Natural resilience in Arctic charr Salvelinus alpinus: life history, spatial and dietary alterations along gradients of interspecific interactions

• Published in: Journal of Fish Biology
• Main Author: Hammar, J.
• Other Authors: National Swedish Fishery Board, National Environment Protection Agency, Swedish Radiation Protection Institute, Swedish Association of Water Regulation Enterprises, DFO, World University Service of Canada, Nordic Council of Ecology, Ymer-80 Foundation, Museum of Natural History
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2014
• Subjects: Arctic charr; Newfoundland; Salvelinus alpinus; Zooplankton
• Online Access: http://dx.doi.org/10.1111/jfb.12321; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fjfb.12321; https://onlinelibrary.wiley.com/doi/pdf/10.1111/jfb.12321

The Arctic charr Salvelinus alpinus species complex has been shown to be exceptionally vulnerable to rapid abiotic and biotic changes. Salvelinus alpinus , however, inhabit environmental extremes ranging from lakes and rivers in the High Arctic to deep multi‐fish species lakes far outside the polar region. Long‐term responses to post‐glacial environmental variations and successively increased interspecific interactions reveal an essential degree of natural ecological resilience and phenotypic flexibility. Case studies in Scandinavia and Newfoundland illustrate the alternate trophic roles of S. alpinus , and its flexible niche use and life‐history changes in order to regain or maintain body size in gradients of lakes with increasing fish species diversity. While allopatric in northern low‐productive upland lakes, landlocked populations are commonly structured by cannibalism. In sympatry with other fish species, S. alpinus mostly serve as prey, with their decreasing growth and body size reflecting the successive diet shift from littoral macro‐benthos to zooplankton and profundal microbenthos as interspecific competition for food and habitat intensifies. Interactions with natural and introduced superior zooplankton feeders and ultimate predators finally become detrimental. Consequently, the niche of S. alpinus is increasingly compressed in lakes along latitudinal and altitudinal gradients, although certain natural key conditions offer S. alpinus temporary asylum in the inescapable process towards local and regional extinction. The water temperature drop during winter allows S. alpinus to temporarily resume the richer littoral dietary and spatial niche use in low diversity lakes. In southern lowland and coastal lakes with more complex fish communities, access to key prey species such as profundal macro‐crustaceans and smelt Osmerus spp. allow S. alpinus to regain its original niche space and characteristics as a large piscivore. In conclusion, S. alpinus along its evolutionary landscape demonstrates associated ...