Ecological niche specialization inferred from morphological variation and otolith strontium of Arctic charr Salvelinus alpinus L. found within open lake systems of southern Baffin Island, Nunavut, Canada

Abstract

The presence of two morphotypes of Arctic charr Salvelinus alpinus was confirmed via morphological variation and otolith strontium (Sr) within three open-lake systems of southern Baffin Island, Nunavut, Canada: Qinngu (LH001), Iqalugaarjuit Lake (PG082) and Qasigiat (PG015). Analysis of otolith Sr indicates that a component of each S. alpinus population within lakes LH001 and PG082 is migratory (large-maturing S. alpinus), whereas another component is lake-resident (small-maturing S. alpinus). Alternatively, small and large maturing S. alpinus may both inhabit tidal habitats during their lifetime in lake PG015. Three morphological characters were identified by principal factor analysis (PFA) as characters that were different between maturity groups for all lakes studied: eye diameter, pectoral fin length and pelvic fin length. As well, upper jaw length (LH001 and PG082) and fork depth (PG015) were identified in PFA as traits that differed between morphs. Univariate tests of morphological characters identified by PFA demonstrated maturity group differences with the exception of eye diameter in Lake PG015 and upper jaw length and pelvic fin length in lake LH001. No difference was found in the MANOVA test of upper and lower gill raker number between small-maturing and undeveloped fish within all lakes studied. Clear morphological variation observed between small-maturing and undeveloped fish in all three lakes of the study suggests ecological niche separation between morphotypes. This is the first documented case of lake-resident S. alpinus use of the tidal habitat in the presence of a migratory large-maturing morphotype.

Maturation, growth and fecundity of Arctic charr, Salvelinus alpinus (L.), life-history variants co-existing in lake systems of Southern Baffin Island, Nunavut, Canada

“…Ovaries of maturing females were preserved for determination of fecundity. Charr that were previously identified as anadromous and lake-resident life-history morphs via strontium and morphological investigation (Loewen et al, 2009) were used in subsequent analyses.…”

“…Within one Southern Baffin charr population, it was observed that lakeresident fish may likely utilise tidal habitats when the physical geography between the lake and river system facilitates ease of passage into tidal habitats (Loewen et al, 2009). Regardless of tidal habitat use, all lakeresident fish from the three study lakes had morphological characteristics that suggest residency, such as long pectoral and pelvic fin lengths, and larger eye diameter.…”

“…Previously published research of Southern Baffin Island Arctic charr identified two life-history forms, anadromous and lake-resident, that exhibit variation in morphology indicative of variation in preferred habitat (Loewen et al, 2009). Within one Southern Baffin charr population, it was observed that lakeresident fish may likely utilise tidal habitats when the physical geography between the lake and river system facilitates ease of passage into tidal habitats (Loewen et al, 2009).…”

“…The map of Canada is shown to highlight the study region of Southern Baffin Island, Nunavut(Loewen et al, 2009): 1 Iqalugaarjuit Lake, Shark Fiord, NU (PG082); 2 Qasigiat, Ptarmigan Fiord, NU (PG015) and 3 Qinngu, Blandford Bay, NU (LH001). Both river systems of Iqalugaarjuit Lake and Qasigiat drain into Cumberland Sound.…”

Geographic influences on fine-scale, hierarchical population structure in northern Canadian populations of anadromous Arctic Char (Salvelinus alpinus)

“…Sampling juveniles, however, introduces the potential problem of sampling resident (non-migratory) Arctic char instead of anadromous individuals. Cumberland sound Arctic char systems have been relatively well studied and to date only two systems used in the present study seem to harbour resident populations (QAS and IQ1, Loewen et al 2009). Thus we are reasonably confident that our samples should be composed almost entirely of anadromous juveniles.…”