The ocean contains one of the largest reservoirs of reduced carbon on Earth in the form of dissolved organic matter (DOM). Heterotrophic bacteria serve as the primary force regulating the degradation of this material, recycling the majority of dissolved organic carbon (DOC) produced in the surface ocean by phytoplankton back to carbon dioxide. While it is known that microbial community structure plays a role in determining the rate and magnitude of DOM turnover, the quantitative contribution of individuals to this process remains unknown. The objective of this dissertation was to investigate the constraints on DOM turnover by bacterial communities by focusing on how a single bacterial strain makes a living in the sea. I found that a single bacterial strain, Alteromonas sp. AltSIO, has the capacity to consume an equivalent magnitude of DOC as diverse bacterial communities, suggesting that bacterial diversity may not be required for the complete removal of labile DOC in the surface ocean. In long-term microcosms, however, bacterial diversity was required for continued degradation of semi-labile DOC. To test the generality of this capacity among individual bacteria, a culture-based study was conducted where >100 phylogenetically diverse bacterial strains were isolated to screen for growth in unamended seawater. No other bacterial strain tested exhibited the capacity to consume a measureable quantity of DOC when grown in isolation, suggesting that this phenomenon may not be common among readily culturable marine bacteria. Physiological investigations of this isolate reveal a broad capacity for processing carbohydrates, yet an apparent preference for disaccharides and inability to metabolize glucose. Genomic analysis confirmed that this strain lacks a glucose-specific permease required for the exogenous uptake of glucose, but is endowed with additional carbohydrate-specific transporters not found in genomes of closely related bacterial strains. Genomic insights also show the potential to reduce nitrate, a high capacity to scavenge iron, and a complete chemotaxis apparatus potentially used for disaccharide acquisition. DOM characterization by ultrahigh resolution mass spectrometry revealed that AltSIO and diverse seawater communities significantly alter the composition of ambient DOM.

Marine dissolved organic matter (DOM) is a complex mixture of molecules found throughout the world's oceans. It plays a key role in the export, distribution, and sequestration of carbon in the oceanic water column, posited to be a source of atmospheric climate regulation. Biogeochemistry of Marine Dissolved Organic Matter, Second Edition, focuses on the chemical constituents of DOM and its biogeochemical, biological, and ecological significance in the global ocean, and provides a single, unique source for the references, information, and informed judgments of the community of marine biogeochemists. Presented by some of the world's leading scientists, this revised edition reports on the major advances in this area and includes new chapters covering the role of DOM in ancient ocean carbon cycles, the long term stability of marine DOM, the biophysical dynamics of DOM, fluvial DOM qualities and fate, and the Mediterranean Sea. Biogeochemistry of Marine Dissolved Organic Matter, Second Edition, is an extremely useful resource that helps people interested in the largest pool of active carbon on the planet (DOC) get a firm grounding on the general paradigms and many of the relevant references on this topic. Features up-to-date knowledge of DOM, including five new chapters The only published work to synthesize recent research on dissolved organic carbon in the Mediterranean Sea Includes chapters that address inputs from freshwater terrestrial DOM

The newly revised and updated third edition of the bestselling book on microbial ecology in the oceans The third edition of Microbial Ecology of the Oceans features new topics, as well as different approaches to subjects dealt with in previous editions. The book starts out with a general introduction to the changes in the field, as well as looking at the prospects for the coming years. Chapters cover ecology, diversity, and function of microbes, and of microbial genes in the ocean. The biology and ecology of some model organisms, and how we can model the whole of the marine microbes, are dealt with, and some of the trophic roles that have changed in the last years are discussed. Finally, the role of microbes in the oceanic P cycle are presented. Microbial Ecology of the Oceans, Third Edition offers chapters on The Evolution of Microbial Ecology of the Ocean; Marine Microbial Diversity as Seen by High Throughput Sequencing; Ecological Significance of Microbial Trophic Mixing in the Oligotrophic Ocean; Metatranscritomics and Metaproteomics; Advances in Microbial Ecology from Model Marine Bacteria; Marine Microbes and Nonliving Organic Matter; Microbial Ecology and Biogeochemistry of Oxygen-Deficient Water Columns; The Ocean’s Microscale; Ecological Genomics of Marine Viruses; Microbial Physiological Ecology of The Marine Phosphorus Cycle; Phytoplankton Functional Types; and more. A new and updated edition of a key book in aquatic microbial ecology Includes widely used methodological approaches Fully describes the structure of the microbial ecosystem, discussing in particular the sources of carbon for microbial growth Offers theoretical interpretations of subtropical plankton biogeography Microbial Ecology of the Oceans is an ideal text for advanced undergraduates, beginning graduate students, and colleagues from other fields wishing to learn about microbes and the processes they mediate in marine systems.

