Spatial distribution of thermal refuges analysed in relation to riverscape hydromorphology using airborne thermal infrared imagery

Water temperature governs the distribution and behaviour of fish. Riverine salmonids use discrete cold water patches, termed thermal refuges, when stream temperature exceeds their thermal tolerances. Currently, little is known about the mechanisms driving the spatial distribution of thermal refuges,...

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Bibliographic Details
Published in:Remote sensing of environment 2015-04, Vol.160, p.43-55
Main Authors: Dugdale, Stephen J., Bergeron, Normand E., St-Hilaire, André
Format: Article
Language:English
Subjects:
Atlantic salmon
Density
Groundwater
Hydromorphology
Landscapes
Refuges
River temperature
Rivers
Riverscape
Salmonid
Salmonidae
Salmonids
Spatial distribution
Streams
Thermal infrared imagery
Thermal refuge
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Summary:Water temperature governs the distribution and behaviour of fish. Riverine salmonids use discrete cold water patches, termed thermal refuges, when stream temperature exceeds their thermal tolerances. Currently, little is known about the mechanisms driving the spatial distribution of thermal refuges, particularly at large scales. Given the threat posed by climate warming to salmon populations in Europe and North America, thermal refuges are increasingly important for salmonids during summer. In this study, we used airborne thermal infrared (TIR) imagery to characterise the spatial distribution of thermal refuges from ~700km of rivers in an eastern Canada salmon watershed. Thermal refuges were classified into a range of categories, and those identified as being driven by groundwater processes were observed to be both the most abundant and most spatially variable. Spatial analysis was used to assemble a range of landscape metrics that were tested for associations with the spatial distribution of groundwater-driven refuges. Associations between landscape metrics and the individual occurrence of thermal refuges were assessed using Jacobs' selectivity index. Results showed that the occurrence of groundwater thermal refuges was significantly associated with high values of channel curvature and close proximity of incoming tributary valleys (X2p
ISSN:0034-4257
1879-0704
DOI:10.1016/j.rse.2014.12.021