IMIS

Arctic aquatic ecosystems are highly vulnerable to anthropogenic disturbances (Becker & Pollard, 2016) and potentially to ongoing climate change (O'Neill et al., 2017). Thus, it is important to gather baseline information and monitor ecosystems throughout the Arctic region to document and determine the potential significance of observed ecological changes within these systems. Freshwater aquatic systems are often small, relatively closed and delimited and represent good opportunities to document existing ecological patterns (Wrona et al., 2013). Within these ecosystems Arctic charr (Salvelinus alpinus (L.)) are often the only fish species found  (Klemetsen, 2013) and as the top predator can provide valuable information about their status and functioning (Kristensen et al., 2006). Research on Arctic charr has traditionally covered  the major geographical areas of northern Europe, Iceland, northern Canada and the Pacific basin drainages of the Asian and  North American coasts (Knudsen et al., 2016). However, research in Greenland has been under-represented. There are some limited studies of land-locked resident Arctic charr stocks (e.g. Sparholt, 1985; Riget et al., 2000b; Jeppesen et al., 2001; Kristensen et al., 2006)  and studies of mercury levels in anadromous stocks (e.g. Riget et al., 2000a). Yet Greenland is one of the Arctic regions most likely to be heavily affected by climate change and other anthropogenic activities (IPCC, 2014). A recent study from three watercourses in South-western Greenland (Davidsen et al., 2020) suggested that the three populations of Arctic charr all consisted of a mixture of trophic groups, one group that specialise within the marine habitat, the estuarine group that may have short-time marine migrations, in addition to two morphs from the freshwater habitats. However, there were no available data of the behavioural differences or temperature preferences between the morphs or about the duration of the marine migration or distance travelled away from the home watercourse. To address these knowledge gaps, we will combine acoustic telemetry and genomics to quantify variation in temperature preferences and movement behaviour, and the extent of marine habitat use of anadromous Arctic Charr. This project will to our knowledge be the first one using acoustic telemetry in Greenland.