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Linking landscape characteristics, streamwater acidity and brown trout (Salmo trutta) distributions in a boreal stream network

Buffam, Ishi (2007). Linking landscape characteristics, streamwater acidity and brown trout (Salmo trutta) distributions in a boreal stream network. Diss. (sammanfattning/summary) Umeå : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2007:33
ISBN 978-91-576-7332-9
[Doctoral thesis]

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Perturbations of stream ecosystems are often mediated by the terrestrial watershed, making the understanding of linkages between watersheds and streams essential. In this thesis I explore the connections between landscape characteristics, streamwater acidity and brown trout (Salmo trutta) distributions in Krycklan, a 67 km2 boreal stream network in northern Sweden. The study focuses on hydrochemical changes during the snowmelt-driven spring flood, a period of episodic acidity which is thought to place a restraint on acid-sensitive biota such as brown trout. pH ranged from 4.5-7.0 at different stream sites during winter baseflow, and declined by 0-2 pH units during spring flood. The magnitude of the pH drop at a given site was in large part controlled by changes in acid neutralizing capacity (ANC) and in natural organic acids associated with dissolved organic carbon (DOC). pH, ANC and DOC were all correlated with landscape characteristics such as proportion of peat wetlands, and stream hydrochemical response during spring flood could be explained by altered hydrological flowpaths through the catchment. The impact of acidity on brown trout distributions within the stream network was evaluated and compared to the apparent influence of other site and catchment-scale environmental factors. In situ bioassays demonstrated a strong relationship between spring flood pH and juvenile brown trout mortality, with a toxicity threshold at pH 4.8-5.4. In field surveys brown trout were not found at any sites which had pH <5.0 during spring flood, and were rare at sites which had pH <5.5 during spring flood, suggesting limitation by acidity for some streams. However, over the whole of the Krycklan stream network brown trout were more consistently associated with alluvial sediment deposits than with high pH or low inorganic aluminum concentrations. Acidity thus apparently influences trout distributions by setting a maximum potential distribution; within that potential distribution, actual dispersal is influenced by other factors, notably presence of physical substrate suitable for feeding and spawning habitat. Fulfilling chemical thresholds is therefore necessary but not sufficient for sustaining brown trout populations. In the context of environmental monitoring or stream restoration, consideration of physical habitat together with chemical conditions is advised.

Authors/Creators:Buffam, Ishi
Title:Linking landscape characteristics, streamwater acidity and brown trout (Salmo trutta) distributions in a boreal stream network
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :March 2007
Number of Pages:37
ALLAppendix I. Buffam, I., H. Laudon, J. Temnerud, C.-M. Mörth, and K. Bishop. 2007. Landscape-scale variability of acidity and dissolved organic carbon during spring flood in a boreal stream network, Journal of Geophysical Research 112: G01022, doi:10.1029/2006JG000218. Appendix II. Buffam, I., H. Laudon, J. Seibert, C.-M. Mörth and K. Bishop. Spatial heterogeneity of the spring flood acid pulse in a boreal stream network. Submitted manuscript. Appendix III. Serrano, I., I. Buffam, D. Palm, E. Brännäs and H. Laudon. Thresholds for survival of brown trout (Salmo trutta L.) embryos and juveniles during the spring flood acid pulse in DOC-rich streams. Submitted manuscript. Appendix IV. Buffam, I., I. Serrano, K. Bishop and H. Laudon. Associations of stream water acidity and other environmental factors with the distribution of Brown Trout (Salmo trutta) within a mesoscale boreal stream network. Manuscript.
Place of Publication:Umeå
ISBN for printed version:978-91-576-7332-9
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:salmo trutta, trout, rivers, ph, acidity, landscape, spring, flooding, population distribution, sweden
Keywords:boreal streams, spatial variability, mesoscale catchments, snowmelt, episodic acidity, pH thresholds, brown trout
Permanent URL:
ID Code:1361
Department:(S) > Dept. of Forest Ecology and Management
Deposited By: Ishi Buffam
Deposited On:12 Mar 2007 00:00
Metadata Last Modified:02 Dec 2014 10:11

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