Showing papers by "Woods Hole Oceanographic Institution published in 2012"
TL;DR: In marine ecosystems, rising atmospheric CO2 and climate change are associated with concurrent shifts in temperature, circulation, stratification, nutrient input, oxygen content, and ocean acidification, with potentially wide-ranging biological effects.
Abstract: In marine ecosystems, rising atmospheric CO2 and climate change are associated with concurrent shifts in temperature, circulation, stratification, nutrient input, oxygen content, and ocean acidification, with potentially wideranging biological effects. Population-level shifts are occurring because of physiological intolerance to new environments, altered dispersal patterns, and changes in species interactions. Together with local climate-driven invasion and extinction, these processes result in altered community structure and diversity, including possible emergence of novel ecosystems. Impacts are particularly striking for the poles and the tropics, because of the sensitivity of polar ecosystems to sea-ice retreat and poleward species migrations as well as the sensitivity of coral-algal symbiosis to minor increases in temperature. Midlatitude upwelling systems, like the California Current, exhibit strong linkages between climate and species distributions, phenology, and demography. Aggregated effects may modify energy and material flows as well as biogeochemical cycles, eventually impacting the overall ecosystem functioning and services upon which people and societies depend.
2,136 citations
Flanders Marine Institute1, University of New South Wales2, Australian Museum3, University of Southern Mississippi4, National Oceanography Centre, Southampton5, University of Hasselt6, WorldFish7, American Museum of Natural History8, San Diego State University9, Museum Victoria10, Natural History Museum11, Dowling College12, University of Hamburg13, James Cook University14, University of Johannesburg15, National Museum of Natural History16, National Taiwan Ocean University17, Scripps Institution of Oceanography18, National Oceanic and Atmospheric Administration19, University of Queensland20, University of Sassari21, Vrije Universiteit Brussel22, Université libre de Bruxelles23, Queensland Museum24, University of California, Merced25, Ghent University26, Naturalis27, Howard University28, University of Gothenburg29, California Academy of Sciences30, Florida Museum of Natural History31, Centre for Environment, Fisheries and Aquaculture Science32, Osaka University33, University of Santiago de Compostela34, University of Alaska Anchorage35, University of Málaga36, National Institute of Water and Atmospheric Research37, National University of Ireland, Galway38, University of Alaska Fairbanks39, Spanish National Research Council40, CABI41, University of Siegen42, Massey University43, University of Copenhagen44, Naturhistorisches Museum45, University of Washington46, Museum für Naturkunde47, Woods Hole Oceanographic Institution48, Western Washington University49, University of Bergen50, Nova Southeastern University51, Shirshov Institute of Oceanology52, National University of Singapore53, Shimane University54, Agnes Scott College55, University of the Ryukyus56, University of California, Davis57, Federal University of Paraná58, University of the Basque Country59, University of Veterinary Medicine Hanover60, Royal Belgian Institute of Natural Sciences61, Tel Aviv University62, Swedish Museum of Natural History63, Joint Nature Conservation Committee64, The Evergreen State College65, Estonian University of Life Sciences66, University of Maine67, Virginia Commonwealth University68, Trinity College, Dublin69, University of Auckland70
TL;DR: The first register of the marine species of the world is compiled and it is estimated that between one-third and two-thirds of marine species may be undescribed, and previous estimates of there being well over one million marine species appear highly unlikely.
822 citations
TL;DR: Here, HAB science is reviewed with an eye toward new concepts and approaches, emphasizing, where possible, the unexpected yet promising new directions that research has taken in this diverse field.
Abstract: The public health, tourism, fisheries, and ecosystem impacts from harmful algal blooms (HABs) have all increased over the past few decades. This has led to heightened scientific and regulatory attention, and the development of many new technologies and approaches for research and management. This, in turn, is leading to significant paradigm shifts with regard to, e.g., our interpretation of the phytoplankton species concept (strain variation), the dogma of their apparent cosmopolitanism, the role of bacteria and zooplankton grazing in HABs, and our approaches to investigating the ecological and genetic basis for the production of toxins and allelochemicals. Increasingly, eutrophication and climate change are viewed and managed as multifactorial environmental stressors that will further challenge managers of coastal resources and those responsible for protecting human health. Here we review HAB science with an eye toward new concepts and approaches, emphasizing, where possible, the unexpected yet promising new directions that research has taken in this diverse field.
769 citations
University of California, Santa Barbara1, Oregon State University2, National Oceanic and Atmospheric Administration3, Conservation International4, University of British Columbia5, Duke University6, University of Alaska Fairbanks7, Stanford University8, University of South Florida9, Woods Hole Oceanographic Institution10, Brown University11, University of Washington12, University of Minnesota13, New England Aquarium14, Rutgers University15
TL;DR: An index comprising ten diverse public goals for a healthy coupled human–ocean system and calculated the index for every coastal country provides a powerful tool to raise public awareness, direct resource management, improve policy and prioritize scientific research.
