The Role of Indonesian Throughflow in a Global Ocean GCM

AbstractIt is now widely accepted that siderophores play a role in marine iron biogeochemical cycling. However, the mechanisms by which siderophores affect the availability of iron from specific sources and the resulting significance of these processes on iron biogeochemical cycling as a whole have remained largely untested. In this study, we develop a model system for testing the effects of siderophore production on iron bioavailability using the marine copiotroph Alteromonas macleodii ATCC 27126. Through the generation of the knockout cell line ΔasbB::kmr, which lacks siderophore biosynthetic capabilities, we demonstrate that the production of the siderophore petrobactin enables the acquisition of iron from mineral sources and weaker iron-ligand complexes. Notably, the utilization of lithogenic iron, such as that from atmospheric dust, indicates a significant role for siderophores in the incorporation of new iron into marine systems. We have also detected petrobactin, a photoreactive siderophore, directly from seawater in the mid-latitudes of the North Pacific and have identified the biosynthetic pathway for petrobactin in bacterial metagenome-assembled genomes widely distributed across the global ocean. Together, these results improve our mechanistic understanding of the role of siderophore production in iron biogeochemical cycling in the marine environment wherein iron speciation, bioavailability, and residence time can be directly influenced by microbial activities.

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The Role of Averaging for Improving Sea Surface Salinity Retrieval from the Soil Moisture and Ocean Salinity (SMOS) Satellite and Impact of Auxiliary Data

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech1954.1 ◽

2007 ◽

Vol 24 (2) ◽

pp. 255-269 ◽

Cited By ~ 10

Author(s):

Sabine Philipps ◽

Christine Boone ◽

Estelle Obligis

Keyword(s):

Soil Moisture ◽

Sensitivity Study ◽

Sea Surface ◽

Sea Surface Salinity ◽

Global Ocean ◽

Surface Salinity ◽

Auxiliary Data ◽

Additional Information ◽

Ocean Salinity

Abstract Soil Moisture and Ocean Salinity (SMOS) was chosen as the European Space Agency’s second Earth Explorer Opportunity mission. One of the objectives is to retrieve sea surface salinity (SSS) from measured brightness temperatures (TBs) at L band with a precision of 0.2 practical salinity units (psu) with averages taken over 200 km by 200 km areas and 10 days [as suggested in the requirements of the Global Ocean Data Assimilation Experiment (GODAE)]. The retrieval is performed here by an inverse model and additional information of auxiliary SSS, sea surface temperature (SST), and wind speed (W). A sensitivity study is done to observe the influence of the TBs and auxiliary data on the SSS retrieval. The key role of TB and W accuracy on SSS retrieval is verified. Retrieval is then done over the Atlantic for two cases. In case A, auxiliary data are simulated from two model outputs by adding white noise. The more realistic case B uses independent databases for reference and auxiliary ocean parameters. For these cases, the RMS error of retrieved SSS on pixel scale is around 1 psu (1.2 for case B). Averaging over GODAE scales reduces the SSS error by a factor of 12 (4 for case B). The weaker error reduction in case B is most likely due to the correlation of errors in auxiliary data. This study shows that SSS retrieval will be very sensitive to errors on auxiliary data. Specific efforts should be devoted to improving the quality of auxiliary data.

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Different processes shape prokaryotic and picoeukaryotic assemblages in the sunlit ocean microbiome

10.1101/374298 ◽

2018 ◽

Cited By ~ 3

Author(s):

Ramiro Logares ◽

Ina M. Deutschmann ◽

Caterina. R. Giner ◽

Anders K. Krabberød ◽

Thomas S. B. Schmidt ◽

...

