Rapid response of a deep-sea benthic community to POM enrichment

an in situ experimental study

U Witte*, N Aberle, M Sand, F Wenzhofer

*Corresponding author for this work

Research output: Contribution to journalArticle

106 Citations (Scopus)

Abstract

A series of in situ enrichment experiments was carried out at 1265 m water depth in the Sognefjord on the west coast of Norway in order to follow the short-term fate of freshly settled phytodetritus in a deep-sea sediment. For all experiments, a deep-sea benthic chamber lander system was used. In the lander chambers, a settling spring bloom was simulated by the injection of 0.2 g of freeze-dried Thalassiosira rotula, an equivalent of 1 g organic C m(-2). The algae were 98% C-13-labeled, thus enabling us to follow the processing of the carbon by bacteria and macrofauna. Experiment duration varied from 8 h to 3 d. The total oxygen consumption of the sediments increased by approximately 25% due to particulate organic matter (POM) enrichment. Macrofauna organisms became immediately labeled with C-13. After 3 d, 100% of the individuals sampled down to 10 cm sediment depth had taken up C-13 from the phytodetritus added. Bacterial uptake of the tracer was fast too, and even bacteria in deeper sediment layers had incorporated the fresh material within 3 d. Our study documents the rapid downward mixing of labile organic matter and the importance of macrofauna for this process. We present the first evidence for the immediate breakdown and incorporation of POM by bacteria even in deep sediment layers. Surprisingly, the initial processing of carbon was dominated by macrofauna, although the group comprises <5% of the benthic biomass. Altogether, approximately 5% of the carbon added had been processed within 3 d, with the majority being released from the sediment as CO2, Due to the good comparability of our study site with midslope settings at continental margins, in general, we propose that the processes we observed are widespread at continental margins and are significant for the biogeochemical cycling of particulate matter on the slope.

Original languageEnglish
Pages (from-to)27-36
Number of pages10
JournalMarine Ecology Progress Series
Volume251
Publication statusPublished - 2003

Keywords

  • continental slope
  • deep sea
  • pulse-chase experiment
  • delta C-13
  • benthic carbon remineralization
  • macrofauna
  • bacteria
  • SCOC
  • NORTH-EAST ATLANTIC
  • IN-SITU
  • CONTINENTAL-SLOPE
  • ORGANIC-MATTER
  • SEASONAL REPRODUCTION
  • MICROBIAL BIOMASS
  • NE ATLANTIC
  • GOBAN SPUR
  • CARBON
  • SEDIMENT

Cite this

Rapid response of a deep-sea benthic community to POM enrichment : an in situ experimental study. / Witte, U; Aberle, N; Sand, M; Wenzhofer, F.

In: Marine Ecology Progress Series, Vol. 251, 2003, p. 27-36.

Research output: Contribution to journalArticle

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abstract = "A series of in situ enrichment experiments was carried out at 1265 m water depth in the Sognefjord on the west coast of Norway in order to follow the short-term fate of freshly settled phytodetritus in a deep-sea sediment. For all experiments, a deep-sea benthic chamber lander system was used. In the lander chambers, a settling spring bloom was simulated by the injection of 0.2 g of freeze-dried Thalassiosira rotula, an equivalent of 1 g organic C m(-2). The algae were 98{\%} C-13-labeled, thus enabling us to follow the processing of the carbon by bacteria and macrofauna. Experiment duration varied from 8 h to 3 d. The total oxygen consumption of the sediments increased by approximately 25{\%} due to particulate organic matter (POM) enrichment. Macrofauna organisms became immediately labeled with C-13. After 3 d, 100{\%} of the individuals sampled down to 10 cm sediment depth had taken up C-13 from the phytodetritus added. Bacterial uptake of the tracer was fast too, and even bacteria in deeper sediment layers had incorporated the fresh material within 3 d. Our study documents the rapid downward mixing of labile organic matter and the importance of macrofauna for this process. We present the first evidence for the immediate breakdown and incorporation of POM by bacteria even in deep sediment layers. Surprisingly, the initial processing of carbon was dominated by macrofauna, although the group comprises <5{\%} of the benthic biomass. Altogether, approximately 5{\%} of the carbon added had been processed within 3 d, with the majority being released from the sediment as CO2, Due to the good comparability of our study site with midslope settings at continental margins, in general, we propose that the processes we observed are widespread at continental margins and are significant for the biogeochemical cycling of particulate matter on the slope.",
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TY - JOUR