Abstract: The ocean plays a critical role in supporting human well-being, from providing food, livelihoods and recreational opportunities to regulating the global climate. Sustainable management aimed at maintaining the flow of a broad range of benefits from the ocean requires a comprehensive and quantitative method to measure and monitor the health of coupled human–ocean systems. We created an index comprising ten diverse public goals for a healthy coupled human–ocean system and calculated the index for every coastal country. Globally, the overall index score was 60 out of 100 (range 36–86), with developed countries generally performing better than developing countries, but with notable exceptions. Only 5% of countries scored higher than 70, whereas 32% scored lower than 50. The index provides a powerful tool to raise public awareness, direct resource management, improve policy and prioritize scientific research.
734 citations
TL;DR: In this paper, a synthesis of the latest observations suggests that more longwave radiation is received at the Earth's surface than previously thought, and that more precipitation is generated, and the additional precipitation is sustained by more energy leaving the surface by evaporation, that is, in the form of latent heat flux.
Abstract: Climate change is governed by changes to the global energy balance. A synthesis of the latest observations suggests that more longwave radiation is received at the Earth's surface than previously thought, and that more precipitation is generated. Climate change is governed by changes to the global energy balance. At the top of the atmosphere, this balance is monitored globally by satellite sensors that provide measurements of energy flowing to and from Earth. By contrast, observations at the surface are limited mostly to land areas. As a result, the global balance of energy fluxes within the atmosphere or at Earth's surface cannot be derived directly from measured fluxes, and is therefore uncertain. This lack of precise knowledge of surface energy fluxes profoundly affects our ability to understand how Earth's climate responds to increasing concentrations of greenhouse gases. In light of compilations of up-to-date surface and satellite data, the surface energy balance needs to be revised. Specifically, the longwave radiation received at the surface is estimated to be significantly larger, by between 10 and 17 Wm−2, than earlier model-based estimates. Moreover, the latest satellite observations of global precipitation indicate that more precipitation is generated than previously thought. This additional precipitation is sustained by more energy leaving the surface by evaporation — that is, in the form of latent heat flux — and thereby offsets much of the increase in longwave flux to the surface.
678 citations
Stanford University1, Dartmouth College2, Cold Regions Research and Engineering Laboratory3, Woods Hole Oceanographic Institution4, Bigelow Laboratory For Ocean Sciences5, Bermuda Institute of Ocean Sciences6, University of South Carolina7, University of California, San Diego8, Clark University9, University of Alaska Fairbanks10, Pierre-and-Marie-Curie University11, University of Toronto12, University of Paris13, Colby College14
TL;DR: Evidence suggests that under-ice phytoplankton blooms may be more widespread over nutrient-rich Arctic continental shelves and that satellite-based estimates of annual primary production in these waters may be underestimated by up to 10-fold.
Abstract: Phytoplankton blooms over Arctic Ocean continental shelves are thought to be restricted to waters free of sea ice Here, we document a massive phytoplankton bloom beneath fully consolidated pack ice far from the ice edge in the Chukchi Sea, where light transmission has increased in recent decades because of thinning ice cover and proliferation of melt ponds The bloom was characterized by high diatom biomass and rates of growth and primary production Evidence suggests that under-ice phytoplankton blooms may be more widespread over nutrient-rich Arctic continental shelves and that satellite-based estimates of annual primary production in these waters may be underestimated by up to 10-fold
651 citations
TL;DR: Comparison of the endmember gas and oil composition with the composition of water column samples showed that the plume was preferentially enriched with water-soluble components, indicating that aqueous dissolution played a major role in plume formation, whereas the fates of relatively insoluble petroleum components were initially controlled by other processes.
Abstract: Quantitative information regarding the endmember composition of the gas and oil that flowed from the Macondo well during the Deepwater Horizon oil spill is essential for determining the oil flow rate, total oil volume released, and trajectories and fates of hydrocarbon components in the marine environment. Using isobaric gas-tight samplers, we collected discrete samples directly above the Macondo well on June 21, 2010, and analyzed the gas and oil. We found that the fluids flowing from the Macondo well had a gas-to-oil ratio of 1,600 standard cubic feet per petroleum barrel. Based on the measured endmember gas-to-oil ratio and the Federally estimated net liquid oil release of 4.1 million barrels, the total amount of C1-C5 hydrocarbons released to the water column was 1.7 × 1011 g. The endmember gas and oil compositions then enabled us to study the fractionation of petroleum hydrocarbons in discrete water samples collected in June 2010 within a southwest trending hydrocarbon-enriched plume of neutrally buoyant water at a water depth of 1,100 m. The most abundant petroleum hydrocarbons larger than C1-C5 were benzene, toluene, ethylbenzene, and total xylenes at concentrations up to 78 μg L-1. Comparison of the endmember gas and oil composition with the composition of water column samples showed that the plume was preferentially enriched with water-soluble components, indicating that aqueous dissolution played a major role in plume formation, whereas the fates of relatively insoluble petroleum components were initially controlled by other processes.