Keyword(s):

Ecosystem Function ◽

Sequence Data ◽

Scale Effects ◽

Dispersal Limitation ◽

Global Scale ◽

Global Ocean ◽

Ecosystem Functions ◽

Ecological Processes ◽

Surface Ocean

ABSTRACTThe smallest members of the sunlit-ocean microbiome (prokaryotes and picoeukaryotes) participate in a plethora of ecosystem functions with planetary-scale effects. Understanding the processes determining the spatial turnover of this assemblage can help us better comprehend the links between microbiome species composition and ecosystem function. Ecological theory predicts thatselection,dispersalanddriftare main drivers of species distributions, yet, the relative quantitative importance of these ecological processes in structuring the surface-ocean microbiome is barely known. Here we quantified the role of selection, dispersal and drift in structuring surface-ocean prokaryotic and picoeukaryotic assemblages by using community DNA-sequence data collected during the global Malaspina expedition. We found that dispersal limitation was the dominant process structuring picoeukaryotic communities, while a balanced combination of dispersal limitation, selection and drift shaped prokaryotic counterparts. Subsequently, we determined the agents exerting abiotic selection as well as the spatial patterns emerging from the action of different ecological processes. We found that selection exerted via temperature had a strong influence on the structure of prokaryotic communities, particularly on species co-occurrences, a pattern not observed among communities of picoeukaryotes. Other measured abiotic variables had limited selective effects on microbiome structure. Picoeukaryotes presented a higher differentiation between neighbouring communities and a higher distance-decay when compared to prokaryotes, agreeing with their higher dispersal limitation. Finally, drift seemed to have a limited role in structuring the sunlit-ocean microbiome. The different predominance of ecological processes acting on particular subsets of the ocean microbiome suggests uneven responses to environmental change.SIGNIFICANCE STATEMENTThe global ocean contains one of the largest microbiomes on Earth and changes on its structure can impact the functioning of the biosphere. Yet, we are far from understanding the mechanisms that structure the global ocean microbiome, that is, the relative importance of environmentalselection,dispersaland random events (drift). We evaluated the role of these processes at the global scale, based on data derived from a circumglobal expedition and found that these ecological processes act differently on prokaryotes and picoeukaryotes, two of the main components of the ocean microbiome. Our work represents a significant contribution to understand the assembly of marine microbial communities, providing also insights on the links between ecological mechanisms, microbiome structure and ecosystem function.

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The Response to a Sudden Change in Indonesian Throughflow in a Global Ocean GCM

Journal of Physical Oceanography ◽

10.1175/1520-0485(1994)024<1895:trtasc>2.0.co;2 ◽

1994 ◽

Vol 24 (9) ◽

pp. 1895-1910 ◽

Cited By ~ 27

Author(s):

Anthony C. Hirst ◽

J. S. Godfrey

Keyword(s):

Sudden Change ◽

Global Ocean ◽

Indonesian Throughflow

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Sustaining observations in the polar oceans

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2013.0337 ◽

2014 ◽

Vol 372 (2025) ◽

pp. 20130337 ◽

Cited By ~ 6

Author(s):

E. P. Abrahamsen

Keyword(s):

Sea Ice ◽

Ocean Circulation ◽

Ice Cover ◽

Global Ocean ◽

Shelf Seas ◽

Polar Oceans ◽

Global Ocean Circulation ◽

Coordination And Collaboration ◽

Temperature Depth

Polar oceans present a unique set of challenges to sustained observations. Sea ice cover restricts navigation for ships and autonomous measurement platforms alike, and icebergs present a hazard to instruments deployed in the upper ocean and in shelf seas. However, the important role of the poles in the global ocean circulation provides ample justification for sustained observations in these regions, both to monitor the rapid changes taking place, and to better understand climate processes in these traditionally poorly sampled areas. In the past, the vast majority of polar measurements took place in the summer. In recent years, novel techniques such as miniature CTD (conductivity–temperature–depth) tags carried by seals have provided an explosion in year-round measurements in areas largely inaccessible to ships, and, as ice avoidance is added to autonomous profiling floats and gliders, these promise to provide further enhancements to observing systems. In addition, remote sensing provides vital information about changes taking place in sea ice cover at both poles. To make these observations sustainable into the future, improved international coordination and collaboration is necessary to gain optimum utilization of observing networks.