T1 - Rapid response of a deep-sea benthic community to POM enrichment

T2 - an in situ experimental study

AU - Witte, U

AU - Aberle, N

AU - Sand, M

AU - Wenzhofer, F

PY - 2003

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N2 - A series of in situ enrichment experiments was carried out at 1265 m water depth in the Sognefjord on the west coast of Norway in order to follow the short-term fate of freshly settled phytodetritus in a deep-sea sediment. For all experiments, a deep-sea benthic chamber lander system was used. In the lander chambers, a settling spring bloom was simulated by the injection of 0.2 g of freeze-dried Thalassiosira rotula, an equivalent of 1 g organic C m(-2). The algae were 98% C-13-labeled, thus enabling us to follow the processing of the carbon by bacteria and macrofauna. Experiment duration varied from 8 h to 3 d. The total oxygen consumption of the sediments increased by approximately 25% due to particulate organic matter (POM) enrichment. Macrofauna organisms became immediately labeled with C-13. After 3 d, 100% of the individuals sampled down to 10 cm sediment depth had taken up C-13 from the phytodetritus added. Bacterial uptake of the tracer was fast too, and even bacteria in deeper sediment layers had incorporated the fresh material within 3 d. Our study documents the rapid downward mixing of labile organic matter and the importance of macrofauna for this process. We present the first evidence for the immediate breakdown and incorporation of POM by bacteria even in deep sediment layers. Surprisingly, the initial processing of carbon was dominated by macrofauna, although the group comprises <5% of the benthic biomass. Altogether, approximately 5% of the carbon added had been processed within 3 d, with the majority being released from the sediment as CO2, Due to the good comparability of our study site with midslope settings at continental margins, in general, we propose that the processes we observed are widespread at continental margins and are significant for the biogeochemical cycling of particulate matter on the slope.

AB - A series of in situ enrichment experiments was carried out at 1265 m water depth in the Sognefjord on the west coast of Norway in order to follow the short-term fate of freshly settled phytodetritus in a deep-sea sediment. For all experiments, a deep-sea benthic chamber lander system was used. In the lander chambers, a settling spring bloom was simulated by the injection of 0.2 g of freeze-dried Thalassiosira rotula, an equivalent of 1 g organic C m(-2). The algae were 98% C-13-labeled, thus enabling us to follow the processing of the carbon by bacteria and macrofauna. Experiment duration varied from 8 h to 3 d. The total oxygen consumption of the sediments increased by approximately 25% due to particulate organic matter (POM) enrichment. Macrofauna organisms became immediately labeled with C-13. After 3 d, 100% of the individuals sampled down to 10 cm sediment depth had taken up C-13 from the phytodetritus added. Bacterial uptake of the tracer was fast too, and even bacteria in deeper sediment layers had incorporated the fresh material within 3 d. Our study documents the rapid downward mixing of labile organic matter and the importance of macrofauna for this process. We present the first evidence for the immediate breakdown and incorporation of POM by bacteria even in deep sediment layers. Surprisingly, the initial processing of carbon was dominated by macrofauna, although the group comprises <5% of the benthic biomass. Altogether, approximately 5% of the carbon added had been processed within 3 d, with the majority being released from the sediment as CO2, Due to the good comparability of our study site with midslope settings at continental margins, in general, we propose that the processes we observed are widespread at continental margins and are significant for the biogeochemical cycling of particulate matter on the slope.

KW - continental slope

KW - deep sea

KW - pulse-chase experiment

KW - delta C-13

KW - benthic carbon remineralization

KW - macrofauna

KW - bacteria

KW - SCOC

KW - NORTH-EAST ATLANTIC

KW - IN-SITU

KW - CONTINENTAL-SLOPE

KW - ORGANIC-MATTER

KW - SEASONAL REPRODUCTION

KW - MICROBIAL BIOMASS

KW - NE ATLANTIC

KW - GOBAN SPUR

KW - CARBON

KW - SEDIMENT

M3 - Article

VL - 251

SP - 27

EP - 36

JO - Marine Ecology Progress Series

JF - Marine Ecology Progress Series

SN - 0171-8630

ER -