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Copepod faecal pellet transfer through the meso- and bathypelagic layers in the Southern Ocean in spring

Copepod faecal pellet transfer through the meso- and bathypelagic layers in the Southern Ocean in spring
Copepod faecal pellet transfer through the meso- and bathypelagic layers in the Southern Ocean in spring
The faecal pellets (FPs) of zooplankton can be important vehicles for the transfer of particulate organic carbon (POC) to the deep ocean, often making large contributions to carbon sequestration. However, the routes by which these FPs reach the deep ocean have yet to be fully resolved. We address this by comparing estimates of copepod FP production to measurements of copepod FP size, shape, and number in the upper mesopelagic (175–205 m) using Marine Snow Catchers, and in the bathypelagic using sediment traps (1500–2000 m). The study is focussed on the Scotia Sea, which contains some of the most productive regions in the Southern Ocean, where epipelagic FP production is likely to be high. We found that, although the size distribution of the copepod community suggests that high numbers of small FPs are produced in the epipelagic, small FPs are rare in the deeper layers, implying that they are not transferred efficiently to depth. Consequently, small FPs make only a minor contribution to FP fluxes in the meso- and bathypelagic, particularly in terms of carbon. The dominant FPs in the upper mesopelagic were cylindrical and elliptical, while ovoid FPs were dominant in the bathypelagic. The change in FP morphology, as well as size distribution, points to the repacking of surface FPs in the mesopelagic and in situ production in the lower meso- and bathypelagic, which may be augmented by inputs of FPs via zooplankton vertical migrations. The flux of carbon to the deeper layers within the Southern Ocean is therefore strongly modulated by meso- and bathypelagic zooplankton, meaning that the community structure in these zones has a major impact on the efficiency of FP transfer to depth.
1726-4170
1511-1525
Belcher, Anna, Christine
604905f0-adc0-4503-b8b3-d5b5f9960771
Manno, Clara
c49cdab0-866e-44fe-b504-e3c9a9924d86
Ward, Peter
714ec347-7b8d-4c5c-b5bd-5376a6f644ae
Henson, Stephanie
d6532e17-a65b-4d7b-9ee3-755ecb565c19
Sanders, Richard
02c163c1-8f5e-49ad-857c-d28f7da66c65
Tarling, Geraint Andrew
41198ea9-1957-4ab4-802d-c063ec337056
Belcher, Anna, Christine
604905f0-adc0-4503-b8b3-d5b5f9960771
Manno, Clara
c49cdab0-866e-44fe-b504-e3c9a9924d86
Ward, Peter
714ec347-7b8d-4c5c-b5bd-5376a6f644ae
Henson, Stephanie
d6532e17-a65b-4d7b-9ee3-755ecb565c19
Sanders, Richard
02c163c1-8f5e-49ad-857c-d28f7da66c65
Tarling, Geraint Andrew
41198ea9-1957-4ab4-802d-c063ec337056

Belcher, Anna, Christine, Manno, Clara, Ward, Peter, Henson, Stephanie, Sanders, Richard and Tarling, Geraint Andrew (2017) Copepod faecal pellet transfer through the meso- and bathypelagic layers in the Southern Ocean in spring. Biogeosciences, 14 (6), 1511-1525. (doi:10.5194/bg-14-1511-2017).

Record type: Article

Abstract

The faecal pellets (FPs) of zooplankton can be important vehicles for the transfer of particulate organic carbon (POC) to the deep ocean, often making large contributions to carbon sequestration. However, the routes by which these FPs reach the deep ocean have yet to be fully resolved. We address this by comparing estimates of copepod FP production to measurements of copepod FP size, shape, and number in the upper mesopelagic (175–205 m) using Marine Snow Catchers, and in the bathypelagic using sediment traps (1500–2000 m). The study is focussed on the Scotia Sea, which contains some of the most productive regions in the Southern Ocean, where epipelagic FP production is likely to be high. We found that, although the size distribution of the copepod community suggests that high numbers of small FPs are produced in the epipelagic, small FPs are rare in the deeper layers, implying that they are not transferred efficiently to depth. Consequently, small FPs make only a minor contribution to FP fluxes in the meso- and bathypelagic, particularly in terms of carbon. The dominant FPs in the upper mesopelagic were cylindrical and elliptical, while ovoid FPs were dominant in the bathypelagic. The change in FP morphology, as well as size distribution, points to the repacking of surface FPs in the mesopelagic and in situ production in the lower meso- and bathypelagic, which may be augmented by inputs of FPs via zooplankton vertical migrations. The flux of carbon to the deeper layers within the Southern Ocean is therefore strongly modulated by meso- and bathypelagic zooplankton, meaning that the community structure in these zones has a major impact on the efficiency of FP transfer to depth.

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Accepted/In Press date: 12 March 2017
e-pub ahead of print date: 24 March 2017
Organisations: Ocean and Earth Science, Ocean Biochemistry & Ecosystems, Marine Biogeochemistry, National Oceanography Centre

Identifiers

Local EPrints ID: 406976
URI: https://eprints.soton.ac.uk/id/eprint/406976
ISSN: 1726-4170
PURE UUID: 85987a3f-0ee9-43ba-b76a-84d283a6be14

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Date deposited: 29 Mar 2017 01:05
Last modified: 09 Dec 2019 18:56

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Contributors

Author: Anna, Christine Belcher
Author: Clara Manno
Author: Peter Ward
Author: Richard Sanders
Author: Geraint Andrew Tarling

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