The University of Southampton
University of Southampton Institutional Repository

RRS "Charles Darwin" Cruise 150, 22 Aug - 15 Sep 2003. Benthic ecology and biogeochemistry of the Pakistan Margin

RRS "Charles Darwin" Cruise 150, 22 Aug - 15 Sep 2003. Benthic ecology and biogeochemistry of the Pakistan Margin
RRS "Charles Darwin" Cruise 150, 22 Aug - 15 Sep 2003. Benthic ecology and biogeochemistry of the Pakistan Margin
RRS Charles Darwin cruise 150 forms part of a larger programme of research (“Benthic processes in the Arabian Sea: interrelationships between benthos, sediment, biogeochemistry and organic matter cycling”, NER/A/S/2000/01280), focusing on the benthic biogeochemistry of the Pakistan Margin, that includes four cruises in total (CD145, 146, 150 and 151). The primary objectives of the present cruise were: a) to revisit a series of five previously established study sites (A140, A300, A950, A1200 and A1850) spanning the Arabian Sea oxygen minimum zone (OMZ) as it impinges on the seabed at the Pakistan Margin; b) to assess the chemical oceanography of the water column overlying these sites, through CTD sensor profiles and chemical determinations on water bottle samples from both the CTD and BBLS; c) to initiate a programme of detailed seabed sampling at these sites to determine a suite of biological, chemical and biogeochemical parameters using a Megacorer and a multicorer; d) to assess and sample the megabenthos of these sites by the combined use of trawling (Agassiz trawl) and seabed photography (WASP); e) as possible, to carry out similar operations at a site located at a depth between A300 and A950; f) as possible, to provide additional general characterization of the seabed in the area of these sites using acoustic remote sensing (EM12 and 3.5 kHz ) and seabed imagery (WASP ).

The cruise successfully achieved all of the planned objectives. The effort of assessing the science of the cruise will take many months of work ashore. Of those parameters that could be initially assessed onboard there was little indication of major change between cruises 145 and 150, other than in the OMZ itself. Minimum oxygen values encountered during cruise 145 were around 400m, but during the present cruise were in the 150-200m range. If a value of 0.5 ml/l is used as a boundary, then it had shallowed from c. 180m (CD145) to c. 80m (CD150). There also appeared to be some elevation of the lower boundary of the OMZ, although this was less marked.
Agassiz trawl, Arabian Sea, bathymetry, benthic communities, biochemistry, biogeochemistry, Charles Darwin, continental slope, cruise 150 2003, CTD observations, foraminifera, geochemistry, Indus Margin, Indian Ocean, megabenthos, megacorer, meiobenthos, multiple corer, organic matter, oxygen minimum zone, Pakistan Margin, protozoa, seabed, sulphate reduction
51
Southampton Oceanography Centre
Bett, B.J.
61342990-13be-45ae-9f5c-9540114335d9
Bett, B.J.
61342990-13be-45ae-9f5c-9540114335d9

Bett, B.J. (2004) RRS "Charles Darwin" Cruise 150, 22 Aug - 15 Sep 2003. Benthic ecology and biogeochemistry of the Pakistan Margin (Southampton Oceanography Centre Cruise Report, 51) Southampton, UK. Southampton Oceanography Centre 144pp.

Record type: Monograph (Project Report)

Abstract

RRS Charles Darwin cruise 150 forms part of a larger programme of research (“Benthic processes in the Arabian Sea: interrelationships between benthos, sediment, biogeochemistry and organic matter cycling”, NER/A/S/2000/01280), focusing on the benthic biogeochemistry of the Pakistan Margin, that includes four cruises in total (CD145, 146, 150 and 151). The primary objectives of the present cruise were: a) to revisit a series of five previously established study sites (A140, A300, A950, A1200 and A1850) spanning the Arabian Sea oxygen minimum zone (OMZ) as it impinges on the seabed at the Pakistan Margin; b) to assess the chemical oceanography of the water column overlying these sites, through CTD sensor profiles and chemical determinations on water bottle samples from both the CTD and BBLS; c) to initiate a programme of detailed seabed sampling at these sites to determine a suite of biological, chemical and biogeochemical parameters using a Megacorer and a multicorer; d) to assess and sample the megabenthos of these sites by the combined use of trawling (Agassiz trawl) and seabed photography (WASP); e) as possible, to carry out similar operations at a site located at a depth between A300 and A950; f) as possible, to provide additional general characterization of the seabed in the area of these sites using acoustic remote sensing (EM12 and 3.5 kHz ) and seabed imagery (WASP ).

The cruise successfully achieved all of the planned objectives. The effort of assessing the science of the cruise will take many months of work ashore. Of those parameters that could be initially assessed onboard there was little indication of major change between cruises 145 and 150, other than in the OMZ itself. Minimum oxygen values encountered during cruise 145 were around 400m, but during the present cruise were in the 150-200m range. If a value of 0.5 ml/l is used as a boundary, then it had shallowed from c. 180m (CD145) to c. 80m (CD150). There also appeared to be some elevation of the lower boundary of the OMZ, although this was less marked.

Text
soccr051.pdf - Other
Download (3MB)

More information

Published date: 2004
Keywords: Agassiz trawl, Arabian Sea, bathymetry, benthic communities, biochemistry, biogeochemistry, Charles Darwin, continental slope, cruise 150 2003, CTD observations, foraminifera, geochemistry, Indus Margin, Indian Ocean, megabenthos, megacorer, meiobenthos, multiple corer, organic matter, oxygen minimum zone, Pakistan Margin, protozoa, seabed, sulphate reduction

Identifiers

Local EPrints ID: 14404
URI: http://eprints.soton.ac.uk/id/eprint/14404
PURE UUID: 0b3ce0a7-0b67-46a4-aca9-36dc473d4166

Catalogue record

Date deposited: 14 Feb 2005
Last modified: 19 Jul 2019 19:19

Export record

Contributors

Author: B.J. Bett

University divisions

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×