Competitive exclusion along climate gradients: energy efficiency influences the distribution of two salmonid fishes

Finstad, Anders G.; Forseth, Torbjørn; Jönsson, Bror; Bellier, Edwige; Hesthagen, Trygve; Jensen, Arne J.; Hessen, Dag O.; Foldvik, Anders

doi:10.1111/j.1365-2486.2010.02335.x

Cited by 103 publications

(121 citation statements)

References 48 publications

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“…Although temperature exerts pronounced effects on physical processes in poikilotherms (e.g., Wootton 1998), we found no implications suggesting that water temperature modified the effect of presence of Arctic char on brown trout food consumption. This corresponds to previous findings of only minor difference in thermal performance between Arctic char and brown trout (Larsson 2005;Forseth et al 2009;Elliott and Elliott 2010;Finstad et al 2011). Change in temperature per se is therefore not likely to alter the competitive outcome between Arctic char and brown trout directly through water temperature.…”

Section: Discussionsupporting

confidence: 89%

Direct and indirect climatic drivers of biotic interactions: ice-cover and carbon runoff shaping Arctic char Salvelinus alpinus and brown trout Salmo trutta competitive asymmetries

et al. 2011

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One of the major challenges in ecological climate change impact science is to untangle the climatic effects on biological interactions and indirect cascading effects through different ecosystems. Here, we test for direct and indirect climatic drivers on competitive impact of Arctic char (Salvelinus alpinus L.) on brown trout (Salmo trutta L.) along a climate gradient in central Scandinavia, spanning from coastal to high-alpine environments. As a measure of competitive impact, trout food consumption was measured using (137)Cs tracer methodology both during the ice-covered and ice-free periods, and contrasted between lakes with or without char coexistence along the climate gradient. Variation in food consumption between lakes was best described by a linear mixed effect model including a three-way interaction between the presence/absence of Arctic char, season and Secchi depth. The latter is proxy for terrestrial dissolved organic carbon run-off, strongly governed by climatic properties of the catchment. The presence of Arctic char had a negative impact on trout food consumption. However, this effect was stronger during ice-cover and in lakes receiving high carbon load from the catchment, whereas no effect of water temperature was evident. In conclusion, the length of the ice-covered period and the export of allochthonous material from the catchment are likely major, but contrasting, climatic drivers of the competitive interaction between two freshwater lake top predators. While future climatic scenarios predict shorter ice-cover duration, they also predict increased carbon run-off. The present study therefore emphasizes the complexity of cascading ecosystem effects in future effects of climate change on freshwater ecosystems.

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Section: Discussionsupporting

confidence: 89%

Direct and indirect climatic drivers of biotic interactions: ice-cover and carbon runoff shaping Arctic char Salvelinus alpinus and brown trout Salmo trutta competitive asymmetries

et al. 2011

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“…In winter, however, competitive dominance may shift as charr are better adapted than trout to feed on zoobenthos under cold and dark conditions (Hammar, 1998;Elliott, 2011;. Correspondingly, charr have also been observed outcompeting trout in cold, ultraoligotrophic lakes situated at high altitudes and latitudes Finstad et al, 2011). Nevertheless, our findings show that, at least in some subarctic lakes, charr and trout can coexist in the littoral zone in the summer.…”

Section: Interspecific Niche Segregation Between Charr and Troutmentioning

confidence: 57%

Seasonal and ontogenetic shifts in the diet of Arctic charr Salvelinus alpinus in a subarctic lake

