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

Evina Gontikaki, Daniel J. Mayor, Barry Thornton, Kenny Black, Ursula Witte

Research output: Contribution to journalArticle

15 Citations (Scopus)

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 days into the dissolved inorganic C pool (DI13C) as well as the bacterial and faunal (metazoan macrofauna and meiofaunal-sized nematode) biomass. After 3 days 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 days 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.
Original languageEnglish
Pages (from-to)39-50
Number of pages12
JournalMarine Ecology Progress Series
Volume421
DOIs
Publication statusPublished - 17 Jan 2011

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Bacillariophyceae
microbial growth
tracer techniques
metazoan
diatom
tracer
incubation
uptake mechanisms
breathing
temperature
respiration
experiment
organic matter
sediments
Chaetoceros
meiofauna
biomass
sediment core
nematode
metabolism

Keywords

  • stable isotope labelling
  • Benthos
  • bacterial growth efficiency
  • bathyal sediments
  • Faroe-Shetland Channel
  • d13C
  • PLFA

Cite this

Processing of 13C-labelled diatoms by a bathyal community at sub-zero temperatures. / Gontikaki, Evina; Mayor, Daniel J.; Thornton, Barry; Black, Kenny; Witte, Ursula.

In: Marine Ecology Progress Series, Vol. 421, 17.01.2011, p. 39-50.

Research output: Contribution to journalArticle

Gontikaki, Evina ; Mayor, Daniel J. ; Thornton, Barry ; Black, Kenny ; Witte, Ursula. / Processing of 13C-labelled diatoms by a bathyal community at sub-zero temperatures. In: Marine Ecology Progress Series. 2011 ; Vol. 421. pp. 39-50.
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N2 - 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 days into the dissolved inorganic C pool (DI13C) as well as the bacterial and faunal (metazoan macrofauna and meiofaunal-sized nematode) biomass. After 3 days 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 days 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.

AB - 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 days into the dissolved inorganic C pool (DI13C) as well as the bacterial and faunal (metazoan macrofauna and meiofaunal-sized nematode) biomass. After 3 days 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 days 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.

KW - stable isotope labelling

KW - Benthos

KW - bacterial growth efficiency

KW - bathyal sediments

KW - Faroe-Shetland Channel

KW - d13C

KW - PLFA

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VL - 421

SP - 39

EP - 50

JO - Marine Ecology Progress Series

JF - Marine Ecology Progress Series

SN - 0171-8630

ER -