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Sample records for undisturbed deep-water marsh

  1. Deep Water Survey Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The deep water biodiversity surveys explore and describe the biodiversity of the bathy- and bentho-pelagic nekton using Midwater and bottom trawls centered in the...

  2. Producing deep-water hydrocarbons

    International Nuclear Information System (INIS)

    Pilenko, Thierry

    2011-01-01

    Several studies relate the history and progress made in offshore production from oil and gas fields in relation to reserves and the techniques for producing oil offshore. The intention herein is not to review these studies but rather to argue that the activities of prospecting and producing deep-water oil and gas call for a combination of technology and project management and, above all, of devotion and innovation. Without this sense of commitment motivating men and women in this industry, the human adventure of deep-water production would never have taken place

  3. Deep Water Horizon (HB1006, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Monitor and measure the biological, chemical, and physical environment in the area of the oil spill from the deep water horizon oil rig in the Gulf of Mexico. A wide...

  4. Long Term Geoelectrical Monitoring of Deep-water Horizon Oil Spill in the Gulf Coast

    Science.gov (United States)

    Heenan, J. W.; Ntarlagiannis, D.; Slater, L. D.; Atekwana, E. A.; Ross, C.; Nolan, J. T.; Atekwana, E. A.

    2011-12-01

    In the aftermath of the catastrophic Deep-water Horizon (DWH) spill in the Gulf Coast, opportunities exist to study the evolution of fresh crude oil contamination in beach sediments and marshes. Grand Terre 1 Island, off the coast of Grand Isle in southern Louisiana, is an uninhabited barrier island, heavily impacted by the DWH spill, and ideal for undisturbed long term monitoring of crude oil degradation processes. A 10 channel Syscal-Pro resistivity / IP instrument (IRIS Instruments, France) is the heart of the fully autonomous geoelectrical monitoring system; the system, which is housed in a weatherproof container, relies solely on solar power, is controlled by an energy efficient PC and can be accessed remotely via web tools. The monitoring scheme involves collecting bi-daily resistivity measurements from surface and shallow boreholes, ranging from January 2011 to the present; environmental parameters, such as T, are continuously recorded at several depths. During regular field trips we perform larger scale geophysical surveys, and geochemical measurements (pH, DO, T, fluid C) to support the continuous geophysical monitoring. The contaminated layer on site is a visually distinctive layer of crude oil, isolated by cleaner sands above and below which is identified by a clear and obvious resistive anomaly in preliminary surveys. Early results show a decrease in average of the resistance values of each dataset over time. Further processing of the data yields a linearly shaped resistive anomaly, which coincides with the location of the oil layer. The changes in subsurface resistivity appear to be focused within this anomaly. Time filtering of the data by the time that they were collected, morning or evening, reveals a diurnal variation. While both time frames follow the same overall trend, the measurements in the morning are slightly more resistive than those in the evening. This indicates that there are environmental factors, such as temperature, that need to be

  5. Marshes on the Move: Testing effects of seawater intrusion on ...

    Science.gov (United States)

    The Northeastern United States is a hotspot for sea level rise (SLR), subjecting coastal salt marshes to erosive loss, shifts in vegetation communities, and altered biogeochemistry due to seawater intrusion. Salt marsh plant community zonation is driven by tradeoffs in stress tolerance and interspecific interactions. As seawater inundates progressively higher marsh elevations, shifts in marsh vegetation communities landward may herald salt marsh “migration”, which could allow continuity of marsh function and ecosystem service provision. To elucidate possible effects of seawater intrusion on marsh-upland edge plant communities, a space-for-time approach was replicated at two Rhode Island salt marshes. At each site, peat blocks (0.5 m x 0.5 m x 0.5 m, n=6) with intact upland-marsh edge vegetation were transplanted downslope into the regularly-inundated mid-marsh. Procedural controls (n=3) were established at each elevation by removing and replacing peat blocks, and natural controls (n=3) consisted of undisturbed plots. During peak productivity, each plot was assessed for species composition, percent cover and average height. Results demonstrate stunting of marsh-upland edge vegetation in response to increased inundation, and the beginnings of colonization of the transplanted plots by salt marsh species. The extent of colonization differed between the two sites, suggesting that site-specific factors govern vegetation responses to increased inundation.

  6. Hydrodynamic erosion process of undisturbed clay

    NARCIS (Netherlands)

    Zhao, G.; Visser, P.J.; Vrijling, J.K.

    2011-01-01

    This paper describes the hydrodynamic erosion process of undisturbed clay due to the turbulent flow, based on theoretical analysis and experimental results. The undisturbed clay has the unique and complicated characteristics of cohesive force among clay particles, which are highly different from

  7. Deep water challenges for drilling rig design

    Energy Technology Data Exchange (ETDEWEB)

    Roth, M. [Transocean Sedco Forex, Houston, TX (United States)

    2001-07-01

    Drilling rigs designed for deep water must meet specific design considerations for harsh environments. The early lessons for rig design came from experiences in the North Sea. Rig efficiency and safety considerations must include structural integrity, isolated/redundant ballast controls, triple redundant DP systems, enclosed heated work spaces, and automated equipment such as bridge cranes, pipe handling gear, offline capabilities, subsea tree handling, and computerized drill floors. All components must be designed to harmonize man and machine. Some challenges which are unique to Eastern Canada include frequent storms and fog, cold temperature, icebergs, rig ice, and difficult logistics. This power point presentation described station keeping and mooring issues in terms of dynamic positioning issues. The environmental influence on riser management during forced disconnects was also described. Design issues for connected deep water risers must insure elastic stability, and control deflected shape. The design must also keep stresses within acceptable limits. Codes and standards for stress limits, flex joints and tension were also presented. tabs., figs.

  8. Passive Acoustic Thermometry Using Low-Frequency Deep Water Noise

    Science.gov (United States)

    2015-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Passive Acoustic Thermometry Using Low-Frequency Deep... thermometry using Cross-correlation processing of deep water ambient noise. OBJECTIVE Our previous research effort has demonstrated that coherent... thermometry using low-frequency deep water ambient noise recorded on the global IMS- CTBTO network Results from this study are expected to help guide the

  9. North Pacific Acoustic Laboratory and Deep Water Acoustics

    Science.gov (United States)

    2016-10-27

    During FY16 the primary effort has been working on manuscripts as summarized below: 1) A test of deep water Rytov theory at 284 Hz and 107 km in... signal , while the ambient noise field is in direct competition with the received signal . Research conducted in the North Pacific Acoustic Laboratory...low-frequency, long-range, deep water, broadband acoustic propagation, the effects of ocean variability on signal coherence, and the fundamental

  10. Connectivity between surface and deep waters determines prokaryotic diversity in the North Atlantic Deep Water.

    Science.gov (United States)

    Frank, Alexander H; Garcia, Juan A L; Herndl, Gerhard J; Reinthaler, Thomas

    2016-06-01

    To decipher the influence of depth stratification and surface provincialism on the dark ocean prokaryotic community composition, we sampled the major deep-water masses in the eastern North Atlantic covering three biogeographic provinces. Their diversity was evaluated using ordination and canonical analysis of 454 pyrotag sequences. Variance partitioning suggested that 16% of the variation in the bacterial community composition was based on depth stratification while 9% of the variation was due to geographic location. General linear mixed effect models showed that the community of the subsurface waters was connected to the dark ocean prokaryotic communities in different biogeographic provinces. Cluster analysis indicated that some prokaryotic taxa are specific to distinct regions in bathypelagic water masses. Taken together, our data suggest that the dark ocean prokaryotic community composition of the eastern North Atlantic is primed by the formation and the horizontal transport of water masses. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  11. Suisun Marsh Secondary Management Area

    Data.gov (United States)

    California Department of Resources — Suisun Marsh or the 'Marsh' means tidal marsh, water-covered areas, diked-off wetlands, seasonal marshes, lowland grasslands, upland grasslands, and cultivated lands...

  12. Suisun Marsh Primary Management Area

    Data.gov (United States)

    California Natural Resource Agency — Suisun Marsh or the 'Marsh' means tidal marsh, water-covered areas, diked-off wetlands, seasonal marshes, lowland grasslands, upland grasslands, and cultivated lands...

  13. Suisun Marsh Primary Management Area

    Data.gov (United States)

    California Department of Resources — Suisun Marsh or the 'Marsh' means tidal marsh, water-covered areas, diked-off wetlands, seasonal marshes, lowland grasslands, upland grasslands, and cultivated lands...

  14. Salt Marshes as Sources and Sinks of Silica

    Science.gov (United States)

    Carey, J.; Fulweiler, R. W.

    2014-12-01

    The role of salt marshes in controlling silica exchange between terrestrial and marine environments is unclear. In some studies, large quantities of dissolved silica (DSi) appear to be exported from marshes via tidal exchange, potentially fueling future diatom production in adjacent waters. In contrast, other studies report insignificant DSi export and found instead that salt marshes appeared to be Si sinks. Further, few studies examine salt marsh Si export in relation to inorganic nitrogen (DIN) and phosphorus (DIP). We address these uncertainties by quantifying net fluxes of DSi and biogenic Si (BSi), as well as DIN and DIP during the spring and summer in a relatively undisturbed southern New England salt marsh (Narragansett Bay, USA). Our data demonstrates that during the spring, when estuarine waters are deplete in DSi, the marsh serves as a net sink of BSi (132 mol h-1) and a source of DSi (31 mol h-1) to the estuary. The spring DIN:DSi ratios of ebbing water were more than five times lower than flood waters. Most importantly, the DSi export rates (6.5 x103 mol d-1 km-2) are an order of magnitude larger than the export by rivers in the region (115 mol d-1 km-2), indicating the marsh tidal exchange is vital in supplying the Si necessary for spring diatom blooms in the estuary. Conversely, during the summer the marsh served as a net Si sink, importing on average 59 mol DSi h-1 and 39 mol BSi h-1. These data highlight that the role of salt marshes in silica cycling appears to have a strong seasonality. We hypothesize that net import of Si increases the residence time of Si in estuarine systems, providing an important and previously over-looked ecosystem service. In the absence of salt marshes, ~5.1 x 104 kmol of Si would be exported from this system during the growing season, possibly decreasing Si availability and altering phytoplankton species composition in the estuary.

  15. Primary production of deep-water Halophila ovalis meadows

    NARCIS (Netherlands)

    Erftemeijer, P.L.A.; Stapel, J.

    1999-01-01

    Monospecific meadows of Halophila ovalis (R. Brown) Hooker f. were studied in deep waters (14-16 m) around Langkai island in South Sulawesi, Indonesia, during May-September 1990, The average shoot density of Halophila in biomass samples (n=10) taken from these meadows was 1099 +/- 195 leaf pairs

  16. Deep water periodic waves as Hamiltonian relative equilibria

    NARCIS (Netherlands)

    van Groesen, Embrecht W.C.; Lie She Liam, L.S.L.; Lakhturov, I.; Andonowati, A.; Biggs, N.

    2007-01-01

    We use a recently derived KdV-type of equation for waves on deep water to study Stokes waves as relative equilibria. Special attention is given to investigate the cornered Stokes-120 degree wave as a singular solution in the class of smooth steady wave profiles.

  17. Short?term statistics of waves observed in deep water

    NARCIS (Netherlands)

    Casas-Prat, M.; Holthuijsen, L.H.

    2010-01-01

    The short?term statistics of 10 million individual waves observed with buoys in deep water have been investigated, corrected for a sample?rate bias, and normalized with the standard deviation of the surface elevation (the range of normalized wave heights is 0 < H < 10). The observed normalized

  18. Real time wave measurements and wave hindcasting in deep waters

    Digital Repository Service at National Institute of Oceanography (India)

    Anand, N.M.; Mandal, S.; SanilKumar, V.; Nayak, B.U.

    Deep water waves off Karwar (lat. 14~'45.1'N, long. 73~'34.8'E) at 75 m water depth pertaining to peak monsoon period have been measured using a Datawell waverider buoy. Measured wave data show that the significant wave height (Hs) predominantly...

  19. Functionality of Root-Associated Bacteria along a Salt Marsh Primary Succession

    NARCIS (Netherlands)

    Wang, Miao; Li, Erqin; Liu, Chen; Jousset, Alexandre; Salles, Joana Falcão

    2017-01-01

    Plant-associated bacteria are known for their high functional trait diversity, from which many are likely to play a role in primary and secondary succession, facilitating plant establishment in suboptimal soils conditions. Here we used an undisturbed salt marsh chronosequence that represents over

  20. Functionality of root-associated bacteria along a salt marsh primary succession

    NARCIS (Netherlands)

    Wang, Miao; Li, Erqin; Liu, Chen; Jousset, Alexandre; Salles, Joana F.

    2017-01-01

    Plant-associated bacteria are known for their high functional trait diversity, from which many are likely to play a role in primary and secondary succession, facilitating plant establishment in suboptimal soils conditions. Here we used an undisturbed salt marsh chronosequence that represents over

  1. Bottom Backscattering Strengths Measured in Shallow and Deep Water

    Science.gov (United States)

    2017-01-18

    to the MF results. 18-01-2017 Memorandum Report Bottom scattering Bottom scattering strength Reverberation Underwater acoustics Active sonar August...Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/7160--17-9701 Bottom Backscattering Strengths Measured in Shallow and Deep Water January...18, 2017 Approved for public release; distribution is unlimited. RogeR C. gauss edwaRd L. Kunz Joseph M. FiaLKowsKi RiChaRd Menis Acoustic Signal

  2. Deep-water northern Gulf of Mexico hydrocarbon plays

    International Nuclear Information System (INIS)

    Peterson, R.H.; Cooke, D.W.

    1995-01-01

    The geologic setting in the deep-water (depths greater than 1,500 feet) Gulf of Mexico is very favorable for the existence of large, commercial hydrocarbon accumulations. These areas have active salt tectonics that create abundant traps, underlying mature Mesozoic source rocks that can be observed expelling oil and gas to the ocean surface, and good quality reservoirs provided by turbidite sand deposits. Despite the limited amount of drilling in the deep-water Gulf of Mexico, 11 deep-water accumulations have been discovered which, when developed, will rank in the top 100 largest fields in the Gulf of Mexico. Proved field discoveries (those with announced development plans) have added over 1 billion barrels of oil equivalent to Gulf of Mexico reserves, and unproved field discoveries may add to additional billion barrels of oil equivalent. The Minerals Management Service, United States Department of the Interior, has completed a gulf-wide review of over 1,086 oil and gas fields and placed every pay sand in each field into a hydrocarbon play (plays are defined by chronostratigraphy, lithostratigraph, structure, and production). Seven productive hydrocarbon plays were identified in the deep-water northern Gulf of Mexico. Regional maps illustrate the productive limits of each play. In addition, field data, dry holes, and wells with sub-economic pay were added to define the facies and structural limits for each play. Areas for exploration potential are identified for each hydrocarbon play. A type field for each play is chosen to demonstrate the play's characteristics

  3. Isotropic thaw subsidence in undisturbed permafrost landscapes

    Science.gov (United States)

    Shiklomanov, Nikolay I.; Streletskiy, Dmitry A.; Little, Jonathon D.; Nelson, Frederick E.

    2013-12-01

    in undisturbed terrain within some regions of the Arctic reveal limited correlation between increasing air temperature and the thickness of the seasonally thawed layer above ice-rich permafrost. Here we describe landscape-scale, thaw-induced subsidence lacking the topographic contrasts associated with thermokarst terrain. A high-resolution, 11 year record of temperature and vertical movement at the ground surface from contrasting physiographic regions of northern Alaska, obtained with differential global positioning systems technology, indicates that thaw of an ice-rich layer at the top of permafrost has produced decimeter-scale subsidence extending over the entire landscapes. Without specialized observation techniques the subsidence is not apparent to observers at the surface. This "isotropic thaw subsidence" explains the apparent stability of active layer thickness records from some landscapes of northern Alaska, despite warming near-surface air temperatures. Integrated over extensive regions, it may be responsible for thawing large volumes of carbon-rich substrate and could have negative impacts on infrastructure.

  4. Perception vs. reality in deep-water exploration

    Energy Technology Data Exchange (ETDEWEB)

    Shanmugam, G. [Mobil Exploration & Producing Technical Center, Dallas, TX (United States)

    1996-12-31

    The common perception in exploration is that deep-water sands are predominantly a product of low- and high-density turbidity currents, and that submarine-fan models with channel/levee and lobe elements are the norm. The reality, however, is that deep-water systems are extremely complex and variable in terms of depositional processes and sand-body geometries. For example, the Bourna Sequence, composed of T{sub a}, T{sub b}, T{sub c}, T{sub d}, and T{sub e} divisions, is believed to be the product of a turbidity current. However, recent core and outcrop studies show that the complete and partial Bouma sequences also can be explained by processes other than turbidity currents, such as sandy debris flows (i.e., {open_quotes}T{sub a}{close_quotes}) and bottom-current reworking (i.e., {open_quotes}T{sub b}, T{sub c} and T{sub d}{close_quotes}). Massive sands are interpreted routinely as high-density turbidites, but the reality is that the term {open_quotes}high-density turbidity current{close_quotes} commonly refers to sandy debris flow in terms of flow theology and sediment-support mechanism. Deep-water sequences in the North Sea, Norwegian Sea, Offshore Gabon, Offshore Nigeria, Gulf of Mexico, and the Ouachita Mountains are generally considered to be turbidite-rich submarine fans. However, the reality is that these sequences are composed predominantly of sandy slumps and debris flows, not turbidites. Fan models are attractive to explorationists because of their predictable sheet-like geometries; however, these simplistic conceptual models are obsolete because they defy reality. Although the turbidite paradigm is alive and well for now in the minds of many sedimentologists and sequence stratigraphers, the turbidites themselves that form the foundation for fan models are becoming an endangered facies!

  5. Perception vs. reality in deep-water exploration

    Energy Technology Data Exchange (ETDEWEB)

    Shanmugam, G. (Mobil Exploration Producing Technical Center, Dallas, TX (United States))

    1996-01-01

    The common perception in exploration is that deep-water sands are predominantly a product of low- and high-density turbidity currents, and that submarine-fan models with channel/levee and lobe elements are the norm. The reality, however, is that deep-water systems are extremely complex and variable in terms of depositional processes and sand-body geometries. For example, the Bourna Sequence, composed of T[sub a], T[sub b], T[sub c], T[sub d], and T[sub e] divisions, is believed to be the product of a turbidity current. However, recent core and outcrop studies show that the complete and partial Bouma sequences also can be explained by processes other than turbidity currents, such as sandy debris flows (i.e., [open quotes]T[sub a][close quotes]) and bottom-current reworking (i.e., [open quotes]T[sub b], T[sub c] and T[sub d][close quotes]). Massive sands are interpreted routinely as high-density turbidites, but the reality is that the term [open quotes]high-density turbidity current[close quotes] commonly refers to sandy debris flow in terms of flow theology and sediment-support mechanism. Deep-water sequences in the North Sea, Norwegian Sea, Offshore Gabon, Offshore Nigeria, Gulf of Mexico, and the Ouachita Mountains are generally considered to be turbidite-rich submarine fans. However, the reality is that these sequences are composed predominantly of sandy slumps and debris flows, not turbidites. Fan models are attractive to explorationists because of their predictable sheet-like geometries; however, these simplistic conceptual models are obsolete because they defy reality. Although the turbidite paradigm is alive and well for now in the minds of many sedimentologists and sequence stratigraphers, the turbidites themselves that form the foundation for fan models are becoming an endangered facies

  6. Installation of deep water sub-sea equipment

    Energy Technology Data Exchange (ETDEWEB)

    Pollack, Jack; Demian, Nabil [SBM-IMODCO Inc., Houston, TX (UNited States)

    2004-07-01

    Offshore oil developments are being planned in water depths exceeding 2000 m. Lowering and positioning large, heavy sub sea hardware, using conventional methods, presents new technical challenges in these ultra deep waters. In 3000 m a safe lift using conventional steel cables will require more capacity to support the cable self weight than the static payload. Adding dynamic loads caused by the motions of the surface vessel can quickly cause the safe capacity of the wire to be exceeded. Synthetic ropes now exist to greatly reduce the lowering line weight. The lower stiffness of these synthetic ropes aggravate the dynamic line tensions due to vessel motions and relatively little is known about the interaction of these ropes on the winches and sheaves required for pay-out and haul-in of these lines under dynamic load. Usage of conventional winches would damage the synthetic rope and risk the hardware being deployed. Reliable and economic installation systems that can operate from existing installation vessels are considered vital for ultra deep-water oil development. The paper describes a Deep Water Sub-Sea Hardware Deployment system consisting of a buoy with variable, pressure-balanced buoyancy, which is used to offset most of the payload weight as it is lowered. The buoyant capacity is controlled by air pumped into the tank from the surface vessel through a reinforced hose. The buoy and payload motion are isolated from the deployment line surface dynamics using a simple passive heave compensator mounted between the buoy and the bottom of the deployment rope. The system components, functionality and dynamic behavior are presented in the paper. (author)

  7. Turbidite Systems in Brazil: From Outcrops to Deep Waters

    Science.gov (United States)

    ´Avila, R. S. F.; Arienti, L. M.; Vesely, F. F.; Santos, S. F.; Voelcker, H. E.

    2012-04-01

    Reliable depositional models depend on careful observation of rocks, to allow the correct description and interpretation of facies and facies associations and their formative processes. They are of paramount importance to characterize deep water depositional systems, which still are the most important siliciclastic reservoirs for the oil industry. Turbidite sandstone reservoirs are responsible for almost 80% of petroleum produced from Brazilian Basins. A comprehensive characterization of these systems, depicting the main differences in terms of their geometries and facies will be presented. In Brazilian basins most of the turbidites were originated from extremely catastrophic flows, essentially linked to fluvio-deltaic influx that generates very dense hyperpycnal flows. Based on outcrop and subsurface data, two main zones with characteristic geometries and facies associations are commonly identified in turbidite systems: the transference zone and the depositional zone. Erosion and bypass dominate in the transference zone, which frequently occur as submarine canyons and channels. Turbidite channels can contain residual conglomeratic facies and coarser sandstone facies. The depositional area comprises lobes that constitute a major exploratory target because of their greater lateral continuity and the concentration of clean reservoirs. Turbidite lobes can be tabular or lenticular deposits associated with channelized bodies. Taking into account outcrop and subsurface data we can distinguish five main turbidite systems: foredeep turbidite systems, prodelta turbidite systems, mixed turbidite systems, meandering channels turbidite systems and channel-levee turbidite systems. In the Brazilian margin, deep water turbidites and other gravity-flow deposits are commonly associated with bottom current deposits, largely in Tertiary strata. Such bottom current deposits, often called contourites, are also important petroleum reservoirs, commonly mistaken as turbidites. Integration

  8. Deep waters : the Ottawa River and Canada's nuclear adventure

    International Nuclear Information System (INIS)

    Krenz, F.H.K.

    2004-01-01

    Deep Waters is an intimate account of the principal events and personalities involved in the successful development of the Canadian nuclear power system (CANDU), an achievement that is arguably one of Canada's greatest scientific and technical successes of the twentieth century. The author tells the stories of the people involved and the problems they faced and overcame and also relates the history of the development of the town of Deep River, built exclusively for the scientists and employees of the Chalk River Project and describes the impact of the Project on the traditional communities of the Ottawa Valley. Public understanding of nuclear power has remained confused, yet decisions about whether and how to use it are of vital importance to Canadians today - and will increase in importance as we seek to maintain our standard of living without doing irreparable damage to the environment around us. Deep Waters examines the issues involved in the use of nuclear power without over-emphasizing its positive aspects or avoiding its negative aspects.

  9. Ultra deep water minimum production riser system for heavy fluid

    Energy Technology Data Exchange (ETDEWEB)

    Saint-Marcoux, Jean-Francois; Wu, Mason [Acergy M.S. Ltd., London (United Kingdom)

    2008-07-01

    Understanding the intricacies of a reservoir is a lengthy process. Deep water reservoirs are often compartmented. The access to the various areas of production requires drilling from several locations. As each of these zones is being brought to production, additional riser facilities are required. Therefore, the concept of a standardized minimum production riser system that is capable of being installed phase after phase is appealing. The minimum functions required for oil production are two-looped production lines, and one or two injection lines, fitting with a riser system dedicated to an isolated oil field. Such a concept is presented in this paper. Acergy has designed, built and installed the large bundled Hybrid Riser Towers of Girassol and Greater Plutonio, and has further streamlined its design and construction methods. Such project requires not only the capacity to engineer the facilities but also to source the material, manage the fabrication in country and execute the complex operations. This requires project management capacities to be able to ensure consistent interfaces, maintain schedule and budget accordingly. The proposed ultra deep water Minimum Production System incorporates lessons learned from all aspects of the Greater Plutonio and Girassol projects to further enhance the ability to handle a wide range of water depths and well fluids (from low to high GOR), including elevated pressure and temperature. The proposed Minimum Production Hybrid Riser Tower (MPHRT) lends itself to be decommissioned and reused if cost-efficient for the field development. (author)

  10. Exploration in the Deep water Niger Delta: Technical to Business Perspectives

    International Nuclear Information System (INIS)

    Feeley, M.H.

    2002-01-01

    Prolific source rocks, high quality deep water reservoirs and a high technical success rate in finding hydrocarbons make the Nigeria deep water one of the top exploration opportunities in the world. Several major discoveries have resulted from exploration on blocks awarded in 1993. Enthusiastic participation by industry in the 2000 Tender Round clearly indicates the continuing appeal of deep water exploration in Nigeria.Commercially, challenges still exist in the Nigerian deep water. Industry has spent more than $2 Billion USD on exploration and appraisal, yet only a handful of developments are moving forward to development. First oil from the deep water is not expected until 2004, 11 years after acreage award and 8 years after discovery. Tougher economic terms, OPEC quota constraints, an abundance of deep water gas, lengthy approval processes and high up-front bonus and exploration costs challenge the economic returns on deep water gas, lengthy approval processes and high up-front bonus and exploration costs challenge the economic returns on deep water investments. Will deep water exploration, development and production deliver the financial returns industry expected when it signed up for the blocks 10 years ago? What are the indications for the 2000 Tender Round blocks?A good explorer learns form experience. What can be learned technically and commercially by looking back over the results of the last 10 years of exploration in Nigeria's deep water? A perspective is provided on the successes, the failures and the challenges to be overcome in realizing the commercial potential of the basin

  11. Seismic Evaluation of Hydrocarbon Saturation in Deep-Water Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Michael Batzle

    2006-04-30

    During this last period of the ''Seismic Evaluation of Hydrocarbon Saturation in Deep-Water Reservoirs'' project (Grant/Cooperative Agreement DE-FC26-02NT15342), we finalized integration of rock physics, well log analysis, seismic processing, and forward modeling techniques. Most of the last quarter was spent combining the results from the principal investigators and come to some final conclusions about the project. Also much of the effort was directed towards technology transfer through the Direct Hydrocarbon Indicators mini-symposium at UH and through publications. As a result we have: (1) Tested a new method to directly invert reservoir properties, water saturation, Sw, and porosity from seismic AVO attributes; (2) Constrained the seismic response based on fluid and rock property correlations; (3) Reprocessed seismic data from Ursa field; (4) Compared thin layer property distributions and averaging on AVO response; (5) Related pressures and sorting effects on porosity and their influence on DHI's; (6) Examined and compared gas saturation effects for deep and shallow reservoirs; (7) Performed forward modeling using geobodies from deepwater outcrops; (8) Documented velocities for deepwater sediments; (9) Continued incorporating outcrop descriptive models in seismic forward models; (10) Held an open DHI symposium to present the final results of the project; (11) Relations between Sw, porosity, and AVO attributes; (12) Models of Complex, Layered Reservoirs; and (14) Technology transfer Several factors can contribute to limit our ability to extract accurate hydrocarbon saturations in deep water environments. Rock and fluid properties are one factor, since, for example, hydrocarbon properties will be considerably different with great depths (high pressure) when compared to shallow properties. Significant over pressure, on the other hand will make the rocks behave as if they were shallower. In addition to the physical properties, the scale and

  12. Loss of 'blue carbon' from coastal salt marshes following habitat disturbance.

    Directory of Open Access Journals (Sweden)

    Peter I Macreadie

    Full Text Available Increased recognition of the global importance of salt marshes as 'blue carbon' (C sinks has led to concern that salt marshes could release large amounts of stored C into the atmosphere (as CO2 if they continue undergoing disturbance, thereby accelerating climate change. Empirical evidence of C release following salt marsh habitat loss due to disturbance is rare, yet such information is essential for inclusion of salt marshes in greenhouse gas emission reduction and offset schemes. Here we investigated the stability of salt marsh (Spartinaalterniflora sediment C levels following seagrass (Thallasiatestudinum wrack accumulation; a form of disturbance common throughout the world that removes large areas of plant biomass in salt marshes. At our study site (St Joseph Bay, Florida, USA, we recorded 296 patches (7.5 ± 2.3 m(2 mean area ± SE of vegetation loss (aged 3-12 months in a salt marsh meadow the size of a soccer field (7 275 m(2. Within these disturbed patches, levels of organic C in the subsurface zone (1-5 cm depth were ~30% lower than the surrounding undisturbed meadow. Subsequent analyses showed that the decline in subsurface C levels in disturbed patches was due to loss of below-ground plant (salt marsh biomass, which otherwise forms the main component of the long-term 'refractory' C stock. We conclude that disturbance to salt marsh habitat due to wrack accumulation can cause significant release of below-ground C; which could shift salt marshes from C sinks to C sources, depending on the intensity and scale of disturbance. This mechanism of C release is likely to increase in the future due to sea level rise; which could increase wrack production due to increasing storminess, and will facilitate delivery of wrack into salt marsh zones due to higher and more frequent inundation.

  13. Loss of ‘Blue Carbon’ from Coastal Salt Marshes Following Habitat Disturbance

    Science.gov (United States)

    Macreadie, Peter I.; Hughes, A. Randall; Kimbro, David L.

    2013-01-01

    Increased recognition of the global importance of salt marshes as ‘blue carbon’ (C) sinks has led to concern that salt marshes could release large amounts of stored C into the atmosphere (as CO2) if they continue undergoing disturbance, thereby accelerating climate change. Empirical evidence of C release following salt marsh habitat loss due to disturbance is rare, yet such information is essential for inclusion of salt marshes in greenhouse gas emission reduction and offset schemes. Here we investigated the stability of salt marsh ( Spartina alterniflora ) sediment C levels following seagrass ( Thallasiatestudinum ) wrack accumulation; a form of disturbance common throughout the world that removes large areas of plant biomass in salt marshes. At our study site (St Joseph Bay, Florida, USA), we recorded 296 patches (7.5 ± 2.3 m2 mean area ± SE) of vegetation loss (aged 3-12 months) in a salt marsh meadow the size of a soccer field (7 275 m2). Within these disturbed patches, levels of organic C in the subsurface zone (1-5 cm depth) were ~30% lower than the surrounding undisturbed meadow. Subsequent analyses showed that the decline in subsurface C levels in disturbed patches was due to loss of below-ground plant (salt marsh) biomass, which otherwise forms the main component of the long-term ‘refractory’ C stock. We conclude that disturbance to salt marsh habitat due to wrack accumulation can cause significant release of below-ground C; which could shift salt marshes from C sinks to C sources, depending on the intensity and scale of disturbance. This mechanism of C release is likely to increase in the future due to sea level rise; which could increase wrack production due to increasing storminess, and will facilitate delivery of wrack into salt marsh zones due to higher and more frequent inundation. PMID:23861964

  14. Deep-water anoxygenic photosythesis in a ferruginous chemocline

    DEFF Research Database (Denmark)

    Crowe, Sean; Maresca, J. A.; Jones, CarriAyne

    2014-01-01

    Ferruginous Lake Matano, Indonesia hosts one of the deepest anoxygenic photosynthetic communities on Earth. This community is dominated by low-light adapted, BChl e-synthesizing green sulfur bacteria (GSB), which comprise ~25% of the microbial community immediately below the oxic-anoxic boundary...... (OAB; 115-120 m in 2010). The size of this community is dependent on the mixing regime within the lake and the depth of the OAB-at ~117 m, the GSB live near their low-light limit. Slow growth and C-fixation rates suggest that the Lake Matano GSB can be supported by sulfide even though it only...... information suggests that deep-water GSB can be supported by a S-cycle, even under ferruginous conditions. The constraints we place on the metabolic capacity and physiology of GSB have important geobiological implications. Biomarkers diagnostic of GSB would be a good proxy for anoxic conditions but could...

  15. Fracturing Pressure of Shallow Sediment in Deep Water Drilling

    Directory of Open Access Journals (Sweden)

    Chuanliang Yan

    2013-01-01

    Full Text Available The shallow sediment in deep water has weak strength and easily gets into plastic state under stress concentration induced by oil and gas drilling. During drilling, the formation around a wellbore can be divided into elastic zone and plastic zone. The unified strength theory was used after yielding. The radius of the plastic zone and the theoretical solution of the stress distribution in these two zones were derived in undrained condition. The calculation model of excess pore pressure induced by drilling was obtained with the introduction of Henkel’s excess pore pressure theory. Combined with hydraulic fracturing theory, the fracturing mechanism of shallow sediment was analyzed and the theoretical formula of fracturing pressure was given. Furthermore, the influence of the parameters of unified strength theory on fracturing pressure was analyzed. The theoretical calculation results agreed with measured results approximately, which preliminary verifies the reliability of this theory.

  16. Catwell and Sherdaps for deep-water production fields

    Energy Technology Data Exchange (ETDEWEB)

    Hopper, H.P.; Rey, R. [Cameron, 34 - Beziers (France)

    2000-07-01

    The names Catwell and SherDaps are derived from: - Catenary Well - Subsea Horizontal Extended Reach Drilling And Production System. Both systems use the technique of being able to drill a well in deep-water either through a platform catenary carrier pipe or a catenary drilling riser. They also offer, in addition, significant advantages when drilling into shallow reservoirs and the ability to enhance production using platform artificial lift systems or easily serviceable pumps either in the well or at the mud-line. Catwell is a platform system with surface wellheads/trees whereas SherDaps uses a group of subsea wellheads/trees/BOP's that are accessible from one permanent catenary drilling riser. Both systems allow drilling/completing and future well intervention from a central location that otherwise would have required several drilling centres (i.e. platforms or subsea) if the conventional approach was followed. It is envisaged that well targets close to a platform will use well conductors possibly with mud-line wellheads, then Catwell to reach the medium range well targets and SherDaps for long range wells. It is considered that this arrangement would allow a single surface drilling/ production centre to have access to well targets giving a foot print range of up to a 20 km diameter. The total Capex savings on a Deep-water Field Development could be in the region of $200 m on a $1 billion development. Opex will be lower with the ability from the drilling center to quickly access any problem well and rectify any faults, minimising lost production. (authors)

  17. Implications of Subduction Rehydration for Earth's Deep Water Cycle

    Science.gov (United States)

    Ruepke, L. H.; Phipps Morgan, J.; Dixon, J.

    2006-12-01

    The presence of liquid water is the principle difference between our Earth and other planets in the solar system. The global ocean is the obvious surface expression of this. The 'standard model' for the genesis of the oceans is that they are exhalations from Earth's deep interior continually rinsed through surface rocks by the global hydrologic cycle. The question of how much water resides within the Earth's deep interior remains unresolved and is a matter of vigorous ongoing scientific debate. We have addressed the question of water distribution between the exosphere and the mantle throughout Earth's history with simple mass balance considerations. In our model, water is outgassed from the mantle into the exosphere (atmosphere + continental crust) during pressure-release melting at mid-ocean ridges and hotspots. Plate subduction may transport water back from the surface into the deeper mantle thereby 'closing' the global geologic water cycle. In series of some 5000 model runs we have thoroughly explored the mutual effect of model parameters. All models correctly predict the formation of the present-day oceans but differ in their predicted sea-level changes through time and in the amount of water in the present-day mantle. To distinguish which model runs are the most realistic we use geochemical constraints and observed sealevel changes during the Phanerozoic. Recently Dixon et al. [2002] estimated water concentrations for some of the major mantle components and concluded that the most primitive (FOZO) are significantly wetter than the recycling associated EM or HIMU mantle components and the even drier depleted mantle source that melts to form MORB. Sealevel changes over hundreds of million of years are notoriously bad constrained. But a maximum drop in sealevel of 400-600m appears to be an upper bound. We find that only those model runs are consistent with these constraints in which deep water subduction is limited and in which the present-day mantle is

  18. Biogeochemical malfunctioning in sediments beneath a deep-water fish farm

    International Nuclear Information System (INIS)

    Valdemarsen, Thomas; Bannister, Raymond J.; Hansen, Pia K.; Holmer, Marianne; Ervik, Arne

    2012-01-01

    We investigated the environmental impact of a deep water fish farm (190 m). Despite deep water and low water currents, sediments underneath the farm were heavily enriched with organic matter, resulting in stimulated biogeochemical cycling. During the first 7 months of the production cycle benthic fluxes were stimulated >29 times for CO 2 and O 2 and >2000 times for NH 4 + , when compared to the reference site. During the final 11 months, however, benthic fluxes decreased despite increasing sedimentation. Investigations of microbial mineralization revealed that the sediment metabolic capacity was exceeded, which resulted in inhibited microbial mineralization due to negative feed-backs from accumulation of various solutes in pore water. Conclusions are that (1) deep water sediments at 8 °C can metabolize fish farm waste corresponding to 407 and 29 mmol m −2 d −1 POC and TN, respectively, and (2) siting fish farms at deep water sites is not a universal solution for reducing benthic impacts. - Highlights: ► We studied the biogeochemistry in sediments beneath a deep-water fish farm. ► Initially, sediment biogeochemical cycling was stimulated to high levels. ► After 10 months, microbial mineralization was inhibited due to organic overloading. ► Conclusion: deep water sediment has an upper limit for organic matter mineralization. ► Conclusion: deep water fish farms can lead to negative environmental impacts. - Siting fish farms at deep water farming locations is not a universal solution for alleviating benthic impacts.

  19. Angola. Petroleum discovery by Elf on the block number 17 in deep water

    International Nuclear Information System (INIS)

    Anon.

    1996-01-01

    This article describes the petroleum discovery in deep water in Angola. The drilling was executed by 1365 meters deep and gave a petroleum of good quality. The Elf company emphasizes that it is its third discovery in deep water in the Guinea gulf after Nkossa and Moho in Congo. (N.C.)

  20. The global distribution of deep-water Antipatharia habitat

    Science.gov (United States)

    Yesson, Chris; Bedford, Faye; Rogers, Alex D.; Taylor, Michelle L.

    2017-11-01

    Antipatharia are a diverse group of corals with many species found in deep water. Many Antipatharia are habitat for associates, have extreme longevity and some species can occur beyond 8500 m depth. As they are major constituents of'coral gardens', which are Vulnerable Marine Ecosystems (VMEs), knowledge of their distribution and environmental requirements is an important pre-requisite for informed conservation planning particularly where the expense and difficulty of deep-sea sampling prohibits comprehensive surveys. This study uses a global database of Antipatharia distribution data to perform habitat suitability modelling using the Maxent methodology to estimate the global extent of black coral habitat suitability. The model of habitat suitability is driven by temperature but there is notable influence from other variables of topography, surface productivity and oxygen levels. This model can be used to predict areas of suitable habitat, which can be useful for conservation planning. The global distribution of Antipatharia habitat suitability shows a marked contrast with the distribution of specimen observations, indicating that many potentially suitable areas have not been sampled, and that sampling effort has been disproportionate to shallow, accessible areas inside marine protected areas (MPAs). Although 25% of Antipatharia observations are located in MPAs, only 7-8% of predicted suitable habitat is protected, which is short of the Convention on Biological Diversity target to protect 10% of ocean habitats by 2020.

