Abstract
Life history strategies and potential marine niche use of Arctic charr Salvelinus alpinus (n = 237, 84-652 mm, total body length, LT ) were determined during the ice-free season (2012) at three different watercourses in south-western Greenland. All Arctic charr were collected from freshwater habitats. Based on stable isotopes of δ34 S, the Arctic charr were categorized as either marine- or freshwater-dependent feeders. The use of time-integrated trophic tracers (stable isotopes of δ13 C, δ15 N, δ34 S) suggested that several trophic groups of Arctic charr operate alongside within each fjord system. The groups suggested were one group that specialized in the marine habitat, in addition to two freshwater resident morphs (small-sized resident and/or large-growing cannibalistic individuals). Stomach contents consisted entirely of freshwater and terrestrial prey (i.e., insects), indicating that marine-dependent feeders also fed in freshwater habitats after return from their marine migration. Growth and maturity patterns further supported variable life history strategies within each watercourse. The life history strategy patterns and marine trophic niche use were consistent across the watercourses along several hundred kilometres of coastline. This study represents the first ecological baseline for partially anadromous populations of Greenland Arctic charr.
Highlights
Arctic research on Arctic charr (Salvelinus alpinus L.) 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), with research in Greenland having been typically under-represented
The sensitivity of Arctic aquatic ecosystems to ongoing climate change (O'Neill et al, 2017), observed changes in climate have been associated with changing patterns of age-specific growth in Greenland Arctic charr likely to be influenced by local factors, including lake morphometry and trophic behaviour (e.g., Jeppesen et al, 2001; Kristensen et al, 2006; Riget et al, 2000b; Sparholt, 1985)
As part of establishing a baseline for Greenland aquatic ecosystems, this study uses stable isotope measures (δ13C, δ15N, δ34S) of individual Arctic charr captured from three separate watercourses in south-western Greenland to describe within- and among-system trophic behaviour, feeding patterns and dependence on marine resources
Summary
Arctic research on Arctic charr (Salvelinus alpinus L.) 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), with research in Greenland having been typically under-represented. Changes in the balance of anadromy and residency driven by climate change are likely to hold significant implications for populations of Arctic charr in Greenland and elsewhere (Reist et al, 2006) given that resource availability can influence important reproductive traits in salmonids, including the onset of maturation, ova size and fecundity (Flemming & Gross, 1991). As part of establishing a baseline for Greenland aquatic ecosystems, this study uses stable isotope measures (δ13C, δ15N, δ34S) of individual Arctic charr captured from three separate watercourses in south-western Greenland to describe within- and among-system trophic behaviour, feeding patterns and dependence on marine resources. We use stable isotope, stomach content, body length, age, sex and maturation stage data to test the following hypotheses: (a) that reliance on marine prey increases with Arctic charr length, (b) that, as a result of (a), there will be a significant difference in anadromous and resident Arctic charr stomach contents, and (c) that the degree of reliance on marine prey resources will influence patterns of maturity between watercourses
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