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Title: The trophic biology of the holothurian Molpadia musculus: implications for organic matter cycling and ecosystem functioning in a deep submarine canyon
Author: Amaro, T
Bianchelli, S
Billett, DSM
Cunha, MR
Pusceddu, A
Danovaro, R
Keywords: Porcupine abyssal-plain
Northern Portuguese shelf
South-Pacif Ocean
Long-term change
Sea sediments
NE Atlantic
Continental margin
Nazaré canyon
Issue Date: 16-Aug-2010
Publisher: European Geosciences Union
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 Nazar, 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 Nazar, Canyon.
Peer review: yes
DOI: 10.5194/bg-7-2419-2010
ISSN: 1726-4170
Appears in Collections:CESAM - Artigos
DBio - Artigos
PT Mar - Artigos

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