摘要
北极的气候变化和紫外辐射水平的变化将具有深远的影响,会影响各营养级的水生物种、构成其生境的物理和化学环境以及作用于淡水生态系统和其内部的过程。诸如温度和降水之类的气候变量与淡水生态系统的相互作用高度复杂并能够以难以预测的方式在生态系统中蔓延。这部分是由于对北极淡水生态系统及其与气候和其他环境变量的相互关系缺乏了解,同时也由于北极地区缺乏长期的淡水监测点和综合的水文—生态学研究计划。本专刊中的文章是25名国际专家和他们各自的网络关于北极淡水水文学和相关的水生生态系统进行的分析的摘要,该摘要最初在2005年作为北极气候影响评估(ACIA)的"第8章——淡水生态系统和渔业"发表。这些文章广泛地概述了北极各种淡水系统的一般水文学和生态学特征,包括对每一个ACIA地区的描述,后面回顾了全新世期间淡水系统的历史变化。接着是气候变化对大尺度水文生态学、水生生物和生态系统结构和功能,以及北极鱼类和渔业影响的评估。还讨论了潜在的增效效应和累积效应以及紫外辐射和污染物的作用。文章利用环北极地区的案例研究结果说明了许多影响的性质和复杂性,以及重要的临界响应(即:那些产生分阶段影响和/或非线性影响的响应)。本期最后总结了关键的发现,并列举了科学认识方面的空白,以及与政策有关的建议。
Changes in climate and ultraviolet radiation levels in the Arctic will have far-reaching impacts, affecting aquatic species at various trophic levels, the physical and chemical environment that makes up their habitat, and the processes that act on and within freshwater ecosystems. Interactions of climatic variables, such as temperature and precipitation, with freshwater ecosystems are highly complex and can propagate through the ecosystem in ways that are difficult to project. This is partly due to a poor understanding of arctic freshwater systems and their basic interrelationships with climate and other environmental variables, and partly due to a paucity of long-term freshwater monitoring sites and integrated hydro-ecological research programs in the Arctic. The papers in this special issue are an abstraction of the analyses performed by 25 international experts and their associated networks on Arctic freshwater hydrology and related aquatic ecosystems that was initially published by the Arctic Climate Impact Assessment (ACIA) in 2005 as 'Chapter 8 - Freshwater Ecosystems and Fisheries' . The papers provide a broad overview of the general hydrological and ecological features of the various freshwater ecosystems in the Arctic, including descriptions of each ACIA region, followed by a review of historical changes in freshwater systems during the Holocene. This is followed by an assessment of the effects of climate change on broad-scale hydro-ecology; aquatic biota and ecosystem structure and function; and arctic fish and fisheries. Potential synergistic and cumulative effects are also discussed, as are the roles of ultraviolet radiation and contaminants. The nature and complexity of many of the effects are illustrated using case studies from around the circumpolar north, together with a discussion of important threshold responses (i.e., those that produce stepwise and/or nonlinear effects). The issue concludes with summary the key findings, a list of gaps in scientific understanding, and policy-related recommendations.