  1. Evolution of completion tools gravel pack systems for deep water

    Energy Technology Data Exchange (ETDEWEB)

    Pineda, Francisco [BJ Services Company, Houston, TX (United States); Vilela, Alvaro; Montanha, Roberto; Hightower, Chad; Acosta, Marco; Farias, Rodrigo [BJ Services do Brasil Ltda., Rio de Janeiro, RJ (Brazil)

    2004-07-01

    Conventional gravel pack or frac pack completions typically require the use of wash pipe to act as a conduit for fluid returns as well as to carry a shifting mechanism to open or close a return port. Using properly sized wash pipe can enhance the placement of the gravel across the entire annular space and the formation. It can also be used in conjunction with a shifting mechanism and a sliding sleeve to force the fluid returns to pass through the bottom of the screen. It can allow a wash-down capability while running the assembly into an open hole. In specialty systems, it can even act as a pumping conduit for post-gravel pack stimulation. However, the use of wash pipe, especially in long horizontal wells, means the loss of valuable rig time due to make up and break out of the wash pipe, or recovery if the wash pipe is stuck. Economic considerations, along with completion efficiencies, are especially important on deep water completions. Not using wash pipe reduces rig time, generating significant cost savings, and also eliminates the risk of a fishing operation. This paper reviews conventional wash pipe applications and describes new systems that accomplish the same goal with a minimum amount of wash pipe or no wash pipe at all. (author)

  2. Bermuda Deep Water Caves 2011: Dives of Discovery between 20110607 and 20110627

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — During the three week NOAA Ocean Exploration project, Bermuda Deep Water Caves 2011: Dives of Discovery, our four member deep team, aided by numerous assistants,...

  3. Cardiorespiratory responses during deep water running with and without horizontal displacement at different cadences

    Directory of Open Access Journals (Sweden)

    A.C. Kanitz

    2014-12-01

    Conclusions: The results indicate that the increase in both cadence and displacement results in significant cardiorespiratory responses as a result of deep water running. This finding is important for adapting exercise prescription to the goals of participants.

  4. Necromass production: studies in undisturbed and logged Amazon Forests

    Science.gov (United States)

    MICHAEL PALACE; MICHAEL KELLER; HUDSON SILVA

    2008-01-01

    Necromass stocks account for up to 20% of carbon stored in tropical forests and have been estimated to be 14–19% of the annual aboveground carbon flux. Both stocks and fluxes of necromass are infrequently measured. In this study, we directly measured the production of fallen coarse necromass (>2 cm diameter) during 4.5 years using repeated surveys in undisturbed...

  5. Necromass in undisturbed and logged forests in the Brazilian Amazon.

    Science.gov (United States)

    Michael Palace; Michael Keller; Gregory P. Asner; Jose Natalino M. Silva; Carlos. Passos

    2007-01-01

    Necromass is an important stock of carbon in tropical forests. We estimated volume, density, and mass of fallen and standing necromass in undisturbed and selectively logged forests at Juruena, Mato Grosso, Brazil (10.488S, 58.478W). We also measured standing dead trees at the Tapajos National Forest, Para, Brazil (3.088S, 54.948W) complementing our earlier study there...

  6. North Pacific Acoustic Laboratory: Deep Water Acoustic Propagation in the Philippine Sea

    Science.gov (United States)

    2016-06-21

    Acoustic Laboratory: Deep Water Acoustic Propagation in the Philippine Sea 5b. GRANT NUMBER NOOO 14-12-1 -0226 5c. PROGRAM ELEMENT NUMBER 6...based on data from the 2009-20 I I NPAL Philippine Sea experiments funded by ONR Grant NOOO 14-08-1-0840 , Fourteen of these publi cations appeared in...North Pacific Acoustic Laboratory: Deep Water Acoustic Propagation in the Philippine Sea ONR Grant NOOO 14-12-1-0226 Period of Performance: 01

  7. Deep Water Ocean Acoustics (DWOA): The Philippine Sea, OBSANP, and THAAW Experiments

    Science.gov (United States)

    2015-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Deep Water Ocean Acoustics (DWOA): The Philippine Sea...receiving arrays that were heretofore difficult or impossible to deploy (Worcester et al., 2009). The experiments include the (1) NPAL Philippine Sea... Philippine Sea. During 2009–2011 three experiments were conducted to study deep-water acoustic propagation and ambient noise in the oceanographically and

  8. Dissolved gaseous Hg (DGM) in the Mediterranean surface and deep waters

    OpenAIRE

    Kotnik J.; Horvat M.

    2013-01-01

    Dissolved gaseous mercury (DGM) was studied in surface and deep waters of the Mediterranean Sea for last 12 years during several oceanographic cruises on board the Italian research vessel Urania and covered both Western and Eastern Mediterranean Basins as well as Adriatic Sea. DGM was measured together with other mercury species (RHg - reactive Hg, THg - total Hg, MeHg - monomethyl Hg and DMeHg - dimethylmercury), and with some water quality parameters in coastal and open sea deep water profi...

  9. Undisturbed trapping boundary for energetic electrons at low altitudes

    International Nuclear Information System (INIS)

    Rossberg, L.

    1978-01-01

    Dawn-dusk traversals of the auroral zone by the German polar orbiting satellite Azur are used to reexamine the previously reported dawn-dusk asymmetry of the boundary position of the 40-keV electrons. This asymmetry, i.e., higher latitudes of the boundary positions in the dawn sector than in the dusk sector, disappears during prolonged periods of low electrojet activity. Symmetric boundary positions, i.e., significantly lower than average boundary positions in the dawn sector, are found whenever the electron flux decreases smoothly to the cosmic ray background over the polar cap and when there is no enhanced precipitation. Similar, undisturbed flux profiles observed by Ogo 6 at E>30keV are used to extend the study to all local times. The resulting average boundary contour has an almost circular shape, centered at 2 0 away from the magnetic pole on the midnight meridian and is compared with the average position of quiet auroral arcs and also with the average pattern of field-aligned currents for AL<100nT. The average boundary contour of undisturbed 30- and 40-keV electron flux profiles is interpreted as the high-latitude limit of stable trapping in the undisturbed magnetosphere

  10. Biosphere 2's Marsh Biome

    Science.gov (United States)

    Molnar, Jennifer; Goodridge, Kelven

    1997-01-01

    The Marsh Biome, which was modeled after the mangroves and marshes of southwest Florida, has an area of 441.2 sq m separated into three hydrologically independent sections: the Freshwater, Oligohaline and Salt Marshes. The divisions are made based on their salinity (approximately 0, 4, and 34 ppt. respectively), but they also contain different biological communities. The Freshwater and Oligohaline Marshes are mostly filled with various grasses and several trees, while the Salt Marsh houses regions of red, black, and white mangroves (Rhizophora mangle, Avicennia germinans, and Languncularia racemosa respectively). Overall, there are an estimated 80 species of plants within the biome. Water in the Salt Marsh follows a meandering stream from the algal turf scrubbers (apparatuses that clean the water of its nutrients and heavy metals while increasing dissolved oxygen levels) which have an outlet in the Salt Marsh section near sites 4 and 5 to the Fringing Red Mangrove section. The sections of the Salt Marsh are separated by walls of concrete with openings to allow the stream to flow through. Throughout this study, conducted through the months of June and July, many conditions within the biome remained fairly constant. The temperature was within a degree or two of 25 C, mostly depending on whether the sample site was in direct sunlight or shaded. The pH throughout the Salt Marsh was 8.0 +/- 0.2, and the lower salinity waters only dropped below this soon after rains. The water rdepth and dissolved oxygen varied, however, between sites.

  11. Measurement of undisturbed di-nitrogen emissions from aquatic ecosystems

    Science.gov (United States)

    Qin, Shuping, Clough, Timothy, Lou, Jiafa; Hu, Chunsheng; Oenema, Oene; Wrage-Mönnig, Nicole; Zhang, Yuming

    2016-04-01

    Increased production of reactive nitrogen (Nr) from atmospheric di-nitrogen (N2) during the last century has greatly contributed to increased food production1-4. However, enriching the biosphere with Nr through N fertilizer production, combustion, and biological N2 fixation has also caused a series of negative effects on global ecosystems 5,6, especially aquatic ecosystems7. The main pathway converting Nr back into the atmospheric N2 pool is the last step of the denitrification process, i.e., the reduction of nitrous oxide (N2O) into N2 by micro-organisms7,8. Despite several attempts9,10, there is not yet an accurate, fast and direct method for measuring undisturbed N2 fluxes from denitrification in aquatic sediments at the field scale11-14. Such a method is essential to study the feedback of aquatic ecosystems to Nr inputs1,2,7. Here we show that the measurement of both N2O emission and its isotope signature can be used to infer the undisturbed N2 fluxes from aquatic ecosystems. The microbial reduction of N2O increases the natural abundance of 15N-N2O relative to 14N-N2O (δ15N-N2O). We observed linear relationships between δ15N-N2O and the logarithmic transformed N2O/(N2+N2O) emission ratios. Through independent measurements, we verified that the undisturbed N2 flux from aquatic ecosystems can be inferred from measurements of N2O emissions and the δ15N-N2O signature. Our method allows the determination of field-scale N2 fluxes from undisturbed aquatic ecosystems, and thereby allows model predictions of denitrification rates to be tested. The undisturbed N2 fluxes observed are almost one order of magnitude higher than those estimated by the traditional method, where perturbation of the system occurs, indicating that the ability of aquatic ecosystems to remove Nr may have been severely underestimated.

  12. Mercury Cycling in Salt Marsh Pond Ecosystems: Cape Cod, MA

    Science.gov (United States)

    Ganguli, P. M.; Gonneea, M. E.; Lamborg, C. H.; Kroeger, K. D.; Swarr, G.; Vadman, K. J.; Baldwin, S.; Brooks, T. W.; Green, A.

    2014-12-01

    We are measuring total mercury (HgT) and monomethylmercury (CH3Hg+ or MMHg) in pore water, surface water, and sediment cores from two salt marsh pond systems on the south shore of Cape Cod, MA to characterize the distribution of mercury species and to identify features that influence mercury speciation and transport. Sage Lot Pond is relatively undisturbed and has low nitrogen loading (12 kg ha-1 y-1). It is part of the Waquoit Bay National Estuarine Reserve and is surrounded by undeveloped wooded uplands. In contrast, Great Pond is highly impacted. Nitrogen loading to the site is elevated (600 kg ha-1 y-1) and the marsh is adjacent to a large residential area. In both systems, a 1 to 2 m organic-rich peat layer overlies the permeable sand aquifer. Groundwater in this region is typically oxic, where pore water within salt marsh peat is suboxic to anoxic. We hypothesize that redox gradients at the transition from the root zone to peat and at the peat-sand interface may provide habitat for MMHg-producing anaerobic bacteria. Preliminary results from a 2-m nearshore depth profile at Sage Lot Pond indicate HgT in groundwater within the sand aquifer occurred primarily in the > 0.2 μm fraction, with unfiltered concentrations exceeding 100 pM. Filtered (fraction of filtered HgT in peat pore water. Although MMHg in both groundwater and pore water remained around 1 pM throughout our depth profile, we observed an increase in sediment MMHg (0.3 to 1.6 μg/kg) at the peat-sand interface. MMHg comprised ~50% of the HgT concentration in pore water suggesting mercury in the salt marsh peat is biologically available.

  13. Spiraling pathways of global deep waters to the surface of the Southern Ocean.

    Science.gov (United States)

    Tamsitt, Veronica; Drake, Henri F; Morrison, Adele K; Talley, Lynne D; Dufour, Carolina O; Gray, Alison R; Griffies, Stephen M; Mazloff, Matthew R; Sarmiento, Jorge L; Wang, Jinbo; Weijer, Wilbert

    2017-08-02

    Upwelling of global deep waters to the sea surface in the Southern Ocean closes the global overturning circulation and is fundamentally important for oceanic uptake of carbon and heat, nutrient resupply for sustaining oceanic biological production, and the melt rate of ice shelves. However, the exact pathways and role of topography in Southern Ocean upwelling remain largely unknown. Here we show detailed upwelling pathways in three dimensions, using hydrographic observations and particle tracking in high-resolution models. The analysis reveals that the northern-sourced deep waters enter the Antarctic Circumpolar Current via southward flow along the boundaries of the three ocean basins, before spiraling southeastward and upward through the Antarctic Circumpolar Current. Upwelling is greatly enhanced at five major topographic features, associated with vigorous mesoscale eddy activity. Deep water reaches the upper ocean predominantly south of the Antarctic Circumpolar Current, with a spatially nonuniform distribution. The timescale for half of the deep water to upwell from 30° S to the mixed layer is ~60-90 years.Deep waters of the Atlantic, Pacific and Indian Oceans upwell in the Southern Oceanbut the exact pathways are not fully characterized. Here the authors present a three dimensional view showing a spiralling southward path, with enhanced upwelling by eddy-transport at topographic hotspots.

  14. Organic carbon isotope systematics of coastal marshes

    NARCIS (Netherlands)

    Middelburg, J.J.; Nieuwenhuize, J.; Lubberts, R.K.; Van de Plassche, O.

    1997-01-01

    Measurements of nitrogen, organic carbon and delta(13)C are presented for Spartina-dominated marsh sediments from a mineral marsh in SW Netherlands and from a peaty marsh in Massachusetts, U.S.A. delta(13)C Of organic carbon in the peaty marsh sediments is similar to that of Spartina material,

  15. Quaternary North Atlantic Surface Paleoceanography in Regions of Potential Deep-water Formation

    Science.gov (United States)

    Ruddiman, W. F.

    1984-01-01

    At the time scale of the Quaternary climate cycles, the sites of formation of North Atlantic Deep Water are not known. The interglacial extreme is presumably exemplified by the modern regions; the Norwegian, Greenland and Labrador Seas. During the major glacial-age coolings in the North Atlantic, the sites may have shifted well to the south, perhaps as far as the limit of the polar front at 40 to 50 N. Still other sites may have been important during intermediate climatic conditions. Because of the close coupling of high-latitude surface waters to North Atlantic Deep Water in the modern ocean, the history of sea-surface temperature (SST) oscillations across the high-latitude North Atlantic is relevant to an understanding of deep-water formation on the longer time scales.

  16. OIL DETECTION IN A COASTAL MARSH WITH POLARIMETRIC SAR

    Directory of Open Access Journals (Sweden)

    E. Ramsey III

    2012-09-01

    Full Text Available The NASA UAVSAR was deployed June 2010 to support Deep Water Horizon oil spill response activities specifically, oil detection and characterization, oil extent mapping in wetlands, coastal resource impact detection, and ecosystem recovery. The UAVSAR platform demonstrated enhanced capability to act rapidly and provide targeted mapping response. Our research focused on the effectiveness of high spatial resolution and fully polarimetric L-band Synthetic Aperture Radar (PolSAR for mapping oil in wetlands, specifically within Barataria Bay in eastern coastal Louisiana. Barataria Bay contained a numerous site observations confirming spatially extensive shoreline oil impacts, multiple oil spill UAVSAR collections, and a near anniversary 2009 collection. PolSAR oil detection relied on decomposition and subsequent classifications of the single look complex (SLC calibrated radar cross sections representing the complex elements of the scattering matrix. Initial analyses results found that shoreline marsh structural damage as well as oil on marsh plants and sediments without canopy structural damage were exhibited as anomalous features on post-spill SLC scenes but were not evident on the pre-spill SLC scene collected in 2009. Pre-spill and post-spill Freeman-Durden (FD and Cloude-Pottier (CP decompositions and the Wishart classifications seeded with the FD and CP classes (Wishart-FD also highlighted these nearshore features as a change in dominate scatter from pre-spill to post-spill. SLC analyses also indicated penetration of oil ladened waters into interior marshes well past the immediate shorelines; however, these post-spill SLC analyses results could not be validated due to the lack of observational data and possible flooding in the pre-spill SLC scene.

  17. Deep water formation in the North Pacific and deglacial CO2 rise

    OpenAIRE

    Rae, James William Buchanan; Sarnthein, Michael; Foster, Gavin; Ridgwell, Andy; Grootes, Pieter; Elliott, Tim

    2014-01-01

    Deep water formation in the North Atlantic and Southern Ocean is widely thought to influence deglacial CO_2 rise and climate change; here we suggest that deep water formation in the North Pacific may also play an important role. We present paired radiocarbon and boron isotope data from foraminifera from sediment core MD02-2489 at 3640 m in the North East Pacific. These show a pronounced excursion during Heinrich Stadial 1, with benthic-planktic radiocarbon offsets dropping to ~350 years, acco...

  18. Louisiana Marsh Management Plan 1995

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — We sampled experimental research areas in the Barataria Basin of Louisiana during March and May, 1995, to examine the effects of structural marsh management on...

  19. Availability of {sup 99}Tc in undisturbed soil cores

    Energy Technology Data Exchange (ETDEWEB)

    Denys, Sebastien; Echevarria, Guillaume E-mail: guillaume.echevarria@ensaia.inpl-nancy.fr; Florentin, Louis; Leclerc-Cessac, Elisabeth; Morel, Jean-Louis

    2003-07-01

    Models for safety assessment of radioactive waste repositories need accurate values of the soil-to-plant transfer of radionuclides. In oxidizing environments, {sup 99}Tc is expected to occur as pertechnetate ({sup 99}TcO{sub 4}{sup -}). Due to its high mobility, leaching of this element in the field might be important, potentially affecting the reliability of estimated transfer parameters of {sup 99}Tc as measured in closed experimental systems such as hydroponics or pot experiments. The aim of this experiment was to measure the leaching of {sup 99}Tc in undisturbed irrigated soil cores under cultivation as well as plant uptake and to study the possible competition between the two transfer pathways. Undisturbed soil cores (50x50 cm) were sampled from a Rendzic Leptosol (R), a colluvial Fluvic Cambisol (F) and a Dystric Cambisol (D) using PVC tubes (three cores sampled per soil type). Each core was equipped with a leachate collector at the bottom, allowing the monitoring of {sup 99}Tc leaching through the cores. Cores were placed in a greenhouse and maize (Zea mays L., cv. DEA, Pioneer[reg]) was sown. After 135 d, maize was harvested and radioactivity determined in both plant and water samples. Results showed that during the growing period, leaching of {sup 99}Tc was limited, due to the high evapotranspiration rate of maize. After harvest, leaching of {sup 99}Tc went on because of the absence of evapotranspiration. Effective uptake (EU) of {sup 99}Tc in leaves and grains was calculated. EU reached 70% of the input in the leaves and was not significantly different among soils. These results confirmed those obtained from pot experiments, even though leaching was allowed to occur in close-to-reality hydraulical conditions. As a consequence, it was concluded that pot experiments are an adequate surrogate for more complex 'close-to-reality' experimental systems for measuring transfer factors.

  20. Alfalfa Responses to Gypsum Application Measured Using Undisturbed Soil Columns

    Directory of Open Access Journals (Sweden)

    Rebecca Tirado-Corbalá

    2017-07-01

    Full Text Available Gypsum is an excellent source of Ca and S, both of which are required for crop growth. Large amounts of by-product gypsum [Flue gas desulfurization gypsum-(FGDG] are produced from coal combustion in the United States, but only 4% is used for agricultural purposes. The objective of this study was to evaluate the effects of (1 untreated, (2 short-term (4-year annual applications of gypsum totaling 6720 kg ha−1, and (3 long-term (12-year annual applications of gypsum totaling 20,200 kg ha−1 on alfalfa (Medicago sativa L. growth and nutrient uptake, and gypsum movement through soil. The study was conducted in a greenhouse using undisturbed soil columns of two non-sodic soils (Celina silt loam and Brookston loam. Aboveground growth of alfalfa was not affected by gypsum treatments when compared with untreated (p > 0.05. Total root biomass (0–75 cm for both soils series was significantly increased by gypsum application (p = 0.04, however, increased root growth was restricted to 0–10 cm depth. Soil and plant analyses indicated no unfavorable environmental impact from of the 4-year and 12-year annual application of FGDG. We concluded that under sufficient water supply, by-product gypsum is a viable source of Ca and S for land application that might benefit alfalfa root growth, but has less effect on aboveground alfalfa biomass production. Undisturbed soil columns were a useful adaptation of the lysimeter method that allowed detailed measurements of alfalfa nutrient uptake, root biomass, and yield and nutrient movement in soil.

  1. Pathways of upwelling deep waters to the surface of the Southern Ocean

    Science.gov (United States)

    Tamsitt, Veronica; Drake, Henri; Morrison, Adele; Talley, Lynne; Dufour, Carolina; Gray, Alison; Griffies, Stephen; Mazloff, Matthew; Sarmiento, Jorge; Wang, Jinbo; Weijer, Wilbert

    2017-04-01

    Upwelling of Atlantic, Indian and Pacific deep waters to the sea surface in the Southern Ocean closes the global overturning circulation and is fundamentally important for oceanic uptake of anthropogenic carbon and heat, nutrient resupply for sustaining oceanic biological production, and the melt rate of ice shelves. Here we go beyond the two-dimensional view of Southern Ocean upwelling, to show detailed Southern Ocean upwelling pathways in three dimensions, using hydrographic observations and particle tracking in high-resolution ocean and climate models. The northern deep waters enter the Antarctic Circumpolar Current (ACC) via narrow southward currents along the boundaries of the three ocean basins, before spiraling southeastward and upward through the ACC. Upwelling is greatly enhanced at five major topographic features, associated with vigorous mesoscale eddy activity. Deep water reaches the upper ocean predominantly south of the southern ACC boundary, with a spatially nonuniform distribution, regionalizing warm water supply to Antarctic ice shelves and the delivery of nutrient and carbon-rich water to the sea surface. The timescale for half of the deep water to upwell from 30°S to the mixed layer is on the order of 60-90 years, which has important implications for the timescale for signals to propagate through the deep ocean. In addition, we quantify the diabatic transformation along particle trajectories, to identify where diabatic processes are important along the upwelling pathways.

  2. Glacier and deep water Holocene dynamics, Adélie Land region, East Antarctica

    NARCIS (Netherlands)

    Denis, D.; Crosta, X.; Schmidt, S.; Carson, D.; Ganeshram, R.; Renssen, H.; Bout-Roumazeilles, V.; Zaragosi, S.; Martin, B.; Giraudeau, J.

    2009-01-01

    This study presents a high-resolution multi-proxy investigation of sediment core MD03-2601 and documents major glacier oscillations and deep water activity during the Holocene in the Adélie Land region, East Antarctica. A comparison with surface ocean conditions reveals synchronous changes of

  3. Development of study on the dynamic characteristics of deep water mooring system

    Science.gov (United States)

    Tang, You-Gang; Zhang, Su-Xia; Zhang, Ruo-Yu; Liu, Hai-Xiao

    2007-09-01

    To meet the needs of those exploiting deepwater resources, TLP and SPAR platforms are used in some areas and are considered excellent platforms in deep water. However, many problems remain to be resolved. The design of mooring systems is a key issue for deep water platforms. Environmental loads in deep water effect the physical characteristics of mooring line materials. The configuration and analysis of mooring systems involve nonlinearity due to this fluid-solid coupling, nonlinear hydrodynamic forces, and their effects on stability of motion. In this paper, some pivotal theories and technical questions are presented, including modeling of mooring lines, the theory and method of coupled dynamics analysis on the mooring system, and the development of methodologies for the study of nonlinear dynamics of mooring systems. Further study on mooring systems in deep water are recommended based on current knowledge, particularly dynamic parameters of different materials and cable configuration, interactions between seabed and cable, mechanisms of mooring system response induced by taut/slack mooring cables, discontinuous stiffness due to system materials, mooring construction, and motion instability, etc.

  4. A New Calculation Method of Dynamic Kill Fluid Density Variation during Deep Water Drilling

    Directory of Open Access Journals (Sweden)

    Honghai Fan

    2017-01-01

    Full Text Available There are plenty of uncertainties and enormous challenges in deep water drilling due to complicated shallow flow and deep strata of high temperature and pressure. This paper investigates density of dynamic kill fluid and optimum density during the kill operation process in which dynamic kill process can be divided into two stages, that is, dynamic stable stage and static stable stage. The dynamic kill fluid consists of a single liquid phase and different solid phases. In addition, liquid phase is a mixture of water and oil. Therefore, a new method in calculating the temperature and pressure field of deep water wellbore is proposed. The paper calculates the changing trend of kill fluid density under different temperature and pressure by means of superposition method, nonlinear regression, and segment processing technique. By employing the improved model of kill fluid density, deep water kill operation in a well is investigated. By comparison, the calculated density results are in line with the field data. The model proposed in this paper proves to be satisfactory in optimizing dynamic kill operations to ensure the safety in deep water.

  5. Tracer element studies on deep water formation and circulation in the European Artic Sea

    International Nuclear Information System (INIS)

    Boenisch, G.

    1991-01-01

    Tracer element investigations (tritium, helium 3, carbon 14, argon 39, krypton 85 and fluorohydrocarbons) were carried out in the European Arctic Sea. The findings are discussed with a view to their validity in the case of deep water formation and circulation. The data cover the period of 1972 through 1989. (BBR) [de

  6. Growth response of a deep-water ferromanganese crust to evolution of the Neogene Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Banakar, V.K.; Hein, J.R.

    nearly ovelapping palaeo-CCD and palaeo-depth of crust formation, increased early Eocene productivity, instability and reworking of the surface rocks on the flanks of the seamount, and lack of oxic deep-water in the nascent Indian Ocean. Crust accretion...

  7. Deep-water Circulation: Processes & Products (16-18 June 2010, Baiona): introduction and future challenges

    Science.gov (United States)

    Hernández-Molina, Francisco Javier; Stow, Dorrik A. V.; Llave, Estefanía; Rebesco, Michele; Ercilla, Gemma; van Rooij, David; Mena, Anxo; Vázquez, Juan-Tomás; Voelker, Antje H. L.

    2011-12-01

    Deep-water circulation is a critical part of the global conveyor belt that regulates Earth's climate. The bottom (contour)-current component of this circulation is of key significance in shaping the deep seafloor through erosion, transport, and deposition. As a result, there exists a high variety of large-scale erosional and depositional features (drifts) that together form more complex contourite depositional systems on continental slopes and rises as well as in ocean basins, generated by different water masses flowing at different depths and at different speeds either in the same or in opposite directions. Yet, the nature of these deep-water processes and the deposited contourites is still poorly understood in detail. Their ultimate decoding will undoubtedly yield information of fundamental importance to the earth and ocean sciences. The international congress Deep-water Circulation: Processes & Products was held from 16-18 June 2010 in Baiona, Spain, hosted by the University of Vigo. Volume 31(5/6) of Geo-Marine Letters is a special double issue containing 17 selected contributions from the congress, guest edited by F.J. Hernández-Molina, D.A.V. Stow, E. Llave, M. Rebesco, G. Ercilla, D. Van Rooij, A. Mena, J.-T. Vázquez and A.H.L. Voelker. The papers and discussions at the congress and the articles in this special issue provide a truly multidisciplinary perspective of interest to both academic and industrial participants, contributing to the advancement of knowledge on deep-water bottom circulation and related processes, as well as contourite sedimentation. The multidisciplinary contributions (including geomorphology, tectonics, stratigraphy, sedimentology, paleoceanography, physical oceanography, and deep-water ecology) have demonstrated that advances in paleoceanographic reconstructions and our understanding of the ocean's role in the global climate system depend largely on the feedbacks among disciplines. New insights into the link between the biota of

  8. Dissolved gaseous Hg (DGM in the Mediterranean surface and deep waters

    Directory of Open Access Journals (Sweden)

    Kotnik J.

    2013-04-01

    Full Text Available Dissolved gaseous mercury (DGM was studied in surface and deep waters of the Mediterranean Sea for last 12 years during several oceanographic cruises on board the Italian research vessel Urania and covered both Western and Eastern Mediterranean Basins as well as Adriatic Sea. DGM was measured together with other mercury species (RHg - reactive Hg, THg - total Hg, MeHg - monomethyl Hg and DMeHg - dimethylmercury, and with some water quality parameters in coastal and open sea deep water profiles, however only DGM will be discussed here. DGM represents a considerable portion of THg (average of about 20 % in Mediterranean waters. Spatial and seasonal variations of measured DGM concentrations were observed in different indentified water masses as well as iwere observed. DGM was the highest in the northern Adriatic, most polluted part of the Mediterranean Sea as the consequence of Hg mining in Idrija and heavy industry of northern Italy.Generally, average DGM concentration was higher in W and E Mediteranean Deep Waters (WMDW and EMDW and Leavantine Intermediate Water (LIW than overlaying Modified Atlantic Water (MAW, however it was the highest in N Adriatic Surface waters and consequently in out flowing Adriatic Deep Waters (ADW. In deep water profiles the portion of DGM typically increased at depths with oxygen minimum and then towards the bottom, especially in areas with strong tectonic activity (Alboran Sea, Strait of Sicily, Tyrrhenian Sea, indicating its bacterial and/or geotectonic origin. A comparison of the results obtained in this study to others performed in the Mediterranean shows no significant differences. Results were also compared to the results obtained in the Pacific and Atlantic Oceans. During last oceanographic cruise in 2011 covering area between Livorno and Lipari Islands a novel method for continuous DGM determination in surface waters (Wangberg and Gardfeldt, 2011 was applied and compared to standard method.

  9. Contrasting trends in North Atlantic deep-water formation in the Labrador Sea and Nordic Seas during the Holocene

    NARCIS (Netherlands)

    Renssen, H.; Goosse, H.; Fichefet, T.

    2005-01-01

    The Holocene North Atlantic deep-water formation is studied in a 9,000-year long simulation with a coupled climate model of intermediate complexity, forced by changes in orbital forcing and atmospheric trace gas concentrations. During the experiment, deep-water formation in the Nordic Seas is

  10. Quantitative imaging of cation adsorption site densities in undisturbed soil

    Science.gov (United States)

    Keck, Hannes; Strobel, Bjarne W.; Gustafsson, Jon-Petter; Koestel, John

    2017-04-01

    The vast majority of present soil system models assume a homogeneous distribution and accessibility of cation adsorption sites (CAS) within soil structural units like e.g. soil horizons. This is however in conflict with several recent studies finding that CAS in soils are not uniformly but patchily distributed at and below the cm-scale. It is likely that the small-scale distribution of CAS has significant impact on the performance of these models. However, systematic approaches to map CAS densities in undisturbed soil with 3-D resolution that could lead to respective model improvements are still lacking. We therefore investigated the 3-D distribution of the CAS in undisturbed soils using X-ray scanning and barium ions as a contrast agent. We appraised the validity of the approach by comparing X-ray image-derived cation exchange coefficients (CEC) with ones obtained using the ammonium acetate method. In the process, we evaluated whether there were larger CAS concentrations at aggregate and biopore boundaries as it is often hypothesized. We sampled eight small soil cores (approx. 10 ccm) from different locations with contrasting soil texture and organic matter contents. The samples were first saturated with a potassium chloride solution (0.1 mol per liter), whereupon a 3-D X-ray image was taken. Then, the potassium chloride solution was flushed out with a barium chloride solution (0.3 mol per liter) with barium replacing the potassium from the CAS due to its larger exchange affinity. After X-ray images as well as electrical conductivity in the effluent indicated that the entire sample had been saturated with the barium chloride, the sample was again rinsed using the potassium chloride solution. When the rinsing was complete a final 3-D X-ray image was acquired. The difference images between final and initial 3-D X-ray images were interpreted as depicting the adsorbed barium as the density of barium exceeds the one of potassium by more than 2 times. The X-ray image

  11. Deep-water formation in the North Atlantic during the latest Cretaceous

    Science.gov (United States)

    Martin, E. E.; Rostami, M. A.; MacLeod, K. G.; Haynes, S.; Poulsen, C. J.; Vande Guchte, A.

    2017-12-01

    Global cooling during the late Campanian-Maastrichtian (78 - 66 Ma) has been linked to changes in ocean circulation. In the North Atlantic, both Northern Component (NCW) and Southern Component (SCW) Waters have been proposed as primary deep water sources in the Late Cretaceous. Neodymium (Nd) isotope records alone do not distinguish between these two alternatives because of similar initial ɛNd values. To provide additional resolution on deep water sources, we compiled an integrated dataset of Nd isotopes from fossil fish teeth, C and O isotopic records, and benthic foraminiferal assemblages from seven northeast (NE) and northwest (NW) North Atlantic DSDP, ODP and IODP sites with estimated paleodepths >2000 m. In the NE, deep water ɛNd values are -9.5 throughout the latest Cretaceous, while values at NW sites are slightly higher ( -8.5) in the Campanian and then decrease to -10 during the Maastrichtian. Although coverage is limited because many sites were below the CCD, distinct patterns occur in the stable isotopic data. NE δ13C values are 1.7‰ throughout while NW δ13C values increase from 1.2 ‰ in the Campanian to 1.9 ‰ in the Maastrichtian, and the increase is correlated with a shift to higher % benthic epifauna. These data suggest formation of oxygen-rich/nutrient-poor NCW in the NE Atlantic during the latest Cretaceous. Decreasing δ13C and increasing ɛNd values from north to south are consistent with flow of NCW into the NW Atlantic during the Campanian. In contrast, lower δ13C in the South Atlantic and ɛNd values that are similar at high northern and southern latitudes, but separated by regions with both higher and lower values, are inconsistent with flow of SCW into the North Atlantic. The shift to lower ɛNd values, higher δ13C values, and abundant epifauna in the NW Atlantic during the Maastrichtian may indicate formation of a proximal deep water mass analogous to modern Labrador Sea Water that introduced nonradiogenic ɛNd from weathering of

  12. Deep water formation in the North Pacific and deglacial CO2 rise

    Science.gov (United States)

    Rae, James W. B.; Sarnthein, Michael; Foster, Gavin L.; Ridgwell, Andy; Grootes, Pieter M.; Elliott, Tim

    2014-06-01

    Deep water formation in the North Atlantic and Southern Ocean is widely thought to influence deglacial CO2 rise and climate change; here we suggest that deep water formation in the North Pacific may also play an important role. We present paired radiocarbon and boron isotope data from foraminifera from sediment core MD02-2489 at 3640 m in the North East Pacific. These show a pronounced excursion during Heinrich Stadial 1, with benthic-planktic radiocarbon offsets dropping to 350 years, accompanied by a decrease in benthic δ11B. We suggest that this is driven by the onset of deep convection in the North Pacific, which mixes young shallow waters to depth, old deep waters to the surface, and low-pH water from intermediate depths into the deep ocean. This deep water formation event was likely driven by an increase in surface salinity, due to subdued atmospheric/monsoonal freshwater flux during Heinrich Stadial 1. The ability of North Pacific Deep Water (NPDW) formation to explain the excursions seen in our data is demonstrated in a series of experiments with an intermediate complexity Earth system model. These experiments also show that breakdown of stratification in the North Pacific leads to a rapid 30 ppm increase in atmospheric CO2, along with decreases in atmospheric δ13C and Δ14C, consistent with observations of the early deglaciation. Our inference of deep water formation is based mainly on results from a single sediment core, and our boron isotope data are unavoidably sparse in the key HS1 interval, so this hypothesis merits further testing. However, we note that there is independent support for breakdown of stratification in shallower waters during this period, including a minimum in δ15N, younging in intermediate water 14C, and regional warming. We also re-evaluate deglacial changes in North Pacific productivity and carbonate preservation in light of our new data and suggest that the regional pulse of export production observed during the B

  13. Biota - 2011 Vegetation Inventory - Marsh Lake, MN

    Data.gov (United States)

    Army Corps of Engineers, Department of the Army, Department of Defense — 2011 Vegetation Classification for Marsh Lake, MN Vegetation Project Report, OMBIL Environmental Stewardship - Level 1 Inventory. Marsh Lake is located on the...

  14. Galveston Bay Marsh Terracing 2001-2002

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Marsh terracing is used to restore coastal wetlands by converting shallow nonvegetated bottom to intertidal marsh. Terraces are constructed from excavated bottom...

  15. Industrial automation in floating production vessels for deep water oil and gas fields

    International Nuclear Information System (INIS)

    de Garcia, A.L.; Ferrante, A.J.

    1990-01-01

    The process supervision in offshore platforms was performed in the past through the use of local pneumatic instrumentation, based on relays, semi-graphic panels and button operated control panels. Considering the advanced technology used in the new floating production projects for deep water, it became mandatory to develop supervision systems capable of integrating different control panels, increasing the level of monitorization and reducing the number of operators and control rooms. From the point of view of field integration, a standardized architecture makes the communication between different production platforms and the regional headquarters, where all the equipment and support infrastructure for the computerized network is installed, possible. This test paper describes the characteristics of the initial systems, the main problems observed, the studies performed and the results obtained in relation to the design and implementation of computational systems with open architecture for automation of process control in floating production systems for deep water in Brazil

  16. [Phylogenetic diversity of microorganisms associated with the deep-water sponge Baikalospongia intermedia].

    Science.gov (United States)

    Kalyzhnaya, O V; Itskovich, V B

    2014-07-01

    The diversity of bacteria associated with deep-water sponge Baikalospongia intermedia was evaluated by sequence analysis of 16S rRNA genes from two sponge samples collected in Lake Baikal from depths of 550 and 1204 m. A total of 64 operational taxonomic units, belonging to nine bacterial phyla, Proteobacteria (classes Alphaproteobacteria,. Betaproteobacteria, Gammaproteobacteria, and Deltaproteobacteria), Actinobacteria, Planctomycetes, Cloroflexi, Verrucomicrobia, Acidobacteria, Chlorobi, and Nitrospirae, including candidate phylum WS5, were identified. Phylogenetic analysis showed that the examined communities contained phylotypes exhibiting homology to uncultured bacteria from different lake ecosystems, freshwater sediments, soil and geological formations. Moreover, a number of phylotypes were relative to psychrophilic, methane-oxidizing, sulfate-reducing bacteria, and to microorganisms resistant to the influence of heavy metals. It seems likely that the unusual habitation conditions of deep-water sponges contribute to the taxonomic diversity of associated bacteria and have an influence on the presence of functionally important microorganisms in bacterial communities.

