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The significance and mechanics of fine-sediment infiltration and accumulation in gravel spawning beds

The significance and mechanics of fine-sediment infiltration and accumulation in gravel spawning beds
The significance and mechanics of fine-sediment infiltration and accumulation in gravel spawning beds
The accumulation of fine sediment within salmonid redds is generally considered to be one of the main factors contributing to a reduction in embryo survival (Chapman 1988; Reiser 1998; Greig et al. 2005a). As a result, research activity has sought to understand the processes by which fine sediment degrades the incubation environment within a redd (Carling 1984; Lisle 1989; Diplas and Parker 1992; Acornley and Sear 1999). From the outset, we differentiate between the process by which fine sediment moves into the salmonid redd termed infiltration and the summation of this process over time that is accumulation. An additional term often used in the context of fine sediment impacts on salmonids is sedimentation. This is taken to refer to the development of a layer of fine sediment over the surface of the spawning gravels. We argue here that it is the accumulation of fine sediment within the redd and/ or the sedimentation of spawning gravels that result in deleterious impacts on incubating and emerging salmonids. The distinction between the two different survival mechanisms— incubation of the embryos within the egg and emergence of the alevins once hatched—is relevant to the type of infiltration process. Generally, one can hypothesize that the finer silt and clay fraction influences thesurvival of the incubating embryos, whereas the coarser sand-sized fraction affects theemergence of alevins. Thus, one might envisageconditions where there are low levels ofvery fine sediment within a spawning gravelbut poor overall survival as a result of entombment.This chapter deals predominantlywith incubation survival. In this chapter, we explain the theoretical basis for the relationship between fine-sediment accumulation in the redd, sedimentation of spawning beds, and the incubation of salmonid embryos. We then consider the processes of fine sediment transport over the riverbed and the nature of the interaction between it and the gravel bed. Empirical and laboratory measurements of fine-sediment accumulation are reviewed to determine the range of natural variability in fine-sediment accumulation within redds and sedimentation of spawning beds between and within river systems. Finally, we review the methods and techniques for quantifying and modeling fine-sediment accumulation.
spawning, gravels, salmon, fine sediment, accumulation
1934874035
65
149-174
American Fisheries Society
Sear, David A.
ccd892ab-a93d-4073-a11c-b8bca42ecfd3
Frostick, Lynn B.
22f4c3ab-9e18-4480-9e9a-e405d90008a3
Rollinson, Gavin
4b1a0613-cd1f-4555-b978-e4cdd8de79a2
Lisle, Thomas E.
f474bad0-69d5-459f-981b-f1af2efc785e
Sear, David A.
DeVries, Paul
Sear, David A.
ccd892ab-a93d-4073-a11c-b8bca42ecfd3
Frostick, Lynn B.
22f4c3ab-9e18-4480-9e9a-e405d90008a3
Rollinson, Gavin
4b1a0613-cd1f-4555-b978-e4cdd8de79a2
Lisle, Thomas E.
f474bad0-69d5-459f-981b-f1af2efc785e
Sear, David A.
DeVries, Paul

Sear, David A., Frostick, Lynn B., Rollinson, Gavin and Lisle, Thomas E. (2008) The significance and mechanics of fine-sediment infiltration and accumulation in gravel spawning beds. In, Sear, David A. and DeVries, Paul (eds.) Salmonid Spawning Habitat in Rivers: Physical Controls, Biological Responses, and Approaches to Remediation. (Symposium, 65) Bethesda, USA. American Fisheries Society, pp. 149-174.

Record type: Book Section

Abstract

The accumulation of fine sediment within salmonid redds is generally considered to be one of the main factors contributing to a reduction in embryo survival (Chapman 1988; Reiser 1998; Greig et al. 2005a). As a result, research activity has sought to understand the processes by which fine sediment degrades the incubation environment within a redd (Carling 1984; Lisle 1989; Diplas and Parker 1992; Acornley and Sear 1999). From the outset, we differentiate between the process by which fine sediment moves into the salmonid redd termed infiltration and the summation of this process over time that is accumulation. An additional term often used in the context of fine sediment impacts on salmonids is sedimentation. This is taken to refer to the development of a layer of fine sediment over the surface of the spawning gravels. We argue here that it is the accumulation of fine sediment within the redd and/ or the sedimentation of spawning gravels that result in deleterious impacts on incubating and emerging salmonids. The distinction between the two different survival mechanisms— incubation of the embryos within the egg and emergence of the alevins once hatched—is relevant to the type of infiltration process. Generally, one can hypothesize that the finer silt and clay fraction influences thesurvival of the incubating embryos, whereas the coarser sand-sized fraction affects theemergence of alevins. Thus, one might envisageconditions where there are low levels ofvery fine sediment within a spawning gravelbut poor overall survival as a result of entombment.This chapter deals predominantlywith incubation survival. In this chapter, we explain the theoretical basis for the relationship between fine-sediment accumulation in the redd, sedimentation of spawning beds, and the incubation of salmonid embryos. We then consider the processes of fine sediment transport over the riverbed and the nature of the interaction between it and the gravel bed. Empirical and laboratory measurements of fine-sediment accumulation are reviewed to determine the range of natural variability in fine-sediment accumulation within redds and sedimentation of spawning beds between and within river systems. Finally, we review the methods and techniques for quantifying and modeling fine-sediment accumulation.

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More information

Published date: October 2008
Keywords: spawning, gravels, salmon, fine sediment, accumulation

Identifiers

Local EPrints ID: 66703
URI: http://eprints.soton.ac.uk/id/eprint/66703
ISBN: 1934874035
PURE UUID: f315b4ea-6e2a-49bc-a83d-df19c2820656
ORCID for David A. Sear: ORCID iD orcid.org/0000-0003-0191-6179

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Date deposited: 13 Jul 2009
Last modified: 11 Dec 2021 03:02

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Contributors

Author: David A. Sear ORCID iD
Author: Lynn B. Frostick
Author: Gavin Rollinson
Author: Thomas E. Lisle
Editor: David A. Sear
Editor: Paul DeVries

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