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Feeding strategies of deep-sea sub-Arctic macrofauna of the Faroe-Shetland Channel: Combining natural stable isotopes and enrichment techniques

Feeding strategies of deep-sea sub-Arctic macrofauna of the Faroe-Shetland Channel: Combining natural stable isotopes and enrichment techniques
Feeding strategies of deep-sea sub-Arctic macrofauna of the Faroe-Shetland Channel: Combining natural stable isotopes and enrichment techniques
The response of a sub-arctic, deep-sea macrofaunal community to a simulated food sedimentation event was studied by means of a stable isotope “pulse-chase” experiment. A food pulse was simulated by adding 500 mg C m?2 of 13C-labelled diatoms, Chaetoceros radicans, to sediment cores retrieved from 1080 m in the Faroe-Shetland Channel. Carbon uptake by specific macrofaunal groups was quantified after 3 and 6 days of incubation. The carbon uptake of the dominant taxon (Polychaeta) was quantified at the genus-, and where possible, species-level, representing a data resolution that is rare in deep-sea tracer studies. The macrofaunal community reacted rapidly to the diatom addition, with 47% and 70% of the animals illustrating 13C-enrichment after 3 and 6 days, respectively. Approximately 95% of C uptake was located in the upper 2 cm due to the particularly shallow vertical distribution of the macrofaunal community and the nonexistent tracer subduction by burrowing species. Polychaetes of the families Ampharetidae and Cirratulidae were among the most heavily labelled with above background enrichment reaching 1300‰. Approximately 0.8 and 2.0 mg C m?2 were processed by the macrofauna after 3 and 6 days, representing 0.2% and 0.4% of the added carbon, respectively. It was not possible to differentiate sub-surface deposit-feeding polychaetes from predator/scavenger- and omnivorous polychaetes using their natural ?15N signatures. However, the combination of natural abundance ?15N data and 13C-labelling experiments proved to be useful for elucidating trophic relations in deep-sea food webs. This study confirms that macrofauna play an active role in the short-term carbon cycling at bathyal depths even at sub-zero temperatures and highlights the need for detailed knowledge of the community structure in understanding carbon processing patterns and early diagenesis of organic matter in marine sediments.
Macrofauna, Food web, Pulse-chase experiment, Bathyal sediments, Benthic response, ?15N, Faroe-Shetland Channel
0967-0637
160-172
Gontikaki, E.
b33956ff-381b-401b-8c78-2c802eef3cae
Mayor, D.J.
461ddc80-a25d-45b5-873f-9cbf4aa93828
Narayanaswamy, B.E.
bfe8be31-a4e6-4ef3-a839-ae36f9387444
Witte, U.
11050d87-974b-4596-8545-68dcc675704e
Gontikaki, E.
b33956ff-381b-401b-8c78-2c802eef3cae
Mayor, D.J.
461ddc80-a25d-45b5-873f-9cbf4aa93828
Narayanaswamy, B.E.
bfe8be31-a4e6-4ef3-a839-ae36f9387444
Witte, U.
11050d87-974b-4596-8545-68dcc675704e

Gontikaki, E., Mayor, D.J., Narayanaswamy, B.E. and Witte, U. (2011) Feeding strategies of deep-sea sub-Arctic macrofauna of the Faroe-Shetland Channel: Combining natural stable isotopes and enrichment techniques. Deep Sea Research Part I: Oceanographic Research Papers, 58 (2), 160-172. (doi:10.1016/j.dsr.2010.11.011).

Record type: Article

Abstract

The response of a sub-arctic, deep-sea macrofaunal community to a simulated food sedimentation event was studied by means of a stable isotope “pulse-chase” experiment. A food pulse was simulated by adding 500 mg C m?2 of 13C-labelled diatoms, Chaetoceros radicans, to sediment cores retrieved from 1080 m in the Faroe-Shetland Channel. Carbon uptake by specific macrofaunal groups was quantified after 3 and 6 days of incubation. The carbon uptake of the dominant taxon (Polychaeta) was quantified at the genus-, and where possible, species-level, representing a data resolution that is rare in deep-sea tracer studies. The macrofaunal community reacted rapidly to the diatom addition, with 47% and 70% of the animals illustrating 13C-enrichment after 3 and 6 days, respectively. Approximately 95% of C uptake was located in the upper 2 cm due to the particularly shallow vertical distribution of the macrofaunal community and the nonexistent tracer subduction by burrowing species. Polychaetes of the families Ampharetidae and Cirratulidae were among the most heavily labelled with above background enrichment reaching 1300‰. Approximately 0.8 and 2.0 mg C m?2 were processed by the macrofauna after 3 and 6 days, representing 0.2% and 0.4% of the added carbon, respectively. It was not possible to differentiate sub-surface deposit-feeding polychaetes from predator/scavenger- and omnivorous polychaetes using their natural ?15N signatures. However, the combination of natural abundance ?15N data and 13C-labelling experiments proved to be useful for elucidating trophic relations in deep-sea food webs. This study confirms that macrofauna play an active role in the short-term carbon cycling at bathyal depths even at sub-zero temperatures and highlights the need for detailed knowledge of the community structure in understanding carbon processing patterns and early diagenesis of organic matter in marine sediments.

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More information

Published date: February 2011
Keywords: Macrofauna, Food web, Pulse-chase experiment, Bathyal sediments, Benthic response, ?15N, Faroe-Shetland Channel
Organisations: Marine Biogeochemistry

Identifiers

Local EPrints ID: 380730
URI: https://eprints.soton.ac.uk/id/eprint/380730
ISSN: 0967-0637
PURE UUID: 9939e9a2-0048-4289-bf3b-862dd41f1f4e

Catalogue record

Date deposited: 19 Aug 2015 11:00
Last modified: 15 Jul 2019 21:07

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