644 citations
TL;DR: In this paper, the authors used reconstructed sea surface temperature datasets and century-long ocean and atmosphere reanalysis products to find that the post-1900 surface ocean warming rate over the path of these currents is two to three times faster than the global mean surface ocean cooling rate.
Abstract: Subtropical western boundary currents are warm, fast-flowing currents that form on the western side of ocean basins. They carry warm tropical water to the mid-latitudes and vent large amounts of heat and moisture to the atmosphere along their paths, affecting atmospheric jet streams and mid-latitude storms, as well as ocean carbon uptake1, 2, 3, 4. The possibility that these highly energetic currents might change under greenhouse-gas forcing has raised significant concerns5, 6, 7, but detecting such changes is challenging owing to limited observations. Here, using reconstructed sea surface temperature datasets and century-long ocean and atmosphere reanalysis products, we find that the post-1900 surface ocean warming rate over the path of these currents is two to three times faster than the global mean surface ocean warming rate. The accelerated warming is associated with a synchronous poleward shift and/or intensification of global subtropical western boundary currents in conjunction with a systematic change in winds over both hemispheres. This enhanced warming may reduce the ability of the oceans to absorb anthropogenic carbon dioxide over these regions. However, uncertainties in detection and attribution of these warming trends remain, pointing to a need for a long-term monitoring network of the global western boundary currents and their extensions.
564 citations
TL;DR: The dinoflagellate genus Alexandrium is one of the major harmful algal bloom (HAB) genera with respect to the diversity, magnitude and consequences of blooms.
546 citations
TL;DR: In this article, seasonal and annual constituent fluxes have been determined using consistent sampling and analytical methods at the pan-Arctic scale and consequently provide the best available estimates for constituent flux from land to the Arctic Ocean and surrounding seas.
Abstract: River inputs of nutrients and organic matter impact the biogeochemistry of arctic estuaries and the Arctic Ocean as a whole, yet there is considerable uncertainty about the magnitude of fluvial fluxes at the pan-Arctic scale. Samples from the six largest arctic rivers, with a combined watershed area of 11.3 × 106 km2, have revealed strong seasonal variations in constituent concentrations and fluxes within rivers as well as large differences among the rivers. Specifically, we investigate fluxes of dissolved organic carbon, dissolved organic nitrogen, total dissolved phosphorus, dissolved inorganic nitrogen, nitrate, and silica. This is the first time that seasonal and annual constituent fluxes have been determined using consistent sampling and analytical methods at the pan-Arctic scale and consequently provide the best available estimates for constituent flux from land to the Arctic Ocean and surrounding seas. Given the large inputs of river water to the relatively small Arctic Ocean and the dramatic impacts that climate change is having in the Arctic, it is particularly urgent that we establish the contemporary river fluxes so that we will be able to detect future changes and evaluate the impact of the changes on the biogeochemistry of the receiving coastal and ocean systems.
543 citations
TL;DR: The ocean component of the Community Climate System Model version 4 (CCSM4) is described, and its solutions from the twentieth-century (20C) simulations are documented in comparison with observations and those of CCSM3 as discussed by the authors.
Abstract: The ocean component of the Community Climate System Model version 4 (CCSM4) is described, and its solutions from the twentieth-century (20C) simulations are documented in comparison with observations and those of CCSM3. The improvements to the ocean model physical processes include new parameterizations to represent previously missing physics and modifications of existing parameterizations to incorporate recent new developments. In comparison with CCSM3, the new solutions show some significant improvements that can be attributed to these model changes. These include a better equatorial current structure, a sharper thermocline, and elimination of the cold bias of the equatorial cold tongue all in the Pacific Ocean; reduced sea surface temperature (SST) and salinity biases along the North Atlantic Current path; and much smaller potential temperature and salinity biases in the near-surface Pacific Ocean. Other improvements include a global-mean SST that is more consistent with the present-day observa...
01 Jul 2012
TL;DR: The magnetotelluric method is a technique for imaging the electrical conductivity and structure of the Earth, from the near-surface down to the 410 km transition zone and beyond as discussed by the authors.
Abstract: The magnetotelluric method is a technique for imaging the electrical conductivity and structure of the Earth, from the near-surface down to the 410 km transition zone and beyond. It is increasingly used in geological applications and the petroleum industry. This book forms the first comprehensive overview of magnetotellurics, from the salient physics and its mathematical representation, to practical implementation in the field, data processing, modeling, and geological interpretation. Electromagnetic induction in 1D, 2D, and 3D media is explored, building from first principles, and with thorough coverage of the practical techniques of time-series processing, distortion, numerical modeling and inversion. The fundamental principles are illustrated with a series of case histories describing geological applications. Technical issues, instrumentation and field practices are described for both land and marine surveys. This book provides a rigorous introduction to the magnetotelluric method for academic researchers and advanced students, and will be of interest to industrial practitioners and geoscientists wanting to incorporate rock conductivity into their interpretations.
