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Processing of 13C-labelled diatoms by a bathyal community at sub-zero temperatures

Processing of 13C-labelled diatoms by a bathyal community at sub-zero temperatures
Processing of 13C-labelled diatoms by a bathyal community at sub-zero temperatures
ABSTRACT: The carbon (C) budget in bathyal permanently cold sediments was assessed by means of a pulse-chase experiment in the deep Faroe-Shetland Channel (FSC). The food pulse was simulated by adding 500 mg C m–2 of the 13C-labelled marine diatom Chaetoceros radicans to sediment cores retrieved from 1080 m in the FSC. The fate of the tracer was followed over 6 d into the dissolved inorganic C pool (DI13C) as well as the bacterial and faunal (metazoan macrofauna and meiofaunal-sized nematode) biomass. After 3 d of incubation, 14.9 and 0.81 mg C m–2 of the algal C was recovered from bacterial and faunal biomass, respectively, while only 3.8 mg C m–2 was respired. Respiration was the dominant tracer pathway after 6 d of incubation (44 mg C m–2). Bacterial tracer uptake did not increase significantly between Days 3 and 6. The tracer recovered from metazoan fauna at the end of the experiment constituted 3.2% (2 mg C m–2) of the total processed C, with meiofauna contributing only ~1% to the total metazoan uptake. The bacterial response was characterised by varying bacterial growth efficiency (BGE). During the first half of the experiment, low respiration and high bacterial uptake of the 13C-labelled substrate resulted in particularly high BGE, while the opposite was observed in the second half of the incubation. We postulate that the high BGE at the start of the experiment represents the absorption and metabolism of the readily available labile components of the added organic matter (OM). The decrease in BGE possibly corresponds to the initiation of the energetically costly hydrolytic processes necessary for the consumption of more recalcitrant OM.
Stable isotope labelling, Benthos, Bacterial growth efficiency, Bathyal sediments, Faroe-Shetland Channel, ?13C, PLFA
39-50
Gontikaki, E.
b33956ff-381b-401b-8c78-2c802eef3cae
Mayor, D.J.
461ddc80-a25d-45b5-873f-9cbf4aa93828
Thornton, B.
ae7b338f-3326-4db1-b6d5-de09a960287b
Black, K.
028f2582-68bf-40be-8431-0f3004db3898
Witte, U.
11050d87-974b-4596-8545-68dcc675704e
Gontikaki, E.
b33956ff-381b-401b-8c78-2c802eef3cae
Mayor, D.J.
461ddc80-a25d-45b5-873f-9cbf4aa93828
Thornton, B.
ae7b338f-3326-4db1-b6d5-de09a960287b
Black, K.
028f2582-68bf-40be-8431-0f3004db3898
Witte, U.
11050d87-974b-4596-8545-68dcc675704e

Gontikaki, E., Mayor, D.J., Thornton, B., Black, K. and Witte, U. (2011) Processing of 13C-labelled diatoms by a bathyal community at sub-zero temperatures. Marine Ecology Progress Series, 421, 39-50. (doi:10.3354/meps08892).

Record type: Article

Abstract

ABSTRACT: The carbon (C) budget in bathyal permanently cold sediments was assessed by means of a pulse-chase experiment in the deep Faroe-Shetland Channel (FSC). The food pulse was simulated by adding 500 mg C m–2 of the 13C-labelled marine diatom Chaetoceros radicans to sediment cores retrieved from 1080 m in the FSC. The fate of the tracer was followed over 6 d into the dissolved inorganic C pool (DI13C) as well as the bacterial and faunal (metazoan macrofauna and meiofaunal-sized nematode) biomass. After 3 d of incubation, 14.9 and 0.81 mg C m–2 of the algal C was recovered from bacterial and faunal biomass, respectively, while only 3.8 mg C m–2 was respired. Respiration was the dominant tracer pathway after 6 d of incubation (44 mg C m–2). Bacterial tracer uptake did not increase significantly between Days 3 and 6. The tracer recovered from metazoan fauna at the end of the experiment constituted 3.2% (2 mg C m–2) of the total processed C, with meiofauna contributing only ~1% to the total metazoan uptake. The bacterial response was characterised by varying bacterial growth efficiency (BGE). During the first half of the experiment, low respiration and high bacterial uptake of the 13C-labelled substrate resulted in particularly high BGE, while the opposite was observed in the second half of the incubation. We postulate that the high BGE at the start of the experiment represents the absorption and metabolism of the readily available labile components of the added organic matter (OM). The decrease in BGE possibly corresponds to the initiation of the energetically costly hydrolytic processes necessary for the consumption of more recalcitrant OM.

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More information

Published date: 2011
Keywords: Stable isotope labelling, Benthos, Bacterial growth efficiency, Bathyal sediments, Faroe-Shetland Channel, ?13C, PLFA
Organisations: Marine Biogeochemistry

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Local EPrints ID: 380738
URI: https://eprints.soton.ac.uk/id/eprint/380738
PURE UUID: 3577c11d-5954-4fc0-8968-bcde63e5fa4a

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Date deposited: 19 Aug 2015 12:37
Last modified: 15 Jul 2019 21:07

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