertebrates of the river showed that the fauna was dominated by acid-tolerant species before liming and during the first year after the start of the treatment. Moderately acid-sensitive species, like Diura nanseni, Isoperla grammatica and Hydropsyche siltalia were found only in small numbers in a few localities in this period. In autumn 1987, the first appearance of the highly acid-sensitive mayfly Baetis rhodani was recorded at two stations in the main river. During the following years, this species colonized other localities and several other sensitive invertebrates, such as Heptagenia sulphurea, Caenis horaria, Hydropsyche pellucidula and Lepidostoma hirtum were also recorded. The change in faunal composition was highly significant compared to unlimed reference stations.     

Species Composition of Freshwater Invertebrates in Relation to Chemical and Physical Factors in High Mountains in Soutwestern Norway

The composition of benthic invertebrates was investigated in three Norwegian alpine watersheds during the period 1991–1997. The watersheds represented an environmental gradient in chemical factors. The Kvenna watershed was relatively well buffered, Lake Øvre Neådalsvatn was poorly buffered, but receives low inputs of atmospheric pollution while Lake Stavsvatn has low buffering capacity and receives larger inputs of acidifying components. Qualitative samples were taken in the inlet rivers, lake littoral zone, lake outlet and in the outlet rivers of the lakes for analyses of species composition. In Ø. Neådalsvatn the water chemical data showed strong seasonal variations with waters of low ionic content during snowmelt and summer, while increased ion concentrations build up during winter. The time of ice break and/or water temperature rise during the growing season affected the life cycle of Siphlonurus lacustris and Parameletus chelifer. Even small changes in pH or ANC seemed to have a strong effect on Baetis rhodani. In the Kvenna watershed eight very sensitive species were found at sites with pH 6.5, Ca 1.2 mg L^-1 and LAl < 10 eq L^-1. Only two highly sensitive species, B. rhodani and Capnia sp. were recorded when pH was 6, concentration of calcium 0.8 mg L^-1 and low labile aluminium < 10 eq L^-1. None of the highly sensitive species occurred in Stavsvatn, a formerly acidified area, where LAl concentrations ranged between 25–40 eq L^-1. Low ionic content and elevated concentrations of labile aluminium are suggested to exclude sensitive invertebrates in alpine lakes. Synergistic effects of dilute water and harsh climate are assumed to increase sensitivity of invertebrates to acid water. Global warming will result in higher precipitation and more snow in the west Norwegian alpine area. This will shorten the growing season, increase the amount of dilute water and consequently threaten invertebrate species living close to their tolerance limits.