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The trophic biology of the holothurian Molpadia musculus: implications for organic matter cycling and ecosystem functioning in a deep submarine canyon

The trophic biology of the holothurian Molpadia musculus: implications for organic matter cycling and ecosystem functioning in a deep submarine canyon
The trophic biology of the holothurian Molpadia musculus: implications for organic matter cycling and ecosystem functioning in a deep submarine canyon
Megafaunal organisms play a key role in ecosystem functioning in the deep-sea through bioturbation, bioirrigation and organic matter cycling. At 3500 m water depth in the Nazaré Canyon, NE Atlantic, very high abundances of the infaunal holothurian Molpadia musculus were observed. To quantify the role of M. musculus in sediment cycling, sediment samples and holothurians were collected using an ROV and in situ experiments were conducted with incubation chambers. The biochemical composition of the sediment (in terms of proteins, carbohydrates and lipids), the holothurians' gut contents and holothurians' faecal material were analysed. In the sediments, proteins were the dominant organic compound, followed by carbohydrates and lipids. In the holothurian's gut contents, protein concentrations were higher than the other compounds, decreasing significantly as the material passed through the digestive tract. Approximately 33±1% of the proteins were digested by the time sediment reached the mid gut, with a total digestion rate equal to 67±1%. Carbohydrates and lipids were ingested in smaller amounts and digested with lower efficiencies (23±11% and 50±11%, respectively). As a result, the biopolymeric C digestion rate was on average 62±3%. We estimated that the population of M. musculus could remove approximately 0.49±0.13 g biopolymeric C and 0.13±0.03 g N m?2 d?1 from the sediments. These results suggest that M. musculus plays a key role in the benthic tropho-dynamics and biogeochemical processes in the Nazaré Canyon.
1726-4170
2419-2432
Amaro, T.
6eb60095-3fdb-455a-86bd-55077ad896e9
Bianchelli, S.
662b6257-767c-4f77-87d1-8b1086820490
Billett, D.S.M.
aab439e2-c839-4cd2-815c-3d401e0468db
Cunha, M.R.
825eb17a-b31d-43aa-af0f-d3b7721a819c
Pusceddu, A.
4be1bead-67d6-472d-a559-2d5256bd50d1
Danovaro, R.
eb18bf32-d311-4a1b-a93b-73cf78a55cec
Amaro, T.
6eb60095-3fdb-455a-86bd-55077ad896e9
Bianchelli, S.
662b6257-767c-4f77-87d1-8b1086820490
Billett, D.S.M.
aab439e2-c839-4cd2-815c-3d401e0468db
Cunha, M.R.
825eb17a-b31d-43aa-af0f-d3b7721a819c
Pusceddu, A.
4be1bead-67d6-472d-a559-2d5256bd50d1
Danovaro, R.
eb18bf32-d311-4a1b-a93b-73cf78a55cec

Amaro, T., Bianchelli, S., Billett, D.S.M., Cunha, M.R., Pusceddu, A. and Danovaro, R. (2010) The trophic biology of the holothurian Molpadia musculus: implications for organic matter cycling and ecosystem functioning in a deep submarine canyon. Biogeosciences, 7 (8), 2419-2432.

Record type: Article

Abstract

Megafaunal organisms play a key role in ecosystem functioning in the deep-sea through bioturbation, bioirrigation and organic matter cycling. At 3500 m water depth in the Nazaré Canyon, NE Atlantic, very high abundances of the infaunal holothurian Molpadia musculus were observed. To quantify the role of M. musculus in sediment cycling, sediment samples and holothurians were collected using an ROV and in situ experiments were conducted with incubation chambers. The biochemical composition of the sediment (in terms of proteins, carbohydrates and lipids), the holothurians' gut contents and holothurians' faecal material were analysed. In the sediments, proteins were the dominant organic compound, followed by carbohydrates and lipids. In the holothurian's gut contents, protein concentrations were higher than the other compounds, decreasing significantly as the material passed through the digestive tract. Approximately 33±1% of the proteins were digested by the time sediment reached the mid gut, with a total digestion rate equal to 67±1%. Carbohydrates and lipids were ingested in smaller amounts and digested with lower efficiencies (23±11% and 50±11%, respectively). As a result, the biopolymeric C digestion rate was on average 62±3%. We estimated that the population of M. musculus could remove approximately 0.49±0.13 g biopolymeric C and 0.13±0.03 g N m?2 d?1 from the sediments. These results suggest that M. musculus plays a key role in the benthic tropho-dynamics and biogeochemical processes in the Nazaré Canyon.

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Published date: 2010
Organisations: Marine Biogeochemistry

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Local EPrints ID: 174099
URI: https://eprints.soton.ac.uk/id/eprint/174099
ISSN: 1726-4170
PURE UUID: 1a7d389c-cf89-4297-a4d3-36a79ff437d3

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Date deposited: 10 Feb 2011 15:14
Last modified: 01 Nov 2017 13:52

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Contributors

Author: T. Amaro
Author: S. Bianchelli
Author: D.S.M. Billett
Author: M.R. Cunha
Author: A. Pusceddu
Author: R. Danovaro

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