  17. Deep-water carbonate dissolution in the northern South China Sea during Marine Isotope Stage 3

    Directory of Open Access Journals (Sweden)

    Na Wang

    2016-01-01

    Full Text Available The production, transportation, deposition, and dissolution of carbonate profoundly form part of the global carbon cycle and affect the amount and distribution of dissolved inorganic carbon (DIC and alkalinity (ALK, which drive atmospheric CO2 changes during glacial/interglacial cycles. These processes may provide significant clues for better understanding of the mechanisms that control the global climate system. In this study, we calculate and analyze the foraminiferal dissolution index (FDX and the fragmentation ratios of planktonic foraminifera for the 60–25 ka B.P. time-span, based on samples from Core 17924 and ODP Site 1144 in the northeastern South China Sea (SCS, so as to reconstruct the deep-water carbonate dissolution during Marine Isotope Stage 3 (MIS 3. Our analysis shows that the dissolution of carbonate increases gradually in Core 17924, whereas it remains stable at ODP Site 1144. This difference is caused by the deep-sea carbonate ion concentration ([CO32−] that affected the dissolution in Core 17924 where the depth of 3440 m is below the saturation horizon. However, the depth of ODP Site 1144 is 2037 m, which is above the lysocline where the water is always saturated with calcium carbonate; the dissolution is therefore less dependent of chemical changes of the seawater. The combined effect of the productivity and the deep-water chemical evolution may decrease deep-water [CO32−] and accelerate carbonate dissolution. The fall of the sea-level increased the input of DIC and ALK to the deep ocean and deepened the carbonate saturation depth, which caused an increase of the deep-water [CO32−]. The elevated [CO32−] partially neutralized the reduced [CO32−] contributed by remineralization of organic matter and slowdown of thermohaline. These consequently are the fundamental reasons for the difference in dissolution rate between these two sites.

  18. Spiraling pathways of global deep waters to the surface of the Southern Ocean

    OpenAIRE

    Tamsitt, Veronica; Drake, Henri F.; Morrison, Adele K.; Talley, Lynne D.; Dufour, Carolina O.; Gray, Alison R.; Griffies, Stephen M.; Mazloff, Matthew R.; Sarmiento, Jorge L.; Wang, Jinbo; Weijer, Wilbert

    2017-01-01

    Upwelling of global deep waters to the sea surface in the Southern Ocean closes the global overturning circulation and is fundamentally important for oceanic uptake of carbon and heat, nutrient resupply for sustaining oceanic biological production, and the melt rate of ice shelves. However, the exact pathways and role of topography in Southern Ocean upwelling remain largely unknown. Here we show detailed upwelling pathways in three dimensions, using hydrographic observations and particle trac...

  19. Antarctic climate, Southern Ocean circulation patterns, and deep water formation during the Eocene

    Science.gov (United States)

    Huck, Claire E.; van de Flierdt, Tina; Bohaty, Steven M.; Hammond, Samantha J.

    2017-07-01

    We assess early-to-middle Eocene seawater neodymium (Nd) isotope records from seven Southern Ocean deep-sea drill sites to evaluate the role of Southern Ocean circulation in long-term Cenozoic climate change. Our study sites are strategically located on either side of the Tasman Gateway and are positioned at a range of shallow (fish teeth at intermediate/deep Indian Ocean pelagic sites (Ocean Drilling Program (ODP) Sites 738 and 757 and Deep Sea Drilling Project (DSDP) Site 264), indicate a dominant Southern Ocean-sourced contribution to regional deep waters (ɛNd(t) = -9.3 ± 1.5). IODP Site U1356 off the coast of Adélie Land, a locus of modern-day Antarctic Bottom Water production, is identified as a site of persistent deep water formation from the early Eocene to the Oligocene. East of the Tasman Gateway an additional local source of intermediate/deep water formation is inferred at ODP Site 277 in the SW Pacific Ocean (ɛNd(t) = -8.7 ± 1.5). Antarctic-proximal shelf sites (ODP Site 1171 and Site U1356) reveal a pronounced erosional event between 49 and 48 Ma, manifested by 2 ɛNd unit negative excursions in seawater chemistry toward the composition of bulk sediments at these sites. This erosional event coincides with the termination of peak global warmth following the Early Eocene Climatic Optimum and is associated with documented cooling across the study region and increased export of Antarctic deep waters, highlighting the complexity and importance of Southern Ocean circulation in the greenhouse climate of the Eocene.

  20. APL-UW Deep Water Propagation 2015-2017: Philippine Sea Data Analysis

    Science.gov (United States)

    2015-09-30

    DISTRIBUTION STATEMENT A: Approved for public release: distribution is unlimited APL-UW Deep Water Propagation 2015-2017: Philippine Sea Data...objective of this research is to determine the validity of these models in a region with different oceanographic features, specifically the Philippine Sea...APPROACH Philippine Sea Analysis Our approach utilizes a combination of at-sea measurements, theoretical modeling and computational simulations. Our

  1. Horizontal single-trip gravel pack and selective simulation system for deep water extended reach wells

    Energy Technology Data Exchange (ETDEWEB)

    Pineda, Francisco [BJ Services Company, Houston, TX (United States); Vilela, Alvaro; Montanha, Roberto; Acosta, Marco; Farias, Rodrigo [BJ Services do Brasil Ltda., Rio de Janeiro, RJ (Brazil)

    2004-07-01

    Most of the reservoirs located in the deep water and ultra-deep water offshore South America are described as unconsolidated sandstone that require sand control on both producers and water injection wells. Horizontal Open Hole Gravel Pack completions are the preferred method of development. If completing heavy oil reservoirs, there is a necessity of longer horizontal open hole sections. Low fracture gradients may limit the length of gravel pack in the open hole section because of the pressure increase during the Beta wave proppant deposition phase. This system allows the gravel pack assembly to be installed and the gravel pack to be pumped during the alpha and beta wave deposition phases without the limitation of high pressures that could fracture the well. The benefits of the Horizontal Single-Trip Gravel Pack and Selective Stimulation System (HSTSSS) using the differential valve include the ability to complete longer horizontal intervals, valuable rig-time savings and, efficient mechanical diversion of the stimulation fluid. This paper outlines the application of the HSTSSS system using a differential valve to complete a horizontal well in offshore deep waters. The need for a differential valve is primarily in horizontal gravel packing operations when normal circulating rates and pressures around the open hole would exceed formation break down pressure. The valve is intended to be easily spaced out and run in the wash pipe. At a predetermined differential pressure the valve opens and the return flow path distance around the bottom of the tailpipe is shortened, thus reducing back pressure preventing filter cake damage without slowing the pump rate. In addition the said valve has to close to allow the selective stimulation to take place. Economic considerations along with completion efficiencies are especially important on deep water, subsea completions. The utilization of differential valves allows completion of extended-reach open hole wells and/or low fracture

  2. Modeling SST gradient changes, the hydrological cycle response, and deep water formation in the North Pacific

    Science.gov (United States)

    Burls, N.; Ford, H. L.; Fedorov, A. V.; Jahn, A.; Jacobs, P.

    2017-12-01

    The absence of deep-water formation and a deep meridional overturning cell in the modern North Pacific has been attributed to the relatively fresh surface conditions in the subarctic. These conditions are, in turn, best explained by the local excess of precipitation over evaporation in the northern Pacific due to net moisture transport from the Atlantic to the Pacific and/or moisture transport associated with the Asian monsoon. Some studies link the lack of deep-water formation in the Pacific directly to its occurrence in the Atlantic via the Atlantic-Pacific seesaw effect and idealized experiments indicate that the smaller width of the Atlantic predisposes it to higher salinity and deep-water formation. We have conducted a series of coupled model experiments across which global mean temperatures and large-scale meridional SST gradients are varied. We perturb either atmospheric CO2 concentrations or the meridional gradient in cloud radiative forcing and run each experiment out to 3000 years so that the deep ocean has equilibrated. As the strength of the meridional temperature gradient decreases across our experiments, a Pacific Meridional Overturning Circulation develops. The strength of this Pacific Meridional Overturning Circulation generally increases as the gradient weakens. In one of these experiments where the meridional SST gradient most closely resembles Pliocene reconstructions, a PMOC exists of comparable in strength to the modern AMOC. We will describe how the hydrological cycle response to reduced meridional SST gradients acts to increase the strength of the PMOC across our sensitivity experiments. Additionally, we will discuss our effort to include carbon isotopes in our Pliocene-like simulation for data-model comparisons. Calcium carbonate accumulation data from Subarctic North Pacific Site 882 and new and previously published carbon isotope records from the Pacific appear to support our modelling results suggesting that weaker meridonal SST gradients

  3. The effects of a 24-week deep water aerobic training program on cardiovascular fitness

    Directory of Open Access Journals (Sweden)

    E Piotrowska-Całka

    2010-06-01

    Full Text Available The purpose of this study was to determine the influence of prolonged deep water aerobic training on cardiovascular fitness. Two groups of women, each consisting of 19 women between the ages of 30-62 participated in this research. Group “A” (mean age of 49.2±8.7 participated in a 24-week deep water training program, exercising twice a week for 45 minutes. All 45 minute sessions were divided into three parts: the warm-up, the aerobic segment, and the cool-down including stretching elements. During the aerobic portion, the subjects were told to exercise at a moderate intensity which was established by used Karvonen’s formula for water exercise and self-regulated by used of a Sport-tester Polar 800i. Subjects in group “A” were tested before and after 24 week program with the Bruce Protocol cardio-effort test when compared to the control group “B” (19 females with an average age of 48.7±8.1. Group “A” demonstrated significant improvement in aerobic capacity after deep water aerobic program (before=10.1±2.2 MET, after=11.1±2.0MET, p<0.01, also were demonstrated significant reduction of response systolic blood pressure and resting heart rate (before 84.5±14.3 bpm, after 75.8±10.0 bpm, p<0.05. The results of these study support the use deep water aerobic training as an alternative form of exercise to land-based training for unfit middle age participants.

  4. Hydrography, Surface Geology and Geomorphology of the Deep Water Sedimentary Basins to the West of Ireland

    OpenAIRE

    Vermeulen, N. J.

    1997-01-01

    This desk study involved the assembly, review and analysis of public domain and available data from an extensive deep water area offshore to the west of Ireland. All major bathymetric and sedimentary basins, in addition to associated shallow plateau and bank areas, were considered. Particular emphasis was placed on the Porcupine Seabight and Rockall Trough as these were considered to be the main areas of interest for the proposed 1996 AIRS (Atlantic Irish Regional Survey) project. Only relati...

  5. North Atlantic deep water formation and AMOC in CMIP5 models

    Science.gov (United States)

    Heuzé, Céline

    2017-07-01

    Deep water formation in climate models is indicative of their ability to simulate future ocean circulation, carbon and heat uptake, and sea level rise. Present-day temperature, salinity, sea ice concentration and ocean transport in the North Atlantic subpolar gyre and Nordic Seas from 23 CMIP5 (Climate Model Intercomparison Project, phase 5) models are compared with observations to assess the biases, causes and consequences of North Atlantic deep convection in models. The majority of models convect too deep, over too large an area, too often and too far south. Deep convection occurs at the sea ice edge and is most realistic in models with accurate sea ice extent, mostly those using the CICE model. Half of the models convect in response to local cooling or salinification of the surface waters; only a third have a dynamic relationship between freshwater coming from the Arctic and deep convection. The models with the most intense deep convection have the warmest deep waters, due to a redistribution of heat through the water column. For the majority of models, the variability of the Atlantic Meridional Overturning Circulation (AMOC) is explained by the volumes of deep water produced in the subpolar gyre and Nordic Seas up to 2 years before. In turn, models with the strongest AMOC have the largest heat export to the Arctic. Understanding the dynamical drivers of deep convection and AMOC in models is hence key to realistically forecasting Arctic oceanic warming and its consequences for the global ocean circulation, cryosphere and marine life.

  6. Hypoxia in deep waters of moderately eutrophic marine lakes, Island of Mljet, eastern Adriatic Sea

    Directory of Open Access Journals (Sweden)

    Enis Hrustić

    2017-12-01

    Full Text Available In this study, we explored the impact of eutrophication and stratification on hypoxia in deep waters of moderately warm Croatian marine lakes. Although the Mljet Lakes (MLs are predominantly oligotrophic, mesotrophic conditions are present at depths below 20 m in the Small Lake (SL and below 30 m in the Big Lake (BL, along with higher apparent oxygen utilization (AOU. Hypoxia at depths ≥ 25 m in SL and and ≥ 40 m in BL was observed between October 2009 and January 2010, and in SL in summer (July and September 2010. Significant differences (p 0.05 between the lakes. An intense and persistent pycnocline throughout the year, comparatively high water temperature, extended water renewal time and summer phytoplankton bloom were identified as physical and biological parameters which might have significantly contributed to increased frequency of hypoxic events in a shallow SL. Significantly (p < 0.05 higher ammonium concentration in SL, especially in its deep water, seems to be a long-term chemical feature related to the poor ventilation and higher sediment oxygen demand. At the current level of eutrophication and the present climate change trends, the MLs and similar systems may experience more persistent and intense stratification, which could further prevent mixing between upper and deep waters, likely leading to increasing duration of hypoxia and its negative impacts on the biodiversity of benthic communities.

  7. Impact of the 2010 Deepwater Horizon oil spill on population size and genetic structure of horse flies in Louisiana marshes.

    Science.gov (United States)

    Husseneder, Claudia; Donaldson, Jennifer R; Foil, Lane D

    2016-01-12

    The greenhead horse fly, Tabanus nigrovittatus Macquart, is frequently found in coastal marshes of the Eastern United States. The greenhead horse fly larvae are top predators in the marsh and thus vulnerable to changes in the environment, and the adults potentially are attracted to polarized surfaces like oil. Therefore, horse fly populations could serve as bioindicators of marsh health and toxic effects of oil intrusion. In this study, we describe the impact of the April 2010 Deep Water Horizon oil spill in the Gulf of Mexico on tabanid population abundance and genetics as well as mating structure. Horse fly populations were sampled biweekly from oiled and unaffected locations immediately after the oil spill in June 2010 until October 2011. Horse fly abundance estimates showed severe crashes of tabanid populations in oiled areas. Microsatellite genotyping of six pristine and seven oiled populations at ten polymorphic loci detected genetic bottlenecks in six of the oiled populations in association with fewer breeding parents, reduced effective population size, lower number of family clusters and fewer migrants among populations. This is the first study assessing the impact of oil contamination at the level of a top arthropod predator of the invertebrate community in salt marshes.

  8. 77 FR 24154 - Fisheries of the Economic Exclusive Zone Off Alaska; Deep-Water Species Fishery by Vessels Using...

    Science.gov (United States)

    2012-04-23

    ... the most recent fisheries data in a timely fashion and would delay the closure of the deep-water... Director, Office of Sustainable Fisheries, National Marine Fisheries Service. BILLING CODE 3510-22-P ...

  9. Bermuda: Search for Deep Water Caves 2009 on the R/V Endurance between 20090905 and 20090930

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Deep-water marine caves are one of the Earth's last largely unexplored frontiers of undiscovered fauna (animal life). More than 150 limestone caves are known to...

  10. Influence of ocean acidification and deep water upwelling on oligotrophic plankton communities in the subtropical North Atlantic

    DEFF Research Database (Denmark)

    Taucher, Jan; Bach, Lennart T.; Boxhammer, Tim

    2017-01-01

    and successfully simulated a deep water upwelling event that induced a pronounced plankton bloom. Our study revealed significant effects of OA on the entire food web, leading to a restructuring of plankton communities that emerged during the oligotrophic phase, and was further amplified during the bloom......Oceanic uptake of anthropogenic carbon dioxide (CO2) causes pronounced shifts in marine carbonate chemistry and a decrease in seawater pH. Increasing evidence indicates that these changes-summarized by the term ocean acidification (OA)-can significantly affect marine food webs and biogeochemical......, which regularly occur in response to upwelling of nutrient-rich deep water in the study region. Therefore, we specifically developed a deep water collection system that allowed us to obtain 85 m3 of seawater from 650 m depth. Thereby, we replaced 20% of each mesocosm's volume with deep water...

  11. Deep-water oilfield development cost analysis and forecasting —— Take gulf of mexico for example

    Science.gov (United States)

    Shi, Mingyu; Wang, Jianjun; Yi, Chenggao; Bai, Jianhui; Wang, Jing

    2017-11-01

    Gulf of Mexico (GoM) is the earliest offshore oilfield which has ever been developed. It tends to breed increasingly value of efficient, secure and cheap key technology of deep-water development. Thus, the analyze of development expenditure in this area is significantly important the evaluation concept of deep-water oilfield all over the world. This article emphasizes on deep-water development concept and EPC contract value in GoM in recent 10 years in case of comparison and selection to the economic efficiency. Besides, the QUETOR has been put into use in this research processes the largest upstream cost database to simulate and calculate the calculating examples’ expenditure. By analyzing and forecasting the deep-water oilfield development expenditure, this article explores the relevance between expenditure index and oil price.

  12. Comparison of aerated marsh-pond-marsh and continuous marsh constructed wetlands for treating swine wastewater.

    Science.gov (United States)

    Forbes, Dean A; Reddy, G B; Hunt, Patrick G; Poach, M E; Ro, Kyoung S; Cyrus, Johnsely S

    2010-01-01

    Increased swine production in North Carolina has resulted in greater waste generation and is demanding some emerging new innovative technologies to effectively treat swine wastewater. One of the cost-effective and passive methods to treat swine wastewater is using constructed wetlands. The objective of this study was to evaluate the N removal under two N loads in 3 different wetland systems: aerated marsh-pond-marsh (M-P-M), aerated marsh-covered pond-marsh (M-FB-M), and continuous marsh (CM) with two days drain and five days flood cycle. Swine wastewater from an anaerobic lagoon was applied to the constructed wetland cells (11 m wide x 40 m length) at two N loading rates of 7 and 12 kg N ha(-1) day(-1)from June to July and August to September 2005, respectively. Weekly inflow and outflow samples were collected for N, P, TS, and COD analysis. Total N reductions (%) at low and high N loading rates were 85.8 and 51.8; 86.3 and 63.3; and 86.2 and 61.8 for M-P-M, M-FB-M, and CM, respectively. Aeration had no significant (P > 0.05) impact on N removal. However, significant (P 0.05) in N reduction was found among wetland systems. Vegetation uptake of N was negligible, ranging from 1.2 to 1.8 %. No significant (P > 0.05) differences in TS and COD removal were observed between the wetland systems.

  13. LBA-ECO TG-07 Trace Gas Fluxes, Undisturbed and Logged Sites, Para, Brazil: 2000-2002

    Science.gov (United States)

    M.M. Keller; R.K. Varner; J.D. Dias; H.S. Silva; P.M. Crill; Jr. de Oliveira; G.P. Asner

    2009-01-01

    Trace gas fluxes of carbon dioxide, methane, nitrous oxide, and nitric oxide were measured manually at undisturbed and logged forest sites in the Tapajos National Forest, near Santarem, Para, Brazil. Manual measurements were made approximately weekly at both the undisturbed and logged sites. Fluxes from clay and sand soils were completed at the undisturbed sites....

  14. Salinization during salt-marsh restoration after managed realignment

    NARCIS (Netherlands)

    Veeneklaas, Roos; Koppenaal, Elske; Bakker, Jan P.; Esselink, Peter

    Salt marshes provide an important and unique habitat for plants and animals. To restore salt marshes, numerous coastal realignment projects have been carried out, but restored marshes often show persistent ecological differences from natural marshes. We evaluate the effects of elevation and marsh

  15. Bearing splitting and near-surface source ranging in the direct zone of deep water

    Science.gov (United States)

    Wu, Jun-Nan; Zhou, Shi-Hong; Peng, Zhao-Hui; Zhang, Yan; Zhang, Ren-He

    2016-12-01

    Sound multipath propagation is very important for target localization and identification in different acoustical zones of deep water. In order to distinguish the multipath characteristics in deep water, the Northwest Pacific Acoustic Experiment was conducted in 2015. A low-frequency horizontal line array towed at the depth of around 150 m on a receiving ship was used to receive the noise radiated by the source ship. During this experiment, a bearing-splitting phenomenon in the direct zone was observed through conventional beamforming of the horizontal line array within the frequency band 160 Hz-360 Hz. In this paper, this phenomenon is explained based on ray theory. In principle, the received signal in the direct zone of deep water arrives from two general paths including a direct one and bottom bounced one, which vary considerably in arrival angles. The split bearings correspond to the contributions of these two paths. The bearing-splitting phenomenon is demonstrated by numerical simulations of the bearing-time records and experimental results, and they are well consistent with each other. Then a near-surface source ranging approach based on the arrival angles of direct path and bottom bounced path in the direct zone is presented as an application of bearing splitting and is verified by experimental results. Finally, the applicability of the proposed ranging approach for an underwater source within several hundred meters in depth in the direct zone is also analyzed and demonstrated by simulations. Project supported by the Program of One Hundred Talented People of the Chinese Academy of Sciences and the National Natural Science Foundation of China (Grant Nos. 11434012 and 41561144006).

  16. North Atlantic deep water formation and AMOC in CMIP5 models

    Directory of Open Access Journals (Sweden)

    C. Heuzé

    2017-07-01

    Full Text Available Deep water formation in climate models is indicative of their ability to simulate future ocean circulation, carbon and heat uptake, and sea level rise. Present-day temperature, salinity, sea ice concentration and ocean transport in the North Atlantic subpolar gyre and Nordic Seas from 23 CMIP5 (Climate Model Intercomparison Project, phase 5 models are compared with observations to assess the biases, causes and consequences of North Atlantic deep convection in models. The majority of models convect too deep, over too large an area, too often and too far south. Deep convection occurs at the sea ice edge and is most realistic in models with accurate sea ice extent, mostly those using the CICE model. Half of the models convect in response to local cooling or salinification of the surface waters; only a third have a dynamic relationship between freshwater coming from the Arctic and deep convection. The models with the most intense deep convection have the warmest deep waters, due to a redistribution of heat through the water column. For the majority of models, the variability of the Atlantic Meridional Overturning Circulation (AMOC is explained by the volumes of deep water produced in the subpolar gyre and Nordic Seas up to 2 years before. In turn, models with the strongest AMOC have the largest heat export to the Arctic. Understanding the dynamical drivers of deep convection and AMOC in models is hence key to realistically forecasting Arctic oceanic warming and its consequences for the global ocean circulation, cryosphere and marine life.

  17. Asymmetric oceanic response to a hurricane: Deep water observations during Hurricane Isaac

    Science.gov (United States)

    Spencer, Laura J.; DiMarco, Steven F.; Wang, Zhankun; Kuehl, Joseph J.; Brooks, David A.

    2016-10-01

    The eye of Hurricane Isaac passed through the center of an array of six deep water water-column current meter moorings deployed in the northern Gulf of Mexico. The trajectory of the hurricane provided for a unique opportunity to quantify differences in the full water-column oceanic response to a hurricane to the left and right of the hurricane trajectory. Prior to the storm passage, relative vorticity on the right side of the hurricane was strongly negative, while on the left, relative vorticity was positive. This resulted in an asymmetry in the near-inertial frequencies oceanic response at depth and horizontally. A shift in the response to a slightly larger inertial frequencies ˜1.11f was observed and verified by theory. Additionally, the storm passage coincided with an asymmetric change in relative vorticity in the upper 1000 m, which persisted for ˜15 inertial periods. Vertical propagation of inertial energy was estimated at 29 m/d, while horizontal propagation at this frequency was approximately 5.7 km/d. Wavelet analysis showed two distinct subinertial responses, one with a period of 2-5 days and another with a period of 5-12 days. Analysis of the subinertial bands reveals that the spatial and temporal scales are shorter and less persistent than the near-inertial variance. As the array is geographically located near the site of the Deep Water Horizon oil spill, the spatial and temporal scales of response have significant implications for the fate, transport, and distribution of hydrocarbons following a deep water spill event.

  18. LBA-ECO ND-11 Regeneration in Undisturbed and Logged Forests, NW Mato Grosso, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set reports the results of field surveys to determine: regeneration diversity and size distribution of plants in primary undisturbed forest; and...

  19. LBA-ECO TG-07 Tree Geometry in an Undisturbed Forest in Cauaxi, Para, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — Canopy measurements in an undisturbed eastern Amazon forest (Cauxi, Para, Brazil. See Figure 1) were derived from a one-time event in 2000 using a hand-held laser...

  20. LBA-ECO ND-11 Regeneration in Undisturbed and Logged Forests, NW Mato Grosso, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set reports the results of field surveys to determine: regeneration diversity and size distribution of plants in primary undisturbed forest; and...

  1. LBA-ECO TG-07 Tree Geometry in an Undisturbed Forest in Cauaxi, Para, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: Canopy measurements in an undisturbed eastern Amazon forest (Cauxi, Para, Brazil. See Figure 1) were derived from a one-time event in 2000 using a...

  2. Offshore support vessel developments for deep water oil and gas E and P

    Energy Technology Data Exchange (ETDEWEB)

    Dielen, Baldo A.M. [SMIT, Rotterdam (Netherlands)

    2008-07-01

    The worldwide trend to move towards more exposed locations and deeper waters for O and G exploration and production activities resulted in an increased need for larger and more powerful tugs and offshore support vessels. These vessels must meet higher operational requirements under higher wind and sea-state conditions. This market-driven need, together with technological developments, is leading towards a new generation of powerful and sophisticated offshore support vessels (OSV's). This paper will describe the actual and future trends in OSV design for deep water offshore use. (author)

  3. Short-crested waves in deep water: a numerical investigation of recent laboratory experiments

    DEFF Research Database (Denmark)

    Fuhrman, David R.; Madsen, Per A.

    2006-01-01

    A numerical study of quasi-steady, doubly-periodic monochromatic short-crested wave patterns in deep water is conducted using a high-order Boussinesq-type model. Simulations using linear wavemaker conditions in the nonlinear model are initially used to approximate conditions from recent laboratory...... inclusion of steady third-order components in the wave generation is shown to significantly reduce the modulations (and other unsteady features), further confirming the explanation. This numerical work makes apparent some previously unknown difficulties associated with the physical generation of even...

  4. Three new records of deep-water goniasterids (Echinodermata: Asteroidea: Goniasteridae) from China seas

    Science.gov (United States)

    Xiao, Ning; Liao, Yulin

    2013-09-01

    In this paper, three deep-water species of the family Goniasteridae, Ceramaster misakiensis (Goto, 1914), Nymphaster arthrocnemis Fisher, 1913 and Pontioceramus grandis Fisher, 1911, are recorded for the first time from Chinese waters based on collections deposited in the Marine Biological Museum, Chinese Academy of Sciences. The specimens examined were collected during the period 1956 to 1978 from the East China and South China Seas at depths of 184 to 472 m. Diagnosis, detailed figures, and the geographic distributions are provided. A revised list of Goniasteridae recorded from Chinese waters is proposed.

  5. Cardiovascular responses during deep water running versus shallow water running in school children

    Directory of Open Access Journals (Sweden)

    Anerao Urja M, Shinde Nisha K, Khatri SM

    2014-03-01

    Full Text Available Overview: As the school going children especially the adolescents’ need workout routine; it is advisable that the routine is imbibed in the school’s class time table. In India as growing number of schools provide swimming as one of the recreational activities; school staff often fails to notice the boredom that is caused by the same activity. Deep as well as shallow water running can be one of the best alternatives to swimming. Hence the present study was conducted to find out the cardiovascular response in these individuals. Methods: This was a Prospective Cross-Sectional Comparative Study done in 72 healthy school going students (males grouped into 2 according to the interventions (Deep water running and Shallow water running. Cardiovascular parameters such as Heart rate (HR, Saturation of oxygen (SpO2, Maximal oxygen consumption (VO2max and Rate of Perceived Exertion (RPE were assessed. Results: Significant improvements in cardiovascular parameters were seen in both the groups i.e. by both the interventions. Conclusion: Deep water running and Shallow water running can be used to improve cardiac function in terms of various outcome measures used in the study.

  6. Evidence for deep-water deposition of abyssal Mediterranean evaporites during the Messinian salinity crisis

    Science.gov (United States)

    Christeleit, Elizabeth C.; Brandon, Mark T.; Zhuang, Guangsheng

    2015-10-01

    Scientific drilling of the abyssal evaporites beneath the deepest parts of the Mediterranean basin gave rise to the idea that the Mediterranean sea completely evaporated at the end of the Messinian. Herein, we show, using new organic geochemical data, that those evaporites were deposited beneath a deep-water saline basin, not in a subaerial saltpan, as originally proposed. Abundant fossil organic lipids were extracted from evaporites in Mediterranean Deep Sea Drilling Project cores. The archaeal lipid distribution and new analyses, using the ACE salinity proxy and TEX86 temperature proxy, indicate that surface waters at the time of evaporite deposition had normal marine salinity, ranging from ∼26 to 34 practical salinity units, and temperatures of 25-28 °C. These conditions require a deep-water setting, with a mixed layer with normal marine salinity and an underlying brine layer at gypsum and halite saturation. After correction for isostatic rebound, our results indicate maximum drawdown of ∼2000 m and ∼2900 m relative to modern sea level in the western and eastern Mediterranean basins, respectively. Our results are consistent with previously proposed scenarios for sea level drawdown based on both subaerial and submarine incision and backfilling of the Rhone and Nile rivers, which require Messinian sea level drops of ∼1300 m and ∼200 m, respectively. This study provides new evidence for an old debate and also demonstrates the importance of further scientific drilling and sampling of deeper part of the abyssal Messinian units.

  7. High biodiversity on a deep-water reef in the eastern Fram Strait.

    Directory of Open Access Journals (Sweden)

    Kirstin S Meyer

    Full Text Available We report on the distribution and abundance of megafauna on a deep-water rocky reef (1796-2373 m in the Fram Strait, west of Svalbard. Biodiversity and population density are high, with a maximum average of 26.7±0.9 species m(-2 and 418.1±49.6 individuals m(-2 on the east side of the reef summit. These figures contrast with the surrounding abyssal plain fauna, with an average of only 18.1±1.4 species and 29.4±4.3 individuals m(-2 (mean ± standard error. The east side of the reef summit, where the highest richness and density of fauna are found, faces into the predominant bottom current, which likely increases in speed to the summit and serves as a source of particulate food for the numerous suspension feeders present there. We conclude that the observed faunal distribution patterns could be the result of hydrodynamic patterns and food availability above and around the reef. To our knowledge, this study is the first to describe the distribution and diversity of benthic fauna on a rocky reef in deep water.

  8. Isotope paleoclimatology and Atlantic deep water history since 15 million years

    International Nuclear Information System (INIS)

    Blanc, P.L.

    1981-12-01

    18 O/ 16 O and 13 C/ 12 C ratios measurements in foraminiferal calcite are applied to the paleoclimatology of the North Atlantic and to the reconstruction of deep water exchanges between the Atlantic and Pacific Oceans, from middle miocene time (15 m.y. ago) to the present, on samples from 2 DSDP wells. Chapters 1 to 4 describe the structural frame and hydrological setting of these sites, and the stratigraphy of the deposits. A .4 m.y. lag between the initiation of the first boreal ice-caps and their extension to northern Europe is explained by the persistency of the North-Atlantic Drift. In chapters 5 to 8, the 13 C/ 12 C ratio of dissolved mineral carbon is used as a tracer of the residence time of the deep waters, the indications of which are preserved in benthonic foraminiferal calcite. It is shown that present-day type thermo-haline circulation was initiated 13.2 m.y. ago in the northern Atlantic, when the volcanic Scotland-Iceland-Greenland ridge subsided; that the closure of the Mediterranean sea during the Messinian (6.2 to 5 m.y. ago) caused this circulation to stop, and that the present circulation started again when the Mediterranean re-opened, at the beginning of the Pliocene [fr

  9. Stakeholders Opinions on Multi-Use Deep Water Offshore Platform in Hsiao-Liu-Chiu, Taiwan.

    Science.gov (United States)

    Sie, Ya-Tsune; Château, Pierre-Alexandre; Chang, Yang-Chi; Lu, Shiau-Yun

    2018-02-06

    This paper describes a group model building activity designed to elicit the potential effects a projected multi-use deep water offshore platform may have on its local environment, including ecological and socio-economic issues. As such a platform is proposed for construction around the island of Hsiao-Liu-Chiu, Taiwan, we organized several meetings with the local stakeholders and structured the debates using group modeling methods to promote consensus. During the process, the participants iteratively built and revised a causal-loop diagram that summarizes their opinions. Overall, local stakeholders concluded that a multi-use deep water offshore marine platform might have beneficial effects for Hsiao-Liu-Chiu because more tourists and fish could be attracted by the structure, but they also raised some potential problems regarding the law in Taiwan and the design of the offshore platform, especially its resistance to extreme weather. We report the method used and the main results and insights gained during the process.

  10. Strong linkages between surface and deep-water dissolved organic matter in the East/Japan Sea

    Science.gov (United States)

    Kim, Tae-Hoon; Kim, Guebuem; Shen, Yuan; Benner, Ronald

    2017-05-01

    Vertical and horizontal distributions of total dissolved amino acids (TDAAs), dissolved organic carbon (DOC), and dissolved organic nitrogen (DON) were measured in the East/Japan Sea (EJS). The euphotic zone of this sea is N-limited, and the N : P ratio is ˜ 13 below 200 m depth. Elevated TDAA concentrations (137 ± 34 nM) and DOC-normalized yields (0.8 ± 0.2 % of DOC) were observed in deep waters ( ≥ 1000 m) of the EJS and compared with those in the deep North Pacific Ocean. Significantly high TDAA concentrations and yields were observed in a region of deep-water formation, indicating the convection of margin-derived bioavailable dissolved organic matter (DOM) to deep waters. Declining TDAA concentrations (36 ± 12 %) and yields (33 ± 13 %) were observed between 1000 and 3000 m throughout the EJS, indicating the utilization of bioavailable DOM in deep waters. Concentrations of the D-enantiomers of amino acids (Ala, Glx, Asx, and Ser) were relatively high in deep waters of the EJS, indicating substantial bacterial contributions to DOM from surface and upper mesopelagic waters. Climate warming during the past few decades in the EJS is weakening deep convection during the winter, and one consequence of this reduction in deep convection is a decline in the supply of bioavailable DOM from surface waters.

  11. Sustainable development of deep-water seaport: the case of Lithuania.

    Science.gov (United States)

    Burskyte, Vilma; Belous, Olga; Stasiskiene, Zaneta

    2011-06-01

    In 2003, the Japan International Cooperation Agency carried out a development feasibility study of Klaipeda Seaport (Lithuania). The focus in this study was the evaluation of environmental impacts of the port expansion because it is located in an ecologically sensitive area. While the Japanese researchers focused on the environmental impact analysis, they did not provide unambiguous conclusions. The problems remained unresolved and required further, more detailed consideration and deeper analysis. Environmental sustainability in seaports is an issue of timely importance in many countries given the rapid increase in port-to-port traffic and harbor capacity. This paper explores the situation in Klaipeda Seaport (Lithuania) which is the northernmost ice-free port on the Eastern coast of the Baltic Sea and its challenges in terms of environmental aspects and current pollution situation. This port plays an important role in the economic development of the region and in creating a sustainable society, i.e., a society that continues to develop economically without increasing its impact on our living environment and where the possible reduction of its current impact can be huge due to the fact that the seaport is a place where transport and logistics intersect and constitute large-scale industrial estates. Increasingly, they also turn towards sustainability. Society faces the need for radical change because of increasing technological progress and increasing environmental impact. Environmental and public issues must be addressed by a systemic approach to find harmony among all the subsystems. Therefore, the authors of the article performed an assessment of the deep-water port of Klaipeda sustainable development opportunities tackling the following tasks: (1) Assessing Klaipeda port and the projected deep-water port of the current environment state; (2) Assessing the impact of the water quality of Klaipeda port, depending on the intensity of activity; (3) Assessing the

  12. Deep water convection and biogeochemical cycling of carbon in the Northern North Atlantic

    International Nuclear Information System (INIS)

    Buch, E.; Gissel Nielsen, T.; Lundsgaard, C.; Bendtsen, J.

    2001-01-01

    In 1998, the Danish Research Council launched the Global Change project 'Biochemical cycling of carbon and ocean circulation in the Northern North Atlantic'. The overall aim of the project was to describe the effect of high latitude carbon dynamics on the global ocean-atmosphere carbon system, in general, and on the atmospheric pCO 2 in particular. At present, knowledge concerning the seasonal differences in turnover rates of organic material in polar and sub-polar regions is limited. Thus, in order to achieve the aim of the project, it was necessary to obtain biological and chemical rate measurements for production and mineralization of dissolved and particulate organic material at high latitudes and relate these to ocean dynamics at different times of the year. This was investigated in the project by performing three cruises to the Greenland Sea area at different times of the year. The purpose of the present chapter is to give a review of: 1) The physical environment of the Northern North Atlantic (ocean circulation, deep convection, North Atlantic Oscillation) and its variability including the recent trends of importance to climate change. 2) The chemical and biological processes of importance to carbon cycle and the importance of the carbon cycle to our understanding of climate variability. Additionally preliminary results from the Danish global change investigation in the Greenland Sea will be presented. With regard to circulation it is concluded that the deep water in the Greenland Sea continues to warm up, indicating that the deep water formation in this area is reduced. The biological investigations are providing a highly needed basic knowledge of the structure and function of the pelagic food web as well as of the microbial food web of the intermediate and deep water. These studies form a basis for assessing the productivity, export mechanisms, mineralization rates and mineralization depth-scales in these areas. Especially the questions about the

  13. Retention and Solute Transport Properties in Disturbed and Undisturbed Soil Samples

    Directory of Open Access Journals (Sweden)

    Lívia Previatello da Silva

    Full Text Available ABSTRACT Solute transport parameters can be determined in miscible displacement experiments, usually performed in columns with disturbed (sieved soil samples. Experiments with undisturbed samples are uncommon, due to the difficulty of taking undisturbed samples at the size required for these experiments. Structural alteration of the disturbed material implies modifications in the pore geometry that determines hydraulic properties, including hydraulic conductivity and retention and properties related to miscible displacement. An existing model for prediction of breakthrough curves based on retention properties was tested using material from a medium-textured Ferralsol, and alterations caused by sample disturbance were investigated. Soil water retention curves and miscible displacement parameters were determined in breakthrough experiments with nitrate salts in columns filled with undisturbed and disturbed soil samples. Data obtained from the undisturbed samples showed a higher dispersion, suggesting homogenization of pore geometry and a reduction in the representative elementary volume by the disaggregation and sieving of the soil material. The transport parameters for nitrate determined in disturbed and undisturbed samples were significantly different and the model was able to simulate the observed breakthrough curves after fitting the pore connectivity parameter.

  14. Biological properties of disturbed and undisturbed Cerrado sensu stricto from Northeast Brazil.

    Science.gov (United States)

    Araújo, A S F; Magalhaes, L B; Santos, V M; Nunes, L A P L; Dias, C T S

    2017-03-01

    The aim of this study was to measure soil microbial biomass and soil surface fauna in undisturbed and disturbed Cerrado sensu stricto (Css) from Sete Cidades National Park, Northeast Brazil. The following sites were sampled under Cerrado sensu stricto (Css) at the park: undisturbed and disturbed Css (slash-and-burn agricultural practices). Total organic and microbial biomass C were higher in undisturbed than in disturbed sites in both seasons. However, microbial biomass C was higher in the wet than in the dry season. Soil respiration did not vary among sites but was higher in the wet than in the dry season. The densities of Araneae, Coleoptera, and Orthoptera were higher in the undisturbed site, whereas the densities of Formicidae were higher in the disturbed site. Non-metric multidimensional scaling analysis separated undisturbed from disturbed sites according to soil biological properties. Disturbance by agricultural practices, such as slash-and-burn, probably resulted in the deterioration of the biological properties of soil under native Cerrado sensu stricto in the Sete Cidades National Park.