Eloranta

Kahilainen

Jones

2010

Journal of Fish Biology

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Arctic charr (Salvelinus alpinus (L.)) is a cold-adapted salmonid fish with a wide circumpolar distribution. Due to its wide fundamental trophic niche (i.e. diet and habitat use), Arctic charr can be used to study energy flow as well as competitive and predator-prey interactions in subarctic lakes. The objective of this thesis was to evaluate how the trophic niche of Arctic charr in subarctic lakes is influenced by various biotic (e.g. intra-and interspecific resource competition and predation) and abiotic (e.g. seasonality and lake morphometry) factors. Stomach contents and stable isotope analyses indicated marked between-lake and between-individual differences in Arctic charr diet and habitat use. In Saanajärvi, Arctic charr relied mainly on littoral production regardless of season or individual size, probably due to high primary production and lack of sympatric fish species in the littoral zone. In contrast, Arctic charr showed a reduced littoral reliance when the littoral trophic niche was dominated by brown trout, and an increased prevalence of piscivorous foraging when coexisting with planktivorous whitefish and benthivorous grayling. The final results from a total of 17 subarctic lakes indicated that Arctic charr shifted from littoral to a more pelagic trophic niche with increasing lake area and fish species richness. The shift of Arctic charr to a more pelagic piscivorous niche in large lakes was evidently promoted by the existence of small, planktivorous prey fish species and increased interspecific resource competition and/or predation in the littoral zone. The results demonstrate that littoral and pelagic food-web compartments in subarctic lakes can be integrated by generalist Arctic charr, but the energy flow pathways supporting this top consumer can be strongly influenced by prevailing intra-and interspecific interactions as well as by the morphometric characteristics of the lakes. The findings highlight that a comprehensive view of food-web structures is fundamental for predicting the likely responses of fish communities and subarctic lake ecosystems to potential environmental changes. Keywords: Energy flow; individual specialization; lake morphometry; littoral production; resource competition; stable isotope analysis; trophic niche. LIST OF ORIGINAL PUBLICATIONSThe thesis is based on the following original articles, which will be referred to in the text by their Roman numerals I-IV. I did most of the planning for each study and contributed to field work in I, III and IV, and to laboratory analyses in all the studies. I was responsible for the data analysis and wrote the first draft of all the papers. All co-authors made a significant contribution to planning and preparation of the final papers. IV Eloranta A.P., Kahilainen K.K., Amundsen P.-A., Knudsen R., Harrod C. & Jones R.I. 2013. Lake size and fish species richness determine resource use by top consumers in subarctic lakes. Manuscript. INTRODUCTION Food webs in lakesLakes are complex ecosystems, whose functioning is tightly connecte...

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“…Finstad et al 2011;Helland et al 2011;Ulvan et al 2012). This will be exacerbated by the difficulties that winter specialists will face in dealing with the epilimnetic summer warming that will accompany shorter winters (Pörtner 2006;Somero 2010).…”

Section: Sensitivity To Climate Change Is Shaped By Winter Strategiesmentioning

confidence: 99%

The role of winter phenology in shaping the ecology of freshwater fish and their sensitivities to climate change

et al. 2012

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Thermal preference and performance provide the physiological frame within which fish species seek strategies to cope with the challenges raised by the low temperatures and low levels of oxygen and food that characterize winter. There are two common coping strategies: active utilization of winter conditions or simple toleration of winter conditions. The former is typical of winter specialist species with low preferred temperatures, and the latter is typical of species with higher preferred temperatures. Reproductive strategies are embodied in the phenology of spawning: the approach of winter conditions cues reproductive activity in many coldwater fish species, while the departure of winter conditions cues reproduction in many cool and warmwater fish species. This cuing system promotes temporal partitioning of the food resources available to young-of-year fish and thus supports high diversity in freshwater fish communities. If the zoogeographic distribution of a species covers a broad range of winter conditions, local populations may exhibit differences in their winter survival strategies that reflect adaptation to local conditions. Extreme winter specialists are found in shallow eutrophic lakes where long periods of ice cover cause winter oxygen levels to drop to levels that are lethal to many fish. The fish communities of these lakes are simple and composed of species that exhibit specialized adaptations for extended tolerance of very low temperatures and oxygen levels. Zoogeographic boundaries for some species may be positioned at points on the landscape where the severity of winter overwhelms the species' repertoire of winter survival strategies. Freshwater fish communities are vulnerable to many of the shifts in environmental conditions expected with climate change. Temperate and northern communities are particularly vulnerable since the repertoires of physiological and behavioural strategies that characterize many of their members have been shaped by the adverse environmental conditions (e.g. cool short summers, long cold winters) that climate change is expected to mitigate. The responses of these strategies to the rapid relaxation of the adversities that shaped them will play a significant role in the overall responses of these fish populations and their communities to climate change.

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Competitive exclusion along climate gradients: energy efficiency influences the distribution of two salmonid fishes

Cited by 103 publications

References 48 publications

Direct and indirect climatic drivers of biotic interactions: ice-cover and carbon runoff shaping Arctic char Salvelinus alpinus and brown trout Salmo trutta competitive asymmetries

Direct and indirect climatic drivers of biotic interactions: ice-cover and carbon runoff shaping Arctic char Salvelinus alpinus and brown trout Salmo trutta competitive asymmetries

Seasonal and ontogenetic shifts in the diet of Arctic charr Salvelinus alpinus in a subarctic lake

The role of winter phenology in shaping the ecology of freshwater fish and their sensitivities to climate change

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