1 Boundaries and definitions for the Arctic and Subarctic regions according to the Programme for the Conservation of Arctic Flora and Fauna (CAFF), shown in polar projection. Boundaries can be defined by the isotherms, habitat, latitude or geopolitical zones. Source map was developed by cartographer Philippe Rekacewicz (UNEP/GRID- Arendal) and is made available by CAFF at _of_the_arctic. (For color version of this figure, the reader is referred to the web version of this book.) 

Context in source publication

Context 1

... Earth’s northern circumpolar regions present landscapes of outstand- ing beauty, incomparable fauna and flora and small, widely dispersed human settlements. These are integrated biological systems, where peo- ples of great resilience remain culturally close to the land and dependant on an array of natural resources, while living with the extremes of short summers and long cold winters (Rausch, 1951; Anisimov et al., 2007). The North encompasses those regions extending from the borders of the Sub- arctic (above 50°N) to beyond the Arctic Circle (north of 66°33 ′ N) ( Fig. 1.1). The latter marks the approximate limit for the current northern treeline and the circumpolar zone characterised seasonally by periods of constant polar night or midnight sun. Treeless tundra habitats dominate the Arctic where the average temperatures for the warmest month do not exceed 10°C; mean annual temperatures for the western subregions of the Arctic range from −20 to +12°C with minimal precipitation varying from 5 to 150mm (Callaghan et al., 2004e). The Arctic transitions into more south- erly Subarctic environments dominated primarily by taiga forests and a more complex mosaic of habitats defined by latitude and altitude. Northern ecosystems were formed by complex abiotic and biotic mechanisms in a crucible driven by episodic climatological processes and environmental perturbation extending across the late Pliocene and Quaternary during the past 3–5 million years (Myr) (e.g. Hopkins et al., 1982; Andersen and Borns, 1994 Dynesius and Jansson, 2000; Jansson and Dynesius, 2002; Callaghan et al., 2004a,c; Hewitt, 2004a,b). Contemporary patterns of faunal complexity reflect extinction events largely coincidental with the thermal maximum that signalled the termination of continental glaciation only 10 thousand years ago (Ka) (e.g. Barnosky et al., 2004). Consequently, northern biotas are typically characterised as relatively sim- ple, low-diversity assemblages with short trophic linkages, few pathogens and limited resilience or capacity for adaptation to environmental change (e.g. Callaghan et al., 2004a) (Table 1.1). A gradient of declining diversity with increasing latitude (from taiga forests to polar deserts) is also accom- panied by a shift or increase in dominance for some species, which may be manifested seasonally or annually (e.g. Callaghan et al., 2004b). High- latitude biotas are now at their minimal extent relative to patterns of diver- sity and geographic distribution that characterised faunas during the mid to late Pleistocene (e.g. Guthrie, 1984; Callaghan et al., 2004a). At high latitudes, vulnerable systems of low diversity continue to undergo significant and in some instances accelerating change due largely to human activity, both local and distant. These perturbations have the potential for broader impacts at a global scale (Callaghan et al., 2004a,d; Anisimov et al., 2007; Lawler et al., 2009; Post et al., 2009). Increasingly, substantial discussion has focused on the status and future of northern ecosystems, but these assessments have been limited to free-living organisms. Parasitism, pathogens and diseases have not yet been an integral component of this discourse (Kutz et al., 2009a). Parasites represent in excess of 40–50% of the organisms on Earth and complex assemblages of macroparasites (helminths and arthropods) and microparasites (viruses, bacteria and protozoans) shape ecosystems, food webs, host demographics and behaviour (e.g. Marcogliese, 2005; Hudson et al., 2006; Dobson et al., 2008). In some ecosystems, the biomass for macroparasites exceeds that for apex predators such as birds and fishes, suggesting a substantial role for otherwise obscure organisms at local to regional scales (Kuris et al., 2008). Parasites can cause disease and mortal- ity may influence the dynamics of wildlife populations and, in the worst- case scenarios, contribute to extinction events. Parasites are ubiquitous and diverse members of all biological commu- nities including those at high latitudes. All animals in circumpolar regions are susceptible to infection by characteristic assemblages of macroparasites and microparasites. Parasites can have subtle to severe effects on individual hosts or broader impacts on host populations that may cascade through ecosystems. Parasitic diseases have dual significance: (1) influencing sus- tainability for species and populations of diverse invertebrates, fishes, birds and mammals and (2) secondarily affecting food security, quality and avail- ability for people. Additionally, as zoonoses, some parasites can infect and cause disease in people and are a primary issue for food safety and human health (e.g. Kutz et al., 2009b; Jenkins et al., 2011). Sustainability, security and safety of ‘country foods’ are of concern at northern latitudes where people maintain a strong reliance on wildlife species. The potential signifi- cance of zoonoses is magnified in the North by the intimate linkage between wildlife and people. Subsistence food chains depend on the harvesting of free-ranging mammals, birds and fish for food, fibre and other animal prod- ucts. Understanding the role and influence of parasites in northern systems emerges from explorations of history, biogeography and the intricate eco- logical linkages among fishes, birds, mammals, domesticated species and people in the context of broader global connections (e.g. Hoberg, 2010). Despite the extreme environmental conditions in the North, the triad of host, parasite and environment remains ...