  15. Comparison of Shear Strength Properties for Undisturbed and Reconstituted Parit Nipah Peat, Johor

    Science.gov (United States)

    Azhar, A. T. S.; Norhaliza, W.; Ismail, B.; Abdullah, M. E.; Zakaria, M. N.

    2016-11-01

    Shear strength of soil is required to determine the soil stability and design the foundations. Peat is known as a soil with complex natural formations which also contributes problems to the researchers, developers, engineers and contractors in constructions and infrastructures. Most researchers conducted experiment and investigation of shear strength on peat using shear box test and simple shear test, but only a few had discovered the behavior of peat using triaxial consolidated undrained test. The aim of this paper is to determine the undrained shear strength properties of reconstituted peat and undisturbed peat of Parit Nipah, Johor for comparison purposes. All the reconstituted peat samples were formed with the size that passed opening sieve 3.35 mm and preconsolidation pressure at 100 kPa. The result of undrained shear strength of reconstituted peat was 21kPa for cohesion with the angle of friction, 41° compare to the undisturbed peat with cohesion 10 kPa and angle of friction, 16°. The undrained shear strength properties result obtained shows that the reconstituted peat has higher strength than undisturbed peat. For relationship deviator stress-strain, σd max and excess pore pressure, Δu, it shows that both of undisturbed and reconstituted gradually increased when σ’ increased, but at the end of the test, the values are slightly dropped. The physical properties of undisturbed and reconstituted peat were also investigated to correlate with the undrained shear strength results.

  16. Characterizing Natural Gas Hydrates in the Deep Water Gulf of Mexico: Applications for Safe Exploration and Production Activities

    Energy Technology Data Exchange (ETDEWEB)

    Bent, Jimmy

    2014-05-31

    In 2000 Chevron began a project to learn how to characterize the natural gas hydrate deposits in the deep water portion of the Gulf of Mexico (GOM). Chevron is an active explorer and operator in the Gulf of Mexico and is aware that natural gas hydrates need to be understood to operate safely in deep water. In August 2000 Chevron worked closely with the National Energy Technology Laboratory (NETL) of the United States Department of Energy (DOE) and held a workshop in Houston, Texas to define issues concerning the characterization of natural gas hydrate deposits. Specifically, the workshop was meant to clearly show where research, the development of new technologies, and new information sources would be of benefit to the DOE and to the oil and gas industry in defining issues and solving gas hydrate problems in deep water.

  17. The diet and feeding ecology of Conger conger (L. 1758 in the deep waters of the Eastern Ionian Sea

    Directory of Open Access Journals (Sweden)

    A. ANASTASOPOULOU

    2013-06-01

    Full Text Available The diet of the European conger eel Conger conger was investigated for the first time in the Eastern Mediterranean. Fish dominated the European conger eel diet in the deep waters of E. Ionian Sea. All other prey taxa were identified as accidental preys. However, intestine analysis showed that Natantia, Brachyura and Cephalopoda might have a more important contribution in the diet of the species. C. conger exhibited a benthopelagic feeding behavior as it preyed upon both demersal and mesopelagic taxa. The high vacuity index and the low stomach and intestine fullness indicated that the feeding intensity of the species in the deep waters of Eastern Ionian Sea was quite low. C. conger feeding strategy was characterised by specialisation in various resource items. A between-phenotype contribution to niche width was observed for some prey categories. European Conger eel feeding specialisation seemed to be an adaptation to a food-scarce environment, as typified in deep-water habitats

  18. Estuaries and Tidal Marshes. Habitat Pac.

    Science.gov (United States)

    Fish and Wildlife Service (Dept. of Interior), Washington, DC.

    This educational packet consists of an overview, three lesson plans, student data sheets, and a poster. The overview examines estuaries and tidal or salt marshes by discussing the plants and animals in these habitats, marsh productivity, benefits and management of the habitats, historical aspects, and development and pollution. A glossary and list…

  19. Deep water overflow in the Faroe Bank Channel; modelling, processes, and impact

    DEFF Research Database (Denmark)

    Rullyanto, Arief

    2015-01-01

    , creating new water masses with distinct temperature, salinity and density characteristics. The change of water mass characteristics not only affects the local environment, but also far distant regions. The Faroe Bank Channel, which is located in the southern part of Faroe Islands, is one of the most...... important overflow regions in the world. It connects two huge ocean basins, the North Atlantic Ocean and the Nordic Seas, and the water mass produced there is an important ingredient of North Atlantic Deep Water, a water mass that found very nearly everywhere in the deep basins of the world’s oceans...... under different circumstances. The focus is on the Faroe Bank Channel, a relatively small region, which has a significant impact on the global ocean circulation and marine organisms that live in its environment....

  20. Studies of deep water formation and circulation in the Weddell Sea using natural and anthropogenic tracers

    International Nuclear Information System (INIS)

    Schlosser, Peter; Bayer, Reinhold

    1991-01-01

    The application of natural and anthropogenic trace substances in oceanographic studies of the Weddell Sea is reviewed. The potential of some steady-state and transient tracers (tritium, CFC-11 and CFC-12, 18 O, and helium isotopes) for studies of deep water formation and circulation is discussed on the basis of data sets collected mainly on cruises of R/V 'Polastern' to the Weddell Sea during the 1980s. CFC/ tritium ratio dating of young water masses is applied to estimate mean age and transit times of water involved in Weddell Sea Bottom Water formation. The history of the CFC-11/tritium ratio through time is derived for Weddell Sea shelf waters. (author). 36 refs.; 18 figs

  1. Deep water velocities and particle displacements induced by acoustic-gravity waves from submarine earthquakes

    Science.gov (United States)

    Oliveira, T. C. A.; Kadri, U.

    2016-02-01

    An uplift of the ocean bottom caused by a submarine earthquake can generate Acoustic-Gravity Waves (AGW), progressive compression-type waves that travel at near the speed of sound in water. The role of AGW for oceans hydrodynamics has recently became a topic of increasing scientific interest. Kadri [Deep ocean water transport by acoustic-gravity waves, J.Geo. Res. Oceans, 119, (2014)] showed theoretically that AGW can contribute to deep ocean currents and circulation. We analyze and simulate the fundamental AGW modes generated by a submarine earthquake. We consider the first five AGW modes and show that they may all induce comparable temporal variations in water particle velocities at different depths in regions far from the epicenter. Results of temporal variations of horizontal and vertical fluid parcel velocities induced by AGW confirm chaotic flow trajectories at different water depths. A realistic example based on the 2004 Indian Ocean earthquake shows that vertical water particle displacements of O(10-2 ) m can be generated at 1 Km depth in a 4 km water depth ocean. We show that the velocity field depends on the presence of the leading AGW modes. Each AGW mode becomes evanescent at a critical time, at which energy is transferred to the next higher modes. Consequently, the main pattern of the velocity field changes as the leading mode change. As an example, for a reference point located at 1000 Km from the epicenter, the first five AGW become evanescent after 1.6, 4.6, 7.7, 10.8 and 13.8 hours, respectively. Our analysis and simulations shed light on the spatio-temporal evolution of the deep water velocities and particle displacements induced by AGW that radiate during submarine earthquakes. Thus, this work is a contribution to understand the role of high moment magnitude submarine earthquakes in deep water mixing mechanism.

  2. In situ growth rates of deep-water octocorals determined from 3D photogrammetric reconstructions

    Science.gov (United States)

    Bennecke, Swaantje; Kwasnitschka, Tom; Metaxas, Anna; Dullo, Wolf-Christian

    2016-12-01

    Growth rates of deep-water corals provide important information on the recovery potential of these ecosystems, for example from fisheries-induced impacts. Here, we present in situ growth dynamics that are currently largely unknown for deep-water octocorals, calculated by applying a non-destructive method. Videos of a boulder harbouring multiple colonies of Paragorgia arborea and Primnoa resedaeformis in the Northeast Channel Coral Conservation Area at the entrance to the Gulf of Maine at 863 m depth were collected in 2006, 2010 and 2014. Photogrammetric reconstructions of the boulder and the fauna yielded georeferenced 3D models for all sampling years. Repeated measurements of total length and cross-sectional area of the same colonies allowed the observation of growth dynamics. Growth rates of total length of Paragorgia arborea decreased over time with higher rates between 2006 and 2010 than between 2010 and 2014, while growth rates of cross-sectional area remained comparatively constant. A general trend of decreasing growth rates of total length with size of the coral colony was documented. While no growth was observed for the largest colony (165 cm in length) between 2010 and 2014, a colony 50-65 cm in length grew 3.7 cm yr-1 between 2006 and 2010. Minimum growth rates of 1.6-2.7 cm yr-1 were estimated for two recruits (<23 cm in 2014) of Primnoa resedaeformis. We successfully extracted biologically meaningful data from photogrammetric models and present the first in situ growth rates for these coral species in the Northwest Atlantic.

  3. A long history of equatorial deep-water upwelling in the Pacific Ocean

    Science.gov (United States)

    Zhang, Yi Ge; Pagani, Mark; Henderiks, Jorijntje; Ren, Haojia

    2017-06-01

    Cold, nutrient- and CO2-rich waters upwelling in the eastern equatorial Pacific (EEP) give rise to the Pacific cold tongue. Quasi-periodic subsidence of the thermocline and attenuation in wind strength expressed by El Niño conditions decrease upwelling rates, increase surface-water temperatures in the EEP, and lead to changes in regional climates both near and far from the equatorial Pacific. EEP surface waters have elevated CO2 concentrations during neutral (upwelling) or La Niña (strong upwelling) conditions. In contrast, approximate air-sea CO2 equilibrium characterizes El Niño events. One hypothesis proposes that changes in physical oceanography led to the establishment of a deep tropical thermocline and expanded mixed-layer prior to 3 million years ago. These effects are argued to have substantially reduced deep-water upwelling rates in the EEP and promoted a "permanent El Niño-like" climate state. For this study, we test this supposition by reconstructing EEP "excess CO2" and upwelling history for the past 6.5 million years using the alkenone-pCO2 methodology. Contrary to previous assertions, our results indicate that average temporal conditions in the EEP over the past ∼6.5 million years were characterized by substantial CO2 disequilibrium and high nutrient delivery to surface waters - characteristics that imply strong upwelling of deep waters. Upwelling appears most vigorous between ∼6.5 to 4.5 million years ago coinciding with high accumulation rates of biogenic material during the late Miocene - early Pliocene "biogenic bloom".

  4. Numerical analysis of wellbore instability in gas hydrate formation during deep-water drilling

    Science.gov (United States)

    Zhang, Huaiwen; Cheng, Yuanfang; Li, Qingchao; Yan, Chuanliang; Han, Xiuting

    2018-02-01

    Gas hydrate formation may be encountered during deep-water drilling because of the large amount and wide distribution of gas hydrates under the shallow seabed of the South China Sea. Hydrates are extremely sensitive to temperature and pressure changes, and drilling through gas hydrate formation may cause dissociation of hydrates, accompanied by changes in wellbore temperatures, pore pressures, and stress states, thereby leading to wellbore plastic yield and wellbore instability. Considering the coupling effect of seepage of drilling fluid into gas hydrate formation, heat conduction between drilling fluid and formation, hydrate dissociation, and transformation of the formation framework, this study established a multi-field coupling mathematical model of the wellbore in the hydrate formation. Furthermore, the influences of drilling fluid temperatures, densities, and soaking time on the instability of hydrate formation were calculated and analyzed. Results show that the greater the temperature difference between the drilling fluid and hydrate formation is, the faster the hydrate dissociates, the wider the plastic dissociation range is, and the greater the failure width becomes. When the temperature difference is greater than 7°C, the maximum rate of plastic deformation around the wellbore is more than 10%, which is along the direction of the minimum horizontal in-situ stress and associated with instability and damage on the surrounding rock. The hydrate dissociation is insensitive to the variation of drilling fluid density, thereby implying that the change of the density of drilling fluids has a minimal effect on the hydrate dissociation. Drilling fluids that are absorbed into the hydrate formation result in fast dissociation at the initial stage. As time elapses, the hydrate dissociation slows down, but the risk of wellbore instability is aggravated due to the prolonged submersion in drilling fluids. For the sake of the stability of the wellbore in deep-water

  5. Standardized North American marsh bird monitoring protocol

    Science.gov (United States)

    Conway, Courtney J.

    2011-01-01

    Little is known about the population status of many marsh-dependent birds in North America but recent efforts have focused on collecting more reliable information and estimates of population trends. As part of that effort, a standardized survey protocol was developed in 1999 that provided guidance for conducting marsh bird surveys throughout North America such that data would be consistent among locations. The original survey protocol has been revised to provide greater clarification on many issues as the number of individuals using the protocol has grown. The Standardized North American Marsh Bird Monitoring Protocol instructs surveyors to conduct an initial 5-minute passive point-count survey followed by a series of 1-minute segments during which marsh bird calls are broadcast into the marsh following a standardized approach. Surveyors are instructed to record each individual bird from the suite of 26 focal species that are present in their local area on separate lines of a datasheet and estimate the distance to each bird. Also, surveyors are required to record whether each individual bird was detected within each 1-minute subsegment of the survey. These data allow analysts to use several different approaches for estimating detection probability. The Standardized North American Marsh Bird Monitoring Protocol provides detailed instructions that explain the field methods used to monitor marsh birds in North America.

  6. Reproductive biology of the deep-water coral Acanella arbuscula (Phylum Cnidaria: Class Anthozoa: Order Alcyonacea), northwest Atlantic

    Science.gov (United States)

    Beazley, Lindsay I.; Kenchington, Ellen L.

    2012-10-01

    Knowledge of the reproductive life-history of deep-water corals is important for assessing their vulnerability to anthropogenic impacts. Yet, the reproductive biology of many deep-water corals, especially members of the subclass Octocorallia, has not been examined. We used histological techniques to describe the reproductive biology of the deep-water gorgonian coral Acanella arbuscula from the northwest Atlantic. All colonies examined were gonochoric, and no embryos or planula larvae were observed in the polyps. Mean polyp-level fecundity (females: 21.0±17.5 oocytes polyp-1, and males: 13.9±13.5 sperm sacs polyp-1) is high compared to other deep-water gorgonians, and polyps closer to the branch tips had the highest fecundities in both females and males. The presence of large oocytes (maximum diameter 717.8 μm) suggests that A. arbuscula produces lecithotrophic larvae. Despite the potentially high fecundity and small size at first reproduction, the paucity of information on dispersal and recruitment, combined with its longevity, vulnerability to bottom fishing gear, and ecological role as a structure-forming species, still warrants the classification of A. arbuscula as a vulnerable marine ecosystem indicator.

  7. Effects of a deep-water running program on muscle function and functionality in elderly women community dwelling

    Directory of Open Access Journals (Sweden)

    Daisy Alberti

    2017-12-01

    Full Text Available Abstract AIMS The aim of the study was to determine the effects of deep-water running on muscle function and functionality in community dwelling old women. METHODS Older women (n=19 were randomly assigned to one of the two groups: deep-water running (DWR: n=09, 64.33±4.24 years, 75.15±12.53 kg, 160.45±7.52 cm; or control group CG: n=10, 64.40±4.22 years, 74.46±12.39 kg, 158.88±5.48 cm. The DWR group carried out 18 weeks of deep-water running, twice/week 50 min sessions. Dynamic isokinetic strength for the lower limb and functionality was assessed before and after intervention. RESULTS DWR group increased peak torque, total work and average power of the knee and hip flexors and extensors. Additionally showed better performance on gait speed, timed up and go test, five-times-sit-to-stand-test repetitions from a chair as well as the six-minute walk test. CONCLUSION The deep-water running program was effective to improve muscle function and functionality.

  8. Developmental plasticity of shell morphology of quagga mussels from shallow and deep-water habitats of the Great Lakes

    Science.gov (United States)

    Suzanne Peyer; John C. Hermanson; Carol Eunmi Lee

    2010-01-01

    The invasive zebra mussel (Dreissena polymorpha) has quickly colonized shallow-water habitats in the North American Great Lakes since the 1980s but the quagga mussel (Dreissena bugensis) is becoming dominant in both shallow and deep-water habitats. While quagga mussel shell morphology differs between shallow and deep habitats, functional causes and consequences of such...

  9. New species and new records of deep-water Pectinoidea (Bivalvia: Propeamussiidae, Entoliidae and Pectinidae) from the South Pacific

    NARCIS (Netherlands)

    Dijkstra, H.H.; Maestrati, P.

    2008-01-01

    Fifty-two deep-water species of Pectinoidea (37 Propeamussiidae, 1 Entoliidae, 14 Pectinidae) are listed from Norfolk Ridge (11 species), Loyalty Islands (4 species), Fiji Islands (30 species), Tonga (26 species), Solomon Islands (26 species) and the Marquesas archipelago (8 species). All species

  10. Experimental study on the influence of chemical sensitizer on pressure resistance in deep water of emulsion explosives

    Science.gov (United States)

    Liu, Lei; zhang, Zhihua; Wang, Ya; Qin, hao

    2018-03-01

    The study on the pressure resistance performance of emulsion explosives in deep water can provide theoretical basis for underwater blasting, deep-hole blasting and emulsion explosives development. The sensitizer is an important component of emulsion explosives. By using reusable experimental devices to simulate the charge environment in deep water, the influence of the content of chemical sensitizer on the deep-water pressure resistance performance of emulsion explosives was studied. The experimental results show that with the increasing of the content of chemical sensitizer, the deep-water pressure resistance performance of emulsion explosives gradually improves, and when the pressure is fairly large, the effect is particularly pronounced; in a certain range, with the increase of the content of chemical sensitizer, that emulsion explosives’ explosion performance also gradually improve, but when the content reaches a certain value, the explosion properties declined instead; under the same emulsion matrix condition, when the content of NANO2 is 0.2%, that the emulsion explosives has good resistance to water pressure and good explosion properties. The correctness of the results above was testified in model blasting.

  11. Transport of a genetically modified Pseudomonas fluorescens and its parent strain through undisturbed tropical soil cores

    NARCIS (Netherlands)

    Guimaraes, V.F.; Cruz, I.V.; Hagler, A.N.; Mendonca-Hagler, L.C.; Elsas, van J.D.

    1997-01-01

    The transport of a genetically modified strain of Pseudomonas fluorescens, BR12, and its parent, BR5, was studied after irrigation of undisturbed clayey and sandy soil cores, simulating heavy tropical rainfall (56.6 mm/h). Vertical transport of both inoculant strains was detected in all soil cores.

  12. Dust emissions from undisturbed and disturbed, crusted playa surfaces: cattle trampling effects

    Science.gov (United States)

    Dry playa lake beds can be significant sources of fine dust emission. This study used a portable field wind tunnel to quantify the PM10 emissions from a bare, fine-textured playa surface located in the far northern Chihuahua Desert. The natural, undisturbed crust and its subjection to two levels of ...

  13. Coarse woody debris in undisturbed and logged forests in the eastern Brazilian Amazon.

    Science.gov (United States)

    Michael Keller; Michael Palace; Gregory P. Asner; Rodrigo Jr. Pereira; Jose Natalino M. Silva

    2004-01-01

    Coarse woody debris (CWD) is an important component of the carbon cycle in tropical forests. We measured the volume and density of fallen CWD at two sites, Cauaxi and Tapajós in the Eastern Amazon. At both sites we studied undisturbed forests (UFs) and logged forests 1 year after harvest. Conventional logging (CL) and reduced impact logging (RIL) were...

  14. Community structure of arbuscular mycorrhizal fungi in undisturbed vegetation revealed by analyses of LSU rdna sequences

    DEFF Research Database (Denmark)

    Rosendahl, Søren; Holtgrewe-Stukenbrock, Eva

    2004-01-01

    Arbuscular mycorrhizal fungi (AMF) form a mutualistic symbiosis with plant roots and are found in most ecosystems. In this study the community structure of AMF in a clade of the genus Glomus was examined in undisturbed costal grassland using LSU rDNA sequences amplified from roots of Hieracium...

  15. AFLP fingerprinting of Kentucky bluegrass (Poa pratensis L.) from undisturbed Dutch grasslands: implications for conservation

    NARCIS (Netherlands)

    Treuren, van R.

    2008-01-01

    Undisturbed grasslands are considered rich sources of promising genotypes for the development of new varieties of Kentucky bluegrass (Poa pratensis L.). Grasslands that have not been resown with commercial cultivars nor treated with high doses of nitrogen fertilizer have become rare in the

  16. Occurrence and biogeography of hydroids (Cnidaria: Hydrozoa) from deep-water coral habitats off the southeastern United States

    Science.gov (United States)

    Henry, Lea-Anne; Nizinski, Martha S.; Ross, Steve W.

    2008-06-01

    Deep-water coral habitats off the southeastern USA (SEUS) support diverse fish and invertebrate assemblages, but are poorly explored. This study is the first to report on the hydroids collected from these habitats in this area. Thirty-five species, including two species that are likely new to science, were identified from samples collected primarily by manned submersible during 2001-2005 from deep-water coral habitats off North Carolina to east-central Florida. Eleven of the species had not been reported since the 19th to mid-20th century. Ten species, and one family, the Rosalindidae, are documented for the first time in the SEUS. Latitudinal ranges of 15 species are extended, and the deepest records in the western North Atlantic for 10 species are reported. A species accumulation curve illustrated that we continue to add to our knowledge of hydroid diversity in these habitats. Sexually mature individuals were collected for 19 species during the summer to early autumn months. Most of the observed species (89%) liberate planula larvae as part of their life cycles, suggesting that these species exhibit a reproductive strategy that reduces the risk of dispersal to sub-optimal habitats. Hydroids occurred across various substrata including coral rubble, live corals, rock and other animal hosts including hydroids themselves. All observed species were regionally widespread with typically deep-neritic to bathyal sub-tropical/tropical distributions. Hydroid assemblages from deep-water SEUS coral habitats were most similar to those from adjacent deep-water habitats off the SEUS (17 shared species), and those in the Straits of Florida/Bahamas and Caribbean/West Indian regions (14 and 8 shared species, respectively). The similarity to sub-tropical and tropical assemblages and the richness of plumularioids in the SEUS deep-water coral habitats support the idea of a Pleistocene intrusion of tropical species northwards following an intensification of the Gulf Stream from the

  17. Dalia integrated production bundle (IPB): an innovative riser solution for deep water fields

    Energy Technology Data Exchange (ETDEWEB)

    Reals, Th Boscals de; Gloaguen, M.; Roche, F. [Total E and P (Angola); Marion, A.; Poincheval, A. [Technip, Paris (France)

    2008-07-01

    The Dalia field is located 210 km north west of Luanda (Angola), about 140 km from shore in 1400 meter water-depth. It was the second major discovery out of 15 made in the block 17 operated by Total. The Dalia Umbilical, Flow lines and Risers EPCI Contract was awarded in 2003. The sea-line network to connect and control the 71 wells and 9 manifolds consist of the following: 40 km of insulated pipe in pipe (12 inches into 17 inches) production flow lines; 45 km of 12 inches water and gas injection lines; 6 off 1.7 km flexible water and gas injection risers; 8 off 1.65 km flexible Integrated Production Bundle (IPB) risers; 75 km of control umbilicals. The flow assurance and associated insulation requirement of the production transport system was one of the main challenges of the project. With a crude temperature of 45 deg C at the wellhead and the required minimum temperature of 35 deg C on arrival at the FPSO, this problem was complex. Understanding that, due to the Joule Thompson effect of the riser gas lift, a 'built in' loss of about 5 deg C is induced and together with further losses through the sub sea pipelines, some up to 6 km long, the agreed solution was 'pipe in pipe' for the production flow lines. The innovative flexible IPB riser, incorporating gas lift and heating to keep the fluid temperature above hydrate formation zone, was the selected riser solution. The IPB is new technology for deep water, developed by Technip for Dalia, and consists of a 12 inches nominal central flexible, surrounded by layers of heat tracing cables, small bore gas lift lines, optical fibres and many insulation layers with an Overall Heat Transfer Coefficient of approximately 3,4 W/m{sup 2}K. After an earlier research and development programme, a further extensive qualification programme was conducted during the course of the project, culminating with the deep water testing phase offshore Brazil. The IPB was then approved for fabrication and installation

  18. Is substrate composition a suitable predictor for deep-water coral occurrence on fine scales?

    Science.gov (United States)

    Bennecke, Swaantje; Metaxas, Anna

    2017-06-01

    Species distribution modelling can be applied to identify potentially suitable habitat for species with largely unknown distributions, such as many deep-water corals. Important variables influencing species occurrence in the deep sea, e.g. substrate composition, are often not included in these modelling approaches because high-resolution data are unavailable. We investigated the relationship between substrate composition and the occurrence of the two deep-water octocoral species Primnoa resedaeformis and Paragorgia arborea, which require hard substrate for attachment. On a scale of 10s of metres, we analysed images of the seafloor taken at two locations inside the Northeast Channel Coral Conservation Area in the Northwest Atlantic. We interpolated substrate composition over the sampling areas and determined the contribution of substrate classes, depth and slope to describe habitat suitability using maximum entropy modelling (Maxent). Substrate composition was similar at both sites - dominated by pebbles in a matrix of sand (>80%) with low percentages of suitable substrate for coral occurrence. Coral abundance was low at site 1 (0.9 colonies of P. resedaeformis per 100 m2) and high at site 2 (63 colonies of P. resedaeformis per 100 m2) indicating that substrate alone is not sufficient to explain varying patterns in coral occurrence. Spatial interpolations of substrate classes revealed the difficulty to accurately resolve sparsely distributed boulders (3-5% of substrate). Boulders were by far the most important variable in the habitat suitability model (HSM) for P. resedaeformis at site 1, indicating the fundamental influence of a substrate class that is the least abundant. At site 2, HSMs identified cobbles and sand/pebble as the most important variables for habitat suitability. However, substrate classes were correlated making it difficult to determine the influence of individual variables. To provide accurate information on habitat suitability for the two coral

  19. Recent changes in deep water formation and spreading in the eastern Mediterranean Sea: a review

    Science.gov (United States)

    Lascaratos, Alex; Roether, Wolfgang; Nittis, Kostas; Klein, Birgit

    1999-08-01

    Observations of the last decade testify that the characteristics of the deep thermohaline circulation in the Eastern Mediterranean Sea have changed thoroughly. The source of the most dense waters of the basin has moved from the Adriatic to the Aegean Sea. This new source has proved to be very efficient since the estimated formation rate for the period 1989-95 was more than 1 Sv, about three times more than the dense water formation rate of the Adriatic Sea. These new waters with hydrological characteristics, that are warmer and more saline, have replaced almost 20% of the older deep waters of the basin, and have uplifted the deep isopycnals by about 500 m. This major event can be attributed to important meteorological anomalies in the Eastern Mediterranean and to changes of circulation patterns. The extended dry period of 1988-93 and the exceptionally cold winters of 1987 and 1992-93 created favorable conditions for increased formation of dense water in the Aegean. Furthermore, changes in the circulation patterns in the intermediate water range (Levantine Intermediate Water LIW and Cretan Intermediate Water), themselves possibly linked to meteorological anomalies, appear to have played an important role in the redistribution of salt. As a result of an interruption to exchanges between the Ionian and Levantine Basin, the salinities in the latter started to rise, high salinity waters were diverted into the Aegean [ Malanotte-Rizzoli, P., Manca, B. B., Ribera dAcala, M., & Theocharis, A. (1998). The Eastern Mediterranean in the 80s and in the 90s: the big transition emerged from the POEM-BC observational evidence. Rapport du Commission International de la Mer Medittanee, 35, 174-175] and the westward transport of LIW was reduced. An additional effect of the deep water discharge from the Aegean and the resulting uplifting of mid-depth waters was to lower salinities in the LIW layer. This effect is most strongly felt in the Ionian Sea. A 3-D primitive equation numerical

  20. Structural setting and evolution of the Mensa and Thunder Horse intraslope basins, northern deep-water Gulf of Mexico: A case study

    NARCIS (Netherlands)

    Weimer, P.; Bouroullec, R.; Berg, A.A. van den; Lapinski, T.G.; Roesink, J.G.; Adson, J.

    2017-01-01

    The Mensa and Thunder Horse intraslope minibasins in southcentralMississippi Canyon, northern deep-water Gulf ofMexico, had a linked structural evolution from the Early Cretaceous through the late Miocene. Analysis of the two minibasins illustrates the complexities of deep-water sedimentation and

  1. Vegetation - Suisun Marsh 1999 [ds160

    Data.gov (United States)

    California Department of Resources — This vegetation mapping project of Suisun Marsh blends ground-based classification, aerial photo interpretation, and GIS editing and processing. The method is based...

  2. Vegetation - Suisun Marsh 2003 [ds162

    Data.gov (United States)

    California Department of Resources — This vegetation mapping project of Suisun Marsh blends ground-based classification, aerial photo interpretation, and GIS editing and processing. The method is based...

  3. Oregon Salt Marshes: How Blue are They?

    Science.gov (United States)

    Two important ecosystem services of wetlands are carbon sequestration and filtration of nutrients and particulates. We quantified the carbon and nitrogen accumulation rates in salt marshes at 135 plots distributed across eight estuaries located in Oregon, USA. Net carbon and ...

  4. Vegetation - Suisun Marsh 2000 [ds161

    Data.gov (United States)

    California Department of Resources — This vegetation mapping project of Suisun Marsh blends ground-based classification, aerial photo interpretation, and GIS editing and processing. The method is based...

  5. Clinical effect of deep water running on non-specific low back pain: A randomised trial

    Directory of Open Access Journals (Sweden)

    A.I. Cuesta-Vargas

    2009-02-01

    Full Text Available Objectives: To evaluate clinical effect of deep water running(DW R on non-specific low back pain. Outcome measures were pain, disability,general health and physical fitness.  Materials and methods: Experimental, randomized,  controlled trial involving 46 persons with CLBP over 15 weekswith two experimental processes, each three times a week. Evidence-basedProgram (EBP, personalized physical exercise program, manual therapy andhealth educa tion was the common process to which was added 20 minutes ofpersonalized intensity DW R at the aerobic threshold. Measurements were made at the beginning and end of the studyof pain, disability, general health and physical fitness.  R esults: The pain of CLBP were homogeneous at baseline.Significant changes between group were don’t found for pain in favour of the EBP+DW R group (p<0.3. The within-group differences were highly significant for all clinical and functional variables. The effect was clinically relevant forpain in the EBP+DW R group (0.70 and in the EBP group (0.58, and for disability degree it was also relevant in theEBP+DW R group (0.48 and relevant for the EBP group (0.36. Conclusion: Significant improvement was seen inCLBP when EBP was complemented with the high-intensity exercise of DW R.

  6. A role for subducted super-hydrated kaolinite in Earth's deep water cycle

    Science.gov (United States)

    Hwang, Huijeong; Seoung, Donghoon; Lee, Yongjae; Liu, Zhenxian; Liermann, Hanns-Peter; Cynn, Hyunchae; Vogt, Thomas; Kao, Chi-Chang; Mao, Ho-Kwang

    2017-12-01

    Water is the most abundant volatile component in the Earth. It continuously enters the mantle through subduction zones, where it reduces the melting temperature of rocks to generate magmas. The dehydration process in subduction zones, which determines whether water is released from the slab or transported into the deeper mantle, is an essential component of the deep water cycle. Here we use in situ and time-resolved high-pressure/high-temperature synchrotron X-ray diffraction and infrared spectra to characterize the structural and chemical changes of the clay mineral kaolinite. At conditions corresponding to a depth of about 75 km in a cold subducting slab (2.7 GPa and 200 °C), and in the presence of water, we observe the pressure-induced insertion of water into kaolinite. This super-hydrated phase has a unit cell volume that is about 31% larger, a density that is about 8.4% lower than the original kaolinite and, with 29 wt% H2O, the highest water content of any known aluminosilicate mineral in the Earth. As pressure and temperature approach 19 GPa and about 800 °C, we observe the sequential breakdown of super-hydrated kaolinite. The formation and subsequent breakdown of super-hydrated kaolinite in cold slabs subducted below 200 km leads to the release of water that may affect seismicity and help fuel arc volcanism at the surface.

  7. Abrupt stop of deep water turnover with lake warming: Drastic consequences for algal primary producers.

    Science.gov (United States)

    Yankova, Yana; Neuenschwander, Stefan; Köster, Oliver; Posch, Thomas

    2017-10-23

    After strong fertilization in the 20 th century, many deep lakes in Central Europe are again nutrient poor due to long-lasting restoration (re-oligotrophication). In line with reduced phosphorus and nitrogen loadings, total organismic productivity decreased and lakes have now historically low nutrient and biomass concentrations. This caused speculations that restoration was overdone and intended fertilizations are needed to ensure ecological functionality. Here we show that recent re-oligotrophication processes indeed accelerated, however caused by lake warming. Rising air temperatures strengthen thermal stabilization of water columns which prevents thorough turnover (holomixis). Reduced mixis impedes down-welling of oxygen rich epilimnetic (surface) and up-welling of phosphorus and nitrogen rich hypolimnetic (deep) water. However, nutrient inputs are essential for algal spring blooms acting as boost for annual food web successions. We show that repeated lack (since 1977) and complete stop (since 2013) of holomixis caused drastic epilimnetic phosphorus depletions and an absence of phytoplankton spring blooms in Lake Zurich (Switzerland). By simulating holomixis in experiments, we could induce significant vernal algal blooms, confirming that there would be sufficient hypolimnetic phosphorus which presently accumulates due to reduced export. Thus, intended fertilizations are highly questionable, as hypolimnetic nutrients will become available during future natural or artificial turnovers.

  8. A role for subducted super-hydrated kaolinite in Earth’s deep water cycle

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Huijeong; Seoung, Donghoon; Lee, Yongjae; Liu, Zhenxian; Liermann, Hanns-Peter; Cynn, Hyunchae; Vogt, Thomas; Kao, Chi-Chang; Mao, Ho-Kwang

    2017-11-20

    Water is the most abundant volatile component in the Earth. It continuously enters the mantle through subduction zones, where it reduces the melting temperature of rocks to generate magmas. The dehydration process in subduction zones, which determines whether water is released from the slab or transported into the deeper mantle, is an essential component of the deep water cycle. Here we use in situ and time-resolved high-pressure/high-temperature synchrotron X-ray diffraction and infrared spectra to characterize the structural and chemical changes of the clay mineral kaolinite. At conditions corresponding to a depth of about 75 km in a cold subducting slab (2.7 GPa and 200 °C), and in the presence of water, we observe the pressure-induced insertion of water into kaolinite. This super-hydrated phase has a unit cell volume that is about 31% larger, a density that is about 8.4% lower than the original kaolinite and, with 29 wt% H2O, the highest water content of any known aluminosilicate mineral in the Earth. As pressure and temperature approach 19 GPa and about 800 °C, we observe the sequential breakdown of super-hydrated kaolinite. The formation and subsequent breakdown of super-hydrated kaolinite in cold slabs subducted below 200 km leads to the release of water that may affect seismicity and help fuel arc volcanism at the surface.

  9. The North Pacific Acoustic Laboratory deep-water acoustic propagation experiments in the Philippine Sea.

    Science.gov (United States)

    Worcester, Peter F; Dzieciuch, Matthew A; Mercer, James A; Andrew, Rex K; Dushaw, Brian D; Baggeroer, Arthur B; Heaney, Kevin D; D'Spain, Gerald L; Colosi, John A; Stephen, Ralph A; Kemp, John N; Howe, Bruce M; Van Uffelen, Lora J; Wage, Kathleen E

    2013-10-01

    A series of experiments conducted in the Philippine Sea during 2009-2011 investigated deep-water acoustic propagation and ambient noise in this oceanographically and geologically complex region: (i) the 2009 North Pacific Acoustic Laboratory (NPAL) Pilot Study/Engineering Test, (ii) the 2010-2011 NPAL Philippine Sea Experiment, and (iii) the Ocean Bottom Seismometer Augmentation of the 2010-2011 NPAL Philippine Sea Experiment. The experimental goals included (a) understanding the impacts of fronts, eddies, and internal tides on acoustic propagation, (b) determining whether acoustic methods, together with other measurements and ocean modeling, can yield estimates of the time-evolving ocean state useful for making improved acoustic predictions, (c) improving our understanding of the physics of scattering by internal waves and spice, (d) characterizing the depth dependence and temporal variability of ambient noise, and (e) understanding the relationship between the acoustic field in the water column and the seismic field in the seafloor. In these experiments, moored and ship-suspended low-frequency acoustic sources transmitted to a newly developed distributed vertical line array receiver capable of spanning the water column in the deep ocean. The acoustic transmissions and ambient noise were also recorded by a towed hydrophone array, by acoustic Seagliders, and by ocean bottom seismometers.

  10. Evidence for the bioerosion of deep-water corals by echinoids in the Northeast Atlantic

    Science.gov (United States)

    Stevenson, Angela; Rocha, Carlos

    2013-01-01

    In situ video observations of echinoids interacting with deep-sea coral are common in the deep-sea, but paradoxically the deep-sea literature is devoid of reports of bioerosion by extant echinoids. Here we present evidence of contemporary bioerosion of cold-water coral by four species of deep-sea echinoids, Gracilechinus elegans, Gracilechinus alexandri, Cidaris cidaris, and Araeosoma fenestratum, showing that they actively predate on the living framework of reef building corals, Lophelia pertusa and Madrepora oculata, in the NE Atlantic. Echinoid specimens were collected in six canyons located in the Bay of Biscay, France and two canyons on the north side of the Porcupine Bank and Goban Spur, Ireland. A total of 44 live specimens from the four taxa (9 of G. elegans, 4 of G. alexandri, 21 of C. cidaris and 10 of A. fenestratum) showed recent ingestion of the coral infrastructure. Upon dissection, live coral skeleton was observed encased in a thick mucus layer within the gastrointestinal tract of G. elegans and G. alexandri while both live and dead coral fragments were found in C. cidaris and A. fenestratum. Echinoid bioerosion limits the growth of shallow-water reefs. Our observations suggest that echinoids may also play an important role in the ecology of deep-water coral reefs.

  11. Clinical effect of deep water running on non-specific low back pain: A randomised trial

    Directory of Open Access Journals (Sweden)

    A.I. Cuesta-Vargas

    2009-01-01

    Full Text Available Objectives: To evaluate clinical effect of deep water running(DW R on non-specific low back pain. Outcome measures were pain, disability,general health and physical fitness.  Materials and methods: Experimental, randomized,  controlled trial involving 46 persons with CLBP over 15 weekswith two experimental processes, each three times a week. Evidence-basedProgram (EBP, personalized physical exercise program, manual therapy andhealth educa tion was the common process to which was added 20 minutes ofpersonalized intensity DW R at the aerobic threshold. Measurements were made at the beginning and end of the studyof pain, disability, general health and physical fitness.  R esults: The pain of CLBP were homogeneous at baseline.Significant changes between group were don’t found for pain in favour of the EBP+DW R group (p<0.3. The within-group differences were highly significant for all clinical and functional variables. The effect was clinically relevant forpain in the EBP+DW R group (0.70 and in the EBP group (0.58, and for disability degree it was also relevant in theEBP+DW R group (0.48 and relevant for the EBP group (0.36. Conclusion: Significant improvement was seen inCLBP when EBP was complemented with the high-intensity exercise of DW R.

