Enhanced preservation of organic matter in sediments deposited within the oxygen minimum zone in the northeastern Arabian Sea

Abstract. The bacterial loop, the consumption of dissolved organic matter (DOM) by bacteria and subsequent transfer of bacterial carbon to higher trophic levels, plays a prominent role in pelagic aquatic food webs. However, its role in sedimentary ecosystems is not well documented. Here we present the results of isotope tracer experiments performed under in situ oxygen conditions in sediments from inside and outside the Arabian Sea Oxygen Minimum Zone (OMZ) to study the importance of the microbial loop in this setting. Particulate organic matter, added as phytodetritus, was processed by bacteria, protozoa and metazoans, while dissolved organic matter was processed only by bacteria and there was very little, if any, transfer to higher trophic levels within the experimental period. This lack of significant transfer of bacterial-derived carbon to metazoan consumers indicates that the bacterial loop is rather inefficient in these sediments. Moreover, metazoans directly consume labile particulate organic matter resources and thus compete with bacteria for phytodetritus.

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Sedimentary pigments and nature of organic matter within the oxygen minimum zone (OMZ) of the Eastern Arabian Sea (Indian margin)

Estuarine Coastal and Shelf Science ◽

10.1016/j.ecss.2016.04.013 ◽

2016 ◽

Vol 176 ◽

pp. 91-101 ◽

Cited By ~ 3

Author(s):

K.T. Rasiq ◽

S. Kurian ◽

S.G. Karapurkar ◽

S.W.A. Naqvi

Keyword(s):

Organic Matter ◽

Arabian Sea ◽

Oxygen Minimum Zone ◽

Sedimentary Pigments ◽

Eastern Arabian Sea ◽

Minimum Zone ◽

Oxygen Minimum

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Temporally invariable bacterial community structure in the Arabian Sea oxygen minimum zone

Aquatic Microbial Ecology ◽

10.3354/ame01704 ◽

2014 ◽

Vol 73 (1) ◽

pp. 51-67 ◽

Cited By ~ 12

Author(s):

A Jain ◽

M Bandekar ◽

J Gomes ◽

D Shenoy ◽

RM Meena ◽

...

Keyword(s):

Community Structure ◽

Bacterial Community ◽

Bacterial Community Structure ◽

Arabian Sea ◽

Oxygen Minimum Zone ◽

Minimum Zone ◽

Oxygen Minimum

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Denitrification exceeds anammox as a nitrogen loss pathway in the Arabian Sea oxygen minimum zone

Deep Sea Research Part I Oceanographic Research Papers ◽

10.1016/j.dsr.2009.10.014 ◽

2010 ◽

Vol 57 (3) ◽

pp. 384-393 ◽

Cited By ~ 68

Author(s):

Silvia E. Bulow ◽

Jeremy J. Rich ◽

Hema S. Naik ◽

Anil K. Pratihary ◽

Bess B. Ward

Keyword(s):

Arabian Sea ◽

Nitrogen Loss ◽

Oxygen Minimum Zone ◽

Minimum Zone ◽

Oxygen Minimum

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Sink or link? The bacterial role in benthic carbon cycling in the Arabian Sea's oxygen minimum zone

Biogeosciences ◽

10.5194/bg-10-6879-2013 ◽

2013 ◽

Vol 10 (11) ◽

pp. 6879-6891 ◽

Cited By ~ 10

Author(s):

L. Pozzato ◽

D. Van Oevelen ◽

L. Moodley ◽

K. Soetaert ◽

J. J. Middelburg

Keyword(s):

Organic Matter ◽

Dissolved Organic Matter ◽

Particulate Organic Matter ◽

Experimental Period ◽

Oxygen Minimum Zone ◽

Trophic Levels ◽

Isotope Tracer ◽

Oxygen Conditions ◽

Minimum Zone ◽

Oxygen Minimum

Abstract. The bacterial loop, the consumption of dissolved organic matter (DOM) by bacteria and subsequent transfer of bacterial carbon to higher trophic levels, plays a prominent role in pelagic food webs. However, its role in sedimentary ecosystems is not well documented. Here we present the results of isotope tracer experiments performed under in situ oxygen conditions in sediments from inside and outside the Arabian Sea's oxygen minimum zone (OMZ) to study the importance of the microbial loop in this setting. Particulate organic matter, added as phytodetritus, was processed by bacteria, protozoa and metazoans, while dissolved organic matter was processed only by bacteria and there was very little, if any, transfer to higher trophic levels within the 7 day experimental period. This lack of significant transfer of bacterial-derived carbon to metazoan consumers indicates that the bacterial loop is rather inefficient, in sediments both inside and outside the OMZ. Moreover, metazoans directly consumed labile particulate organic matter resources and thus competed with bacteria for phytodetritus.

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