Exploring trophic niches and parasite communities of sympatric Arctic charr and brown trout populations of southern Norway

Rachel A. Paterson,Rune Knudsen,Romana K. Salis,Jelena Nefjodova

doi:10.1007/s10750-019-3956-1

Rachel A. Paterson, Rune Knudsen + Show 2 more

Open Access

https://doi.org/10.1007/s10750-019-3956-1

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Abstract

Catchment-scale variation between lake habitats has the potential to simultaneously influence the trophic niche and parasite community of fish hosts. In this study, we investigated the trophic niche and parasite community of sympatric Arctic charr and brown trout populations from two inter-connected southern Norwegian lakes at different altitudes. Arctic charr and brown trout occupied profundal and littoral habitats in each lake, respectively, whereas brown trout replaced Arctic charr in pelagic habitats of the lower altitude lake. Distinct between-lake differences in diet and parasite community composition were noted for brown trout; however, both fish species showed highly overlapping trophically transmitted parasite communities regardless of the habitats each species used. Our results suggest that environmental differences over relatively limited geographical distances have the potential to influence fish habitat use and parasite community structure.

Highlights

Environment-induced alterations to distribution patterns of co-evolved species have the potential to uncouple trophic interactions essential for maintaining freshwater ecosystem structure and function (Winder & Schindler, 2004)
Whilst temperature-related shifts in freshwater fish distribution patterns associated with range expansion or constrictions of cold and coolwater species are recognised (Comte et al, 2013), interactions involving parasites are frequently overlooked, despite the significant role parasites play in aquatic food web complexity and topology (Amundsen et al, 2009)
Sympatric Arctic charr and brown trout populations were sampled in August 2017 from two lakes of the Skjenaldelva catchment, southern Trøndelag, Norway; Vavatnet (63°190N, 09°320E; 425 ha; max. depth 70 m, 300 m.a.s.l.) and Gangasvatnet (63°160N, 09°380E; 549 ha, max. depth 33 m, 153 m.a.s.l.)

Summary

Introduction

Environment-induced alterations to distribution patterns of co-evolved species have the potential to uncouple trophic interactions essential for maintaining freshwater ecosystem structure and function (Winder & Schindler, 2004). Whilst temperature-related shifts in freshwater fish distribution patterns associated with range expansion or constrictions of cold and coolwater species are recognised (Comte et al, 2013), interactions involving parasites are frequently overlooked, despite the significant role parasites play in aquatic food web complexity and topology (Amundsen et al, 2009). Sympatric Arctic charr (Salvelinus alpinus (L.)) and brown trout (Salmo trutta L.) populations in Norwegian lakes provide ideal study systems to assess local variability in trophic niche and parasite assemblages. The higher temperature tolerance of brown trout (Elliott & Elliott, 2010) may to some extent facilitate the range expansion of this cool-water fish species into lake habitat niches made vacant by rising water temperatures

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