Systems Biogeochemistry of Major Marine Biomes

Aninda Mazumdar, Wriddhiman Ghosh, Aninda Mazumdar, Wriddhiman Ghosh

• Publisher: Wiley
• Year: 2022
• Print ISBN:
  9781119554387
• eBook ISBN:
  9781119554363
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Geophysics

Systems Biogeochemistry of Major Marine Biomes

A comprehensive system-level discussion of the geomicrobiology of the Earth's oceans

In Systems Biogeochemistry of Major Marine Biomes, a team of distinguished researchers delivers a systemic overview of biogeochemistry across a number of major physiographies of the global ocean: the waters and sediments overlying continental margins; the deep sub-surfaces; the Arctic and Antarctic oceans; and the physicochemical extremes such as the hypersaline and sulfidic marine zones, cold methane seeps and hydrothermal ecosystems.

The book explores state-of-the-art advances in marine geomicrobiology and investigates the drivers of biogeochemical processes. It highlights the imperatives of the unique, fringe, and cryptic processes while studying the geological manifestations and ecological feedbacks of in situ microbial metabolisms. Taking a holistic approach toward the understanding of marine biogeochemical provinces, this book emphasizes the centrality of culture-dependent and culture-independent (meta-omics-based) microbiological information within a systems biogeochemistry framework.

Perfect for researchers and scientists in the fields of geochemistry, geophysics, geomicrobiology, oceanography, and marine science, Systems Biogeochemistry of Major Marine Biomes will also earn a place in the libraries of policymakers and advanced graduate students seeking a one-stop reference on marine biogeochemistry.

Biome I
Continental Margins

1
Biogeochemistry of Marine Oxygen Minimum Zones with Special Emphasis on the Northern Indian Ocean

Svetlana Fernandes^1,†, Subhrangshu Mandal^2,†, Kalyani Sivan^1,3, Aditya Peketi¹, and Aninda Mazumdar^1*

¹ CSIR‐National Institute of Oceanography, Dona Paula, Goa , 403004, India

² Department of Microbiology, Bose Institute, P‐1/12 CIT Scheme VIIM, Kolkata, 700054, West Bengal, India

³ Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India

^* Corresponding Author: Aninda Mazumdar ([email protected]) ORCiD code: 0000‐0002‐7897‐1646

^† Equal contribution

ABSTRACT

Oxygen minimum zones (OMZs) enclose O₂ depleted subsurface water masses in the global ocean extending approximately 150 to 1200 m below sea level. The most pronounced OMZs occur in Eastern Tropical North Pacific off Mexico and California (ETNP), Eastern Tropical South Pacific off Peru and Chile (ETSP), and the Arabian Sea (AS) defined by secondary nitrite maxima attributed to intense denitrification in the water column. These OMZs sites are critical for biogeochemical processes that control the biodiversity and primary productivity of the ocean. The preservation of organic carbon is efficient within the sediments underlying oxygen‐depleted waters as a result of incomplete decomposition as it sinks through the water column and diminished bioturbation activity. The partially degraded (reactive) organic matter fuels microbe‐mediated biogeochemical processes in the anoxic marine sediments where sulfate reduction is a significant remineralization pathway. The OMZs exert a strong influence on the abundance, diversity, and composition of microbial communities. Recent geochemical and environmental genomic studies identified the prevalence of C, N, and S cycles in the OMZs. Here, we review the progress and current understanding of the C–S–N cycle in the OMZ sediments with regard to its biogeochemistry and microbial ecology, and present a brief account of the mechanism of the formation of OMZs in the northern Indian Ocean.

1.1. INTRODUCTION

Oxygen minimum zones (OMZs) are oxygen‐depleted intermediate‐depth water masses in the global ocean, usually between 150 and 1200 m below sea level (mbsl). The upper threshold of dissolved oxygen (DO) concentrations defining the OMZs is ~20 μM (Figure 1.1; Paulmier and Ruiz‐Pino, 2009; Ruvalcaba Baroni et al., 2020), while the lower concentration of DO detected in an OMZ may be <2 nM O₂ (Revsbech et al., 2009), amounting to functionally anoxic conditions. Oceanic regions generally classified as OMZs include (1) the Eastern Tropical North Pacific off Mexico and California (ETNP), (2) the Eastern Tropical South Pacific off Peru and Chile (ETSP), (3) the Bay of Bengal (BoB), and (4) the Arabian Sea (AS). Of these OMZs, the ETNP, ETSP, and the AS have also been classified as anoxic marine zones (Ulloa et al., 2012), owing to the buildup of secondary nitrite maxima (SNM) within the water column. The SNM forms because of denitrification in the water column, which occurs when DO concentrations drop to <5 mM (Anderson et al., 2007; Banse et al., 2017). The functionally anoxic parts of these OMZs occupy only ~0.8% of the world ocean but are responsible for ~35% of the production of N₂ through denitrification (Ward et al., 2009).

Figure 1.1 Global annual oxygen concentration (ml l^–1) at 150 mbsl.

Source: World Ocean Atlas 2009.

The buildup of OMZs is controlled by the interplay of physical and biological processes coupled with regional geography. Inadequate ventilation of the oxygenated water masses (e.g. the northern Indian Ocean), upwelling of nutrient‐rich deep waters (leading to high productivity in the euphotic zone), and subsequent microbial respiration of organic particulates (phytodetritus, fecal pellets, dead organisms, etc.) lead to a depletion of DO in the water column, resulting in the formation of OMZs (Behrenfeld et al., 2006; Regaudie‐de‐Gioux and Duarte, 2012). OMZs are high in nutrient concentrations and support highly productive fishing regions (Garçon et al., 2019).

In the northern Indian Ocean, OMZs occur in both the AS and the BoB (Figure 1.2) because of their closed northern geographical boundaries and monsoon‐driven seasonal upwelling (Naqvi, 1991; Stramma et al., 2008). The DO concentration within the Arabian Sea (ASOMZ) reflects a balance between biological O₂ consumption and O₂ replenishment. The primary source of intermediate water (Indian Ocean Central Water: ICW) (Stramma et al., 1996; Schott and McCreary, 2001; Rixen et al., 2020) in the northern Indian Ocean include contributions from the Antarctic Intermediate Water (AAIW), Subantarctic Mode Water (SAMW) and the Indonesian intermediate waters (Lachkar et al., 2019). The dense and highly saline Persian Gulf water (PGW) and relatively less saline but denser Red Sea water (RSW) are the lateral sources of intermediate water in the AS (Bower et al., 2005).

1.1.1. The Arabian Sea Oxygen Minimum Zone

The AS is believed to contain the thickest and most intense of the OMZs (Agnihotri et al., 2003; Naqvi et al., 2010a; Prakash et al., 2012; Banse et al., 2014; Acharya and Panigrah...

Table of contents

• Cover
• Table of Contents
• Title Page
• Copyright Page
• LIST OF CONTRIBUTORS
• PREFACE
• Biome I: Continental Margins
• Biome II: Ocean Depths
• Biome III: Polar Oceans
• Biome IV: Extreme Environments
• Index
• End User License Agreement