Can fish introductions alter nutrient cycles in previously fishless high-latitude lakes?

TY - JOUR

T1 - Can fish introductions alter nutrient cycles in previously fishless high-latitude lakes?

AU - Milardi, M.

AU - Lappalainen, J.

AU - McGowan, S.

AU - Weckström, J.

N1 - Funding details: Academy of Finland Funding details: Maj ja Tor Nesslingin Säätiö Funding text 1: The authors would like to thank Daniel Schindler for his help with the bioenergetic and nutrient modeling. We would also like to thank Petri Ekholm and Jussi Vuorenmaa at the Finnish Environmental Centre for their help with catchment area load and for providing the P deposition rates, respectively. We would also like to acknowledge the V?rri? Research Station personnel for helping with field sampling, the Finnish Meteorological Institute for providing N atmospheric deposition data, Mari Kovero for providing additional information on diatoms and three anonymous reviewers for their useful comments to the paper. This project was started by Anne Liljendahl and funded by the Maj and Tor Nessling Foundation and the Academy of Finland (FICCA-program, Cliche Consortium).

PY - 2017

Y1 - 2017

N2 - The additional input and enhanced cycling of nutrients derived from introduced fish can be a significant factor altering nutrient dynamics in oligotrophic lakes. To test this, we used a bioenergetic model to estimate the fish-derived nutrient load in Lake Kuutsjärvi, a historically fishless boreal lake of northern Fennoscandia. The lake was selected because of the absence of other anthropogenic stressors, a known stocking history and the possibility of quantitatively estimating the size-structure and biomass of the fish population through a mass removal. Subsequently, we used a mass balance model to compare fish-derived nutrients with other nutrient load pathways. For comparison over longer timescales, we used lake sediment records of diatoms, chlorophyll and carotenoid pigments, C:N ratios and stable isotopes to infer whether fish introduction produced detectable changes in the lake trophic state, primary productivity and terrestrial nutrient input. Based on the nutrient mass balance model, we found that phosphorus and nitrogen derived from fish were 0.46% and 2.2%, respectively, of the total load to the lake, suggesting that fish introduction could not markedly increase the nutrient load. Accordingly, the palaeolimnological record indicated little increase in primary production but instead a shift from pelagic to benthic production after fish introduction.

AB - The additional input and enhanced cycling of nutrients derived from introduced fish can be a significant factor altering nutrient dynamics in oligotrophic lakes. To test this, we used a bioenergetic model to estimate the fish-derived nutrient load in Lake Kuutsjärvi, a historically fishless boreal lake of northern Fennoscandia. The lake was selected because of the absence of other anthropogenic stressors, a known stocking history and the possibility of quantitatively estimating the size-structure and biomass of the fish population through a mass removal. Subsequently, we used a mass balance model to compare fish-derived nutrients with other nutrient load pathways. For comparison over longer timescales, we used lake sediment records of diatoms, chlorophyll and carotenoid pigments, C:N ratios and stable isotopes to infer whether fish introduction produced detectable changes in the lake trophic state, primary productivity and terrestrial nutrient input. Based on the nutrient mass balance model, we found that phosphorus and nitrogen derived from fish were 0.46% and 2.2%, respectively, of the total load to the lake, suggesting that fish introduction could not markedly increase the nutrient load. Accordingly, the palaeolimnological record indicated little increase in primary production but instead a shift from pelagic to benthic production after fish introduction.

KW - Bioenergetic model

KW - Chlorophyll and carotenoid pigments

KW - Diatoms

KW - Fish introduction

KW - Nutrient cycle

KW - Stable isotopes

U2 - 10.4081/jlimnol.2016.1364

DO - 10.4081/jlimnol.2016.1364

M3 - Article

SN - 1129-5767

VL - 76

SP - 1

EP - 14

JO - Journal of Limnology

JF - Journal of Limnology

IS - 1

ER -