TL;DR: By quantifying the amount of oil at different locations (wellhead, ocean surface, and atmosphere), it is concluded that just over 2 million barrels of oil (after accounting for containment) and all of the released methane remained in the deep sea.
Abstract: The unprecedented nature of the Deepwater Horizon oil spill required the application of research methods to estimate the rate at which oil was escaping from the well in the deep sea, its disposition after it entered the ocean, and total reservoir depletion. Here, we review what advances were made in scientific understanding of quantification of flow rates during deep sea oil well blowouts. We assess the degree to which a consensus was reached on the flow rate of the well by comparing in situ observations of the leaking well with a time-dependent flow rate model derived from pressure readings taken after the Macondo well was shut in for the well integrity test. Model simulations also proved valuable for predicting the effect of partial deployment of the blowout preventer rams on flow rate. Taken together, the scientific analyses support flow rates in the range of ∼50,000–70,000 barrels/d, perhaps modestly decreasing over the duration of the oil spill, for a total release of ∼5.0 million barrels of oil, not accounting for BP's collection effort. By quantifying the amount of oil at different locations (wellhead, ocean surface, and atmosphere), we conclude that just over 2 million barrels of oil (after accounting for containment) and all of the released methane remained in the deep sea. By better understanding the fate of the hydrocarbons, the total discharge can be partitioned into separate components that pose threats to deep sea vs. coastal ecosystems, allowing responders in future events to scale their actions accordingly.
TL;DR: Using genetic parentage analyses, patterns of larval dispersal for two species of exploited coral reef fish within a network of marine reserves on the Great Barrier Reef are resolved and provide compelling evidence that adequately protected reserve networks can make a significant contribution to the replenishment of populations on both reserve and fished reefs at a scale that benefits local stakeholders.
TL;DR: The redox state of arc magmas is tracked from mantle source to emplacement in the crust on the basis of copper’s (Cu) affinity for reduced sulfur phases, suggesting that the formation of sulfide-bearing cumulates under reducing conditions may be a critical step in continent formation.
Abstract: Arc magmas are important building blocks of the continental crust. Because many arc lavas are oxidized, continent formation is thought to be associated with oxidizing conditions. On the basis of copper's (Cu's) affinity for reduced sulfur phases, we tracked the redox state of arc magmas from mantle source to emplacement in the crust. Primary arc and mid-ocean ridge basalts have identical Cu contents, indicating that the redox states of primitive arc magmas are indistinguishable from that of mid-ocean ridge basalts. During magmatic differentiation, the Cu content of most arc magmas decreases markedly because of sulfide segregation. Because a similar depletion in Cu characterizes global continental crust, the formation of sulfide-bearing cumulates under reducing conditions may be a critical step in continent formation.
TL;DR: This analysis suggests that while atmospheric deposition is the main source of inorganic Hg to open ocean systems, most of the CH₃Hg accumulating in ocean fish is derived from in situ production within the upper waters (<1000 m), and that the deeper waters of the oceans are responding slowly to changes in atmospheric Hg inputs.
Oregon State University1, Harvard University2, Duke University3, University of Oregon4, University of Utah5, University of Wisconsin-Madison6, Northern Arizona University7, Peking University8, University of Colorado Boulder9, National Oceanic and Atmospheric Administration10, National Center for Atmospheric Research11, University of Hawaii at Manoa12, Brown University13, Montana State University14, California Institute of Technology15, University of Minnesota16, Woods Hole Oceanographic Institution17, University of South Florida18, Georgia Institute of Technology19, Columbia University20, University of Chile21
TL;DR: A major effort by the paleoclimate research community to characterize changes through the development of well-dated, high-resolution records of the deep and intermediate ocean as well as surface climate indicates that the superposition of two modes explains much of the variability in regional and global climate during the last deglaciation.
Abstract: Deciphering the evolution of global climate from the end of the Last Glacial Maximum approximately 19 ka to the early Holocene 11 ka presents an outstanding opportunity for understanding the transient response of Earth’s climate system to external and internal forcings. During this interval of global warming, the decay of ice sheets caused global mean sea level to rise by approximately 80 m; terrestrial and marine ecosystems experienced large disturbances and range shifts; perturbations to the carbon cycle resulted in a net release of the greenhouse gases CO2 and CH4 to the atmosphere; and changes in atmosphere and ocean circulation affected the global distribution and fluxes of water and heat. Here we summarize a major effort by the paleoclimate research community to characterize these changes through the development of well-dated, high-resolution records of the deep and intermediate ocean as well as surface climate. Our synthesis indicates that the superposition of two modes explains much of the variability in regional and global climate during the last deglaciation, with a strong association between the first mode and variations in greenhouse gases, and between the second mode and variations in the Atlantic meridional overturning circulation.
TL;DR: The most important sources of atmospheric moisture at the global scale are identified, both oceanic and terrestrial, and a characterization is made of how continental regions are influenced by water from different moisture source regions as discussed by the authors.
