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The magnitude and significance of sediment oxygen demand in gravel spawning beds for the incubation of salmonid embryos

The magnitude and significance of sediment oxygen demand in gravel spawning beds for the incubation of salmonid embryos
The magnitude and significance of sediment oxygen demand in gravel spawning beds for the incubation of salmonid embryos
Globally, salmon populations are under pressure and in those where numbers are severely depleted, density independent factors such as the accumulation of fine sediment and subsequent mortality of incubating embryos are critical factors in their conservation. Although progress has been made in identifying the processes by which fine sediment can lead to embryo mortality, this has focussed on the physical blockage of gravel pores. This paper presents new knowledge on the role of sediment-associated organic matter in controlling the supply of dissolved oxygen to incubating salmon embryos within gravel river beds. We report a new approach to the measurement of sediment oxygen demand (SOD) from interstitial sediments accumulated within salmon redds and demonstrate this across a range of salmon river types. The effects of varying SOD on dissolved oxygen supply to incubating salmon embryos are quantified for the first time, using the physically based Sediment Intrusion and Dissolved Oxygen (SIDO-UK) model. The results reveal the importance of the mass of accumulating sediment and sediment consumption rates (sediment oxygen consumption [SOC]), which constitute the overall SOD over time for a particular sediment sample. Higher SOC result in reductions in dissolved oxygen that are deleterious to salmonids; however, these are subordinate to the effects of sediment mass. Larger quantities of sediment accumulating within the redd not only create a higher SOD but also physically block the pores within the gravels, leading to a more drastic decline in oxygen supply through the combined effects of reduced seepage velocity and dissolved oxygen concentration. We seek to generalize the results by exploring the influence of catchment characteristics on field measures of SOD and SOC. This work makes a significant and novel contribution to improving our fundamental understanding of hyporheic processes within salmonid spawning gravels whilst providing resource managers with evidence of the deleterious effects of sediment-associated organic matter on salmon recruitment.
1535-1459
1642-1654
Sear, D.A.
ccd892ab-a93d-4073-a11c-b8bca42ecfd3
Pattison, I.
dd3b13b4-1475-4c1a-9e6f-b28fdb252766
Collins, A.L.
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Smallman, D.J.
4f8bde56-89fd-4ac1-aab5-39976a6c96b8
Jones, J.I
a7509386-7b2d-4176-9292-3588f8218e5c
Naden, P.S.
1a82ce0f-6536-421f-9a04-53cf5f8c627b
Sear, D.A.
ccd892ab-a93d-4073-a11c-b8bca42ecfd3
Pattison, I.
dd3b13b4-1475-4c1a-9e6f-b28fdb252766
Collins, A.L.
b57bb1d2-6440-4c15-a4e9-5f3492f6121f
Smallman, D.J.
4f8bde56-89fd-4ac1-aab5-39976a6c96b8
Jones, J.I
a7509386-7b2d-4176-9292-3588f8218e5c
Naden, P.S.
1a82ce0f-6536-421f-9a04-53cf5f8c627b

Sear, D.A., Pattison, I., Collins, A.L., Smallman, D.J., Jones, J.I and Naden, P.S. (2017) The magnitude and significance of sediment oxygen demand in gravel spawning beds for the incubation of salmonid embryos. River Research and Applications, 33 (10), 1642-1654. (doi:10.1002/rra.3212).

Record type: Article

Abstract

Globally, salmon populations are under pressure and in those where numbers are severely depleted, density independent factors such as the accumulation of fine sediment and subsequent mortality of incubating embryos are critical factors in their conservation. Although progress has been made in identifying the processes by which fine sediment can lead to embryo mortality, this has focussed on the physical blockage of gravel pores. This paper presents new knowledge on the role of sediment-associated organic matter in controlling the supply of dissolved oxygen to incubating salmon embryos within gravel river beds. We report a new approach to the measurement of sediment oxygen demand (SOD) from interstitial sediments accumulated within salmon redds and demonstrate this across a range of salmon river types. The effects of varying SOD on dissolved oxygen supply to incubating salmon embryos are quantified for the first time, using the physically based Sediment Intrusion and Dissolved Oxygen (SIDO-UK) model. The results reveal the importance of the mass of accumulating sediment and sediment consumption rates (sediment oxygen consumption [SOC]), which constitute the overall SOD over time for a particular sediment sample. Higher SOC result in reductions in dissolved oxygen that are deleterious to salmonids; however, these are subordinate to the effects of sediment mass. Larger quantities of sediment accumulating within the redd not only create a higher SOD but also physically block the pores within the gravels, leading to a more drastic decline in oxygen supply through the combined effects of reduced seepage velocity and dissolved oxygen concentration. We seek to generalize the results by exploring the influence of catchment characteristics on field measures of SOD and SOC. This work makes a significant and novel contribution to improving our fundamental understanding of hyporheic processes within salmonid spawning gravels whilst providing resource managers with evidence of the deleterious effects of sediment-associated organic matter on salmon recruitment.

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s1-ln26953998-25538549-1939656818Hwf-298729708IdV64649230426953998PDF_HI0001 - Accepted Manuscript
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Accepted/In Press date: 12 August 2017
e-pub ahead of print date: 10 October 2017
Published date: December 2017

Identifiers

Local EPrints ID: 415335
URI: http://eprints.soton.ac.uk/id/eprint/415335
ISSN: 1535-1459
PURE UUID: 68a01c96-91c2-495e-9e88-bcd105199ad9
ORCID for D.A. Sear: ORCID iD orcid.org/0000-0003-0191-6179

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Date deposited: 07 Nov 2017 17:30
Last modified: 07 Oct 2020 06:26

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