Citation | Scrivener, JC and Tripp, DB. 1998. Changes in spawning gravel characteristics after forest harvesting in Queen Charlotte Islands and Carnation Creek Watersheds and the apparent impacts on incubating salmonid eggs. In: Hogan, D.L., P.J. Tschaplinski, and S. Chatwin (Editors). B.C. Min. For., Res. Br., Victoria, B.C. Land Manage. Handb. No. 41. |
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Organization | FLNRO |
URL | https://www.for.gov.bc.ca/hfd/pubs/docs/Lmh/Lmh41.htm |
Abstract/Description or Keywords | In earlier presentations, results were outlined and discussed concerning landslide prediction, channel morphology changes, channel scour and fill processes, and fine sediment movements in coastal streams of British Columbia. Forest harvesting impacts on these processes were also demonstrated. These processes are known to affect the composition of streambed gravels and their incubating salmon eggs in Oregon (Hall et al. 1987), Washington (Cederholm and Reid 1987), and Alaska (McNeil and Ahnell 1964). Sediment composition of the streambed influences two critical properties of salmon incubation gravels: permeability and porosity. Permeability affects delivery and removal rates of oxygen, carbon dioxide, and other metabolites (Wickett 1958; McNeil and Ahnell 1964), which influence fish embryo survival (Alderdice et al. 1958; Rombough 1983). Small pore size can restrict intergravel movement of alevins and create a barrier to fry emergence (Dill and Northcote 1970; Scrivener and Brownlee 1989). Other studies also show that unseasonal surges of fine sediments can reduce the number of benthic organisms inhabiting a stream (Hall et al. 1987) and ultimately affect fish food availability and fish growth after emergence (Phillips 1971). Mass movements of gravel and sand into channels not only affected the composition of spawning gravels, but also their stability. Stability declined for channel structures, channel topography, and the riparian zone when mass wasting processes increased sediment loading of streams on the Queen Charlotte Islands (Hogan 1986; Hogan and Schwab 1991). Streambed scouring also increased (Tripp and Poulin 1986), with obvious consequences for the survival of incubating salmonid embryos. |
Information Type | Article |
Regional Watershed | Coast Region |
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Project status | complete |
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