  12. Survey and analysis of deep water mineral deposits using nuclear methods

    International Nuclear Information System (INIS)

    Staehle, C.M.; Noakes, J.E.; Spaulding, J.

    1991-01-01

    Present knowledge of the location, quality, quantity and recoverability of sea floor minerals is severely limited, particularly in the abyssal depths and deep water within the 200 mile Exclusion Economic Zone (EEZ) surrounding the U.S. Pacific Islands. To improve this understanding and permit exploitation of these mineral reserves much additional data is needed. This paper will discuss a sponsored program for extending existing proven nuclear survey methods currently used on the shallow continental margins of the Atlantic and Gulf of Mexico into the deeper waters of the Pacific. This nuclear technology can be readily integrated and extended to depths of 2000 m using the existing RCV-150 remotely operated vehicle (ROV) and the PISCESE V manned deep submersible vehicle (DSV) operated by The University of Hawaii's, Hawaii Underseas Research Laboratory (HURL). Previous papers by the authors have also proposed incorporating these nuclear analytical methods for survey of the deep ocean through the use of Autonomous Underwater Vehicle (AUX). Such a vehicle could extend the use of passive nuclear instrument operation, in addition to conventional analytical methods, into the abyssal depths and do so with speed and economy not otherwise possible. The natural radioactivity associated with manganese nodules and crustal deposits is sufficiently above normal background levels to allow discrimination and quantification in near real time

  13. Evidence of lipofuscin accumulation in the deep-water red shrimp Aristaeomorpha foliacea (Risso, 1827

    Directory of Open Access Journals (Sweden)

    V. MEZZASALMA

    2008-12-01

    Full Text Available Lipofuscin, a non-degradable, degenerative fluorescent pigment which accumulates in post-mitotic cells, represents a promising method for ageing marine crustaceans. The presence and accumulation of lipofuscin has been studied in the deep-water red shrimp Aristaeomorpha foliacea (Risso, 1827 to assess its use as a tool for ageing larger (i.e., older specimens and thus improve knowledge of the growth and longevity of this species. Specimens, gathered during experimental trawl surveys carried out in the Strait of Sicily (Mediterranean Sea, were stored directly on-board in 10% buffered formaldehyde solution; their brain was thereafter removed, prepared with various current histological techniques and examined with a binocular microscope. Thin sections of the olfactory lobe cell mass were also analyzed using fluorescence microscopy, and the lipofuscin concentration was measured through image analysis. Various indices were computed for each individual by pooling data from many images: number and coverage of the lipofuscin granules per unit area, and mean individual area of the granules. Lipofuscin was detected in all specimens investigated with characteristics (grain typology and dimension strictly resembling those already described in other crustacean species. The present preliminary results encourage further studies to develop and validate a methodology based on the use of lipofuscin for improving the relative ageing of large A. foliacea shrimps.

  14. Tsukamurella spongiae sp. nov., a novel actinomycete isolated from a deep-water marine sponge.

    Science.gov (United States)

    Olson, Julie B; Harmody, Dedra K; Bej, Asim K; McCarthy, Peter J

    2007-07-01

    A Gram-positive, rod-shaped, non-spore-forming bacterium (strain K362(T)) was isolated from a deep-water marine sponge collected off the coast of Curaçao in the Netherlands Antilles. On the basis of 16S rRNA gene sequence similarities, strain K362(T) was shown to belong to the genus Tsukamurella, being most closely related to Tsukamurella pulmonis (99.2 %), Tsukamurella tyrosinosolvens (98.9 %), Tsukamurella strandjordii (98.8 %), Tsukamurella pseudospumae (98.8 %) and Tsukamurella spumae (98.8 %). A combination of the substrate utilization patterns, the fatty acid and mycolic acid profiles and the DNA-DNA hybridization results supported the affiliation of strain K362(T) to the genus Tsukamurella and enabled the genotypic and phenotypic differentiation of strain K362(T) from the seven recognized Tsukamurella species. Strain K362(T) therefore represents a novel species of the genus Tsukamurella, for which the name Tsukamurella spongiae sp. nov. is proposed. The type strain is K362(T) (=DSM 44990(T)=NRRL B-24467(T)).

  15. Seamount egg-laying grounds of the deep-water skate Bathyraja richardsoni.

    Science.gov (United States)

    Henry, L-A; Stehmann, M F W; De Clippele, L; Findlay, H S; Golding, N; Roberts, J M

    2016-08-01

    Highly localized concentrations of elasmobranch egg capsules of the deep-water skate Bathyraja richardsoni were discovered during the first remotely operated vehicle (ROV) survey of the Hebrides Terrace Seamount in the Rockall Trough, north-east Atlantic Ocean. Conductivity-temperature-depth profiling indicated that the eggs were bathed in a specific environmental niche of well-oxygenated waters between 4·20 and 4·55° C, and salinity 34·95-35·06, on a coarse to fine-grained sandy seabed on the seamount's eastern flank, whereas a second type of egg capsule (possibly belonging to the skate Dipturus sp.) was recorded exclusively amongst the reef-building stony coral Solenosmilia variabilis. The depths of both egg-laying habitats (1489-1580 m) provide a de facto refuge from fisheries mortality for younger life stages of these skates. © 2016 The Authors. Journal of Fish Biology published by John Wiley & Sons Ltd on behalf of The Fisheries Society of the British Isles.

  16. Characterization of the Deep Water Surface Wave Variability in the California Current Region

    Science.gov (United States)

    Villas Bôas, Ana B.; Gille, Sarah T.; Mazloff, Matthew R.; Cornuelle, Bruce D.

    2017-11-01

    Surface waves are crucial for the dynamics of the upper ocean not only because they mediate exchanges of momentum, heat, energy, and gases between the ocean and the atmosphere, but also because they determine the sea state. The surface wave field in a given region is set by the combination of local and remote forcing. The present work characterizes the seasonal variability of the deep water surface wave field in the California Current region, as retrieved from over two decades of satellite altimetry data combined with wave buoys and wave model hindcast (WaveWatch III). In particular, the extent to which the local wind modulates the variability of the significant wave height, peak period, and peak direction is assessed. During spring/summer, regional-scale wind events of up to 10 m/s are the dominant forcing for waves off the California coast, leading to relatively short-period waves (8-10 s) that come predominantly from the north-northwest. The wave climatology throughout the California Current region shows average significant wave heights exceeding 2 m during most of the year, which may have implications for the planning and retrieval methods of the Surface Water and Ocean Topography (SWOT) satellite mission.

  17. Vortex shedding control of circular cylinder by perforated shroud in deep water

    Directory of Open Access Journals (Sweden)

    Ozkan Gokturk M.

    2017-01-01

    Full Text Available The aim of the present study is to control the vortex shedding downstream of a circular cylinder (inner cylinder by the existence of outer perforated cylinder concentrically located around the inner cylinder in deep water. The flow characteristics downstream of concentrically placed coupled cylinders were investigated quantitatively by the Particle Image Velocimetry (PIV technique. Diameter of the outer perforated cylinder and inner cylinder were kept constant as Do=100 mm and Di=50 mm. The depth-averaged free-stream velocity was also kept constant as U=100 mm/s which corresponded to the Reynolds number of ReDo=10,000 based on the outer cylinder diameter. Experiments were conducted for six porosities (β = 0.3, 0.4, 0.5, 0.6, 0.7 and 0.8 in order to show the effect of these parameters on the flow control. Maximum values of both Reynolds shear stress, and turbulence kinetic energy, significantly decreased with the existence of outer perforated cylinder and also, the location of peak magnitudes of turbulence statistics occurred at locations further downstream compared to the bare cylinder case. The most effective control was revealed for the porosity of β=0.7.

  18. Vortex shedding control of circular cylinder by perforated shroud in deep water

    Science.gov (United States)

    Ozkan, Gokturk M.; Durhasan, Tahir; Pinar, Engin; Aksoy, Muhammed M.; Akilli, Huseyin; Sahin, Beşir

    The aim of the present study is to control the vortex shedding downstream of a circular cylinder (inner cylinder) by the existence of outer perforated cylinder concentrically located around the inner cylinder in deep water. The flow characteristics downstream of concentrically placed coupled cylinders were investigated quantitatively by the Particle Image Velocimetry (PIV) technique. Diameter of the outer perforated cylinder and inner cylinder were kept constant as Do=100 mm and Di=50 mm. The depth-averaged free-stream velocity was also kept constant as U=100 mm/s which corresponded to the Reynolds number of ReDo=10,000 based on the outer cylinder diameter. Experiments were conducted for six porosities (β = 0.3, 0.4, 0.5, 0.6, 0.7 and 0.8) in order to show the effect of these parameters on the flow control. Maximum values of both Reynolds shear stress, and turbulence kinetic energy, significantly decreased with the existence of outer perforated cylinder and also, the location of peak magnitudes of turbulence statistics occurred at locations further downstream compared to the bare cylinder case. The most effective control was revealed for the porosity of β=0.7.

  19. Managing mainland salt marshes for breeding birds

    OpenAIRE

    Maier, Martin

    2014-01-01

    The Wadden Sea region is one of the most important breeding areas in Western Europe for coastal breeding bird species. It is expected that management of salt marshes is important for successful conservation of breeding bird populations but the impact of management on the habitat quality for breeding birds is still not fully understood. In this study the effects of management on the three crucial habitat characteristics for breeding birds were studied on mainland salt marshes: effects of manag...

  20. Marsh Sediment and Species Composition in Hudson River Tidal Marshes: Change over the Last Millennium

    Science.gov (United States)

    Peteet, D. M.; Pederson, D. C.; Kurdyla, D.; Guilderson, T.; Kleinstein, D.; Higgiston, P.

    2004-05-01

    Understanding the signature of the Hudson River watershed to changes in the hydrological cycle is possible using marsh archives downriver. A suite of lower Hudson River tidal marshes is examined to identify changes in organic vs. inorganic content in the context of environmental change. Complex vegetational changes in the various marshes, identified by pollen and macrofossil studies, demonstrate the response to natural climate variability as well as human-induced changes of the last four centuries. While Piermont Marsh shows high inorganic content related to drought during the Medieval Warm Period, the subsequent Little Ice Age that followed shows a drop in this input. However, the nineteenth century of landscape disturbance reveals an increase again in upland watershed inorganics, followed by decline in the twentieth century. Jamaica Bay and Staten Island marshes to date show reduced inorganic input to these wetlands from the watershed up to the twentieth century. Jamaica Bay, NY marsh cores indicate increases in organic content in the twentieth century which may be related to dramatic land use changes in the surrounding New York area. An increase in the sand-sized fraction of organics may be attributed to the changes in local marsh plant production, but multiple hypotheses are being tested. Comparisons with adjacent Hackensack Meadowlands marshes demonstrate that local marsh plant production can dramatically alter the organic content and thus the carbon sequestration in the marshes. Species compositional changes in most of the marshes in the twentieth century resulted in a loss of biodiversity with the invasive increase of Typha (cattail) and Phragmites. This loss is linked to eutrophication of the estuary.

  1. Habitat heterogeneity: importance of salt marsh pools and high marsh surfaces to fish production in two Gulf of Maine salt marshes

    Science.gov (United States)

    R.A. MacKenzie; M. Dionne

    2008-01-01

    Both permanent high marsh pools and the intertidal surfaces of Spartina patens high marshes in southern Maine, USA, proved to be important habitat for resident mummichog Fundulus heteroclitus production. Manipulations of fish movement onto high marsh Surfaces revealed similar growth rates and production among fish that were (1) restricted to pools, (2) had access to...

  2. Sand in the salt marsh : Contribution of high-energy conditions to salt-marsh accretion

    NARCIS (Netherlands)

    de Groot, Alma V.; Veeneklaas, Roos M.; Bakker, Jan P.

    2011-01-01

    The environmental dynamics at barrier-island salt marshes are reflected in lateral and vertical textural patterns of the marsh sediment. During normal conditions, fine-grained sediment is deposited, whereas during high-energy conditions also sand accretion can occur. This paper describes the

  3. Sand in the salt marsh: Contribution of high-energy conditions to salt-marsh accretion

    NARCIS (Netherlands)

    Groot, de A.V.; Veeneklaas, R.M.; Bakker, J.P.

    2011-01-01

    The environmental dynamics at barrier-island salt marshes are reflected in lateral and vertical textural patterns of the marsh sediment. During normal conditions, fine-grained sediment is deposited, whereas during high-energy conditions also sand accretion can occur. This paper describes the

  4. Sea level driven marsh expansion in a coupled model of marsh erosion and migration

    Science.gov (United States)

    Kirwan, Matthew L.; Walters, David C.; Reay, William G.; Carr, Joel

    2016-01-01

    Coastal wetlands are among the most valuable ecosystems on Earth, where ecosystem services such as flood protection depend nonlinearly on wetland size and are threatened by sea level rise and coastal development. Here we propose a simple model of marsh migration into adjacent uplands and couple it with existing models of seaward edge erosion and vertical soil accretion to explore how ecosystem connectivity influences marsh size and response to sea level rise. We find that marsh loss is nearly inevitable where topographic and anthropogenic barriers limit migration. Where unconstrained by barriers, however, rates of marsh migration are much more sensitive to accelerated sea level rise than rates of edge erosion. This behavior suggests a counterintuitive, natural tendency for marsh expansion with sea level rise and emphasizes the disparity between coastal response to climate change with and without human intervention.

  5. Growth response of a deep-water ferromanganese crust to evolution of the Neogene Indian Ocean

    Science.gov (United States)

    Banakar, V.K.; Hein, J.R.

    2000-01-01

    A deep-water ferromanganese crust from a Central Indian Ocean seamount dated previously by 10Be and 230Th(excess) was studied for compositional and textural variations that occurred throughout its growth history. The 10Be/9Be dated interval (upper 32 mm) yields an uniform growth rate of 2.8 ?? 0.1 mm/Ma [Frank, M., O'Nions, R.K., 1998. Sources of Pb for Indian Ocean ferromanganese crusts: a record of Himalayan erosion. Earth Planet. Sci. Lett., 158, pp. 121-130.] which gives an extrapolated age of ~ 26 Ma for the base of the crust at 72 mm and is comparable to the maximum age derived from the Co-model based growth rate estimates. This study shows that Fe-Mn oxyhydroxide precipitation did not occur from the time of emplacement of the seamount during the Eocene (~ 53 Ma) until the late Oligocene (~ 26 Ma). This paucity probably was the result of a nearly overlapping palaeo-CCD and palaeo-depth of crust formation, increased early Eocene productivity, instability and reworking of the surface rocks on the flanks of the seamount, and lack of oxic deep-water in the nascent Indian Ocean. Crust accretion began (older zone) with the formation of isolated cusps of Fe-Mn oxide during a time of high detritus influx, probably due to the early-Miocene intense erosion associated with maximum exhumation of the Himalayas (op. cit.). This cuspate textured zone extends from 72 mm to 42 mm representing the early-Miocene period. Intense polar cooling and increased mixing of deep and intermediate waters at the close of the Oligocene might have led to the increased oxygenation of the bottom-water in the basin. A considerable expansion in the vertical distance between the seafloor depth and the CCD during the early Miocene in addition to the influx of oxygenated bottom-water likely initiated Fe-Mn crust formation. Pillar structure characterises the younger zone, which extends from 40 mm to the surface of the crust, i.e., ~ 15 Ma to Present. This zone is characterised by > 25% higher

  6. Six new deep-water sternaspid species (Annelida, Sternaspidae from the Pacific Ocean

    Directory of Open Access Journals (Sweden)

    Sergio Salazar-Vallejo

    2013-11-01

    Full Text Available Most sternaspid species have been described from shallow water, and Caulleryaspis Sendall & Salazar-Vallejo, 2013 includes one deep water species: C. gudmundssoni Sendall & Salazar-Vallejo, 2013 from Iceland. In Sternaspis Otto, 1821, the most speciose genus, most species were described from shallow water and only three thrive in deep water: S. maior Chamberlin, 1919 from the Gulf of California, S. princeps Selenka, 1885 from New Zealand, and S. riestchi Caullery, 1944 from Indonesia. The study of some deep sea sternaspids from the Pacific Ocean in the collections of six research institutions resulted in the discovery of six undescribed species, and for three of them there were abundant materials showing ventro-caudal shield development. Caulleryaspis fauchaldi sp. n. is described based on specimens from Oregon and California; it differs from the known species because it has a shield with rounded anterior margins and its peg chaetae form thin, small spines. Caulleryaspis nuda sp. n. was collected off Oregon; it is unique because its shield lacks a layer of sediment particles firmly attached, but has instead a thin layer of small particles loosely attached. Four other species are newly described in Sternaspis: S. annenkovae sp. n. was collected east off the northern Kurile Islands in about 4,000 m depth; it differs from other species bya bicolored body, with the introvert darker than the abdomen, and its ventro-caudal shield plates are divergent resulting in a divided fan. The second species, S. maureri sp.n. was found off Peru in 1296–6489 m water depths and in the Southwestern Pacific in 795–3830 m; it resembles S. williamsae sp. n. but differs because its shield has better-developed ribs, the fan has a shallow or indistinct median notch and has lateral notches well-developed. The third species, S. uschakovi sp. n., was found in the Okhotsk Sea in 592–1366 m, off California in 1585 m, Gulf of California in 1200–1274 m, and Western

  7. Six new deep-water sternaspid species (Annelida, Sternaspidae) from the Pacific Ocean.

    Science.gov (United States)

    Salazar-Vallejo, Sergio I; Buzhinskaja, Galina

    2013-01-01

    Most sternaspid species have been described from shallow water, and Caulleryaspis Sendall & Salazar-Vallejo, 2013 includes one deep water species: C. gudmundssoni Sendall & Salazar-Vallejo, 2013 from Iceland. In Sternaspis Otto, 1821, the most speciose genus, most species were described from shallow water and only three thrive in deep water: S. maior Chamberlin, 1919 from the Gulf of California, S. princeps Selenka, 1885 from New Zealand, and S. riestchi Caullery, 1944 from Indonesia. The study of some deep sea sternaspids from the Pacific Ocean in the collections of six research institutions resulted in the discovery of six undescribed species, and for three of them there were abundant materials showing ventro-caudal shield development. Caulleryaspis fauchaldi sp. n. is described based on specimens from Oregon and California; it differs from the known species because it has a shield with rounded anterior margins and its peg chaetae form thin, small spines. Caulleryaspis nuda sp. n. was collected off Oregon; it is unique because its shield lacks a layer of sediment particles firmly attached, but has instead a thin layer of small particles loosely attached. Four other species are newly described in Sternaspis: S. annenkovae sp. n. was collected east off the northern Kurile Islands in about 4,000 m depth; it differs from other species by having a bicolored body, with the introvert darker than the abdomen, and its ventro-caudal shield plates are divergent resulting in a divided fan. The second species, S. maureri sp. n. was found off Peru in 1296-6489 m water depths and in the Southwestern Pacific in 795-3830 m; it resembles S. williamsae sp. n. but differs because its shield has better-developed ribs, the fan has a shallow or indistinct median notch and has lateral notches well-developed. The third species, S. uschakovi sp. n., was found in the Okhotsk Sea in 592-1366 m, off California in 1585 m, Gulf of California in 1200-1274 m, and Western Mexico in 2548 m; it

  8. Deep-water gamma-spectrometer based on HP(Ge) detector

    International Nuclear Information System (INIS)

    Sokolov, A.; Danengirsh, S.; Popov, S.; Pchelincev, A; Gostilo, V.; Kravchenko, S.; Shapovalov, V.; Druzhinin, A.

    1995-01-01

    Full text: For radionuclide monitoring of the sea bottom near underwater storage of high active waste of nuclear industries and near places of accidents with nuclear submarines the spectrometers of gamma-radiation, which allow to carry out the measurements on the great depth, are needed. Usually, these problems are solved with devices, which are cast down into the water, using the rope, and transmit the signals on the surface by the cable. However, the depth of immersion is limited by this construction and often the conditions of measurement are complicated. The deep water gamma-spectrometer based on HP(Ge) detector for the measurement on the depth up to 3000 m is developed. The spectrometer is completely autonomic and is put up in the selected place, using the manipulator of a deep-water apparatus. The spectrometer is created in two cylindrical cases with 170 mm diameter and 1100 mm length, bearing the high hydrostatic pressure. The part of the case around the detector is created from titanium and has especial construction with a thin wall for increasing the efficiency of registration in the region of low-energy gamma-radiation. The cooling of the semiconductor detector is provided by a coolant which supports the working temperature of the detector during more than 24 hours. The electronic system of the spectrometer includes high voltage supply f or the detector, preamplifier, analog processor, analog-digital converter and a device for collecting and storing information in flash memory. The power supply of the spectrometer is provided by a battery of accumulators, which can be recharged on the surface. The programming of the processor is carried out before immersion by connecting the spectrometer to personal computer using standard interface RS-232. During 24 hours the spectrometer provides registration of 16 spectrums each in 4096 channels. The reading of the information by the computer is carried out after lifting up the spectrometer on the surface in the same

  9. Mechanical stratigraphy of deep-water sandstones: insights from a multisciplinary field and laboratory study

    Science.gov (United States)

    Agosta, Fabrizio; di Celma, Claudio; Tondi, Emanuele; Corradetti, Amerigo; Cantalamessa, Gino

    2010-05-01

    Turbidite sandstones found in deep-water fold-and-thrust belts are increasingly exploited as hydrocarbon reservoirs. Within these rocks, the fluid flow is profoundly affected by the complex interaction between primary sedimentological and stratigraphic attributes (i.e, facies, layering, reservoir quality, stacking patterns, bed connectivity and lateral extent) and fracture characteristics (i.e., length, spacing, distribution, orientation, connectivity). Unfortunately, most of these features are at, or below, the resolution of conventional seismic datasets and, for this reason, their identification and localization represent one of the fundamental challenges facing exploration, appraisal and production of the sandstone reservoirs. In this respect, whereas considerable effort has been afforded to a characterization of the sedimentological and stratigraphic aspects of sandstones, detailed analysis of fractures in this type of successions has received significantly less attention. In this work, we combine field and laboratory analyses to assess the possible mechanical control exerted by the rock properties (grain size, intergranualr porosity, and Young modulus), as well as the influence of bed thickness, on joint density in turbidite sandstones. Joints are mode-I fractures occurring parallel to the greatest principle stress axis, which solve opening displacement and do not show evidence of shearing and enhance the values of total porosity forming preferential hydraulic conduits for fluid flow. Within layered rocks, commonly, joints form perpendicular to bedding due to overburden or exhumation. The empirical relation between joint spacing and bed thickness, documented in the field by many authors, has been mechanically related to the stress perturbation taking place around joints during their formation. Furthermore, close correlations between joint density and rock properties have been already established. In this present contribution, we focus on the bed

  10. Spatial and temporal variability of deep-water algal assemblages in the Northwestern Mediterranean: The effects of an exceptional storm

    Science.gov (United States)

    Navarro, Laura; Ballesteros, Enric; Linares, Cristina; Hereu, Bernat

    2011-11-01

    There are deep-water populations of the endemic and threatened Mediterranean brown alga Cystoseira zosteroides in the Medes Islands Marine Reserve (NW Mediterranean). Here, the distribution, population structure, individual growth, mortality and recruitment rates of this species over two years are described in relation to the effects of an exceptional storm. We found a high spatial variability in the structure and dynamics of C. zosteroides populations at small geographical scales, suggesting that environmental factors acting at the population level display a key role in population size structure, mortality and recruitment. The elevated mortality rates recorded at some locations (almost 80%) is amongst the highest recorded for perennial algae as a consequence of a single storm, emphasizing the importance of episodic catastrophic events in the maintenance of these deep-water, slow-growing populations. These findings are of particular importance not only to fully understand the ecology of C. zosteroides, but also for its conservation.

  11. Changes in the deep-water benthos of eastern Lake Erie between 1979 and 1993

    Energy Technology Data Exchange (ETDEWEB)

    Dermott, R.; Kerec, D. [Fisheries and Oceans, Burlington, Ontario (Canada)

    1995-06-01

    In order to examine changes of the benthic community and benthic biomass as a result of mussel colonization, a survey of the deep-water benthic fauna in eastern Lake Erie was repeated in 1993 using the same sites and methods as in a 1979 survey. During 1979, the community beyond 30 m was dominated by oligochaete worms and the burrowing amphipod Diporeia, which represented 50 and 40% of the total benthic biomass respectively. By 1993, quagga mussels (Dreissena bugensis) formed over 90% of the benthic biomass. Mussels were present at all 13 sites. Densities of individuals >2 mm in length averaged 3,241 mussels m{sup -2}. Of these mussels, 97% were quagga mussels. Total density of all sizes retained on a 180 {mu}m sieve averaged 34,800 mussels m{sup -2} but total biomass decreased from 1.58 to 0.98 g m{sup -2}. The density of the amphipod Diporeia was reduced from 1,844 in 1979 to 218 m{sup -2} in 1993. While present at all sites during 1979, Diporeia remained common only at two sites and were absent at 8 of the 13 sites in 1993. The native fingernail clams, Pisidium spp., were reduced from 327 to 82 m{sup -2}. No significant reduction occurred in the worm and chironomid populations, however the dry biomass of the chironomids was reduced from 0.07 to 0.0008 g m{sup -2}. These reductions may be due to competition with the mussels for freshly settling algae. The meiofauna, which included small nematodes, ostracods, and harpacticoids retained on a 180 {mu}m sieve, all increased in density. Perhaps they benefited from an increase in the detritus deposited as pseudofeces around the mussels.

  12. Modeling modified Circumpolar Deep Water intrusions onto the Prydz Bay continental shelf, East Antarctica

    Science.gov (United States)

    Liu, Chengyan; Wang, Zhaomin; Cheng, Chen; Xia, Ruibin; Li, Bingrui; Xie, Zelin

    2017-07-01

    An eddy-resolving coupled regional ocean-sea ice-ice shelf model is employed to locate the hot spots where modified Circumpolar Deep Water (mCDW) intrudes onto the continental shelf within Prydz Bay, and locate the paths through which mCDW is transported to the Amery Ice Shelf (AIS) calving front. Evaluation of the model output is with satellite, hydrographic and borehole data. Two critical windows responsible for mCDW intrusions are identified. The first is the eastern branch of the cyclonic Prydz Bay gyre (PBG) that carries mCDW to the ice front line, accounting for an annual mean heat transport of ˜8.7 ×1011 J s-1. The second is located to the east of the Four Ladies Bank (FLB) where mCDW is channeled through submarine troughs, accounting for an annual mean heat transport of ˜16.2 ×1011 J s-1. The eddy-induced heat transport accounts for ˜23% in the path of the PBG and ˜52% in the path of the eastern coastal current, with respect to their total onshore heat transport. The seasonal pulsing of mCDW intrusions is greatly dependent on the seasonal cycle of the Antarctic Slope Current (ASC) that peaks with a maximum of ˜29.3 Sv at 75°E in June. In austral winter, mCDW is allowed to access the eastern flank of the AIS calving front with potential consequences for the basal mass balance of the AIS. The dynamic effects of small-scale troughs on the longshore ASC play an important role in the onshore mCDW transport.

  13. Simplified calculation methods for all-vertical-piled wharf in offshore deep water

    Science.gov (United States)

    Wang, Yuan-zhan; He, Lin-lin

    2017-04-01

    All-vertical-piled wharf is a kind of high-piled wharf, but it is extremely different from the traditional ones in some aspects, such as the structural property, bearing characteristics, failure mechanism, and static or dynamic calculation methods. In this paper, the finite element method (FEM) and theoretical analysis method are combined to analyze the structural property, bearing behavior and failure mode of the all-vertical-piled wharf in offshore deep water, and to establish simplified calculation methods determining the horizontal static ultimate bearing capacity and the dynamic response for the all-vertical-piled wharf. Firstly, the bearing capability and failure mechanism for all-vertical-piled wharf are studied by use of FEM, and the failure criterion is put forward for all-vertical-piled wharf based on the `plastic hinge'. According to the failure criterion and P-Y curve method, the simplified calculation method of the horizontal static ultimate bearing capacity for all-vertical-piled wharf is proposed, and it is verified that the simplified method is reasonable by comparison with the FEM. Secondly, the displacement dynamic magnification factor for the all-vertical-piled wharf under wave cyclic loads and ship impact loads is calculated by the FEM and the theory formula based on the single degree of freedom (SDOF) system. The results obtained by the two methods are in good agreement with each other, and the simplified calculation method of the displacement dynamic magnification factor for all-vertical-piled wharf under dynamic loads is proposed. Then the simplified calculation method determining the dynamic response for the all-vertical-piled wharf is proposed in combination with P-Y curve method. That is, the dynamic response of the structure can be obtained through the static calculation results of P-Y curve method multiplied by the displacement dynamic magnification factor. The feasibility of the simplified dynamic response method is verified by

  14. Numerical comparison between deep water and intermediate water depth expressions applied to a wave energy converter

    Directory of Open Access Journals (Sweden)

    Pedro Beirão

    2015-09-01

    Full Text Available The energy that can be captured from the sea waves and converted into electricity should be seen as a contribution to decrease the excessive dependency and growing demand of fossil fuels. Devices suitable to harness this kind of renewable energy source and convert it into electricity—wave energy converters (WECs—are not yet commercially competitive. There are several types of WECs, with different designs and working principles. One possible classification is their distance to the shoreline and thus their depth. Near-shore devices are one of them since they are typically deployed at intermediate water depth (IWD. The selection of the WEC deployment site should be a balance between several parameters; water depth is one of them. Another way of classifying WECs is grouping them by their geometry, size and orientation. Considering a near-shore WEC belonging to the floating point category, this paper is focused on the numerical study about the differences arising in the power captured from the sea waves when the typical deep water (DW assumption is compared with the more realistic IWD consideration. Actually, the production of electricity will depend, among other issues, on the depth of the deployment site. The development of a dynamic model including specific equations for the usual DW assumption as well as for IWD is also described. Derived equations were used to build a time domain simulator (TDS. Numerical results were obtained by means of simulations performed using the TDS. The objective is to simulate the dynamic behavior of the WEC due to the action of sea waves and to characterize the wave power variations according with the depth of the deployment site.

  15. Basic prerequisites and the practice of using deep water tables for burying liquid radioactive wastes

    International Nuclear Information System (INIS)

    Spitsyn, V.I.; Pimenov, M.K.; Balukova, V.D.; Leontichuk, A.S.; Kokorin, I.N.; Yudin, F.P.; Rakov, N.A.

    In the USSR, creating reservoirs for liquid radioactive wastes is one of the promising methods of safely disposing of them in deep water tables, in zones with a standing regime or a slow rate of subterranean water exchange. The results of investigations and the practice of burying (the wastes) indicate the reliability and effectiveness of such a method of final waste disposal when the basic requirements of environmental protection are observed. Geological formations and collector strata that guarantee the localization of the liquid radioactive wastes placed in them for many tens and even hundreds of thousands of years can be studied and chosen in different regions. The basic requirements and criteria to which the geological structures and collector strata must correspond for ensuring the safe burial of wastes have been formulated. Wastes are buried only after a comprehensive, scientifically based evaluation of the sanitary-radiation safety for this generation and future ones, taking into account the burial regime and the physico-chemical processes that accompany combining wastes with rocks and stratal waters, as well as the time of holding wastes to maximum permissible concentrations. Positive and negative factors that characterize the method are analyzed. Possible emergency situations with subterranean burial are evaluated. The composition and methods of the geological survey, hydrodynamic, geophysical, physico-chemical and sanitary-radiation investigations; methods of calculating and predicting the movement of wastes underground;methods of preparing wastes for burial and chemical methods of restoring the suitability of wells; design characteristics and conditions of preparing wells for use; methods of estimating heating and processes of radiolysis for a medium containing highly radioactive wastes; methods of operational and remote control of the burial process and the condition of the ambient medium, etc. are briefly examined

  16. Lytic viral infection of bacterioplankton in deep waters of the western Pacific Ocean

    Science.gov (United States)

    Li, Y.; Luo, T.; Sun, J.; Cai, L.; Liang, Y.; Jiao, N.; Zhang, R.

    2014-05-01

    As the most abundant biological entities in the ocean, viruses influence host mortality and nutrient recycling mainly through lytic infection. Yet, the ecological characteristics of virioplankton and viral impacts on host mortality and biogeochemical cycling in the deep sea are largely unknown. In the present study, viral abundance and lytic infection were investigated throughout the water column in the western Pacific Ocean. Both the prokaryotic and viral abundance and production showed a significantly decreasing trend from epipelagic to meso- and bathypelagic waters. Viral abundance decreased from 0.36-1.05 × 1010 particles L-1 to 0.43-0.80 × 109 particles L-1, while the virus : prokaryote ratio varied from 7.21 to 16.23 to 2.45-23.40, at the surface and 2000 m, respectively. Lytic viral production rates in surface and 2000 m waters were, on average, 1.03 × 1010 L-1 day-1 and 5.74 × 108 L-1 day-1. Relatively high percentages of prokaryotic cells lysed by viruses at 1000 and 2000 m were observed, suggesting a significant contribution of viruses to prokaryotic mortality in the deep ocean. The carbon released by viral lysis in deep western Pacific Ocean waters was from 0.03 to 2.32 μg C L-1 day-1. Our findings demonstrated a highly dynamic and active viral population in these deep waters and suggested that virioplankton play an important role in the microbial loop and subsequently biogeochemical cycling in deep oceans.

  17. Large-scale geographic variation in distribution and abundance of Australian deep-water kelp forests.

    Directory of Open Access Journals (Sweden)

    Ezequiel M Marzinelli

    Full Text Available Despite the significance of marine habitat-forming organisms, little is known about their large-scale distribution and abundance in deeper waters, where they are difficult to access. Such information is necessary to develop sound conservation and management strategies. Kelps are main habitat-formers in temperate reefs worldwide; however, these habitats are highly sensitive to environmental change. The kelp Ecklonia radiate is the major habitat-forming organism on subtidal reefs in temperate Australia. Here, we provide large-scale ecological data encompassing the latitudinal distribution along the continent of these kelp forests, which is a necessary first step towards quantitative inferences about the effects of climatic change and other stressors on these valuable habitats. We used the Autonomous Underwater Vehicle (AUV facility of Australia's Integrated Marine Observing System (IMOS to survey 157,000 m2 of seabed, of which ca 13,000 m2 were used to quantify kelp covers at multiple spatial scales (10-100 m to 100-1,000 km and depths (15-60 m across several regions ca 2-6° latitude apart along the East and West coast of Australia. We investigated the large-scale geographic variation in distribution and abundance of deep-water kelp (>15 m depth and their relationships with physical variables. Kelp cover generally increased with latitude despite great variability at smaller spatial scales. Maximum depth of kelp occurrence was 40-50 m. Kelp latitudinal distribution along the continent was most strongly related to water temperature and substratum availability. This extensive survey data, coupled with ongoing AUV missions, will allow for the detection of long-term shifts in the distribution and abundance of habitat-forming kelp and the organisms they support on a continental scale, and provide information necessary for successful implementation and management of conservation reserves.

  18. Large-scale geographic variation in distribution and abundance of Australian deep-water kelp forests.

    Science.gov (United States)

    Marzinelli, Ezequiel M; Williams, Stefan B; Babcock, Russell C; Barrett, Neville S; Johnson, Craig R; Jordan, Alan; Kendrick, Gary A; Pizarro, Oscar R; Smale, Dan A; Steinberg, Peter D

    2015-01-01

    Despite the significance of marine habitat-forming organisms, little is known about their large-scale distribution and abundance in deeper waters, where they are difficult to access. Such information is necessary to develop sound conservation and management strategies. Kelps are main habitat-formers in temperate reefs worldwide; however, these habitats are highly sensitive to environmental change. The kelp Ecklonia radiate is the major habitat-forming organism on subtidal reefs in temperate Australia. Here, we provide large-scale ecological data encompassing the latitudinal distribution along the continent of these kelp forests, which is a necessary first step towards quantitative inferences about the effects of climatic change and other stressors on these valuable habitats. We used the Autonomous Underwater Vehicle (AUV) facility of Australia's Integrated Marine Observing System (IMOS) to survey 157,000 m2 of seabed, of which ca 13,000 m2 were used to quantify kelp covers at multiple spatial scales (10-100 m to 100-1,000 km) and depths (15-60 m) across several regions ca 2-6° latitude apart along the East and West coast of Australia. We investigated the large-scale geographic variation in distribution and abundance of deep-water kelp (>15 m depth) and their relationships with physical variables. Kelp cover generally increased with latitude despite great variability at smaller spatial scales. Maximum depth of kelp occurrence was 40-50 m. Kelp latitudinal distribution along the continent was most strongly related to water temperature and substratum availability. This extensive survey data, coupled with ongoing AUV missions, will allow for the detection of long-term shifts in the distribution and abundance of habitat-forming kelp and the organisms they support on a continental scale, and provide information necessary for successful implementation and management of conservation reserves.

  19. Response of deep-water corals to oil and chemical dispersant exposure

    Science.gov (United States)

    DeLeo, Danielle M.; Ruiz-Ramos, Dannise V.; Baums, Iliana B.; Cordes, Erik E.

    2016-07-01

    Cold-water corals serve as important foundation species by building complex habitat within deep-sea benthic communities. Little is known about the stress response of these foundation species yet they are increasingly exposed to anthropogenic disturbance as human industrial presence expands further into the deep sea. A recent prominent example is the Deepwater Horizon oil-spill disaster and ensuing clean-up efforts that employed chemical dispersants. This study examined the effects of bulk oil-water mixtures, water-accommodated oil fractions, the dispersant Corexit 9500A®, and the combination of hydrocarbons and dispersants on three species of corals living near the spill site in the Gulf of Mexico between 500 and 1100 m depths: Paramuricea type B3, Callogorgia delta and Leiopathes glaberrima. Following short-term toxicological assays (0-96 h), all three coral species examined showed more severe health declines in response to dispersant alone (2.3-3.4 fold) and the oil-dispersant mixtures (1.1-4.4 fold) than in the oil-only treatments. Higher concentrations of dispersant alone and the oil-dispersant mixtures resulted in more severe health declines. C. delta exhibited somewhat less severe health declines than the other two species in response to oil and oil/dispersant mixture treatments, likely related to its increased abundance near natural hydrocarbon seeps. These experiments provide direct evidence for the toxicity of both oil and dispersant on deep-water corals, which should be taken into consideration in the development of strategies for intervention in future oil spills.

  20. On the interaction of deep water waves and exponential shear currents

    Science.gov (United States)

    Cheng, Jun; Cang, Jie; Liao, Shi-Jun

    2009-05-01

    A train of periodic deep-water waves propagating on a steady shear current with a vertical distribution of vorticity is investigated by an analytic method, namely the homotopy analysis method (HAM). The magnitude of the vorticity varies exponentially with the magnitude of the stream function, while remaining constant on a particular streamline. The so-called Dubreil-Jacotin transformation is used to transfer the original exponentially nonlinear boundary-value problem in an unknown domain into an algebraically nonlinear boundary-value problem in a known domain. Convergent series solutions are obtained not only for small amplitude water waves on a weak current but also for large amplitude waves on a strong current. The nonlinear wave-current interaction is studied in detail. It is found that an aiding shear current tends to enlarge the wave phase speed, sharpen the wave crest, but shorten the maximum wave height, while an opposing shear current has the opposite effect. Besides, the amplitude of waves and fluid velocity decay over the depth more quickly on an aiding shear current but more slowly on an opposing shear current than that of waves on still water. Furthermore, it is found that Stokes criteria of wave breaking is still valid for waves on a shear current: a train of propagating waves on a shear current breaks as the fiuid velocity at crest equals the wave phase speed. Especially, it is found that the highest waves on an opposing shear current are even higher and steeper than that of waves on still water. Mathematically, this analytic method is rather general in principle and can be employed to solve many types of nonlinear partial differential equations with variable coefficients in science, finance and engineering.