Abstract: [1] The most important sources of atmospheric moisture at the global scale are herein identified, both oceanic and terrestrial, and a characterization is made of how continental regions are influenced by water from different moisture source regions. The methods used to establish source-sink relationships of atmospheric water vapor are reviewed, and the advantages and caveats associated with each technique are discussed. The methods described include analytical and box models, numerical water vapor tracers, and physical water vapor tracers (isotopes). In particular, consideration is given to the wide range of recently developed Lagrangian techniques suitable both for evaluating the origin of water that falls during extreme precipitation events and for establishing climatologies of moisture source-sink relationships. As far as oceanic sources are concerned, the important role of the subtropical northern Atlantic Ocean provides moisture for precipitation to the largest continental area, extending from Mexico to parts of Eurasia, and even to the South American continent during the Northern Hemisphere winter. In contrast, the influence of the southern Indian Ocean and North Pacific Ocean sources extends only over smaller continental areas. The South Pacific and the Indian Ocean represent the principal source of moisture for both Australia and Indonesia. Some landmasses only receive moisture from the evaporation that occurs in the same hemisphere (e.g., northern Europe and eastern North America), while others receive moisture from both hemispheres with large seasonal variations (e.g., northern South America). The monsoonal regimes in India, tropical Africa, and North America are provided with moisture from a large number of regions, highlighting the complexities of the global patterns of precipitation. Some very important contributions are also seen from relatively small areas of ocean, such as the Mediterranean Basin (important for Europe and North Africa) and the Red Sea, which provides water for a large area between the Gulf of Guinea and Indochina (summer) and between the African Great Lakes and Asia (winter). The geographical regions of Eurasia, North and South America, and Africa, and also the internationally important basins of the Mississippi, Amazon, Congo, and Yangtze Rivers, are also considered, as is the importance of terrestrial sources in monsoonal regimes. The role of atmospheric rivers, and particularly their relationship with extreme events, is discussed. Droughts can be caused by the reduced supply of water vapor from oceanic moisture source regions. Some of the implications of climate change for the hydrological cycle are also reviewed, including changes in water vapor concentrations, precipitation, soil moisture, and aridity. It is important to achieve a combined diagnosis of moisture sources using all available information, including stable water isotope measurements. A summary is given of the major research questions that remain unanswered, including (1) the lack of a full understanding of how moisture sources influence precipitation isotopes; (2) the stationarity of moisture sources over long periods; (3) the way in which possible changes in intensity (where evaporation exceeds precipitation to a greater of lesser degree), and the locations of the sources, (could) affect the distribution of continental precipitation in a changing climate; and (4) the role played by the main modes of climate variability, such as the North Atlantic Oscillation or the El Nino–Southern Oscillation, in the variability of the moisture source regions, as well as a full evaluation of the moisture transported by low-level jets and atmospheric rivers.
TL;DR: It is shown that the initial stratification and resulting bloom are instead caused by eddy-driven slumping of the basin-scale north-south density gradient, resulting in a patchy bloom beginning 20 to 30 days earlier than would occur by warming.
Abstract: Springtime phytoplankton blooms photosynthetically fix carbon and export it from the surface ocean at globally important rates. These blooms are triggered by increased light exposure of the phytoplankton due to both seasonal light increase and the development of a near-surface vertical density gradient (stratification) that inhibits vertical mixing of the phytoplankton. Classically and in current climate models, that stratification is ascribed to a springtime warming of the sea surface. Here, using observations from the subpolar North Atlantic and a three-dimensional biophysical model, we show that the initial stratification and resulting bloom are instead caused by eddy-driven slumping of the basin-scale north-south density gradient, resulting in a patchy bloom beginning 20 to 30 days earlier than would occur by warming.
TL;DR: Risks to public health and marine biota are addressed by showing that though Cs isotopes are elevated 10–1,000× over prior levels in waters off Japan, radiation risks are below those generally considered harmful to marine animals and human consumers, and even below those from naturally occurring radionuclides.
Abstract: The Tōhoku earthquake and tsunami of March 11, 2011, resulted in unprecedented radioactivity releases from the Fukushima Dai-ichi nuclear power plants to the Northwest Pacific Ocean. Results are presented here from an international study of radionuclide contaminants in surface and subsurface waters, as well as in zooplankton and fish, off Japan in June 2011. A major finding is detection of Fukushima-derived 134Cs and 137Cs throughout waters 30–600 km offshore, with the highest activities associated with near-shore eddies and the Kuroshio Current acting as a southern boundary for transport. Fukushima-derived Cs isotopes were also detected in zooplankton and mesopelagic fish, and unique to this study we also find 110mAg in zooplankton. Vertical profiles are used to calculate a total inventory of ∼2 PBq 137Cs in an ocean area of 150,000 km2. Our results can only be understood in the context of our drifter data and an oceanographic model that shows rapid advection of contaminants further out in the Pacific. Importantly, our data are consistent with higher estimates of the magnitude of Fukushima fallout and direct releases [Stohl et al. (2011) Atmos Chem Phys Discuss 11:28319–28394; Bailly du Bois et al. (2011) J Environ Radioact, 10.1016/j.jenvrad.2011.11.015]. We address risks to public health and marine biota by showing that though Cs isotopes are elevated 10–1,000× over prior levels in waters off Japan, radiation risks due to these radionuclides are below those generally considered harmful to marine animals and human consumers, and even below those from naturally occurring radionuclides.
