Differential effects of freshwater browning across fish species: consequences for individual- to community-level fish traits in north temperate lakes

Abstract

The browning of freshwater ecosystems is increasingly evident in temperate and northern regions, with widespread ramifications for lake physics, chemistry, and biology. Contrasting results on how freshwater browning may impact fish have been reported, but there has been no comprehensive examination of how browning may cause cascading effects on individual- to population- to community-level traits of freshwater fishes. We addressed this knowledge gap by summarizing the existing literature and conducting a series of original analyses to: (i) explore the effects of a brown water gradient on populations of eight economically important species of fish across 871 lakes; and (ii) examine how a brown water gradient may influence community trait compositions across 303 lakes. From our literature synthesis, we found that fish growth is often negatively associated with browner waters, despite browning generally showing no effect on fish foraging. We also demonstrated that browner waters had greater abundances of northern pike (Esox lucius) and walleye (Sander vitreus), but lower numbers of lake trout (Salvelinus namaycush), yellow perch (Perca flavescens), largemouth bass (Micropterus salmoides), smallmouth bass (M. dolomieu), and lake whitefish (Coregonus clupeaformis). Moreover, we showed that fish communities were significantly more likely to contain species with larger eyes in browner lakes. Lastly, we examined relationships between various metrics of browning (i.e. dissolved organic carbon, Secchi transparency, water colour) and present a framework for how the effects of freshwater browning on fish may scale from individuals to populations to communities.

Keywords

freshwater browning; fish; dissolved organic carbon; Secchi transparency; water colour; individual-level traits; population-level traits; community-level traits

Published in

Biological Reviews
2025
Publisher: WILEY

SLU Authors

• Andersson, Matilda

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

• Van Dorst, Renee

  • Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences
    
  • Norwegian Institute for Nature Research (NINA)

• Huss, Magnus

  • Department of Aquatic Resources (SLU Aqua), Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Fish and Aquacultural Science

Publication identifier

• DOI: https://doi.org/10.1111/brv.70074

Permanent link to this page (URI)

https://res.slu.se/id/publ/143890