  1. Ventilation of the Baltic Sea deep water: A brief review of present knowledge from observations and models

    Directory of Open Access Journals (Sweden)

    Hans Burchard

    2006-06-01

    Full Text Available The ventilation of the Baltic Sea deep wateris driven by either gale-forced barotropic or baroclinic salt water inflows.During the past two decades, the frequency of large barotropic inflows(mainly in winter has decreased and the frequency of medium-intensity baroclinic inflows(observed in summer has increased. As a result of entrainment of ambient oxygen-rich water,summer inflows are also important for the deep water ventilation.Recent process studies of salt water plumes suggest that the entrainmentrates are generally smaller than those predicted by earlier entrainment models.In addition to the entrance area, the Słupsk Sill andthe Słupsk Furrow are important locations for the transformation of water masses. Passing the Słupsk Furrow, both gravity-driven dense bottom flows and sub-surface cyclonic eddies,which are eroded laterally by thermohaline intrusions,ventilate the deep water of the eastern Gotland Basin.A recent study of the energy transfer from barotropic to baroclinicwave motion using a two-dimensional shallow water model suggests thatabout 30% of the energy needed below the halocline for deep water mixingis explained by the breaking of internal waves.In the deep water decade-long stagnation periods with decreasingoxygen and increasing hydrogen sulphide concentrations might be caused by anomalously largefreshwater inflows and anomalously high mean zonal wind speeds. In differentstudies the typical response time scale of average salinity was estimated tobe between approximately 20 and 30 years.The review summarizes recent research resultsand ends with a list of open questions and recommendations.

  2. Evidence of Enhanced Respired Carbon in Eastern Equatorial Pacific Deep-Waters over the last 30,000 years

    Science.gov (United States)

    Umling, N. E.; Thunell, R.

    2016-12-01

    Rapid decreases in glacial deep water reservoir ages have been observed in the Eastern Equatorial Pacific (EEP; this study), North Pacific (Rae et al., 2014), Southwest Pacific (Sikes et al., 2016), and North Atlantic (Skinner et al., 2013). It has been hypothesized that release of a deep ocean 14C-depleted, respired-carbon reservoir to the surface ocean and atmosphere is the most likely mechanism for the observed increases in atmospheric CO2 concentrations recorded in ice cores during the last glacial-interglacial transition (Broecker and Barker, 2007). This study examines whether oxygenation, organic carbon flux, and carbonate chemistry in the EEP deep-waters reflect an increase in respired carbon associated with recorded 14C-depletions using isotopic and trace element records from three Panama Basin cores (2,650-3,200 m water-depth). An increase in glacial deep-water respired carbon storage would result in a shift of DIC speciation towards lower carbonate ion concentrations along with deoxygenation of bottom waters. Specifically, we use the boron to calcium (B/Ca) and uranium to calcium (U/Ca) ratios of the benthic foraminifera Cibicidoides wuellerstorfi to reconstruct deep-water carbonate ion concentration (Yu and Elderfield, 2007; Raizsch et al., 2011). Additionally, bottom water oxygenation is estimated from the difference in δ13C of benthic foraminifera living in pore waters at the anoxic boundary and of those living in bottom water (Δ δ13C; Hoogakker et al., 2015, 2016), while carbon flux was assessed from the U/Ca and Cd/Ca of foraminiferal authigenic coatings.

  3. A new species of deep-water Holothuroidea (Echinodermata of the genus Synallactes from off western Mexico

    Directory of Open Access Journals (Sweden)

    Claude Massin

    2010-08-01

    Full Text Available An undescribed species of Synallactes was collected during a deep-water benthic fauna survey off the Pacific coast of Mexico in the East Pacific, with the R/V El Puma. This new species differs from all the other known Synallactes by the presence of huge massive rods in the tube feet, some of them club-shaped. The later ossicle shape is unique among Holothuroidea. This is the first record of a Synallactes in the Gulf of California.

  4. 224Ra distribution in surface and deep water of Long Island Sound: sources and horizontal transport rates

    Science.gov (United States)

    Torgersen, Thomas; Turekian, K. K.; Turekian, V. C.; Tanaka, N.; DeAngelo, Edward; O'Donnell, J.

    1996-10-01

    Measurements of surface water and deep water 224Ra (half-life 3.64 days) distributions in Long Island Sound (LIS) were conducted in July 1991. Because the pycnocline structure of LIS had been in place for about 50 days in July (long compared to the half-life of 224Ra), 224Ra in the surface water and the deep water operate as separate systems. In the surface water, the fine-grain sediments of nearshore and saltmarsh environments provide a strong source of 224Ra, which is horizontally mixed away from the shore to central LIS. A one-dimensional model of 224Ra distribution suggests across-LIS horizontal eddy dispersivity of 5-50 m 2 s -1. In the deep water, the mid-LIS sediment flux of 224Ra is enhanced by ˜2x relative to the periphery, and the horizontal eddy flux is from central LIS to the periphery. A second one-dimensional model suggests a cross-LIS horizontal eddy dispersivity below the thermocline of 5-50 m 2 s -1. 224Ra fluxes into the deep water of the central LIS are likely enhanced by (1) inhomogeneous sediment or (2) a reduced scavenging of 224Ra in the sediments of central LIS brought about by low oxygen conditions (hypoxia) and the loss of the MnO 2 scavenging layer in the sediments. These rates of horizontal eddy dispersivity are significantly less than the estimate of 100-650 m 2 s -1 (Riley, 1967) but are consistent with the transport necessary to explain the dynamics of oxygen depletion in summer LIS. These results demonstrate the use of 224Ra for quantifying the parameters needed to describe estuarine mixing and transport.

  5. Paraffin dispersant application for cleaning subsea flow lines in the deep water Gulf of Mexico cottonwood development

    Energy Technology Data Exchange (ETDEWEB)

    Jennings, David; White, Jake; Pogoson, Oje [Baker Hughes Inc., Houston, TX (United States); Barros, Dalmo; Ramachandran, Kartik; Bonin, George; Waltrich, Paulo; Shecaira, Farid [PETROBRAS America, Houston, TX (United States); Ziglio, Claudio [Petroleo Brasileiro S.A. (CENPES/PETROBRAS), Rio de Janeiro, RJ (Brazil). Centro de Pesquisa e Desenvolvimento

    2012-07-01

    This paper discusses a paraffin dispersant (in seawater) application to clean paraffin deposition from a severely restricted 17.4-mile dual subsea flow line system in the Gulf of Mexico Cottonwood development. In principle, dispersant treatments are simple processes requiring effective dispersant packages and agitation to break-up and disperse deposition. Dispersants have been used onshore for treating wax deposition for decades. Implementation of a treatment in a long deep water production system, however, poses numerous challenges. The Cottonwood application was one of the first ever deep water dispersant applications. The application was designed in four separate phases: pre-treatment displacement for hydrate protection, dispersant treatment for paraffin deposition removal, pigging sequence for final flow line cleaning, and post-treatment displacement for hydrate protection. In addition, considerable job planning was performed to ensure the application was executed in a safe and environmentally responsible manner. Two dynamically positioned marine vessels were used for pumping fluids and capturing returns. The application was extremely successful in restoring the deep water flow lines back to near pre-production state. Final pigging operations confirmed the flow lines were cleaned of all restrictions. Significant paraffin deposition was removed in the application. Approximately 900 bbls of paraffin sludge was recovered from the 4000 bbl internal volume flow line loop. Furthermore, the application was completed with zero discharge of fluids. The application provided significant value for the Cottonwood development. It allowed production from wells to be brought on-line at a higher capacity, thereby generating increased revenue. It also allowed resumption of routine pigging operations. As such, the Cottonwood dispersant application illustrates that with proper planning and execution, paraffin dispersant treatments can be highly effective solutions for cleaning

  6. Large zero-tension plate lysimeters for soil water and solute collection in undisturbed soils

    Directory of Open Access Journals (Sweden)

    A. Peters

    2009-09-01

    Full Text Available Water collection from undisturbed unsaturated soils to estimate in situ water and solute fluxes in the field is a challenge, in particular if soils are heterogeneous. Large sampling devices are required if preferential flow paths are present. We present a modular plate system that allows installation of large zero-tension lysimeter plates under undisturbed soils in the field. To investigate the influence of the lysimeter on the water flow field in the soil, a numerical 2-D simulation study was conducted for homogeneous soils with uni- and bimodal pore-size distributions and stochastic Miller-Miller heterogeneity. The collection efficiency was found to be highly dependent on the hydraulic functions, infiltration rate, and lysimeter size, and was furthermore affected by the degree of heterogeneity. In homogeneous soils with high saturated conductivities the devices perform poorly and even large lysimeters (width 250 cm can be bypassed by the soil water. Heterogeneities of soil hydraulic properties result into a network of flow channels that enhance the sampling efficiency of the lysimeter plates. Solute breakthrough into zero-tension lysimeter occurs slightly retarded as compared to the free soil, but concentrations in the collected water are similar to the mean flux concentration in the undisturbed soil. To validate the results from the numerical study, a dual tracer study with seven lysimeters of 1.25×1.25 m area was conducted in the field. Three lysimeters were installed underneath a 1.2 m filling of contaminated silty sand, the others deeper in the undisturbed soil. The lysimeters directly underneath the filled soil material collected water with a collection efficiency of 45%. The deeper lysimeters did not collect any water. The arrival of the tracers showed that almost all collected water came from preferential flow paths.

  7. Carbon dioxide and methane fluxes in grazed and undisturbed mountain peatlands in the Ecuadorian Andes

    Directory of Open Access Journals (Sweden)

    M.E. Sánchez

    2017-10-01

    Full Text Available Peatlands are widespread throughout the tropical Andean páramo. Despite the large carbon stocks in these ecosystems, carbon dioxide (CO2 and methane (CH4 flux data are lacking. In addition, cattle grazing is widespread in the páramo and could alter gas fluxes. Therefore, our objectives were to measure CO2 and CH4 fluxes with the static chamber technique in an undisturbed and in an intensively cattle grazed peatland in the mountains of Ecuador. We found that hummocks in the undisturbed site had higher net ecosystem exchange (NEE, gross primary production (GPP, ecosystem respiration (ER, and CH4 fluxes, compared to lawns. In contrast, microtopography at the grazed site did not predict CO2 fluxes, whereas vegetation cover was correlated for all three metrics (NEE, ER, and GPP. At low vegetation cover, NEE was positive (losing carbon. CH4 emissions in the undisturbed site were low (8.1 mg CH4 m-2 d-1. In contrast, CH4 emissions at the grazed site were much greater (132.3 mg CH4 m-2 d-1. This is probably attributable to trampling and nutrient inputs from cattle. In summary, the two peatlands differed greatly in CO2 and CH4 exchange rates, which could be due to the variation in climate and hydrology, or alternatively to intensive grazing by cattle.

  8. Dominance of the multicoloured Asian lady beetle Harmonia axyridis in an undisturbed wild meadow ecosystem

    Directory of Open Access Journals (Sweden)

    Élise Bélanger

    2011-12-01

    Full Text Available Fifteen years after its arrival in Quebec (Canada, the multicoloured Asian lady beetle Harmonia axyridis (Pallas 1773 (Coleoptera: Coccinellidae has become one of the dominant coccinellid species in agricultural, forested and urban areas. Several studies conducted in North American agricultural ecosystems show that the arrival of H. axyridis and other exotic coccinellid species was followed by decreases in the populations of native coccinellid species. In this study, the abundances of H. axyridis and other native and exotic species were determined in an undisturbed wild meadow located in a protected area. In 2009 and 2010, mainly Solidago canadensis L. (Asteraceae and Asclepias syriaca L. (Asclepiadaceae infested with aphids were surveyed. A total of 1522 individuals, belonging to seven different species, were recorded. In 2009, on all the plants monitored, H. axyridis was clearly the dominant species (69% of the coccinellid assemblage. In addition, this exotic species constituted 84% of the coccinellid assemblage, including Propylea quatuordecimpunctata (L. and Coccinella septempunctata (L. It is likely the dominance of the eurytopic Asian lady beetle in agricultural, forested, urban and undisturbed open ecosystems, poses a threat to native lady beetles. These results also provide evidence that undisturbed wild meadow ecosystems will not constitute a natural refuge from Harmonia axyridis for native species of lady beetles.

  9. Astronomically paced changes in deep-water circulation in the western North Atlantic during the middle Eocene

    Science.gov (United States)

    Vahlenkamp, Maximilian; Niezgodzki, Igor; De Vleeschouwer, David; Bickert, Torsten; Harper, Dustin; Kirtland Turner, Sandra; Lohmann, Gerrit; Sexton, Philip; Zachos, James; Pälike, Heiko

    2018-02-01

    North Atlantic Deep Water (NADW) currently redistributes heat and salt between Earth's ocean basins, and plays a vital role in the ocean-atmosphere CO2 exchange. Despite its crucial role in today's climate system, vigorous debate remains as to when deep-water formation in the North Atlantic started. Here, we present datasets from carbonate-rich middle Eocene sediments from the Newfoundland Ridge, revealing a unique archive of paleoceanographic change from the progressively cooling climate of the middle Eocene. Well-defined lithologic alternations between calcareous ooze and clay-rich intervals occur at the ∼41-kyr beat of axial obliquity. Hence, we identify obliquity as the driver of middle Eocene (43.5-46 Ma) Northern Component Water (NCW, the predecessor of modern NADW) variability. High-resolution benthic foraminiferal δ18O and δ13C suggest that obliquity minima correspond to cold, nutrient-depleted, western North Atlantic deep waters. We thus link stronger NCW formation with obliquity minima. In contrast, during obliquity maxima, Deep Western Boundary Currents were weaker and warmer, while abyssal nutrients were more abundant. These aspects reflect a more sluggish NCW formation. This obliquity-paced paleoceanographic regime is in excellent agreement with results from an Earth system model, in which obliquity minima configurations enhance NCW formation.

  10. ILS - a passive insulation solution to answer cool down time challenges on ultra deep water flow lines

    Energy Technology Data Exchange (ETDEWEB)

    Hallot, R.; Couprie, St. [Bouygues Offshore, Montigny-le-Bretonneux, 78 - St-Quentin-Yvelines (France); Chomard, A. [Institut Francais du Petrole (IFP), 92 - Rueil-Malmaison (France)

    2002-12-01

    Flow assurance issues are more and more driving the design of Deep Water Flow-lines and Cool Down Time requirement has a major impact on the global system design for most West African sub-sea field developments. Bouygues Offshore and IFP have developed a new thermal insulation solution, named ILS (Liquid solid Insulation), based on the use of phase change materials (PCM). In normal flowing conditions, the PCM liquefied by the oil's heat flux acts as a heat accumulator. During production shutdowns and resulting cool down, the phase change material's crystallization restores partially this stored heat to the flow-line. Therefore, such an insulated coating produces a significant thermal inertia to the flow-line and the cool down delay before hydrates formation is 2 to 4 tunes longer in regard to the existing insulation technologies. Due to the incompressibility, the low density and the low cost of chosen phase change materials, ILS is able to deal with deep-water and ultra deep-water flow assurance requirements and to compete with existing pipe-in-pipe or syntactic thermal insulation. This paper presents the principle of the ILS solution and the main results achieved through the development program, from the theoretical analysis to the qualification tests. (authors)

  11. Carbon sequestration by Australian tidal marshes

    KAUST Repository

    Macreadie, Peter I.

    2017-03-10

    Australia\\'s tidal marshes have suffered significant losses but their recently recognised importance in CO2 sequestration is creating opportunities for their protection and restoration. We compiled all available data on soil organic carbon (OC) storage in Australia\\'s tidal marshes (323 cores). OC stocks in the surface 1 m averaged 165.41 (SE 6.96) Mg OC ha-1 (range 14-963 Mg OC ha-1). The mean OC accumulation rate was 0.55 ± 0.02 Mg OC ha-1 yr-1. Geomorphology was the most important predictor of OC stocks, with fluvial sites having twice the stock of OC as seaward sites. Australia\\'s 1.4 million hectares of tidal marshes contain an estimated 212 million tonnes of OC in the surface 1 m, with a potential CO2-equivalent value of $USD7.19 billion. Annual sequestration is 0.75 Tg OC yr-1, with a CO2-equivalent value of $USD28.02 million per annum. This study provides the most comprehensive estimates of tidal marsh blue carbon in Australia, and illustrates their importance in climate change mitigation and adaptation, acting as CO2 sinks and buffering the impacts of rising sea level. We outline potential further development of carbon offset schemes to restore the sequestration capacity and other ecosystem services provided by Australia tidal marshes.

  12. Marsh Soil Responses to Nutrients: Belowground Structural and Organic Properties.

    Science.gov (United States)

    Coastal marsh responses to nutrient enrichment apparently depend upon soil matrix and whether the system is primarily biogenic or minerogenic. Deteriorating organic rich marshes (Jamaica Bay, NY) receiving wastewater effluent had lower belowground biomass, organic matter, and soi...

  13. The natural regeneration of salt marsh on formerly reclaimed land

    NARCIS (Netherlands)

    Garbutt, Angus; Wolters, Mineke

    Question: Does the vegetation of restored salt marshes increasingly resemble natural reference communities over time? Location: The Essex estuaries, southeast England. Methods: Abandoned reclamations, where coastal defences had been breached in storm events, and Current salt marsh recreation schemes

  14. Vegetation Loss Decreases Salt Marsh Denitrification Capacity: Implications for Marsh Erosion.

    Science.gov (United States)

    Hinshaw, Sarra E; Tatariw, Corianne; Flournoy, Nikaela; Kleinhuizen, Alice; Taylor, Caitlin; Sobecky, Patricia A; Mortazavi, Behzad

    2017-08-01

    Salt marshes play a key role in removing excess anthropogenic nitrogen (N) loads to nearshore marine ecosystems through sediment microbial processes such as denitrification. However, in the Gulf of Mexico, the loss of marsh vegetation because of human-driven disturbances such as sea level rise and oil spills can potentially reduce marsh capacity for N removal. To investigate the effect of vegetation loss on ecosystem N removal, we contrasted denitrification capacity in marsh and subtidal sediments impacted by the Deepwater Horizon oil spill using a combination of 29 N 2 and 30 N 2 production (isotope pairing), denitrification potential measurements (acetylene block), and quantitative polymerase chain reaction (qPCR) of functional genes in the denitrification pathway. We found that, on average, denitrification capacity was 4 times higher in vegetated sediments because of a combination of enhanced nitrification and higher organic carbon availability. The abundance of nirS-type denitrifers indicated that marsh vegetation regulates the activity, rather than the abundance, of denitrifier communities. We estimated that marsh sediments remove an average of 3.6 t N km -2 y -1 compared to 0.9 t N km -2 y -1 in unvegetated sediments. Overall, our findings indicate that marsh loss results in a substantial loss of N removal capacity in coastal ecosystems.

  15. Habitat value of a developing estuarine brackish marsh

    OpenAIRE

    Hampel, H.; Cattrijsse, A.; Vincx, M.

    2002-01-01

    Marsh creation receives worldwide attention in mitigating loss of coastal wetlands and in management retreat of estuaries. In the Westerschelde, the former Selena Polder, south of "Het Verdronken Land van Saeftinghe", evolved into the Sieperda marsh after several dyke breaches. Soon after the tides regained access to the polder, a tidal creek was formed. Ten years after, a developing marsh system is found close to a mature marsh system. This situation offered the rare and unique opportunity t...

  16. Spatial response of coastal marshes to increased atmospheric CO2

    OpenAIRE

    Ratliff, Katherine M.; Braswell, Anna E.; Marani, Marco

    2015-01-01

    Coastal marshes provide numerous ecosystem services, are an important carbon sink, and are exposed to drowning as sea-level rise accelerates. Using a meta-analysis of the available observational data, we model the coupled marsh vegetation and morphological dynamics. We find that the fertilization effect of elevated atmospheric CO2 significantly increases marsh resilience to drowning and decreases the spatial extent of marsh retreat under high rates of sea-level rise. While this direct CO2 fer...

  17. Circumpolar Deep Water transport and current structure at the Amundsen Sea shelf break

    Science.gov (United States)

    Assmann, Karen M.; Wåhlin, Anna K.; Heywood, Karen J.; Jenkins, Adrian; Kim, Tae Wan; Lee, Sang Hoon

    2017-04-01

    The West Antarctic Ice Sheet has been losing mass at an increasing rate over the past decades. Ocean heat transport to the ice-ocean interface has been identified as an important contributor to this mass loss and the role it plays in ice sheet stability makes it crucial to understand its drivers in order to make accurate future projections of global sea level. While processes closer to the ice-ocean interface modulate this heat transport, its ultimate source is located in the deep basin off the continental shelf as a core of relatively warm, salty water underlying a colder, fresher shallow surface layer. To reach the marine terminating glaciers and the base of floating ice shelves, this warm, salty water mass must cross the bathymetric obstacle of the shelf break. Glacial troughs that intersect the Amundsen shelf break and deepen southwards towards the ice shelf fronts have been shown to play an important role in transporting warm, salty Circumpolar Deep Water (CDW) towards the ice shelves. North of the shelf break, circulation in the Amundsen Sea occupies an intermediate regime between the eastward Antarctic Circumpolar Current that impinges on the shelf break in the Bellingshausen Sea and the westward southern limb of the Ross Gyre that follows the shelf break in the Ross Sea. Hydrographic and mooring observations and numerical model results at the mouth of the central shelf break trough leading to Pine Island and Thwaites Glaciers show a westward wind-driven shelf break current overlying an eastward undercurrent that turns onto the shelf in the trough. It is thought that the existence of the latter feature facilitates the on-shelf transport of CDW. A less clearly defined shelf break depression further west acts as the main pathway for CDW to Dotson and eastern Getz Ice shelves. Model results indicate that a similar eastward undercurrent exists here driving the on-shelf transport of CDW. Two moorings on the upper slope east of the trough entrance show a

  18. Tidal Marshes: The Boundary between Land and Ocean.

    Science.gov (United States)

    Gosselink, James

    An overview of the ecology of the tidal marshes along the gulf coast of the United States is presented. The following topics are included: (1) the human impact on tidal marshes; (2) the geologic origins of tidal marshes; (3) a description of the physical characteristics and ecosystem of the marshlands; (4) a description of the marshland food chain…

  19. VALUING AN INTERVENTION: MARSH MIGRATION AND ECOSYSTEM SERVICES

    Science.gov (United States)

    There is growing interest in valuing ecosystem services provided by marsh systems. Ecosystem services represent a flow of benefits to society from the existence or functioning of the marsh. Therefore, to “put a value on” the marsh itself, or estimate a value of the na...

  20. Recent Trends in Bird Abundance on Rhode Island Salt Marshes

    Science.gov (United States)

    Salt marsh habitat is under pressure from development on the landward side, and sea level rise from the seaward side. The resulting loss of habitat is potentially disastrous for salt marsh dependent species. To assess the population status of three species of salt marsh dependent...

  1. Effect of hurricanes and violent storms on salt marsh

    Science.gov (United States)

    Leonardi, N.; Ganju, N. K.; Fagherazzi, S.

    2016-12-01

    Salt marsh losses have been documented worldwide because of land use change, wave erosion, and sea-level rise. It is still unclear how resistant salt marshes are to extreme storms and whether they can survive multiple events without collapsing. Based on a large dataset of salt marsh lateral erosion rates collected around the world, here, we determine the general response of salt marsh boundaries to wave action under normal and extreme weather conditions. As wave energy increases, salt marsh response to wind waves remains linear, and there is not a critical threshold in wave energy above which salt marsh erosion drastically accelerates. We apply our general formulation for salt marsh erosion to historical wave climates at eight salt marsh locations affected by hurricanes in the United States. Based on the analysis of two decades of data, we find that violent storms and hurricanes contribute less than 1% to long-term salt marsh erosion rates. In contrast, moderate storms with a return period of 2.5 mo are those causing the most salt marsh deterioration. Therefore, salt marshes seem more susceptible to variations in mean wave energy rather than changes in the extremes. The intrinsic resistance of salt marshes to violent storms and their predictable erosion rates during moderate events should be taken into account by coastal managers in restoration projects and risk management plans.

  2. 30 CFR 203.60 - Who may apply for royalty relief on a case-by-case basis in deep water in the Gulf of Mexico or...

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Who may apply for royalty relief on a case-by-case basis in deep water in the Gulf of Mexico or offshore of Alaska? 203.60 Section 203.60 Mineral... basis in deep water in the Gulf of Mexico or offshore of Alaska? You may apply for royalty relief under...

  3. LBA-ECO TG-07 Trace Gas Fluxes, Undisturbed and Logged Sites, Para, Brazil: 2000-2002

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: Trace gas fluxes of carbon dioxide, methane, nitrous oxide, and nitric oxide were measured manually at undisturbed and logged forest sites in the Tapajos...

  4. Flow paths of water and sediment in a tidal marsh: relations with marsh developmental stage and tidal inundation height

    NARCIS (Netherlands)

    Temmerman, S.; Bouma, T.J.; Govers, G.; Lauwaet, D.

    2005-01-01

    This study provides new insights in the relative role of tidal creeks and the marsh edge in supplying water and sediments to and from tidal marshes for a wide range of tidal inundation cycles with different high water levels and for marsh zones of different developmental stage. Net import or export

  5. Runoff and soil erosion for an undisturbed tropical woodland in the Brazilian Cerrado

    Science.gov (United States)

    Oliveira, Paulo Tarso S.; Nearing, Mark; Wendland, Edson

    2015-04-01

    The Brazilian Cerrado is a large and important economic and environmental region that is experiencing major loss of its natural landscapes due to pressures of food and energy production, which has caused large increases in soil erosion. However the magnitude of the soil erosion increases in this region is not well understood, in part because scientific studies of surface runoff and soil erosion are scarce or nonexistent in undisturbed Cerrado vegetation. In this study we measured natural rainfall-driven rates of runoff and soil erosion for an undisturbed tropical woodland classified as "cerrado sensu stricto denso" and bare soil to compute the Universal Soil Loss Equation (USLE) cover and management factor (C-factor) to help evaluate the likely effects of land use change on soil erosion rates. Replicated data on precipitation, runoff, and soil loss on plots (5 x 20 m) under bare soil and cerrado were collected for 55 erosive storms occurring in 2012 and 2013. The measured annual precipitation was 1247.4 mm and 1113.0 mm for 2012 and 2013, resulting in a rainfall erosivity index of 4337.1 MJ mm ha-1 h-1 and 3546.2 MJ mm ha-1 h-1, for each year respectively. The erosive rainfall represented 80concentrated in the wet season, which generally runs from October through March. In the plots on bare soil, the runoff coefficient for individual rainfall events (total runoff divided by total rainfall) ranged from 0.003 to 0.860 with an average value and standard deviation of 0.212 ± 0.187. Moreover, the runoff coefficient found for the bare soil plots (~20infiltration capacity. In forest areas the leaf litter and the more porous soil tend to promote the increase of infiltration and water storage, rather than rapid overland flow. Indeed, runoff coefficients ranged from 0.001 to 0.030 with an average of less than 1under undisturbed cerrado. The soil losses measured under bare soil and cerrado were 15.68 t ha-1yr-1 and 0.24 t ha-1 yr-1 in 2012, and 14.82 t ha-1 yr-1, 0.11 t ha-1

  6. Impounded Marshes on Subsided Islands: Simulated Vertical Accretion, Processes, and Effects, Sacramento-San Joaquin Delta, CA USA

    Directory of Open Access Journals (Sweden)

    Steven J. Deverel

    2014-06-01

    Full Text Available There is substantial interest in stopping and reversing the effects of subsidence in the Sacramento–San Joaquin Delta (Delta where organic soils predominate. Also, the passage of California Assembly Bill 32 in 2006 created the potential to trade credits for carbon sequestered in wetlands on subsided Delta islands. The primary purpose of the work described here was to estimate future vertical accretion and understand processes that affect vertical accretion and carbon sequestration in impounded marshes on subsided Delta islands. Using a cohort-accounting model, we simulated vertical accretion from 4,700 calibrated years before present (BP at a wetland area located within Franks Tract State Recreation Area (lat 38.059, long −121.611, hereafter, “Franks Wetland”—a small, relatively undisturbed marsh island—and at the Twitchell Island subsidence-reversal demonstration project since 1997. We used physical and chemical data collected during the study as well as literature values for model inputs. Model results compared favorably with measured rates of vertical accretion, mass of carbon sequestered, bulk density and organic matter content. From 4,700 to model-estimated 350 years BP, the simulated rate of vertical accretion at Franks Wetland averaged about 0.12 cm yr-1, which is within the range of rates in tidal wetlands worldwide. Our model results indicate that large sediment inputs during the last 150 to 200 years resulted in a higher accretion rate of 0.3 cm yr -1. On Twitchell Island, greater organic inputs resulted in average vertical accretion rates as high as 9.2 cm yr -1. Future simulations indicate that the managed impounded marsh will accrete highly organic material at rates of about 3 cm yr -1. Model results coupled with GIS analysis indicate that large areas of the periphery of the Delta, if impounded and converted to freshwater marsh, could be restored to tidal elevations within 50 to 100 years. Most of the

  7. Hydrocarbon accumulation conditions and exploration direction of Baiyun–Liwan deep water areas in the Pearl River Mouth Basin

    Directory of Open Access Journals (Sweden)

    Heming Lin

    2014-12-01

    Full Text Available An integrated geologic study was performed in the Baiyun–Liwan deep water areas, Pearl River Mouth Basin, based on the achievements obtained during the past five exploration stages. The following understandings were obtained. (1 The Baiyun Sag has superior source rock conditions and has experienced three tectonic evaluation stages like rifting, rifting-depression and depression. The Wenchang–Enping Fms deposited during the rifting stage have large hydrocarbon generation potentials. During the rifting-depression and depression stages, the deposition in the study area was controlled by the Oligocene and Miocene shelf slope break zones. The Oligocene Zhuhai Fm shallow marine delta-longshore depositional system and the Miocene Zhujiang–Hanjiang Fms deep fan depositional system were formed, and they are the most favorable reservoir-caprock assemblages in the study area. (2 The Hydrocarbon accumulation pattern in the deep waters is different from that in the northern shallow waters. Shelf slope break zone, composite conduction system consisting of structural ridge, fault, sandbody, unconformity and fluid diapir as well as late tectonic movement are the three major factors controlling hydrocarbon migration and accumulation in the study area. (3 The Liwan 3-1 gas field is a typical example. The superior trapping conditions, high-quality reservoirs of delta distributary channel controlled by shelf slope break zone, vertical conduction system consisting of fault and diapir, as well as the overlying massive marine mudstone caprock provide favorable geologic conditions for the formation of large gas fields. Four areas were identified as the targets of gas exploration in the near future: the deep water fan system in the central sag, the structural-stratigraphic traps in the uplifted areas on both sides of the main sag of Baiyun, a series of large structural traps on the fault terrace to the southwest of the main sag, and the ultra-deep frontiers in

  8. Better well control through safe drilling margin identification, influx analysis and direct bottom hole pressure control method for deep water

    Energy Technology Data Exchange (ETDEWEB)

    Veeningen, Daan [National Oilwell Varco IntelliServ (NOV), Houston, TX (United States)

    2012-07-01

    Currently, well control events are almost exclusively detected by using surface measurements. Measuring a volume increase in the 'closed loop' mud circulation system; a standpipe pressure decrease; or changes in a variety of drilling parameters provide indicators of a kick. Especially in deep water, where the riser comprises a substantial section of the well bore, early kick detection is paramount for limiting the severity of a well bore influx and improve the ability to regain well control. While downhole data is presently available from downhole tools nearby the bit, available data rates are sparse as mud pulse telemetry bandwidth is limited and well bore measurements compete with transmission of other subsurface data. Further, data transfer is one-directional, latency is significant and conditions along the string are unknown. High-bandwidth downhole data transmission system, via a wired or networked drill string system, has the unique capability to acquire real-time pressure and temperature measurement at a number of locations along the drill string. This system provides high-resolution downhole data available at very high speed, eliminating latency and restrictions that typically limit the availability of downhole data. The paper describes well control opportunities for deep water operations through the use of downhole data independent from surface measurements. First, the networked drill string provides efficient ways to identify pore pressure, fracture gradient, and true mud weight that comprise the safe drilling margin. Second, the independent measurement capability provides early kick detection and improved ability to analyze an influx even with a heterogeneous mud column through distributed along-string annular pressure measurements. Third, a methodology is proposed for a direct measurement method using downhole real-time pressure for maintaining constant bottom hole pressure during well kills in deep water. (author)

  9. Holocene North Atlantic Deep Water variability through a centennial-scale study of its precursor watermasses

    Science.gov (United States)

    Hall, I.; Bianchi, G.; Evans, J.; Cortijo, E.; Keigwin, L.; Schonfeld, J.

    2003-04-01

    Holocene climate proxy records increasingly indicate the presence of millennial- and centennial-scale climatic events that are subdued compared to their glacial counterparts. Nonetheless, it appears that their pacing and underlying cause(s) may be similar irrespective of whether the system is in a glacial or interglacial mode. Meridional circulation of the ocean plays a key role in the poleward transport of heat and freshwater. These ocean fluxes are intimately linked to the formation of North Atlantic Deep Water (NADW). Variability in deep ocean flow along Reykjanes Ridge, south of Iceland, has been demonstrated by grain size and lithological proxies with significant components of the variance in the band 1-2 ka. This is matched by records related to iceberg incursions that also show periodicity in this band recently ascribed to solar forcing. We present results of an ongoing study aimed at the centennial-scale monitoring of the principal deep inflows contributing to the formation of NADW over the past 10,000 years. Four cores from downstream of (west to east) Labrador Sea, Denmark Strait Overflow, Iceland-Scotland Ridge Overflow (ISOW) and Wyville-Thomson Ridge Overflow waters have been targeted for their strategic position and high sedimentation rates. Kasten core NEAP-4K and box core NEAP-4B from Bjorn Drift, northern Iceland Basin (1,627 m depth) display long-term trends in the grain size data (sortable silt mean size) that indicate a decrease in average relative flow speed starting at ~5 ka BP until ~1,5 ka BP. Superimposed on these trends are rapid centennial- to millennial-scale fluctuations in flow speed that allow the establishment of crucial correlations with proxy records of both ice-rafted debris sedimentation in the region and heat/moisture transport over the Atlantic coast of Ireland. Such evidence supports a role for the thermohaline circulation as an amplifier of small climate forcing in the Holocene as was observed in glacial times. Although no

  10. Comparison between critical velocity and anaerobic threshold in deep water running

    Directory of Open Access Journals (Sweden)

    Fernando de Oliveira

    2006-06-01

    Full Text Available The comparison between critical velocity and anaerobic threshold has not been investigated in deep water running. Therefore, the aim of this study was to compare these two variables in this activity. Ten subjects of both sexes (23.1 ± 2.2 years, 174.0 ± 10.0 cm, 66.5 ± 18.7 kg and without previous practice in the activity weresubmitted to: 1 two to four familiarization sessions; 2 a progressive test, starting with velocity of 0.15 m.s-1 and increments of 0,05 m.s-1 every three minutes; 3 three tests of constant velocities in different days, with velocities ranging from 0.25 to 0.40 m.s-1. The comparison between anaerobic threshold (velocity at 3.5 mM and critical velocity (identified by three different equations was performed by analysis of variance and the Bland-Altman method. No significant differences were identified among the variables (p = 0.28, however, the limits of agreement provided by the Bland-Altman plots were very large (between –0.054 e +0.080 m.s-1. These results suggest caution when using the critical velocity to estimate the anaerobic threshold. RESUMO A comparação entre velocidade crítica e limiar anaeróbio não tem sido realizada em atividades como corrida aquática. Assim, o objetivo desse estudo foi comparar essas duas variáveis, ambas identificadas nesse tipo de exercício. Dez sujeitos de ambos os sexos (23,1 ± 2,2 anos, 174,0 ± 10,0 cm, 66,5 ± 18,7 kg, sem experiência prévia na modalidade, foram submetidos a: 1 de duas a quatro sessões de familiarização; 2 um teste de intensidade progressiva, com velocidade inicial de 0,15 m.s-1 e incrementos de 0,05 m.s-1 a cada três minutos; 3 três testes de velocidade constante, realizados em dias diferentes, com velocidades entre 0,25 a 0,40m.s-1. A comparação entre o limiar anaeróbio (velocidade referente a 3,5mM e a velocidade crítica (obtida por três equações diferentes foi feita pela análise de variância (ANOVA e técnica de Bland-Altman. Não foram

  11. Adventitious shoot regeneration of Fraxinus nigra Marsh

    Science.gov (United States)

    Rochelle R. Beasley; Paula M. Pijut

    2010-01-01

    Fraxinus nigra Marsh. (black ash) is a native ash species occurring in Newfoundland west to Manitoba and south to Iowa, Illinois, West Virginia, and Virginia. Although it is not a commercially important species, it has significant ethnobotanical importance to Native American tribes of the eastern United States.

  12. Hydrodynamic Modeling of Santa Marta's Big Marsh

    International Nuclear Information System (INIS)

    Saldarriaga, Juan

    1991-01-01

    The ecological degradation of Santa Marta's Big Marsh and their next areas it has motivated the realization of diagnosis studies and design by several state and private entities. One of the recommended efforts for international advisory it was to develop an ecological model that allowed the handling of the water body and the economic test of alternative of solution to those ecological problems. The first part of a model of this type is in turn a model that simulates the movement of the water inside the marsh, that is to say, a hydrodynamic model. The realization of this was taken charge to the civil engineering department, on the part of Colciencias. This article contains a general explanation of the hydrodynamic pattern that this being developed by a professors group. The ecological causes are described and antecedent, the parts that conform the complex of the Santa Marta big Marsh The marsh modeling is made and it is explained in qualitative form the model type Hydrodynamic used

  13. Methane emission from tidal freshwater marshes

    NARCIS (Netherlands)

    Van der Nat, F.J.; Middelburg, J.J.

    2000-01-01

    In two tidal freshwater marshes, methane emission, production and accumulation in the pore-water have been studied. The two sites differ in their dominant vegetation, i.e., reed and bulrush, and in their heights above sea level. The reed site was elevated in relation to the bulrush site and had

  14. Restoration of salt marshes in the Netherlands

    NARCIS (Netherlands)

    Bakker, J.P.; Esselink, P.; Dijkema, K.S.; Duin, van W.E.; Jong, de D.J.

