This is Chapter 8 of the Arctic Climate Impact Assessment
Lead Authors: Frederick J.Wrona,Terry D. Prowse, James D. Reist; Contributing Authors: Richard Beamish, John J. Gibson, John Hobbie, Erik Jeppesen, Jackie King, Guenter Koeck, Atte Korhola, Lucie Lévesque, Robie Macdonald, Michael Power,Vladimir Skvortsov,Warwick Vincent; Consulting Authors: Robert Clark, Brian Dempson, David Lean, Hannu Lehtonen, Sofia Perin, Richard Pienitz, Milla Rautio, John Smol, Ross Tallman, Alexander Zhulidov
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.
This chapter begins with 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. The chapter continues with a review of the effects of climate change on broad-scale hydro-ecology; aquatic ecosystem structure and function; and arctic fish, fisheries, and aquatic wildlife. Special attention is paid to changes in runoff, water levels, and river- and lake-ice regimes; to biogeochemical processes, including carbon dynamics; to rivers, lakes, ponds, and wetlands; to aquatic biodiversity and adaptive capacities; to fish populations, fish habitat, anadromy, and fisheries resources; and to aquatic mammals and waterfowl. 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 chapter concludes with a summary of key findings, a list of gaps in scientific understanding, and policy-related recommendations.
Chapter 8: Freshwater Ecosystems and Fisheries
8.2. Freshwater ecosystems in the Arctic
8.3. Historical changes in freshwater ecosystems
8.4. Climate change effects
8.4.1. Broad-scale effects on freshwater systems
8.4.2. Effects on hydro-ecology of contributing basins
8.4.3. Effects on general hydro-ecology
8.4.4. Changes in aquatic biota and ecosystem structure and function
8.5. Climate change effects on arctic fish, fisheries, and aquatic wildlife
8.5.1. Information required to project responses of arctic fish
8.5.2. Approaches to projecting climate change effects on arctic fish populations
8.5.3. Climate change effects on arctic freshwater fish populations
8.5.4. Effects of climate change on arctic anadromous fish
8.5.5. Impacts on arctic freshwater and anadromous fisheries
8.5.6. Impacts on aquatic birds and mammals
8.6. Ultraviolet radiation effects on freshwater ecosystems
8.7. Global change and contaminants
8.8. Key findings, science gaps, and recommendations