Using stable isotopes to confirm the trophic ecology of Arctic charr morphotypes from Lake Hazen, Nunavut, Canada

Abstract

Stable isotopes of carbon and nitrogen were used to examine differences in the feeding ecology of sympatric morphotypes of Arctic charr Salvelinus alpinus from Lake Hazen, Ellesmere Island, in the Canadian High Arctic. Large and small morphotypes possessed significantly different carbon and nitrogen signatures with large-form Arctic charr being more depleted in 13 C and more enriched in 15 N than the small-form. Isotope and stomach content analyses yielded consistent results and indicated short-and long-term reliance on fish as a food for large Arctic charr. Large-form individuals predate on juveniles but do not predate on small-form individuals d250 mm. The observed cannibalism by large-form individuals, therefore, does not act to maintain the bimodal length-frequency distribution in Lake Hazen. Bimodality is argued to arise for ecological reasons connected with differing habitat use by the morphotypes and the associated differences in resource consumption opportunities. 2002 The Fisheries Society of the British Isles

Consequences of large temporal variability of zooplankton δ15 N for modeling fish trophic position and variation

“…Body size of fish is often correlated with ␦ 15 N (Beaudoin et al 1999;Fry et al 1999), and this relationship is commonly interpreted as an ontogenetic shift to higher trophic positions (Guiguer et al 2002). However, relationships between body size and ␦ 15 N can also result from other processes, including shifts in habitat use (Genner et al 2003), and temporal variability of food sources (Fig.…”

The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review

“…[206] The proposed effect of differential feeding behaviour of adult char [208] on their Hg levels cannot currently be distinguished from the effect of opportunistic cannibalism, a factor that is known to contribute greatly to variability of d 15 N (and thus Hg) in char. [225,226,230] Cannibalism played an important role in Arctic char Hg levels in a lake on Svalbard. [231] The highest concentrations were observed in piscivorous Arctic char (0.04 to 0.44 mg g À1 WW), whereas the invertebrate-feeding Arctic char had significantly lower concentrations.…”

“…DOC) and stratification produce an environment favouring photoreduction to Hg 0 , which then evades to the atmosphere. [29] Landlocked Arctic char Lakes in the Canadian Arctic Archipelago have simple food webs in which Arctic char are often the only species of fish present, feeding primarily on the dominant benthic invertebrate, chironomids, or as cannibals on other char [206,225] while some adults exhibit cannibalistic feeding behaviour on juveniles. [166,226] Between 2005 and 2007, Hg biomagnification was investigated in the food webs supporting landlocked Arctic char populations in 18 lakes on: Ellesmere Island (n ¼ 4), Cornwallis Island (n ¼ 9), Victoria Island (n ¼ 1), Kent Peninsula (n ¼ 3) and Ungava Peninsula (n ¼ 1).…”

Physical and Biological Factors Affecting Mercury and Perfluorinated Contaminants in Arctic Char (<i>Salvelinus alpinus</i>) of Pingualuit Crater Lake (Nunavik, Canada) + Supplementary Appendices (See Article Tools)

“…Longer-term diet information, reflected in the values of dorsal muscle tissue δ 13 C and δ 15 N signatures, was collected for the fish originally obtained from Pingualuk Lake (n = 20) and Laflamme Lake (n = 9), as well as for eight char removed from the stomach contents of larger individuals from Pingualuk Lake. samples were processed according to the methods described in Guiguer et al (2002), and all stable isotope ratios are reported in conventional δ notation, where δ 13 C or δ 15 N = [(r sample -r standard )/r standard ] • 1000, and r = 13 C/ 12 C or 15 N/ 14 N.…”