    2002-01-01

    The conquest of land from the sea has been a long tradition in the Netherlands. When salt marshes were high enough, they were embanked when it was economically feasible, and transformed into intensively exploited agricultural land. This resulted in the transformation of halophytic communities to

  15. Restoration of salt marshes in the Netherlands

    NARCIS (Netherlands)

    Bakker, JP; Esselink, Peter; Dijkema, KS; van Duin, WE; de Jong, D.J.

    The conquest of land from the sea has been a long tradition in the Netherlands. When salt marshes were high enough, they were embanked when it was economically feasible, and transformed into intensively exploited agricultural land. This resulted in the transformation of halophytic communities to

  16. Structural Classification of Marshes with Polarimetric SAR Highlighting the Temporal Mapping of Marshes Exposed to Oil

    Directory of Open Access Journals (Sweden)

    Elijah Ramsey

    2015-09-01

    Full Text Available Empirical relationships between field-derived Leaf Area Index (LAI and Leaf Angle Distribution (LAD and polarimetric synthetic aperture radar (PolSAR based biophysical indicators were created and applied to map S. alterniflora marsh canopy structure. PolSAR and field data were collected near concurrently in the summers of 2010, 2011, and 2012 in coastal marshes, and PolSAR data alone were acquired in 2009. Regression analyses showed that LAI correspondence with the PolSAR biophysical indicator variables equaled or exceeded those of vegetation water content (VWC correspondences. In the final six regressor model, the ratio HV/VV explained 49% of the total 77% explained LAI variance, and the HH-VV coherence and phase information accounted for the remainder. HV/HH dominated the two regressor LAD relationship, and spatial heterogeneity and backscatter mechanism followed by coherence information dominated the final three regressor model that explained 74% of the LAD variance. Regression results applied to 2009 through 2012 PolSAR images showed substantial changes in marsh LAI and LAD. Although the direct cause was not substantiated, following a release of freshwater in response to the 2010 Deepwater Horizon oil spill, the fairly uniform interior marsh structure of 2009 was more vertical and dense shortly after the oil spill cessation. After 2010, marsh structure generally progressed back toward the 2009 uniformity; however, the trend was more disjointed in oil impact marshes.

  17. Oxygen transfer in marsh-pond-marsh constructed wetlands treating swine wastewater.

    Science.gov (United States)

    Ro, Kyoung S; Hunt, Patrick G; Johnson, Melvin H; Matheny, Terry A; Forbes, Dean; Reddy, Gudigopuram B

    2010-01-01

    Oxygen transfer efficiencies of various components of the marsh-pond-marsh (M-P-M) and marsh-floating bed-marsh (M-FB-M) wetlands treating swine wastewater were determined by performing oxygen mass balance around the wetlands. Biological oxygen demand (BOD) and total nitrogen (TN) loading and escaping rates from each wetland were used to calculate carbonaceous and nitrogenous oxygen demands. Ammonia emissions were measured using a wind tunnel. Oxygen transfer efficiencies of the aerated ponds were estimated by conducting the ASCE standard oxygen transfer test in a tank using the same aeration device. Covering pond water surface with the floating bed slightly decreased oxygen transfer efficiency. The diffused membrane aeration (26.7 kg O2 ha-1 d-1) of M-P-M was surprisingly not as effective as plant aeration in the marsh (38.9 to 42.0 kg O2 ha-1 d-1). This unusually low oxygen transfer efficiency of the diffused aeration was attributed to its low submergence depth of 0.8 m compared to typical depth of 4.5 m. The wetlands consisting entirely of marsh removed similar amounts of C and N without investing additional equipment and energy costs of aerating ponds in the middle of wetlands.

  18. Structural classification of marshes with Polarimetric SAR highlighting the temporal mapping of marshes exposed to oil

    Science.gov (United States)

    Ramsey, Elijah W.; Rangoonwala, Amina; Jones, Cathleen E.

    2015-01-01

    Empirical relationships between field-derived Leaf Area Index (LAI) and Leaf Angle Distribution (LAD) and polarimetric synthetic aperture radar (PolSAR) based biophysical indicators were created and applied to map S. alterniflora marsh canopy structure. PolSAR and field data were collected near concurrently in the summers of 2010, 2011, and 2012 in coastal marshes, and PolSAR data alone were acquired in 2009. Regression analyses showed that LAI correspondence with the PolSAR biophysical indicator variables equaled or exceeded those of vegetation water content (VWC) correspondences. In the final six regressor model, the ratio HV/VV explained 49% of the total 77% explained LAI variance, and the HH-VV coherence and phase information accounted for the remainder. HV/HH dominated the two regressor LAD relationship, and spatial heterogeneity and backscatter mechanism followed by coherence information dominated the final three regressor model that explained 74% of the LAD variance. Regression results applied to 2009 through 2012 PolSAR images showed substantial changes in marsh LAI and LAD. Although the direct cause was not substantiated, following a release of freshwater in response to the 2010 Deepwater Horizon oil spill, the fairly uniform interior marsh structure of 2009 was more vertical and dense shortly after the oil spill cessation. After 2010, marsh structure generally progressed back toward the 2009 uniformity; however, the trend was more disjointed in oil impact marshes.             

  19. Dragmacidin G, a Bioactive Bis-Indole Alkaloid from a Deep-Water Sponge of the Genus Spongosorites

    Directory of Open Access Journals (Sweden)

    Amy E. Wright

    2017-01-01

    Full Text Available A deep-water sponge of the genus Spongosorites has yielded a bis-indole alkaloid which we have named dragmacidin G. Dragmacidin G was first reported by us in the patent literature and has recently been reported by Hitora et al. from a sponge of the genus Lipastrotheya. Dragmacidin G is the first in this series of compounds to have a pyrazine ring linking the two indole rings. It also has a rare N-(2-mercaptoethyl-guanidine side chain. Dragmacidin G shows a broad spectrum of biological activity including inhibition of methicillin-resistant Staphylococcus aureus, Mycobacterium tuberculosis, Plasmodium falciparum, and a panel of pancreatic cancer cell lines.

  20. Aboral brooding in the deep water sea star Ctenodiscus australis Lütken, 1871 (Asteroidea) from the Southwestern Atlantic

    Science.gov (United States)

    Rivadeneira, Pamela R.; Brogger, Martín I.; Penchaszadeh, Pablo E.

    2017-05-01

    Different stages of development and growth were found in the dorsal surface under the paxillae of Ctenodiscus australis. The maximum number of broods found per specimen was 73 and in some cases different stages were observed on the same female. Oocytes were present in females of all months sampled and were diverse in size (120-850 μm in diameter). Continuous presence and variation in size and stage were also observed in the broods. The typical developmental stage resembles a modified brachiolaria. All these observations suggest continuous reproduction in this deep water species and it also provides new information about reproduction in the Ctenodiscidae family.

  1. A micropalaeontological perspective on export productivity, oxygenation and temperature in NE Atlantic deep-waters across Terminations I and II

    Science.gov (United States)

    Grunert, Patrick; Skinner, Luke; Hodell, David A.; Piller, Werner E.

    2015-08-01

    Census counts of benthic foraminifera were studied from the SW Iberian Margin to reconstruct past changes in deep-water hydrography across Terminations I and II. Detailed benthic faunal data (> 125 μm size-fraction) allow us to evaluate the limitations imposed by taphonomic processes and restricted size-fractions. The comparison of recent (mudline) and fossil assemblages at IODP Site U1385 indicates the quick post-mortem disintegration of shells of astrorhizoid taxa (~ 80% of the present-day fauna), resulting in impoverished fossil assemblages. While the application of quantitative proxy methods is problematic under these circumstances, the fossil assemblages can still provide a qualitative palaeoenvironmental signal that, while most fully expressed in the 125-212 μm size-fraction, is nonetheless also expressed to some degree in the > 212 μm size-fraction. Variations in the benthic foraminiferal assemblages reveal information about changing organic matter supply, deep-water oxygenation and temperature. MIS 2 is generally characterized by an elevated trophic state and variable oxic conditions, with oxygenation minima culminating in the Younger Dryas (YD) and Heinrich Stadials (HS) 1, 2 and 3. Low oxic conditions coincide with decreased water-temperature and lower benthic δ13C, pointing to the strong influence of a southern sourced water-mass during these periods. HS 1 is the most extreme of these intervals, providing further evidence for a severe temporary reduction or even shutdown of AMOC. With the inception of MIS 1, organic matter supply reduced and a better ventilated deep-water environment bathed by NEADW is established. For Termination II, clear indications of southern-sourced water are limited to the early phase of HS 11. During the latter part of HS 11, the deep-water environment seems to be determined by strongly increased supply of organic matter, potentially explaining the decoupling of benthic δ13C and Mg/Ca records of earlier studies as a

  2. Coastal Meringues: Are Salt Marshes Inflated with Excess Void Spaces?

    Science.gov (United States)

    Gunnell, J. R.

    2016-02-01

    Failure to stay above sea level is among many ways that salt marshes may be destroyed. This race against the sea is carried out by vertical accretion. Accretion is partly the accumulation of material mediated by vegetative and sedimentary feedbacks. Prognoses for salt marshes based on studies of these variables have proven useful, but they may also be failing to read between the lines. After all, the majority of a salt marsh's volume is typically comprised of void spaces, which seem to be under-examined in our current predictions of salt marsh survival. Salt marshes may be inflated with excess void spaces, occupying greater volumes than sedimentary predictions would otherwise assume. To test this hypothesis, benthic porosity measurements were drawn from a USGS database of thousands of seabed samples along the U.S. Atlantic and Gulf coasts. Seabed porosities were used to geostatistically interpolate expected porosities at selected salt marsh sites. Measurements of known salt marsh porosities were drawn from several case studies in the literature. These salt marsh porosity measurements were georeferenced so they could be compared to the expected seabed porosity determined by spatial interpolation. Initial results show that these salt marshes tend to be more porous than the benthic sediments surrounding them. This excess porosity can be an important contributor to marsh volume (i.e. elevation), and ultimately to marsh survival. Furthermore, it raises several questions about the source of this void space and the mechanism of its retention. Salt marsh volume appears to be greater than we would expect based on the sum of its parts. Therefore, predictions of salt marsh accretion may systematically underestimate void volumes and be overly pessimistic about marsh response to relative sea level rise.

  3. Temporal comparison and predictors of fish species abundance and richness on undisturbed coral reef patches.

    Science.gov (United States)

    Wagner, Elena L E S; Roche, Dominique G; Binning, Sandra A; Wismer, Sharon; Bshary, Redouan

    2015-01-01

    Large disturbances can cause rapid degradation of coral reef communities, but what baseline changes in species assemblages occur on undisturbed reefs through time? We surveyed live coral cover, reef fish abundance and fish species richness in 1997 and again in 2007 on 47 fringing patch reefs of varying size and depth at Mersa Bareika, Ras Mohammed National Park, Egypt. No major human or natural disturbance event occurred between these two survey periods in this remote protected area. In the absence of large disturbances, we found that live coral cover, reef fish abundance and fish species richness did not differ in 1997 compared to 2007. Fish abundance and species richness on patches was largely related to the presence of shelters (caves and/or holes), live coral cover and patch size (volume). The presence of the ectoparasite-eating cleaner wrasse, Labroides dimidiatus, was also positively related to fish species richness. Our results underscore the importance of physical reef characteristics, such as patch size and shelter availability, in addition to biotic characteristics, such as live coral cover and cleaner wrasse abundance, in supporting reef fish species richness and abundance through time in a relatively undisturbed and understudied region.

  4. Temporal comparison and predictors of fish species abundance and richness on undisturbed coral reef patches

    Directory of Open Access Journals (Sweden)

    Elena L.E.S. Wagner

    2015-12-01

    Full Text Available Large disturbances can cause rapid degradation of coral reef communities, but what baseline changes in species assemblages occur on undisturbed reefs through time? We surveyed live coral cover, reef fish abundance and fish species richness in 1997 and again in 2007 on 47 fringing patch reefs of varying size and depth at Mersa Bareika, Ras Mohammed National Park, Egypt. No major human or natural disturbance event occurred between these two survey periods in this remote protected area. In the absence of large disturbances, we found that live coral cover, reef fish abundance and fish species richness did not differ in 1997 compared to 2007. Fish abundance and species richness on patches was largely related to the presence of shelters (caves and/or holes, live coral cover and patch size (volume. The presence of the ectoparasite-eating cleaner wrasse, Labroides dimidiatus, was also positively related to fish species richness. Our results underscore the importance of physical reef characteristics, such as patch size and shelter availability, in addition to biotic characteristics, such as live coral cover and cleaner wrasse abundance, in supporting reef fish species richness and abundance through time in a relatively undisturbed and understudied region.

  5. Developmental plasticity of shell morphology of quagga mussels from shallow and deep-water habitats of the Great Lakes.

    Science.gov (United States)

    Peyer, Suzanne M; Hermanson, John C; Lee, Carol Eunmi

    2010-08-01

    The invasive zebra mussel (Dreissena polymorpha) has quickly colonized shallow-water habitats in the North American Great Lakes since the 1980s but the quagga mussel (Dreissena bugensis) is becoming dominant in both shallow and deep-water habitats. While quagga mussel shell morphology differs between shallow and deep habitats, functional causes and consequences of such difference are unknown. We examined whether quagga mussel shell morphology could be induced by three environmental variables through developmental plasticity. We predicted that shallow-water conditions (high temperature, food quantity, water motion) would yield a morphotype typical of wild quagga mussels from shallow habitats, while deep-water conditions (low temperature, food quantity, water motion) would yield a morphotype present in deep habitats. We tested this prediction by examining shell morphology and growth rate of quagga mussels collected from shallow and deep habitats and reared under common-garden treatments that manipulated the three variables. Shell morphology was quantified using the polar moment of inertia. Of the variables tested, temperature had the greatest effect on shell morphology. Higher temperature (approximately 18-20 degrees C) yielded a morphotype typical of wild shallow mussels regardless of the levels of food quantity or water motion. In contrast, lower temperature (approximately 6-8 degrees C) yielded a morphotype approaching that of wild deep mussels. If shell morphology has functional consequences in particular habitats, a plastic response might confer quagga mussels with a greater ability than zebra mussels to colonize a wider range of habitats within the Great Lakes.

  6. Biology of a deep-water sea anemone (Anthozoa: Actiniidae) from eastern Canada: Spawning, development, and growth

    Science.gov (United States)

    Mercier, Annie; Baillon, Sandrine; Daly, Marymegan; Macrander, Jason; Hamel, Jean-François

    2017-03-01

    Knowledge of the general biology and reproductive ecology of deep-water species can help predict their resilience to environmental and anthropogenic disturbances. The present study centers on live specimens of a deep-water sea anemone which were collected at bathyal depths between 1100 and 1400 m and kept in a mesocosm for over 6 years. Morphology and DNA sequencing confirmed that the species belongs to the genus Urticina. Male and female (9-10 cm pedal disk diameter, 90 tentacles) spawned 4 years post collection, in early spring (March). Both sexes released gametes through the mouth. The negatively buoyant oocytes (550-600 μm in diameter) quickly settled on the rocks and soft sediments surrounding the female. Lecithotrophic embryonic and larval development occurred on the substratum. Fully developed planula larvae were detected after 17-21 days. Planulae started to crawl and swim around but remained demersal. Metamorphosis and settlement occurred after 30-35 days, exclusively on hard substrata and preferentially on undersurfaces. Offspring grew slowly, developing 8 tentacles after 5 months and 24 tentacles after 12 months (3-4 mm pedal disk diameter). After 2.6 years of growth, the captive-born sea anemones reached 12-16 mm in pedal disk diameter and possessed 48-54 tentacles.

  7. Bacterioplankton communities of Crater Lake, OR: Dynamic changes with euphotic zone food web structure and stable deep water populations

    Science.gov (United States)

    Urbach, E.; Vergin, K.L.; Larson, G.L.; Giovannoni, S.J.

    2007-01-01

    The distribution of bacterial and archaeal species in Crater Lake plankton varies dramatically over depth and with time, as assessed by hybridization of group-specific oligonucleotides to RNA extracted from lakewater. Nonmetric, multidimensional scaling (MDS) analysis of relative bacterial phylotype densities revealed complex relationships among assemblages sampled from depth profiles in July, August and September of 1997 through 1999. CL500-11 green nonsulfur bacteria (Phylum Chloroflexi) and marine Group I crenarchaeota are consistently dominant groups in the oxygenated deep waters at 300 and 500 m. Other phylotypes found in the deep waters are similar to surface and mid-depth populations and vary with time. Euphotic zone assemblages are dominated either by ??-proteobacteria or CL120-10 verrucomicrobia, and ACK4 actinomycetes. MDS analyses of euphotic zone populations in relation to environmental variables and phytoplankton and zooplankton population structures reveal apparent links between Daphnia pulicaria zooplankton population densities and microbial community structure. These patterns may reflect food web interactions that link kokanee salmon population densities to community structure of the bacterioplankton, via fish predation on Daphnia with cascading consequences to Daphnia bacterivory and predation on bacterivorous protists. These results demonstrate a stable bottom-water microbial community. They also extend previous observations of food web-driven changes in euphotic zone bacterioplankton community structure to an oligotrophic setting. ?? 2007 Springer Science+Business Media B.V.

  8. [Spatiotemporal succession of algae functional groups and the influence of environment change in a deep-water reservoir].

    Science.gov (United States)

    Lu, Jin-Suo; Hu, Ya-Pan

    2013-07-01

    Algae functional group has become an important theory and method of algae research in recent years. In order to explore the spatiotemporal succession of algae functional groups and the influence of environment change, water samples were collected in August, 2011 from a deep-water reservoir in Northwest China. The research combined the methods of on-line monitoring and laboratory analysis. The results showed that there were 10 functional groups of algae in the reservoir. They were designated as B, D, P, X1, X3, F, G, J, L(M) and MP. Wherein, the groups B, P, F, X1, MP, D and J were comparatively common functional groups, and the groups X3, G and L(M) were less common. The populations of groups B, D, P, X1 and X3 were larger than those of the others. Besides, the analysis of changes in the environment factors suggested that temperature was the most important factor influencing the spatiotemporal succession of algae functional groups. The strategy of algal growth followed the law: R/CR in spring --> CR/C in late spring and early summer C/CR/R/CS/S in late summer and early autumn --> CR/R in late autumn and winter. The purpose of this article is to provide theoretical support for water withdrawal safety in deep-water reservoirs.

  9. Unusual Deep Water sponge assemblage in South China-Witness of the end-Ordovician mass extinction.

    Science.gov (United States)

    Li, Lixia; Feng, Hongzhen; Janussen, Dorte; Reitner, Joachim

    2015-11-05

    There are few sponges known from the end-Ordovician to early-Silurian strata all over the world, and no records of sponge fossils have been found yet in China during this interval. Here we report a unique sponge assemblage spanning the interval of the end-Ordovician mass extinction from the Kaochiapien Formation (Upper Ordovician-Lower Silurian) in South China. This assemblage contains a variety of well-preserved siliceous sponges, including both Burgess Shale-type and modern type taxa. It is clear that this assemblage developed in deep water, low energy ecosystem with less competitors and more vacant niches. Its explosion may be related to the euxinic and anoxic condition as well as the noticeable transgression during the end-Ordovician mass extinction. The excellent preservation of this assemblage is probably due to the rapid burial by mud turbidites. This unusual sponge assemblage provides a link between the Burgess Shale-type deep water sponges and the modern forms. It gives an excellent insight into the deep sea palaeoecology and the macroevolution of Phanerozoic sponges, and opens a new window to investigate the marine ecosystem before and after the end-Ordovician mass extinction. It also offers potential to search for exceptional fossil biota across the Ordovician-Silurian boundary interval in China.

  10. Endemic Lake Baikal sponges from deep water. 1: Potential cryptic speciation and discovery of living species known only from fossils.

    Science.gov (United States)

    Itskovich, Valeria B; Kaluzhnaya, Oxana V; Veynberg, Elena; Erpenbeck, Dirk

    2015-07-23

    We revealed new deep-water species and cryptic speciation within freshwater sponges of the endemic family Lubomirskiidae (Porifera; Demospongiae; Spongillina) based on molecular and spicule morphology analyses of ITS and CO1 mtDNA. Lubomirskiidae contains a group of closely related species which are a dominant component of the benthos in Lake Baikal, the world's deepest and most ancient lake. Spicule morphology was similar between two Recent samples and species only known previously from fossils in Late Pliocene (3.2-2.8 mya) sediments. Despite the morphological similarity with the cosmopolitan family Spongillidae, molecular analysis of ITS sequences has reliably assigned these species to Lubomirskiidae. This not only indicates that species identification of freshwater fossil sponge spicules should be made with caution, but also suggests that the structure of megascleres may not be a reliable character for interpretations of paleoclimatic reconstructions for the Baikal region. Our results do not support the current classification of Lubomirskiidae into its morphologically defined genera and species, suggesting a strong discrepancy between molecular and morphological variation in Baikalian sponges. This present contribution is the first part of a study on the phylogenetic relationships of the Lake Baikal deep water sponge fauna.

  11. Effect of Vegetation on Sediment Transport across Salt Marshes

    Science.gov (United States)

    Coleman, D. J.; Kirwan, M. L.; Guntenspergen, G. R.; Ganju, N. K.

    2016-12-01

    Salt marshes are a classic example of ecogeomorphology where interactions between plants and sediment transport govern the stability of a rapidly evolving ecosystem. In particular, plants slow water velocities which facilitates deposition of mineral sediment, and the resulting change in soil elevation influences the growth and species distribution of plants. The ability of a salt marsh to withstand sea level rise (SLR) is therefore dependent, among other factors, on the availability of mineral sediment. Here we measure suspended sediment concentrations (SSC) along a transect from tidal channel to marsh interior, exploring the role biomass plays in regulating the magnitude and spatial variability in vertical accretion. Our study was conducted in Spartina alterniflora dominated salt marshes along the Atlantic Coast from Massachusetts to Georgia. At each site, we deployed and calibrated optical back scatter turbidity probes to measure SSC in 15 minute intervals in a tidal channel, on the marsh edge, and in the marsh interior. We visited each site monthly to measure plant biomass via clip plots and vertical accretion via two types of sediment tiles. Preliminary results confirm classic observations that biomass is highest at the marsh edge, and that SSC and vertical accretion decrease across the marsh platform with distance from the channel. We expect that when biomass is higher, such as in southern sites like Georgia and months late in the growing season, SSC will decay more rapidly with distance into the marsh. Higher biomass will likely also correspond to increased vertical accretion, with the greatest effect at marsh edge locations. Our study will likely demonstrate how salt marsh plants interact with sediment transport dynamics to control marsh morphology and thus contribute to marsh resilience to SLR.

  12. Novel techniques and insights into the deployment of pop-up satellite archival tags on a small-bodied deep-water chondrichthyan

    Science.gov (United States)

    Shipley, Oliver N.; Howey, Lucy A.; Tolentino, Emily R.; Jordan, Lance K. B.; Brooks, Edward J.

    2017-01-01

    Acquiring movement data for small-bodied, deep-water chondrichthyans is challenged by extreme effects of capture and handling stress, and post-release predation, however, it is urgently required to examine important fisheries interactions and assess the ecological role of these species within deep-water food webs. Here we suggest a novel release-cage mechanism to deploy pop-up satellite archival tags, as well as present vertical habitat data for a data-deficient, small-bodied, deep-water bycatch species, the Cuban dogfish (Squalus cubensis). Data were gathered from seven of eight High Rate X-Tags deployed on mature Cuban dogfish in the Exuma Sound, The Bahamas. Recovery periods appeared variable between individuals and are likely driven by capture-and-handling stress and tag burden. Application of the cross-correlation function to time-series depth and temperature data indicated three of the seven individuals suffered mortality through predation, which occurred during daytime, and suggests Cuban dogfish may constitute a proportion of deep-water apex predator diet in the Exuma Sound. Two animals were successfully released via a novel release-cage mechanism and displayed either no, or rapid (preference for specific bathymetric structures. These techniques provide an important first step into acquiring and presenting vertical habitat data for small-bodied, deep-water chondrichthyans, which can be directly applied to fisheries and ecosystem-based management approaches.

  13. Sea-Level Rise Impacts on Hudson River Marshes

    Science.gov (United States)

    Hooks, A.; Nitsche, F. O.

    2015-12-01

    The response of tidal marshes to increasing sea-level rise is uncertain. Tidal marshes can adapt to rising sea levels through vertical accretion and inland migration. Yet tidal marshes are vulnerable to submergence if the rate of sea-level rise exceeds the rate of accretion and if inland migration is limited by natural features or development. We studied how Piermont and Iona Island Marsh, two tidal marshes on the Hudson River, New York, would be affected by sea-level rise of 0.5m, 1m, and 1.5m by 2100. This study was based on the 2011-2012 Coastal New York LiDAR survey. Using GIS we mapped sea-level rise projections accounting for accretion rates and calculated the submerged area of the marsh. Based on the Hudson River National Estuarine Research Reserve Vegetation 2005 dataset, we studied how elevation zones based on vegetation distributions would change. To evaluate the potential for inland migration, we assessed land cover around each marsh using the National Land Cover Database 2011 Land Cover dataset and examined the slope beyond the marsh boundaries. With an accretion rate of 0.29cm/year and 0.5m of sea-level rise by 2100, Piermont Marsh would be mostly unchanged. With 1.5m of sea-level rise, 86% of Piermont Marsh would be flooded. For Iona Island Marsh with an accretion rate of 0.78cm/year, sea-level rise of 0.5m by 2100 would result in a 4% expansion while 1.5m sea-level rise would cause inundation of 17% of the marsh. The results indicate that Piermont and Iona Island Marsh may be able to survive rates of sea-level rise such as 0.5m by 2100 through vertical accretion. At rates of sea-level rise like 1.5m by 2100, vertical accretion cannot match sea-level rise, submerging parts of the marshes. High elevations and steep slopes limit Piermont and Iona Island Marsh's ability to migrate inland. Understanding the impacts of sea-level rise on Piermont and Iona Island Marsh allows for long-term planning and could motivate marsh conservation programs.

  14. Carbon Storage in Tagus Salt Marsh Sediments

    Energy Technology Data Exchange (ETDEWEB)

    Cacador, Isabel, E-mail: icacador@fc.ul.pt; Costa, Ana Luisa [University of Lisbon, Institute of Oceanography, Faculty of Sciences (Portugal); Vale, Carlos [Institute for Sea and Fisheries Research (IPIMAR) (Portugal)

    2004-06-15

    Seasonal variation of above ground and belowground biomass of Spartina maritima and Halimione portulacoides, decomposition rates of belowground detritus in litterbags, and carbon partitioning in plant components and sediments were determined in two Tagus estuary marshes with different environmental conditions. Total biomass was higher in the saltier marsh from 7,190 to 6,593 g m{sup -2} dw and below ground component contributed to more than 90%. Litterbag experiment showed that 30 to 50% of carbonis decomposed within a month (decomposition rate from 0.024 to 0.060 d{sup -1}). Slower decomposition in subsequent periods agrees with accumulation of carbon concentration in sediment. Atmospheric carbon annually transferred to the plant belowground biomass is stored more efficiently in sediments of Corroios than Pancas.

  15. Colloid and Phosphorus Leaching From Undisturbed Soil Cores Sampled Along a Natural Clay Gradient

    DEFF Research Database (Denmark)

    Vendelboe, Anders Lindblad; Møldrup, Per; Heckrath, Goswin Johann

    2011-01-01

    was to correlate easily measurable soil properties, such as clay content and water-dispersible colloids, to colloid and phosphorus leaching. The clay contents across the gradient ranged from 0.11 to 0.23 kg kgj1. Irrigating with artificial rainwater, all samples showed a high first flush of colloids and phosphorus......The presence of strongly sorbing compounds in groundwater and tile drains can be a result of colloid-facilitated transport. Colloid and phosphorus leaching from macropores in undisturbed soil cores sampled across a natural clay gradient at Aarup, Denmark, were studied. The aim of the study...... followed by lower and stable colloid and phosphorus concentrations. The mass of particles leached at first flush was independent of clay content and was attributed to the instant release of particles associated with the macropore walls and released upon contact with flowing water. Below a clay content of È...

  16. A method for measuring element fluxes in an undisturbed soil: nitrogen and carbon from earthworms

    International Nuclear Information System (INIS)

    Bouche, M.B.

    1984-01-01

    Data on chemical cycles, as nitrogen or carbon cycles, are extrapolated to the fields or ecosystems without the possibility for checking conclusions; i.e. from scientific knowledge (para-ecology). A new method, by natural introduction of an earthworm compartment into an undisturbed soil, with earthworms labelled both by isotopes ( 15 N, 14 C) and by staining is described. This method allows us to measure fluxes of chemicals. The first results, gathered during the improvement of the method in partly artificial conditions, are cross-checked with other data given by direct observation in the field. Measured flux (2.2 mg N/g fresh mass empty gut/day/15 0 C) is far more important than para-ecological estimations; animal metabolism plays directly an important role in nitrogen and carbon cycles. (author)

  17. Study of nitrogen losses at the microcosm in undisturbed soil samples subjected to thermal shocks

    Directory of Open Access Journals (Sweden)

    J. Cancelo-González

    2013-05-01

    Full Text Available Laboratory thermal shocks of different intensity and rainfall simulations were performed in undisturbed Leptic Umbrisol soil samples. Samples were collected in field using specially designed lysimeter boxes to allow sampling, thermal shocks and surface runoff and subsurface flow water collection during the rainfall simulations. Temperature was recorded during heating and degree-hours of accumulated heat were calculated and nitrogen losses in surface and subsurface water collected after two rainfall simulations were determined. Results show losses of total nitrogen from treatments 200 oC and 67 degrees-hours heat supplied in the leachate obtained after 150 mm of simulated rainfall compared with non-heat treated soils. Is remarkable that soils subjected to higher intensity heat treatments (400 oC and 278 67 degrees-hours show greater losses of N-Nitrate and N-Ammonia by subsurface flow, while this behavior was not observed in the other heat treatments.

  18. Experimental predator removal causes rapid salt marsh die-off.

    Science.gov (United States)

    Bertness, Mark D; Brisson, Caitlin P; Coverdale, Tyler C; Bevil, Matt C; Crotty, Sinead M; Suglia, Elena R

    2014-07-01

    Salt marsh habitat loss to vegetation die-offs has accelerated throughout the western Atlantic in the last four decades. Recent studies have suggested that eutrophication, pollution and/or disease may contribute to the loss of marsh habitat. In light of recent evidence that predators are important determinants of marsh health in New England, we performed a total predator exclusion experiment. Here, we provide the first experimental evidence that predator depletion can cause salt marsh die-off by releasing the herbivorous crab Sesarma reticulatum from predator control. Excluding predators from a marsh ecosystem for a single growing season resulted in a >100% increase in herbivory and a >150% increase in unvegetated bare space compared to plots with predators. Our results confirm that marshes in this region face multiple, potentially synergistic threats. © 2014 The Authors. Ecology Letters published by John Wiley & Sons Ltd and CNRS.

  19. Gamma ray transmission for hydraulic conductivity measurement of undisturbed soil columns

    Directory of Open Access Journals (Sweden)

    Anderson Camargo Moreira

    2007-03-01

    Full Text Available This work had the objective to determine the Hydraulic Conductivity K(theta function for different depth levels z, of columns of undisturbed soil, using the gamma ray transmission technique applied to the Sisson method. The results indicated a growing behavior for K(theta and a homogeneous soil density, both in relation to the increase of the depth. The methodology of gamma ray transmission showed satisfactory results on the determination of the hydraulic conductivity in columns of undisturbed soil, besides being very reliable and a nondestructive method.O estudo da condutividade hidráulica para solos não saturados é essencial quando aplicado às situações relacionadas à irrigação, drenagem e transporte de nutrientes no solo, é uma importante propriedade para desenvolvimentos de culturas agrícolas. Este trabalho tem o objetivo de determinar a função Condutividade Hidráulica K(teta, em diferentes níveis z de profundidade, em colunas de solo indeformado, utilizando a transmissão de raios gama aplicada ao método de Sisson. Os resultados indicam um comportamento crescente para K(teta e uma densidade de solo homogênea, ambos em relação ao aumento da profundidade. A metodologia de transmissão de raios gama mostrou resultados bastante satisfatórios na determinação da condutividade hidráulica em colunas de solo indeformado, além de ser muito confiável e não destrutivo.

  20. The water balance components of undisturbed tropical woodlands in the Brazilian cerrado

    Science.gov (United States)

    Oliveira, P. T. S.; Wendland, E.; Nearing, M. A.; Scott, R. L.; Rosolem, R.; da Rocha, H. R.

    2015-06-01

    Deforestation of the Brazilian cerrado region has caused major changes in hydrological processes. These changes in water balance components are still poorly understood but are important for making land management decisions in this region. To better understand pre-deforestation conditions, we determined the main components of the water balance for an undisturbed tropical woodland classified as "cerrado sensu stricto denso". We developed an empirical model to estimate actual evapotranspiration (ET) by using flux tower measurements and vegetation conditions inferred from the enhanced vegetation index and reference evapotranspiration. Canopy interception, throughfall, stemflow, surface runoff, and water table level were assessed from ground measurements. We used data from two cerrado sites, Pé de Gigante (PDG) and Instituto Arruda Botelho (IAB). Flux tower data from the PDG site collected from 2001 to 2003 were used to develop the empirical model to estimate ET. The other hydrological processes were measured at the field scale between 2011 and 2014 at the IAB site. The empirical model showed significant agreement (R2 = 0.73) with observed ET at the daily timescale. The average values of estimated ET at the IAB site ranged from 1.91 to 2.60 mm day-1 for the dry and wet seasons, respectively. Canopy interception ranged from 4 to 20 % and stemflow values were approximately 1 % of the gross precipitation. The average runoff coefficient was less than 1 %, while cerrado deforestation has the potential to increase that amount up to 20-fold. As relatively little excess water runs off (either by surface water or groundwater), the water storage may be estimated by the difference between precipitation and evapotranspiration. Our results provide benchmark values of water balance dynamics in the undisturbed cerrado that will be useful to evaluate past and future land-cover and land-use changes for this region.

  1. Estimate of biomass and carbon pools in disturbed and undisturbed oak forests in Tunisia

    Directory of Open Access Journals (Sweden)

    Lobna Zribi

    2016-07-01

    Full Text Available Aim of the study. To estimate biomass and carbon accumulation in a young and disturbed forest (regenerated after a tornado and an aged cork oak forest (undisturbed forest as well as its distribution among the different pools (tree, litter and soil. Area of study. The north west of Tunisia Material and methods. Carbon stocks were evaluated in the above and belowground cork oak trees, the litter and the 150 cm of the soil. Tree biomass was estimated in both young and aged forests using allometric biomass equations developed for wood stem, cork stem, wood branch, cork branch, leaves, roots and total tree biomass based on combinations of diameter at breast height, total height and crown length as independent variables. Main results. Total tree biomass in forests was 240.58 Mg ha-1 in the young forest and 411.30 Mg ha-1 in the aged forest with a low root/shoot ratio (0.41 for young forest and 0.31 for aged forest. Total stored carbon was 419.46 Mg C ha-1 in the young forest and 658.09 Mg C ha-1 in the aged forest. Carbon stock (Mg C ha-1 was estimated to be113.61(27.08% and 194.08 (29.49% in trees, 3.55 (0.85% and 5.73 (0.87% in litter and 302.30 (72.07% and 458.27 (69.64% in soil in the young and aged forests, respectively. Research highlights. Aged undisturbed forest had the largest tree biomass but a lower potential for accumulation of carbon in the future; in contrast, young disturbed forest had both higher growth and carbon storage potential. Keywords: Tree biomass; disturbance; allometry; cork oak forests; soil organic carbon stock.

  2. Estimate of biomass and carbon pools in disturbed and undisturbed oak forests in Tunisia

    Energy Technology Data Exchange (ETDEWEB)

    Zribi, L.; Chaar, H.; Khaldi, A.; Henchi, B.; Mouillot, F.; Gharbi, F.

    2016-07-01

    Aim of the study. To estimate biomass and carbon accumulation in a young and disturbed forest (regenerated after a tornado) and an aged cork oak forest (undisturbed forest) as well as its distribution among the different pools (tree, litter and soil). Area of study. The north west of Tunisia. Material and methods. Carbon stocks were evaluated in the above and belowground cork oak trees, the litter and the 150 cm of the soil. Tree biomass was estimated in both young and aged forests using allometric biomass equations developed for wood stem, cork stem, wood branch, cork branch, leaves, roots and total tree biomass based on combinations of diameter at breast height, total height and crown length as independent variables. Main results. Total tree biomass in forests was 240.58 Mg ha-1 in the young forest and 411.30 Mg ha-1 in the aged forest with a low root/shoot ratio (0.41 for young forest and 0.31 for aged forest). Total stored carbon was 419.46 Mg C ha-1 in the young forest and 658.09 Mg C ha-1 in the aged forest. Carbon stock (Mg C ha-1) was estimated to be113.61(27.08%) and 194.08 (29.49%) in trees, 3.55 (0.85%) and 5.73 (0.87%) in litter and 302.30 (72.07%) and 458.27 (69.64%) in soil in the young and aged forests, respectively. Research highlights. Aged undisturbed forest had the largest tree biomass but a lower potential for accumulation of carbon in the future; in contrast, young disturbed forest had both higher growth and carbon storage potential. (Author)

  3. Continuous arterial PO2 profiles in unrestrained, undisturbed aquatic turtles during routine behaviors.

    Science.gov (United States)

    Williams, Cassondra L; Hicks, James W

    2016-11-15

    Mammals and birds maintain high arterial partial pressure of oxygen (P O 2 ) values in order to preserve near-complete hemoglobin (Hb) oxygen (O 2 ) saturation. In diving mammals and birds, arterial O 2 follows a primarily monotonic decline and then recovers quickly after dives. In laboratory studies of submerged freshwater turtles, arterial O 2 depletion typically follows a similar pattern. However, in these studies, turtles were disturbed, frequently tethered to external equipment and confined either to small tanks or breathing holes. Aquatic turtles can alter cardiac shunting patterns, which will affect arterial P O 2  values. Consequently, little is known about arterial O 2 regulation and use in undisturbed turtles. We conducted the first study to continuously measure arterial P O 2  using implanted microelectrodes and a backpack logger in undisturbed red-eared sliders during routine activities. Arterial P O 2  profiles during submergences varied dramatically, with no consistent patterns. Arterial P O 2  was also lower than previously reported during all activities, with values rarely above 50 mmHg (85% Hb saturation). There was no difference in mean P O 2  between five different activities: submerged resting, swimming, basking, resting at the surface and when a person was present. These results suggest significant cardiac shunting occurs during routine activities as well as submergences. However, the lack of relationship between P O 2  and any activity suggests that cardiac shunts are not regulated to maintain high arterial P O 2  values. These data support the idea that cardiac shunting is the passive by-product of regulation of vascular resistances by the autonomic nervous system. © 2016. Published by The Company of Biologists Ltd.

  4. Continuous arterial PO2 profiles in unrestrained, undisturbed aquatic turtles during routine behaviors

    Science.gov (United States)

    Hicks, James W.

