Twining B.S.,Bigelow Laboratory for Ocean Sciences |
Baines S.B.,State University of New York at Stony Brook
Annual Review of Marine Science | Year: 2013
Trace metals are required for numerous processes in phytoplankton and can influence the growth and structure of natural phytoplankton communities. The metal contents of phytoplankton reflect biochemical demands as well as environmental availability and influence the distribution of metals in the ocean. Metal quotas of natural populations can be assessed from analyses of individual cells or bulk particle assemblages or inferred from ratios of dissolved metals and macronutrients in the water column. Here, we review the available data from these approaches for temperate, equatorial, and Antarctic waters in the Pacific and Atlantic Oceans. The data show a generalized metal abundance ranking of Fe≈Zn>Mn≈Ni≈Cu≫Co≈Cd; however, there are notable differences between taxa and regions that inform our understanding of ocean metal biogeochemistry. Differences in the quotas estimated by the various techniques also provide information on metal behavior. Therefore, valuable information is lost when a single metal stoichiometry is assumed for all phytoplankton. © 2013 by Annual Reviews. All rights reserved.
Emerson D.,Bigelow Laboratory for Ocean Sciences
Biochemical Society Transactions | Year: 2012
Today high Fe(II) environments are relegated to oxic-anoxic habitats with opposing gradients of O2 and Fe(II); however, during the late Archaean and early Proterozoic eons, atmospheric O2 concentrations were much lower and aqueous Fe(II) concentrations were significantly higher. In current Fe(II)-rich environments, such as hydrothermal vents, mudflats, freshwater wetlands or the rhizosphere, rusty mat-like deposits are common. The presence of abundant biogenic microtubular or filamentous iron oxyhydroxides readily reveals the role of FeOB (iron-oxidizing bacteria) in iron mat formation. Cultivation and cultivation-independent techniques, confirm that FeOB are abundant in these mats. Despite remarkable similarities in morphological characteristics between marine and freshwater FeOB communities, the resident populations of FeOB are phylogenetically distinct, with marine populations related to the class Zetaproteobacteria, whereas freshwater populations are dominated by members of the Gallionallaceae, a family within the Betaproteobacteria. Little is known about the mechanism of how FeOB acquire electrons from Fe(II), although it is assumed that it involves electron transfer from the site of iron oxidation at the cell surface to the cytoplasmic membrane. Comparative genomics between freshwater and marine strains reveals few shared genes, except for a suite of genes that include a class of molybdopterin oxidoreductase that could be involved in iron oxidation via extracellular electron transport. Other genes are implicated as well, and the overall genomic analysis reveals a group of organisms exquisitely adapted for growth on iron. ©The Authors Journal compilation ©2012 Biochemical Society.
Carpenter L.J.,University of York |
Archer S.D.,Bigelow Laboratory for Ocean Sciences |
Beale R.,Plymouth Marine Laboratory
Chemical Society Reviews | Year: 2012
The oceans contribute significantly to the global emissions of a number of atmospherically important volatile gases, notably those containing sulfur, nitrogen and halogens. Such gases play critical roles not only in global biogeochemical cycling but also in a wide range of atmospheric processes including marine aerosol formation and modification, tropospheric ozone formation and destruction, photooxidant cycling and stratospheric ozone loss. A number of marine emissions are greenhouse gases, others influence the Earth's radiative budget indirectly through aerosol formation and/or by modifying oxidant levels and thus changing the atmospheric lifetime of gases such as methane. In this article we review current literature concerning the physical, chemical and biological controls on the sea-air emissions of a wide range of gases including dimethyl sulphide (DMS), halocarbons, nitrogen-containing gases including ammonia (NH3), amines (including dimethylamine, DMA, and diethylamine, DEA), alkyl nitrates (RONO2) and nitrous oxide (N 2O), non-methane hydrocarbons (NMHC) including isoprene and oxygenated (O)VOCs, methane (CH4) and carbon monoxide (CO). Where possible we review the current global emission budgets of these gases as well as known mechanisms for their formation and loss in the surface ocean. © The Royal Society of Chemistry 2012.