TL;DR: The presence of recently damaged and deceased corals beneath the path of a previously documented plume emanating from the Macondo well provides compelling evidence that the oil impacted deep-water ecosystems.
Abstract: To assess the potential impact of the Deepwater Horizon oil spill on offshore ecosystems, 11 sites hosting deep-water coral communities were examined 3 to 4 mo after the well was capped. Healthy coral communities were observed at all sites >20 km from the Macondo well, including seven sites previously visited in September 2009, where the corals and communities appeared unchanged. However, at one site 11 km southwest of the Macondo well, coral colonies presented widespread signs of stress, including varying degrees of tissue loss, sclerite enlargement, excess mucous production, bleached commensal ophiuroids, and covering by brown flocculent material (floc). On the basis of these criteria the level of impact to individual colonies was ranked from 0 (least impact) to 4 (greatest impact). Of the 43 corals imaged at that site, 46% exhibited evidence of impact on more than half of the colony, whereas nearly a quarter of all of the corals showed impact to >90% of the colony. Additionally, 53% of these corals’ ophiuroid associates displayed abnormal color and/or attachment posture. Analysis of hopanoid petroleum biomarkers isolated from the floc provides strong evidence that this material contained oil from the Macondo well. The presence of recently damaged and deceased corals beneath the path of a previously documented plume emanating from the Macondo well provides compelling evidence that the oil impacted deep-water ecosystems. Our findings underscore the unprecedented nature of the spill in terms of its magnitude, release at depth, and impact to deep-water ecosystems.
TL;DR: This paper presented an overview of the El Nino-Southern Oscillation (ENSO) phenomenon and Pacific decadal variability (PDV) simulated in a multicentury preindustrial control integration of the NCAR Community Climate System Model version 4 (CCSM4) at nominal 1° latitude-longitude resolution.
Abstract: This study presents an overview of the El Nino–Southern Oscillation (ENSO) phenomenon and Pacific decadal variability (PDV) simulated in a multicentury preindustrial control integration of the NCAR Community Climate System Model version 4 (CCSM4) at nominal 1° latitude–longitude resolution Several aspects of ENSO are improved in CCSM4 compared to its predecessor CCSM3, including the lengthened period (3–6 yr), the larger range of amplitude and frequency of events, and the longer duration of La Nina compared to El Nino However, the overall magnitude of ENSO in CCSM4 is overestimated by ~30% The simulated ENSO exhibits characteristics consistent with the delayed/recharge oscillator paradigm, including correspondence between the lengthened period and increased latitudinal width of the anomalous equatorial zonal wind stress Global seasonal atmospheric teleconnections with accompanying impacts on precipitation and temperature are generally well simulated, although the wintertime deepening of the Al
Woods Hole Oceanographic Institution1, University of Las Palmas de Gran Canaria2, Bar-Ilan University3, Aix-Marseille University4, Linnaeus University5, University of Hawaii6, University of Southern California7, San Francisco State University8, National Sun Yat-sen University9, Montana State University10, National Autonomous University of Mexico11, University of Vigo12, Max Planck Society13, University of Tokyo14, University of Valencia15, University of Southern Mississippi16, University of Georgia17, Leibniz Association18, Oregon State University19, University of Massachusetts Dartmouth20, University of California, Santa Cruz21, National Oceanography Centre, Southampton22, Old Dominion University23, Oregon Health & Science University24, National Oceanography Centre25, Plymouth Marine Laboratory26, University of Copenhagen27, Lamont–Doherty Earth Observatory28, University of Texas at Austin29, University of Miami30
TL;DR: This database is limited spatially, lacking large regions of the ocean especially in the Indian Ocean, but can nevertheless be used to study spatial and temporal distributions and variations of marine N2 fixation, to validate geochemical estimates and to parameterize and validate biogeochemical models.
