Estimation of forest harvesting-induced stream temperature changes and bioenergetic consequences for cutthroat trout in a coastal stream in British Columbia, Canada

• Published in: Aquatic sciences 2012-07, Vol.74 (3), p.427-441
• Main Authors: Leach, J. A., Moore, R. D., Hinch, S. G., Gomi, T.
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal populations; Animal, plant and microbial ecology; Bioenergetics; Biological and medical sciences; Biomedical and Life Sciences; Clearcutting; Coastal streams; Creeks; Creeks & streams; Ecology; Environmental impact; Food supply; Forestry; Freshwater; Freshwater & Marine Ecology; Fundamental and applied biological sciences. Psychology; General aspects; General forest ecology; Generalities. Production, biomass. Quality of wood and forest products. General forest ecology; Growth rate; Habitats; Life Sciences; Marine & Freshwater Sciences; Oceanography; Oncorhynchus clarki clarki; Research Article; Salmon; Statistical models; Summer; Synecology; Timber industry; Trout; Water temperature
• ISSN: 1015-1621; 1420-9055
• DOI: 10.1007/s00027-011-0238-z

Data from a paired-catchment study in south coastal British Columbia, Canada, were analyzed to assess the thermal effects of clearcut harvesting with no riparian buffer on a fish-bearing headwater stream. The approach used time series of daily mean water temperatures for East Creek (control) and A Creek (treatment), both before and after harvest. Statistical models were developed to predict (a) what the temperatures would have been in the post-harvest period had harvesting not occurred, and (b) what temperatures would have been in the pre-harvest period had harvesting already occurred. The Wisconsin Bioenergetics Model was used to simulate growth of coastal cutthroat trout ( Oncorhynchus clarki clarki ) for the first year following fry emergence using the predicted and observed stream temperatures to generate scenarios representing with-harvest and no-harvest thermal regimes. A Monte Carlo approach was used to quantify the effects of uncertainty associated with the regression models on predicted stream temperature and trout growth. Summer daily mean temperatures in the with-harvest scenario were up to higher than those for the no-harvest scenario. Harvesting-induced warming reduced growth rates during summer, but increased growth rates during autumn and spring. In the with-harvest scenario, trout were 0.2–2.0 g (absolute weight) smaller throughout the winter period than in the no-harvest scenario. However, the bioenergetic simulations suggest that trout growth may be more sensitive to potential changes in food supply following harvesting than to direct impacts of stream temperature changes.