The Encyclopedia is a complete and authoritative reference work for this rapidly evolving field. Over 200 international scientists, each experts in their specialties, have written over 330 separate topics on different aspects of geochemistry including geochemical thermodynamics and kinetics, isotope and organic geochemistry, meteorites and cosmochemistry, the carbon cycle and climate, trace elements, geochemistry of high and low temperature processes, and ore deposition, to name just a few. The geochemical behavior of the elements is described as is the state of the art in analytical geochemistry. Each topic incorporates cross-referencing to related articles, and also has its own reference list to lead the reader to the essential articles within the published literature. The entries are arranged alphabetically, for easy access, and the subject and citation indices are comprehensive and extensive. Geochemistry applies chemical techniques and approaches to understanding the Earth and how it works. It touches upon almost every aspect of earth science, ranging from applied topics such as the search for energy and mineral resources, environmental pollution, and climate change to more basic questions such as the Earth’s origin and composition, the origin and evolution of life, rock weathering and metamorphism, and the pattern of ocean and mantle circulation. Geochemistry allows us to assign absolute ages to events in Earth’s history, to trace the flow of ocean water both now and in the past, trace sediments into subduction zones and arc volcanoes, and trace petroleum to its source rock and ultimately the environment in which it formed. The earliest of evidence of life is chemical and isotopic traces, not fossils, preserved in rocks. Geochemistry has allowed us to unravel the history of the ice ages and thereby deduce their cause. Geochemistry allows us to determine the swings in Earth’s surface temperatures during the ice ages, determine the temperatures and pressures at which rocks have been metamorphosed, and the rates at which ancient magma chambers cooled and crystallized. The field has grown rapidly more sophisticated, in both analytical techniques that can determine elemental concentrations or isotope ratios with exquisite precision and in computational modeling on scales ranging from atomic to planetary.

A core text on principles, laboratory/field methodologies, and data interpretation for fluorescence applications in aquatic science, for advanced students and researchers.

Bacterioplankton communities play a crucial role marine biogeochemical cycles because they mediate the flux of dissolved organic matter (DOM), which is equal to about half of primary production in the ocean. These bacterial communities are also known to be incredibly diverse and comprised of bacteria from several different phylogenetic groups. However, the relationship between microbial diversity and biogeochemical cycling remains unclear. My dissertation focused on determining the contributions of abundant bacterial phylogenetic groups to the biogeochemical flux of DOM in the ocean. One specific goal if this dissertation was the identification and quantification of bacteria that assimilate the organic sulfur compound dimethylsulfoniopropionate (DMSP). DMSP can be hydrolyzed to produce dimethylsulfide (DMS), a sulfurous gas hypothesized to moderate changes in global temperature. However, most dissolved DMSP is assimilated into bacterial biomass, a process that satisfies nearly all of the bacterial S demand in the surface waters of the ocean. Since the biogeochemical fate of DMSP can affect either climate regulation or S transfer through marine food webs, it is important to identify bacteria that metabolize DMSP. To identify and quantify bacteria assimilating DMSP, I used a combination of micro-autoradiography and fluorescence in situ hybridization (Micro-FISH) to follow 35 S-DMSP assimilation into marine bacterial communities. In addition to DMSP flux, I also investigated the ecological activity of SAR11 bacteria. Gene sequences belonging to the SAR11 clade typically dominate 16S rRNA clone libraries from the ocean, and investigations with fluorescence in situ hybridization confirm that SAR11 bacteria often make up 25--35% of bacterioplankton communities. (Abstract shortened by UMI.).