Abstract: . Marine N2 fixing microorganisms, termed diazotrophs, are a key functional group in marine pelagic ecosystems. The biological fixation of dinitrogen (N2) to bioavailable nitrogen provides an important new source of nitrogen for pelagic marine ecosystems and influences primary productivity and organic matter export to the deep ocean. As one of a series of efforts to collect biomass and rates specific to different phytoplankton functional groups, we have constructed a database on diazotrophic organisms in the global pelagic upper ocean by compiling about 12 000 direct field measurements of cyanobacterial diazotroph abundances (based on microscopic cell counts or qPCR assays targeting the nifH genes) and N2 fixation rates. Biomass conversion factors are estimated based on cell sizes to convert abundance data to diazotrophic biomass. The database is limited spatially, lacking large regions of the ocean especially in the Indian Ocean. The data are approximately log-normal distributed, and large variances exist in most sub-databases with non-zero values differing 5 to 8 orders of magnitude. Reporting the geometric mean and the range of one geometric standard error below and above the geometric mean, the pelagic N2 fixation rate in the global ocean is estimated to be 62 (52–73) Tg N yr−1 and the pelagic diazotrophic biomass in the global ocean is estimated to be 2.1 (1.4–3.1) Tg C from cell counts and to 89 (43–150) Tg C from nifH-based abundances. Reporting the arithmetic mean and one standard error instead, these three global estimates are 140 p 9.2 Tg N yr−1, 18 p 1.8 Tg C and 590 p 70 Tg C, respectively. Uncertainties related to biomass conversion factors can change the estimate of geometric mean pelagic diazotrophic biomass in the global ocean by about p70%. It was recently established that the most commonly applied method used to measure N2 fixation has underestimated the true rates. As a result, one can expect that future rate measurements will shift the mean N2 fixation rate upward and may result in significantly higher estimates for the global N2 fixation. The evolving database can nevertheless be used to study spatial and temporal distributions and variations of marine N2 fixation, to validate geochemical estimates and to parameterize and validate biogeochemical models, keeping in mind that future rate measurements may rise in the future. The database is stored in PANGAEA ( doi:10.1594/PANGAEA.774851 ).
TL;DR: It is hypothesized that biodegradation and photooxidation share responsibility for the accumulation of oxygen in the oil residues, revealing that molecular-level transformations of petroleum hydrocarbons lead to increasing amounts of, apparently recalcitrant, oxyhydrocarbons that dominate the solvent-extractable material from oiled samples.
Abstract: Following the Deepwater Horizon disaster, the effect of weathering on surface slicks, oil-soaked sands, and oil-covered rocks and boulders was studied for 18 months. With time, oxygen content increased in the hydrocarbon residues. Furthermore, a weathering-dependent increase of an operationally defined oxygenated fraction relative to the saturated and aromatic fractions was observed. This oxygenated fraction made up >50% of the mass of weathered samples, had an average carbon oxidation state of −1.0, and an average molecular formula of (C5H7O)n. These oxygenated hydrocarbon residues were devoid of natural radiocarbon, confirming a fossil source and excluding contributions from recent photosynthate. The incorporation of oxygen into the oil’s hydrocarbons, which we refer to as oxyhydrocarbons, was confirmed from the detection of hydroxyl and carbonyl functional groups and the identification of long chain (C10–C32) carboxylic acids as well as alcohols. On the basis of the diagnostic ratios of alkanes and pol...
TL;DR: In this paper, it was shown that, contrary to the widely held view, H 2 O loss or gain in melt inclusions is not limited by redox reactions and significant fluxes of H + through the host olivine are possible on very short time scales.
Abstract: The solubility of H 2 O in silicate melt drops substantially with decreasing pressure, so that a magma initially containing several weight percent H 2 O in a crustal magma reservoir is left with only a few thousand parts per million following ascent and eruption at the Earth’s surface. This rapid release of volatiles makes determining the pre-eruptive H 2 O contents of magmas very difficult. Olivine-hosted melt inclusions are thought to retain their H 2 O because they are protected from decompression by the strength of the host crystal, and pre-eruptive concentrations obtained from melt inclusions have been used to both estimate the amount of H 2 O in the upper mantle and investigate its role in the melt generation process. The greatest uncertainty involved in constraining upper mantle conditions from melt inclusions is the potential for rapid diffusive loss or gain of H + (protons) through the host olivine. Here we present results from hydration and dehydration experiments that demonstrate that, contrary to the widely held view, H 2 O loss or gain in melt inclusions is not limited by redox reactions and significant fluxes of H + through the host olivine are possible on very short time scales. We also show that the Fe 3+ /ΣFe of an olivine-hosted melt inclusion maintains equilibrium with the external environment via diffusion of point defects through the host olivine. Our results demonstrate that, while pre-eruptive H 2 O and Fe 3+ /ΣFe can be reliably estimated, olivine-hosted melt inclusions do not necessarily retain a record of the H 2 O and O 2 fugacity conditions at which they formed. High-H 2 O melt inclusions are particularly susceptible to diffusive dehydration, and therefore are not reliable proxies for the state of the upper mantle.
TL;DR: In this paper, an analysis of sea snail specimens, extracted live from the Southern Ocean in January and February 2008, showed that the shells of these organisms are already dissolving and aragonite may become undersaturated by 2050 in the upper layers of the Southern ocean.
Abstract: As a result of ocean acidification, aragonite may become undersaturated by 2050 in the upper layers of the Southern Ocean. Analyses of sea snail specimens, extracted live from the Southern Ocean in January and February 2008, show that the shells of these organisms are already dissolving.
TL;DR: This work shows that structured, socially cohesive bacterial populations exist in the wild and form organizational patterns similar to those of animal and plant populations that mediate competition between populations rather than solely increase the success of individuals.