Agency: NSF | Branch: Standard Grant | Program: | Phase: ANTARCTIC ORGANISMS & ECOSYST | Award Amount: 1.09M | Year: 2016
The Southern Ocean in the vicinity of Antarctica is a region characterized by seasonally-driven marine phytoplankton blooms that are often dominated by microalgal species which produce large amounts of dimethylsulfoniopropionate (DMSP). DMSP can be converted to the compound dimethylsulfide (DMS) which is a molecule that can escape into the atmosphere where it is known to have strong condensation properties that are involved in regional cloud formation. Production of DMSP can influence the diversity and composition of microbial assemblages in seawater and the types and activities of microbes in the seawater will likely affect the magnitude of DMSP\DMS production. The proposal aims to examine the role of DMSP in structuring the microbial communities in Antarctic waters and how this structuring may influence DMSP cycling. The project will leverage the Antarctic research to introduce concepts and data linking microbial diversity and biogeochemistry to a range of audiences (including high school and undergraduate students in Maine). The project will also engage teacher and students in rural K-8 schools and will allow a collaboration with a science writer and illustrator who will join the team in the field. The writer will use the southern ocean experience as the setting for a poster and a book about the proposed research and the scientists studying extreme environments.
The project will examine (1) the extent to which the cycling of DMSP in southern ocean waters influences the composition and diversity of bacterial and protistan assemblages; (2) conversely, whether the composition and diversity of southern ocean protistan and bacterial assemblages influence the magnitude and rates of DMSP cycling; (3) the expression of DMSP degradation genes by marine bacteria seasonally and in response to additions of DMSP; and, to synthesize these results by quantifying (4) the microbial networks resulting from the presence of DMSP-producers and DMSP-consumers along with their predators, all involved in the cycling of DMSP in southern ocean waters. The work will be accomplished by conducting continuous growth experiments with DMSP-amended natural samples during field sampling of different microbial communities present in summer and fall. Data from the molecular (such as 16S/ 18S tag sequences, DMSP-cycle gene transcripts) and biogeochemical (such as biogenic sulfur cycling, bacterial production, microbial biomass) investigations will be integrated via network analysis.
Agency: NSF | Branch: Standard Grant | Program: | Phase: | Award Amount: 745.25K | Year: 2015
Coral reefs worldwide have suffered catastrophic losses of calcifying (reef-building) organisms such as corals and crustose coralline algae (CCA). These calcifiers construct and cement the reef together, providing a complex three-dimensional structure for a diverse array of reef-associated species. On many reefs, these calcifiers have been replaced by non-calcifying, fleshy species such as seaweeds and other invertebrates. Such drastic shifts in ecosystem structure and function, documented since the 1980s, are driven by complex interactions between anthropogenically induced changes to the marine environment (i.e., eutrophication, sedimentation, or over-fishing), climate-related change (increase frequency and severity of storms, global warming, and ocean acidification), outbreaks of predators, and the spread of disease. Traditionally, investigations have largely focused on one stressor at a time, and rarely explore the complexity introduced when combinations of stressors impact a marine ecosystem, a reality most coral reefs face. This project examines an important, yet difficult to study, interaction between climate driven physical parameters (seawater temperature and pH) and the disease ecology of a coralline fungal infection, recently identified by investigators on this project, for an understudied but critical component of reef ecosystems. The primary scientific and societal broader impacts of this project will be advancing our ability to predict the future effects of climate change on disease outbreaks that negatively affect carbonate accretion and primary production of key taxa in coral reef ecosystems. This project supports the education and training of undergraduate students and a postdoctoral scholar in an international arena, engages the governors Coral Reef Advisory Group in American Samoa, and informs the general public through in-person discussions online (Google Hangout) and at a Café Scientifique.
Many tropical species of CCA are particularly sensitive to slight changes in temperature and pH in an experimental setting and the central hypothesis is that climate induced change will hasten the spread and severity of the coralline fungal disease (CFD). The exact mechanisms of how and why a previously healthy CCA host becomes infected by the endolithic fungi are unclear. Thus the two major goals of the proposed research include: 1) a description of the CFD dynamics (incidence, prevalence, and mechanism of transmission across, and progression within, various coralline host species), and 2) an exploration of how climate-driven global change (i.e., rising SST and seawater acidity) will affect these dynamics using lab experiments and field observations. A combination of high-resolution, large-scale benthic imagery and novel sensor technology arrayed across reef habitats on Palmyra Atoll will be used to relate the spatial distribution of infected or resistant host CCA species, fungal colony-forming units, and environmental conditions over time in a natural setting at a reef-scale. High frequency time series of seawater pH, pCO2, salinity, and temperature data, calibrated and complemented by discrete sampling for additional carbonate parameters (total alkalinity and dissolved inorganic carbon), will be related with biological data (disease prevalence, incidence, and host physiology). In addition, these field measurements will inform laboratory experiments performed at an organismal scale and designed to test alternative hypotheses about agents of disease progression within a calcareous host.