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12 The IMO: The Role of the Classification Societies in Promoting Global Ocean Governance

10.1093/law/9780198823957.003.0012 ◽

2018 ◽

Author(s):

Delgado Ismael Cobos

Keyword(s):

International Organizations ◽

International Association ◽

Active Participation ◽

International Maritime Organization ◽

Global Ocean ◽

Member States ◽

Ocean Governance

This chapter discusses the role of classification societies in their capacity as recognized organizations (ROs) acting on behalf of maritime administrations to ensure that ships, old and new, meet their obligations under International Maritime Organization (IMO) regulations and standards. Another aspect of the role of classification societies is to ensure that ships are designed, constructed, and maintained in compliance with the standards set by the International Association of Classification Societies (IACS). The chapter helps to that the IMO acting alone cannot provide all the answers to all of the issues regarding ocean governance. After all, the Organization relies heavily on the active participation not only of its Member States but also on those intergovernmental international organizations (IGOs) and non-governmental international organizations (NGOs) that are affiliated to it. In many situations, they have the specialized expertise and experience required to ensure that whatever regulations are adopted by the IMO are practicable.

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Part V Regional Perspectives on Global Ocean Governance, 16 The Role of the World Ocean Council and the Ocean Business Community in Global Ocean Governance

10.1093/law/9780198824152.003.0016 ◽

2018 ◽

Author(s):

Holthus Paul

Keyword(s):

Sustainable Development Goals ◽

World Ocean ◽

Institutional Development ◽

Business Community ◽

Global Ocean ◽

The Sustainable Development ◽

Ocean Governance ◽

The World ◽

Development Goals

This chapter discusses the role of the World Ocean Council (WOC) and the international ocean business community in global ocean governance (GOG). It first provides an overview of the institutional development and profile of the WOC before considering the work and role and work of the WOC on ocean governance with and for the ocean business community. It then examines the Sustainable Development Goals (SDGs) in relation to ocean business and the WOC, as well as the size, complexity trends in the ocean economy and ocean business community, which are fundamental to understanding their importance to GOG. It also analyses GOG issues relevant to the ocean business community and WOC that the United Nations and its associated bodies must address and concludes with an assessment of the role of the ocean business community and WOC in the future of the GOG agenda.

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Microbial community structure in the western tropical South Pacific

Biogeosciences ◽

10.5194/bg-15-3909-2018 ◽

2018 ◽

Vol 15 (12) ◽

pp. 3909-3925 ◽

Cited By ~ 8

Author(s):

Nicholas Bock ◽

France Van Wambeke ◽

Moïra Dion ◽

Solange Duhamel

Keyword(s):

Community Structure ◽

Microbial Community ◽

Microbial Communities ◽

Microbial Community Structure ◽

N2 Fixation ◽

Phytoplankton Biomass ◽

South Pacific ◽

Global Ocean ◽

Bottom Up

Abstract. Oligotrophic regions play a central role in global biogeochemical cycles, with microbial communities in these areas representing an important term in global carbon budgets. While the general structure of microbial communities has been well documented in the global ocean, some remote regions such as the western tropical South Pacific (WTSP) remain fundamentally unexplored. Moreover, the biotic and abiotic factors constraining microbial abundances and distribution remain not well resolved. In this study, we quantified the spatial (vertical and horizontal) distribution of major microbial plankton groups along a transect through the WTSP during the austral summer of 2015, capturing important autotrophic and heterotrophic assemblages including cytometrically determined abundances of non-pigmented protists (also called flagellates). Using environmental parameters (e.g., nutrients and light availability) as well as statistical analyses, we estimated the role of bottom–up and top–down controls in constraining the structure of the WTSP microbial communities in biogeochemically distinct regions. At the most general level, we found a “typical tropical structure”, characterized by a shallow mixed layer, a clear deep chlorophyll maximum at all sampling sites, and a deep nitracline. Prochlorococcus was especially abundant along the transect, accounting for 68 ± 10.6 % of depth-integrated phytoplankton biomass. Despite their relatively low abundances, picophytoeukaryotes (PPE) accounted for up to 26 ± 11.6 % of depth-integrated phytoplankton biomass, while Synechococcus accounted for only 6 ± 6.9 %. Our results show that the microbial community structure of the WTSP is typical of highly stratified regions, and underline the significant contribution to total biomass by PPE populations. Strong relationships between N2 fixation rates and plankton abundances demonstrate the central role of N2 fixation in regulating ecosystem processes in the WTSP, while comparative analyses of abundance data suggest microbial community structure to be increasingly regulated by bottom–up processes under nutrient limitation, possibly in response to shifts in abundances of high nucleic acid bacteria (HNA).

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