Abstract: In animals and plants, social structure can reduce conflict within populations and bias aggression toward competing populations; however, for bacteria in the wild it remains unknown whether such population-level organization exists. Here, we show that environmental bacteria are organized into socially cohesive units in which antagonism occurs between rather than within ecologically defined populations. By screening approximately 35,000 possible mutual interactions among Vibrionaceae isolates from the ocean, we show that genotypic clusters known to have cohesive habitat association also act as units in terms of antibiotic production and resistance. Genetic analyses show that within populations, broad-range antibiotics are produced by few genotypes, whereas all others are resistant, suggesting cooperation between conspecifics. Natural antibiotics may thus mediate competition between populations rather than solely increase the success of individuals.
TL;DR: Data demonstrate that diatom P deficiency results in changes in cellular P allocation through polyphosphate production, increased P transport, a switch to utilization of dissolved organic P through increased production of metalloenzymes, and a remodeling of the cell surface through production of sulfolipids.
Abstract: Phosphorus (P) is a critical driver of phytoplankton growth and ecosystem function in the ocean. Diatoms are an abundant class of marine phytoplankton that are responsible for significant amounts of primary production. With the control they exert on the oceanic carbon cycle, there have been a number of studies focused on how diatoms respond to limiting macro and micronutrients such as iron and nitrogen. However, diatom physiological responses to P deficiency are poorly understood. Here, we couple deep sequencing of transcript tags and quantitative proteomics to analyze the diatom Thalassiosira pseudonana grown under P-replete and P-deficient conditions. A total of 318 transcripts were differentially regulated with a false discovery rate of <0.05, and a total of 136 proteins were differentially abundant (p<0.05). Significant changes in the abundance of transcripts and proteins were observed and coordinated for multiple biochemical pathways, including glycolysis and translation. Patterns in transcript and protein abundance were also linked to physiological changes in cellular P distributions, and enzyme activities. These data demonstrate that diatom P deficiency results in changes in cellular P allocation through polyphosphate production, increased P transport, a switch to utilization of dissolved organic P through increased production of metalloenzymes, and a remodeling of the cell surface through production of sulfolipids. Together, these findings reveal that T. pseudonana has evolved a sophisticated response to P deficiency involving multiple biochemical strategies that are likely critical to its ability to respond to variations in environmental P availability.
TL;DR: Detailed airborne, surface, and subsurface chemical measurements, primarily obtained in May and June 2010, are used to quantify initial hydrocarbon compositions along different transport pathways during the Deepwater Horizon oil spill, suggesting relatively little variation in leaking hydrocarbon composition over time.
Abstract: Detailed airborne, surface, and subsurface chemical measurements, primarily obtained in May and June 2010, are used to quantify initial hydrocarbon compositions along different transport pathways (i.e., in deep subsurface plumes, in the initial surface slick, and in the atmosphere) during the Deepwater Horizon oil spill. Atmospheric measurements are consistent with a limited area of surfacing oil, with implications for leaked hydrocarbon mass transport and oil drop size distributions. The chemical data further suggest relatively little variation in leaking hydrocarbon composition over time. Although readily soluble hydrocarbons made up ∼25% of the leaking mixture by mass, subsurface chemical data show these compounds made up ∼69% of the deep plume mass; only ∼31% of the deep plume mass was initially transported in the form of trapped oil droplets. Mass flows along individual transport pathways are also derived from atmospheric and subsurface chemical data. Subsurface hydrocarbon composition, dissolved oxygen, and dispersant data are used to assess release of hydrocarbons from the leaking well. We use the chemical measurements to estimate that (7.8 ± 1.9) × 106 kg of hydrocarbons leaked on June 10, 2010, directly accounting for roughly three-quarters of the total leaked mass on that day. The average environmental release rate of (10.1 ± 2.0) × 106 kg/d derived using atmospheric and subsurface chemical data agrees within uncertainties with the official average leak rate of (10.2 ± 1.0) × 106 kg/d derived using physical and optical methods.
TL;DR: A 25,000-year-long record of the radiocarbon content of deep-sea corals collected from the Southern Ocean shows evidence of the 14C-depletion that must have accompanied CO2 sequestration, adding support to the existing model of deglacial CO2 dynamics.
Abstract: Changes in the upwelling and degassing of carbon from the Southern Ocean form one of the leading hypotheses for the cause of glacial-interglacial changes in atmospheric carbon dioxide We present a 25,000-year-long Southern Ocean radiocarbon record reconstructed from deep-sea corals, which shows radiocarbon-depleted waters during the glacial period and through the early deglaciation This depletion and associated deep stratification disappeared by ~146 ka (thousand years ago), consistent with the transfer of carbon from the deep ocean to the surface ocean and atmosphere via a Southern Ocean ventilation event Given this evidence for carbon exchange in the Southern Ocean, we show that existing deep-ocean radiocarbon records from the glacial period are sufficiently depleted to explain the ~190 per mil drop in atmospheric radiocarbon between ~17 and 145 ka