    2016-01-01

    ABSTRACT Mammals and birds maintain high arterial partial pressure of oxygen (PO2) values in order to preserve near-complete hemoglobin (Hb) oxygen (O2) saturation. In diving mammals and birds, arterial O2 follows a primarily monotonic decline and then recovers quickly after dives. In laboratory studies of submerged freshwater turtles, arterial O2 depletion typically follows a similar pattern. However, in these studies, turtles were disturbed, frequently tethered to external equipment and confined either to small tanks or breathing holes. Aquatic turtles can alter cardiac shunting patterns, which will affect arterial PO2 values. Consequently, little is known about arterial O2 regulation and use in undisturbed turtles. We conducted the first study to continuously measure arterial PO2 using implanted microelectrodes and a backpack logger in undisturbed red-eared sliders during routine activities. Arterial PO2 profiles during submergences varied dramatically, with no consistent patterns. Arterial PO2 was also lower than previously reported during all activities, with values rarely above 50 mmHg (85% Hb saturation). There was no difference in mean PO2 between five different activities: submerged resting, swimming, basking, resting at the surface and when a person was present. These results suggest significant cardiac shunting occurs during routine activities as well as submergences. However, the lack of relationship between PO2 and any activity suggests that cardiac shunts are not regulated to maintain high arterial PO2 values. These data support the idea that cardiac shunting is the passive by-product of regulation of vascular resistances by the autonomic nervous system. PMID:27618860

  5. Hydrologic aspects of marsh ponds during winter on the Gulf Coast Chenier Plain, USA: Effects of structural marsh management

    Science.gov (United States)

    Bolduc, F.; Afton, A.D.

    2004-01-01

    The hydrology of marsh ponds influences aquatic invertebrate and waterbird communities. Hydrologic variables in marsh ponds of the Gulf Coast Chenier Plain are potentially affected by structural marsh management (SMM: levees, water control structures and impoundments) that has been implemented since the 1950s. Assuming that SMM restricts tidal flows and drainage of rainwater, we predicted that SMM would increase water depth, and concomitantly decrease salinity and transparency in impounded marsh ponds. We also predicted that SMM would increase seasonal variability in water depth in impounded marsh ponds because of the potential incapacity of water control structures to cope with large flooding events. In addition, we predicted that SMM would decrease spatial variability in water depth. Finally, we predicted that ponds of impounded freshwater (IF), oligohaline (IO), and mesohaline (IM) marshes would be similar in water depth, temperature, dissolved oxygen (O2), and transparency. Using a priori multivariate analysis of variance (MANOVA) contrast, we tested these predictions by comparing hydrologic variables within ponds of impounded and unimpounded marshes during winters 1997-1998 to 1999-2000 on Rockefeller State Wildlife Refuge, near Grand Chenier, Louisiana. Specifically, we compared hydrologic variables (1) between IM and unimpounded mesohaline marsh ponds (UM); and (2) among IF, IO, and IM marshes ponds. As predicted, water depth was higher and salinity and O2 were lower in IM than in UM marsh ponds. However, temperature and transparency did not differ between IM and UM marsh ponds. Water depth varied more among months in IM marsh ponds than within those of UM marshes, and variances among and within ponds were lower in IM than UM marshes. Finally, all hydrologic variables, except salinity, were similar among IF, IO, and IM marsh ponds. Hydrologic changes within marsh ponds due to SMM should (1) promote benthic invertebrate taxa that tolerate low levels of O2 and

  6. Biogenic silica in tidal freshwater marsh sediments and vegetation (Schelde estuary, Belgium)

    NARCIS (Netherlands)

    Struyf, E.; van Damme, S.; Gribsholt, B.; Middelburg, J.J.; Meire, P.

    2005-01-01

    To date, estuarine ecosystem research has mostly neglected silica cycling in freshwater intertidal marshes. However, tidal marshes can store large amounts of biogenic silica (BSi) in vegetation and sediment. BSi content of the typical freshwater marsh plants Phragmites australis, Impatiens

  7. Salt Marshes as Potential Indicatore of Global Climate Change

    DEFF Research Database (Denmark)

    Kim, Daehyun; Cairens, David; Jung, S.H.

    2011-01-01

    as indicators of global climate change, focusing upon three major aspects: sedimentary, vegetation, and biogeochemical dynamics. The previous literature concerned with these aspects commonly argues that the primary impact of climate change on salt marshes occurs via sea-level variations, because hydrologic......Coastal scientists postulate that salt marshes are significantly affected by dynamics of global climate. However, few studies have explicitly proposed a perspective that regards salt marshes as potential indicators of climate change. This review article evaluates the possibility of salt marshes...

  8. New records of rhodolith-forming species (Corallinales, Rhodophyta) from deep water in Espírito Santo State, Brazil

    Science.gov (United States)

    Henriques, Maria Carolina; Villas-Boas, Alexandre; Rodriguez, Rafael Riosmena; Figueiredo, Marcia A. O.

    2012-06-01

    Little is known about the diversity of non-geniculate coralline red algae (Rhodophyta, Corallinophycidae) from deep waters in Brazil. Most surveys undertaken in this country have been carried out in shallow waters. In 1994, however, the REVIZEE program surveyed the sustainable living resources potential of the Brazilian exclusive economic zone to depths of 500 m. In the present study, the rhodolith-forming coralline algae from the continental shelf of Espírito Santo State were identified. Samples were taken from 54 to 60 m depth by dredging during ship cruises in 1997. Three rhodolith-forming species were found: Spongites yendoi (Foslie) Chamberlain , Lithothamnion muelleri Lenormand ex Rosanoff and Lithothamnion glaciale Kjellman. These records extend the distribution ranges of these species into Brazilian waters and extend the depth distribution of non-geniculate coralline red algae into Brazilian water to 58 m.

  9. Deep water masses in the Iceland Basin during the Last Interglacial (MIS 5e: Evidence from benthic foraminiferal data

    Directory of Open Access Journals (Sweden)

    Nadezhda P. Lukashina

    2015-04-01

    Full Text Available The Last Interglacial period, marine isotope stage (MIS 5e, is a potential analogue for the Holocene. In this study, we investigated a marine sediment core, AMK-4442, recovered from the northern part of the Iceland Basin. The multiproxy approach used in this study, which includes foraminiferal and lithological analyses, identifies the difference in intensity of deep circulation between MIS 5e and the Holocene. Our data indicate that during early MIS 5e, the Iceland-Scotland Overflow Water (ISOW flux into the Iceland Basin was suppressed. We suggest that the less active North Atlantic Deep Water (NADW formation at this time was related to the obstruction of warm surface water inflow into the Nordic Seas.

  10. Seismic Analysis of Deep Water Pile Foundation Based on Three-Dimensional Potential-Based Fluid Elements

    Directory of Open Access Journals (Sweden)

    Kai Wei

    2013-01-01

    Full Text Available This paper investigates the use of three-dimensional (3D ϕ-u potential-based fluid elements for seismic analyses of deep water pile foundation. The mathematical derivations of the potential-based formulations are presented for reference. The potential-based modeling technique is studied and validated through experimental data and analytical solutions. Earthquake time history analyses for a 9-pile foundation in dry and different water environments are conducted, respectively. The seismic responses are discussed to investigate the complex effect of earthquake-induced fluid-structure interaction. Through the analyses, the potential-based fluid and interface elements are shown to perform adequately for the seismic analyses of pile foundation-water systems, and some interesting conclusions and recommendations are drawn.

  11. An unusual new species of paguroid (Crustacea, Anomura, Paguridae) from deep waters of the Gulf of Mexico.

    Science.gov (United States)

    Lemaitre, Rafael; Vázquez-Bader, Ana Rosa; Gracia, Adolfo

    2014-01-01

    A new hermit crab species of the family Paguridae, Tomopaguropsisahkinpechensis sp. n., is described from deep waters (780-827 m) of the Gulf of Mexico. This is the second species of Tomopaguropsis known from the western Atlantic, and the fifth worldwide. The new species is morphologically most similar to a species from Indonesia, Tomopaguropsiscrinita McLaughlin, 1997, the two having ocular peduncles that diminish in width distally, reduced corneas, dense cheliped setation, and males lacking paired pleopods 1. The calcified figs on the branchiostegite and anterodorsally on the posterior carapace, and the calcified first pleonal somite that is not fused to the last thoracic somite, are unusual paguroid characters. A discussion of the affinities and characters that define this new species is included, along with a key to all five species of Tomopaguropsis.

  12. An unusual new species of paguroid (Crustacea, Anomura, Paguridae from deep waters of the Gulf of Mexico

    Directory of Open Access Journals (Sweden)

    Rafael Lemaitre

    2014-10-01

    Full Text Available A new hermit crab species of the family Paguridae, Tomopaguropsis ahkinpechensis sp. n., is described from deep waters (780–827 m of the Gulf of Mexico. This is the second species of Tomopaguropsis known from the western Atlantic, and the fifth worldwide. The new species is morphologically most similar to a species from Indonesia, T. crinita McLaughlin, 1997, the two having ocular peduncles that diminish in width distally, reduced corneas, dense cheliped setation, and males lacking paired pleopods 1. The calcified figs on the branchiostegite and anterodorsally on the posterior carapace, and the calcified first pleonal somite that is not fused to the last thoracic somite, are unusual paguroid characters. A discussion of the affinities and characters that define this new species is included, along with a key to all five species of Tomopaguropsis.

  13. An unusual new species of paguroid (Crustacea, Anomura, Paguridae) from deep waters of the Gulf of Mexico

    Science.gov (United States)

    Lemaitre, Rafael; Vázquez-Bader, Ana Rosa; Gracia, Adolfo

    2014-01-01

    Abstract A new hermit crab species of the family Paguridae, Tomopaguropsis ahkinpechensis sp. n., is described from deep waters (780–827 m) of the Gulf of Mexico. This is the second species of Tomopaguropsis known from the western Atlantic, and the fifth worldwide. The new species is morphologically most similar to a species from Indonesia, Tomopaguropsis crinita McLaughlin, 1997, the two having ocular peduncles that diminish in width distally, reduced corneas, dense cheliped setation, and males lacking paired pleopods 1. The calcified figs on the branchiostegite and anterodorsally on the posterior carapace, and the calcified first pleonal somite that is not fused to the last thoracic somite, are unusual paguroid characters. A discussion of the affinities and characters that define this new species is included, along with a key to all five species of Tomopaguropsis. PMID:25408613

  14. Apristurus breviventralis, a new species of deep-water catshark (Chondrichthyes: Carcharhiniformes: Scyliorhinidae) from the Gulf of Aden.

    Science.gov (United States)

    Kawauchi, Junro; Weigmann, Simon; Nakaya, Kazuhiro

    2014-11-03

    A new deep-water catshark of the genus Apristurus Garman, 1913 is described based on nine specimens from the Gulf of Aden in the northwestern Indian Ocean. Apristurus breviventralis sp. nov. belongs to the 'brunneus group' of the genus and is characterized by having pectoral-fin tips reaching beyond the midpoint between the paired fin bases, a much shorter pectoral-pelvic space than the anal-fin base, a low and long-based anal fin, and a first dorsal fin located behind pelvic-fin insertion. The new species most closely resembles the western Atlantic species Apristurus canutus, but is distinguishable in having greater nostril length than internarial width and longer claspers in adult males. Apristurus breviventralis sp. nov. represents the sixth species of Apristurus from the western Indian Ocean and the 38th species globally. 

  15. THE OPTIMAL RATIO OF NILE TILAPIA (Oreochromis niloticus AND COMMON CARP (Cyprinus carpio FOR IMPROVING PRODUCTIVITY ON DEEP WATER POND

    Directory of Open Access Journals (Sweden)

    Imam Taufik

    2013-06-01

    Full Text Available Pond productivity can be increased by applied polyculture system in the deep pond. The purpose of this experiment is to examine the optimal ratio between nile tilapia and common carp, in order to increase the productivity. Nine concrete tanks (15 m2 with water depth of 2.2 m and were completed by water inlet, water outlet, and aeration. Both of nile tilapia and common carp with size ranging of 5-8 cm in total length were used. Stock density was 150 ind./m2. The difference ratio of both fish tilapia and carp of fish stocked as a treatment. The fish ratio this experiment were as followed: A 100%; B 80%:20%; C 60%:40%. Fish fed by pellet until at ad libitum. The duration of experiment was 100 days. Parameters such as survival, growth, and productivity were observed every ten days during the experiment period. Water quality parameters were also periodically observed. The results showed that survival of nile tilapia among the treatments were not significantly different (P>0.05 where survival of common carp at B treatment was better than C treatment (P<0.05. The highest of growth of absolute weight (94.86±2.85 g and total length (14.71±1 cm of nile tilapia at B treatment was found (P<0.05 where the best of growth of absolute weight (106.52±10.47 g and total length (11.57±1.78 cm of common carp was also found at B treatment (P<0.05. Biomass productivity at B treatment was the highest compared with A treatment (P<0.05. Combination between polyculture and the deep water pond technology could increase productivity. The polyculture system and the deep water pond technology would be able to keep constant water quality within in the threshold accordance with the regulation for fish culture.

  16. Sedimentological analysis and bed thickness statistics from a Carboniferous deep-water channel-levee complex: Myall Trough, SE Australia

    Science.gov (United States)

    Palozzi, Jason; Pantopoulos, George; Maravelis, Angelos G.; Nordsvan, Adam; Zelilidis, Avraam

    2018-02-01

    This investigation presents an outcrop-based integrated study of internal division analysis and statistical treatment of turbidite bed thickness applied to a Carboniferous deep-water channel-levee complex in the Myall Trough, southeast Australia. Turbidite beds of the studied succession are characterized by a range of sedimentary structures grouped into two main associations, a thick-bedded and a thin-bedded one, that reflect channel-fill and overbank/levee deposits, respectively. Three vertically stacked channel-levee cycles have been identified. Results of statistical analysis of bed thickness, grain-size and internal division patterns applied on the studied channel-levee succession, indicate that turbidite bed thickness data seem to be well characterized by a bimodal lognormal distribution, which is possibly reflecting the difference between deposition from lower-density flows (in a levee/overbank setting) and very high-density flows (in a channel fill setting). Power law and exponential distributions were observed to hold only for the thick-bedded parts of the succession and cannot characterize the whole bed thickness range of the studied sediments. The succession also exhibits non-random clustering of bed thickness and grain-size measurements. The studied sediments are also characterized by the presence of statistically detected fining-upward sandstone packets. A novel quantitative approach (change-point analysis) is proposed for the detection of those packets. Markov permutation statistics also revealed the existence of order in the alternation of internal divisions in the succession expressed by an optimal internal division cycle reflecting two main types of gravity flow events deposited within both thick-bedded conglomeratic and thin-bedded sandstone associations. The analytical methods presented in this study can be used as additional tools for quantitative analysis and recognition of depositional environments in hydrocarbon-bearing research of ancient

  17. Estimating carbonate parameters from hydrographic data for the intermediate and deep waters of the Southern Hemisphere oceans

    Science.gov (United States)

    Bostock, H. C.; Mikaloff Fletcher, S. E.; Williams, M. J. M.

    2013-10-01

    Using ocean carbon data from global datasets, we have developed several multiple linear regression (MLR) algorithms to estimate alkalinity and dissolved inorganic carbon (DIC) in the intermediate and deep waters of the Southern Hemisphere (south of 25° S) from only hydrographic data (temperature, salinity and dissolved oxygen). A Monte Carlo experiment was used to identify a potential density (σθ) of 27.5 as an optimal break point between the two regimes with different MLR algorithms. The algorithms provide a good estimate of DIC (R2=0.98) and alkalinity (R2=0.91), and excellent agreement for aragonite and calcite saturation states (R2=0.99). Combining the algorithms with the CSIRO Atlas of Regional Seas (CARS), we have mapped the calcite saturation horizon (CSH) and aragonite saturation horizon (ASH) for the Southern Ocean at a spatial resolution of 0.5°. These maps are more detailed and more consistent with the oceanography than the previously gridded GLODAP data. The high-resolution ASH map reveals a dramatic circumpolar shoaling at the polar front. North of 40° S the CSH is deepest in the Atlantic (~ 4000 m) and shallower in the Pacific Ocean (~ 2750 m), while the CSH sits between 3200 and 3400 m in the Indian Ocean. The uptake of anthropogenic carbon by the ocean will alter the relationships between DIC and hydrographic data in the intermediate and deep waters over time. Thus continued sampling will be required, and the MLR algorithms will need to be adjusted in the future to account for these changes.

  18. Estimating carbonate parameters from hydrographic data for the intermediate and deep waters of the Southern Hemisphere oceans

    Directory of Open Access Journals (Sweden)

    H. C. Bostock

    2013-10-01

    Full Text Available Using ocean carbon data from global datasets, we have developed several multiple linear regression (MLR algorithms to estimate alkalinity and dissolved inorganic carbon (DIC in the intermediate and deep waters of the Southern Hemisphere (south of 25° S from only hydrographic data (temperature, salinity and dissolved oxygen. A Monte Carlo experiment was used to identify a potential density (σθ of 27.5 as an optimal break point between the two regimes with different MLR algorithms. The algorithms provide a good estimate of DIC (R2=0.98 and alkalinity (R2=0.91, and excellent agreement for aragonite and calcite saturation states (R2=0.99. Combining the algorithms with the CSIRO Atlas of Regional Seas (CARS, we have mapped the calcite saturation horizon (CSH and aragonite saturation horizon (ASH for the Southern Ocean at a spatial resolution of 0.5°. These maps are more detailed and more consistent with the oceanography than the previously gridded GLODAP data. The high-resolution ASH map reveals a dramatic circumpolar shoaling at the polar front. North of 40° S the CSH is deepest in the Atlantic (~ 4000 m and shallower in the Pacific Ocean (~ 2750 m, while the CSH sits between 3200 and 3400 m in the Indian Ocean. The uptake of anthropogenic carbon by the ocean will alter the relationships between DIC and hydrographic data in the intermediate and deep waters over time. Thus continued sampling will be required, and the MLR algorithms will need to be adjusted in the future to account for these changes.

  19. A fast complex domain-matching pursuit algorithm and its application to deep-water gas reservoir detection

    Science.gov (United States)

    Zeng, Jing; Huang, Handong; Li, Huijie; Miao, Yuxin; Wen, Junxiang; Zhou, Fei

    2017-12-01

    The main emphasis of exploration and development is shifting from simple structural reservoirs to complex reservoirs, which all have the characteristics of complex structure, thin reservoir thickness and large buried depth. Faced with these complex geological features, hydrocarbon detection technology is a direct indication of changes in hydrocarbon reservoirs and a good approach for delimiting the distribution of underground reservoirs. It is common to utilize the time-frequency (TF) features of seismic data in detecting hydrocarbon reservoirs. Therefore, we research the complex domain-matching pursuit (CDMP) method and propose some improvements. First is the introduction of a scale parameter, which corrects the defect that atomic waveforms only change with the frequency parameter. Its introduction not only decomposes seismic signal with high accuracy and high efficiency but also reduces iterations. We also integrate jumping search with ergodic search to improve computational efficiency while maintaining the reasonable accuracy. Then we combine the improved CDMP with the Wigner-Ville distribution to obtain a high-resolution TF spectrum. A one-dimensional modeling experiment has proved the validity of our method. Basing on the low-frequency domain reflection coefficient in fluid-saturated porous media, we finally get an approximation formula for the mobility attributes of reservoir fluid. This approximation formula is used as a hydrocarbon identification factor to predict deep-water gas-bearing sand of the M oil field in the South China Sea. The results are consistent with the actual well test results and our method can help inform the future exploration of deep-water gas reservoirs.

  20. Functionality of Root-Associated Bacteria along a Salt Marsh Primary Succession

    Directory of Open Access Journals (Sweden)

    Miao Wang

    2017-10-01

    Full Text Available Plant-associated bacteria are known for their high functional trait diversity, from which many are likely to play a role in primary and secondary succession, facilitating plant establishment in suboptimal soils conditions. Here we used an undisturbed salt marsh chronosequence that represents over 100 years of soil development to assess how the functional traits of plant associated bacteria respond to soil type, plant species and plant compartment. We isolated and characterized 808 bacterial colonies from the rhizosphere soil and root endosphere of two salt marsh plants, Limonium vulgare and Artemisia maritima, along the chronosequence. From these, a set of 59 strains (with unique BOX-PCR patterns, 16S rRNA sequence and unique to one of the treatments were further screened for their plant growth promoting traits (siderophore production, IAA production, exoprotease production and biofilm formation, traits associated with bacterial fitness (antibiotic and abiotic stress resistance – pH, osmotic and oxidative stress, and salinity and metabolic potential. An overall view of functional diversity (multivariate analysis indicated that the distributional pattern of bacterial functional traits was driven by soil type. Samples from the late succession (Stage 105 year showed the most restricted distribution, harboring strains with relatively low functionalities, whereas the isolates from intermediate stage (35 year showed a broad functional profiles. However, strains with high trait performance were largely from stage 65 year. Grouping the traits according to category revealed that the functionality of plant endophytes did not vary along the succession, thus being driven by plant rather than soil type. In opposition, the functionality of rhizosphere isolates responded strongly to variations in soil type as observed for antibiotic resistance (P = 0.014. Specifically, certain Pseudomonas sp. and Serratia sp. strains revealed high resistance against abiotic

  1. Gulf-Wide Information System, Environmental Sensitivity Index Marsh, Geographic NAD83, LDWF (2001) [esi_fresh_marsh_LDWF_2001

    Data.gov (United States)

    Louisiana Geographic Information Center — This data set contains Environmental Sensitivity Index (ESI) fresh marsh data of coastal Louisiana. The ESI is a classification and ranking system, which...

  2. Delineation of marsh types and marsh-type change in coastal Louisiana for 2007 and 2013

    Science.gov (United States)

    Hartley, Stephen B.; Couvillion, Brady R.; Enwright, Nicholas M.

    2017-05-30

    The Bureau of Ocean Energy Management researchers often require detailed information regarding emergent marsh vegetation types (such as fresh, intermediate, brackish, and saline) for modeling habitat capacities and mitigation. In response, the U.S. Geological Survey in cooperation with the Bureau of Ocean Energy Management produced a detailed change classification of emergent marsh vegetation types in coastal Louisiana from 2007 and 2013. This study incorporates two existing vegetation surveys and independent variables such as Landsat Thematic Mapper multispectral satellite imagery, high-resolution airborne imagery from 2007 and 2013, bare-earth digital elevation models based on airborne light detection and ranging, alternative contemporary land-cover classifications, and other spatially explicit variables. An image classification based on image objects was created from 2007 and 2013 National Agriculture Imagery Program color-infrared aerial photography. The final products consisted of two 10-meter raster datasets. Each image object from the 2007 and 2013 spatial datasets was assigned a vegetation classification by using a simple majority filter. In addition to those spatial datasets, we also conducted a change analysis between the datasets to produce a 10-meter change raster product. This analysis identified how much change has taken place and where change has occurred. The spatial data products show dynamic areas where marsh loss is occurring or where marsh type is changing. This information can be used to assist and advance conservation efforts for priority natural resources.

  3. Distribution of tree species in an undisturbed northern hardwood-spruce-fir forest, the Bowl, N. H.

    Science.gov (United States)

    C. Wayne Martin

    1977-01-01

    Knowledge acquired from forests that have never been logged can provide clues to the long-term effects of resource utilization. In 1974, a survey was made of the vegetation of the Bowl Research Natural Area in central New Hampshire, known to be undisturbed by humans; and an adjacent watershed known to have been logged in the late 1880's. There were no significant...

  4. Nitrogen transformations and greenhouse gas emissions from a riparian wetland soil: An undisturbed soil column study

    Energy Technology Data Exchange (ETDEWEB)

    Munoz-Leoz, Borja [Department of Chemical and Environmental Engineering, University of the Basque Country, UPV/EHU, E-48013 Bilbao (Spain); Antigueedad, Inaki [Department of Geodynamic, University of the Basque Country, UPV/EHU, E-48940 Leioa (Spain); Garbisu, Carlos [Department of Ecosystems, NEIKER-Tecnalia, E-48160 Derio (Spain); Ruiz-Romera, Estilita, E-mail: estilita.ruiz@ehu.es [Department of Chemical and Environmental Engineering, University of the Basque Country, UPV/EHU, E-48013 Bilbao (Spain)

    2011-01-15

    Riparian wetlands bordering intensively managed agricultural fields can act as biological filters that retain and transform agrochemicals such as nitrate and pesticides. Nitrate removal in wetlands has usually been attributed to denitrification processes which in turn imply the production of greenhouse gases (CO{sub 2} and N{sub 2}O). Denitrification processes were studied in the Salburua wetland (northern Spain) by using undisturbed soil columns which were subsequently divided into three sections corresponding to A-, Bg- and B2g-soil horizons. Soil horizons were subjected to leaching with a 200 mg NO{sub 3}{sup -} L{sup -1} solution (rate: 90 mL day{sup -1}) for 125 days at two different temperatures (10 and 20 {sup o}C), using a new experimental design for leaching assays which enabled not only to evaluate leachate composition but also to measure gas emissions during the leaching process. Column leachate samples were analyzed for NO{sub 3}{sup -} concentration, NH{sub 4}{sup +} concentration, and dissolved organic carbon. Emissions of greenhouse gases (CO{sub 2} and N{sub 2}O) were determined in the undisturbed soil columns. The A horizon at 20 {sup o}C showed the highest rates of NO{sub 3}{sup -} removal (1.56 mg N-NO{sub 3}{sup -} kg{sup -1} DW soil day{sup -1}) and CO{sub 2} and N{sub 2}O production (5.89 mg CO{sub 2} kg{sup -1} DW soil day{sup -1} and 55.71 {mu}g N-N{sub 2}O kg{sup -1} DW soil day{sup -1}). For the Salburua wetland riparian soil, we estimated a potential nitrate removal capacity of 1012 kg N-NO{sub 3}{sup -} ha{sup -1} year{sup -1}, and potential greenhouse gas emissions of 5620 kg CO{sub 2} ha{sup -1} year{sup -1} and 240 kg N-N{sub 2}O ha{sup -1} year{sup -1}. - Research Highlights: {yields}A new experimental design is proposed for leaching assays to simulate nitrogen transformations in riparian wetland soil. {yields}Denitrification is the main process responsible for nitrate removal in the riparian zone of Salburua wetland. {yields

  5. Colloid mobilization in an undisturbed sediment core under semiarid recharge rates

    Science.gov (United States)

    Liu, Ziru; Flury, Markus; Harsh, James B.; Mathison, Jon B.; Vogs, Carolina

    2013-08-01

    The semiarid US Department of Energy Hanford site has a deep vadose zone with low recharge rates. Contaminants originating from nuclear waste processing are expected to move slowly through the vadose zone. The movement of certain contaminants can be facilitated by colloids. We hypothesized that the low recharge rates and low water contents in semiarid regions, however, tend to inhibit movement of colloidal particles, thereby reducing the risk for colloid-facilitated contaminant transport. The goal of this study was to investigate whether in situ natural colloids can be mobilized and transported in undisturbed, deep vadose zone sediments at the Hanford site under typical, semiarid recharge rates. We sampled an undisturbed sediment core (i.d. 50 cm, 59.5 cm height) from a depth of 17 m below ground at the Hanford 200 Area. The core was set up as a laboratory lysimeter and exposed to an infiltration rate of 18 mm/yr by applying simulated pore water onto the surface. Particle concentrations were quantified in the column outflow, and selected samples were examined microscopically and for elemental composition (transmission electron microscopy and energy dispersive X-ray). Measured water contents and potentials were used to calibrate a numerical model (HYDRUS-1D), which was then applied to simulate colloid mobilization from the sediment core. During 5.3 years of monitoring, natural colloids like silicates, aluminosilicates, and Fe-oxides were observed in the core outflow, indicating the continuous mobilization of in situ colloids. The total amount of particles mobilized during 5.3 years corresponded to 1.1% of the total dispersible colloids inside the core. Comparison of the amounts of colloids released with weathering rates suggests that mineral weathering can be a major source of the mobilized colloids. The fitted colloid release rate coefficient was 6 to 7 orders of magnitude smaller than coefficients reported from previous studies, where disturbed Hanford sediments

  6. Ammonium transformation in a nitrogen-rich tidal freshwater marsh

    DEFF Research Database (Denmark)

    Gribsholt, B.; Andersson, M.; Boschker, H.T.S.

    2006-01-01

    The fate and transport of watershed-derived ammonium in a tidal freshwater marsh fringing the nutrient rich Scheldt River, Belgium, was quantified in a whole ecosystem 15N labeling experiment. In late summer (September) we added 15N-NH4+ to the flood water entering a 3477 m2 tidal freshwater marsh...

  7. Dragonflies are biocontrol agents in Wisconsin cranberry marshes

    Science.gov (United States)

    Dragonflies (Order Odonata) are abundant predators that emerge in large hatch events each summer in Wisconsin cranberry marshes. They seem to be a potential group of biocontrol agents for pest management that may be influenced by the diversity found on the marsh. In fact, our evidence shows that dra...

  8. Pettaquamscutt Cove Salt Marsh: Environmental Conditions and Historical Ecological Change

    Science.gov (United States)

    Using historic air photos and U.S. Coast Survey maps, historic vegetation changes were identified. Using surveys of vegetation and elevation, we measure elevation of Narrow River salt marshes, and compare it with other salt marshes in Rhode Island and neighboring states. Water ...

  9. Tidal influences on carbon assimilation by a salt marsh

    Energy Technology Data Exchange (ETDEWEB)

    Kathilankal, James C; Mozdzer, Thomas J; Fuentes, Jose D; D' Odorico, Paolo; McGlathery, Karen J; Zieman, Jay C [Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22904 (United States)], E-mail: jf6s@virginia.edu

    2008-10-15

    Salt marshes are among the most productive ecosystems on Earth, and play an important role in the global carbon cycle. Net carbon dioxide (CO{sub 2}) ecosystem exchanges in coastal salt marshes remain poorly investigated. In Spartina alterniflora dominated North American Atlantic coast marshes, the lack of a clear understanding of how Spartina alterniflora responds to flooding limits our current ability to understand and predict salt marsh response to sea-level rise. Here we investigate the processes influencing ecosystem-level carbon exchanges between a S. alterniflora dominated salt marsh on the eastern shore of Virginia and the atmosphere. We examined the impacts of tidal inundation on the marsh-atmosphere carbon exchanges through a combination of eddy covariance measurements and in situ photosynthetic measurements. Maximum daytime carbon fluxes were observed during the middle of the growing season (July and August) and amounted to -10 {mu}mol CO{sub 2} m{sup -2} s{sup -1}, and the marsh assimilated 130 gC m{sup -2} during the 2007 growing season. Our study is the first to quantify the effects of tidal inundation on marsh plants, which caused anywhere from 3% to 91% reductions in atmospheric carbon fluxes, with a mean reduction of 46 {+-} 26%, when compared to non-flooded conditions.

  10. Mangrove expansion into salt marshes alters associated faunal communities

    Science.gov (United States)

    Delbert L. Smee; James A. Sanchez; Meredith Diskin; Carl Trettin

    2017-01-01

    Climate change is altering the distribution of foundation species, with potential effects on organisms that inhabit these environments and changes to valuable ecosystem functions. In the Gulf of Mexico, black mangroves (Avicennia germinans) are expanding northward into salt marshes dominated by Spartina alterniflora (hereafter Spartina). Salt marshes are essential...

  11. Does vegetation in restored salt marshes equal naturally developed vegetation

    NARCIS (Netherlands)

    Loon-Steensma, van J.M.; Dobben, van H.F.; Slim, P.A.; Huiskes, H.P.J.; Dirkse, G.M.

    2015-01-01

    Question: Do low stone dams built to prevent erosion and to restore salt marshes through increased sedimentation affect plant species composition? Location: Dutch Wadden Sea area (ca. 53°N 5°E). Methods: Relevés (N = 170) were made of the vegetation of two restored salt marsh sites on the barrier

  12. Spatial patterns in accretion on barrier-island salt marshes

    NARCIS (Netherlands)

    Groot, de A.V.; Veeneklaas, R.M.; Kuijper, D.P.J.; Bakker, J.P.

    2011-01-01

    On minerogenic barrier-island salt marshes, sedimentation is spatially heterogeneous. Although the main forcing factors for sedimentation are known, much less is known about the characteristic sizes of this spatial patterning. Such patterning gives information on the spatial component of salt-marsh

  13. Oregon Salt Marshes: How Blue are They? November 12, 2015

    Science.gov (United States)

    We quantified carbon and nitrogen accumulation rates in salt marshes at 135 plots distributed across eight estuaries in Oregon, USA. Net carbon and nitrogen accumulation rates were quantified by measuring the content of these constituents in sediment that accumulated in marsh ha...

  14. Effects of vegetation patterns and grazers on tidal marshes

    NARCIS (Netherlands)

    Elschot, Kelly

    2015-01-01

    Increasing grazing pressures threaten grasslands on a global scale. Therefore, it is important to understand the impact of grazers on the functioning of an ecosystem. In this study, we focused on the effects of small and large grazers on the marsh vegetation and important marsh dynamics, such as

  15. Effects of vegetation patterns and grazers on tidal marshes

    NARCIS (Netherlands)

    Elschot, K.

    2015-01-01

    SUMMARYsoil. These effects of large-bodied grazers on soil properties in tidal marshes has beenlargely neglected so far, but need to be considered when we want to introduce livestockto ungrazed marshes.Next to above-ground grazing, we also find small grazers that grub for below-groundstorage organs

  16. Marsh-atmosphere CO2 exchange in a New England salt marsh

    Science.gov (United States)

    Forbrich, Inke; Giblin, Anne E.

    2015-09-01

    We studied marsh-atmosphere exchange of carbon dioxide in a high marsh dominated salt marsh during the months of May to October in 2012-2014. Tidal inundation at the site occurred only during biweekly spring tides, during which we observed a reduction in fluxes during day and night. We estimated net ecosystem exchange (NEE), gross primary production (GPP), and ecosystem respiration (Reco) using a modified PLIRTLE model, which requires photosynthetically active radiation, temperature, and normalized difference vegetation index (NDVI) as control variables. NDVI decreased during inundation, when the marsh canopy was submerged. Two-time series of NDVI, including and excluding effects of tidal inundation, allowed us to quantify the flux reduction during inundation. The effect of the flux reduction was small (2-4%) at our site, but is likely higher for marshes at a lower elevation. From May to October, GPP averaged -863 g C m-2, Reco averaged 591 g C m-2, and NEE averaged -291 g C m-2. In 2012, which was an exceptionally warm year, we observed an early start of net carbon uptake but higher respiration than in 2013 and 2014 due to higher-air temperature in August. This resulted in the lowest NEE during the study period (-255.9±6.9 g C m-2). The highest seasonal net uptake (-336.5±6.3 g C m-2) was observed in 2013, which was linked to higher rainfall and temperature in July. Mean sea level was very similar during all 3 years which allowed us to isolate the importance of climatic factors.

  17. Dynamic interactions between coastal storms and salt marshes: A review

    Science.gov (United States)

    Leonardi, Nicoletta; Carnacina, Iacopo; Donatelli, Carmine; Ganju, Neil Kamal; Plater, Andrew James; Schuerch, Mark; Temmerman, Stijn

    2018-01-01

    This manuscript reviews the progresses made in the understanding of the dynamic interactions between coastal storms and salt marshes, including the dissipation of extreme water levels and wind waves across marsh surfaces, the geomorphic impact of storms on salt marshes, the preservation of hurricanes signals and deposits into the sedimentary records, and the importance of storms for the long term survival of salt marshes to sea level rise. A review of weaknesses, and strengths of coastal defences incorporating the use of salt marshes including natural, and hybrid infrastructures in comparison to standard built solutions is then presented. Salt marshes are effective in dissipating wave energy, and storm surges, especially when the marsh is highly elevated, and continuous. This buffering action reduces for storms lasting more than one day. Storm surge attenuation rates range from 1.7 to 25 cm/km depending on marsh and storms characteristics. In terms of vegetation properties, the more flexible stems tend to flatten during powerful storms, and to dissipate less energy but they are also more resilient to structural damage, and their flattening helps to protect the marsh surface from erosion, while stiff plants tend to break, and could increase the turbulence level and the scour. From a morphological point of view, salt marshes are generally able to withstand violent storms without collapsing, and violent storms are responsible for only a small portion of the long term marsh erosion. Our considerations highlight the necessity to focus on the indirect long term impact that large storms exerts on the whole marsh complex rather than on sole after-storm periods. The morphological consequences of storms, even if not dramatic, might in fact influence the response of the system to normal weather conditions during following inter-storm periods. For instance, storms can cause tidal flats deepening which in turn promotes wave energy propagation, and exerts a long term detrimental

  18. Dynamic interactions between coastal storms and salt marshes: A review

    Science.gov (United States)

    Leonardi, Nicoletta; Carnacina, Iacopo; Donatelli, Carmine; Ganju, Neil K.; Plater, Andrew James; Schuerch, Mark; Temmerman, Stijn

    2018-01-01

    This manuscript reviews the progresses made in the understanding of the dynamic interactions between coastal storms and salt marshes, including the dissipation of extreme water levels and wind waves across marsh surfaces, the geomorphic impact of storms on salt marshes, the preservation of hurricanes signals and deposits into the sedimentary records, and the importance of storms for the long term survival of salt marshes to sea level rise. A review of weaknesses, and strengths of coastal defences incorporating the use of salt marshes including natural, and hybrid infrastructures in comparison to standard built solutions is then presented.Salt marshes are effective in dissipating wave energy, and storm surges, especially when the marsh is highly elevated, and continuous. This buffering action reduces for storms lasting more than one day. Storm surge attenuation rates range from 1.7 to 25 cm/km depending on marsh and storms characteristics. In terms of vegetation properties, the more flexible stems tend to flatten during powerful storms, and to dissipate less energy but they are also more resilient to structural damage, and their flattening helps to protect the marsh surface from erosion, while stiff plants tend to break, and could increase the turbulence level and the scour. From a morphological point of view, salt marshes are generally able to withstand violent storms without collapsing, and violent storms are responsible for only a small portion of the long term marsh erosion.Our considerations highlight the necessity to focus on the indirect long term impact that large storms exerts on the whole marsh complex rather than on sole after-storm periods. The morphological consequences of storms, even if not dramatic, might in fact influence the response of the system to normal weather conditions during following inter-storm periods. For instance, storms can cause tidal flats deepening which in turn promotes wave energy propagation, and exerts a long term

  19. Salt Marshes as Potential Indicatore of Global Climate Change

    DEFF Research Database (Denmark)

    Kim, Daehyun; Cairens, David; Jung, S.H.

    2011-01-01

    Coastal scientists postulate that salt marshes are significantly affected by dynamics of global climate. However, few studies have explicitly proposed a perspective that regards salt marshes as potential indicators of climate change. This review article evaluates the possibility of salt marshes...... as indicators of global climate change, focusing upon three major aspects: sedimentary, vegetation, and biogeochemical dynamics. The previous literature concerned with these aspects commonly argues that the primary impact of climate change on salt marshes occurs via sea-level variations, because hydrologic...... fluctuations regulate the frequency, duration, and depth of over-marsh flooding events. Sedimentary, floristic, and biogeochemical dynamics prove to be significantly influenced by sealevel changes regardless of climate zones, and hence, undoubtedly possess a potential for indicating climate signatures. However...

  20. The Global Carbon Sink in Tidal Salt Marshes

    Science.gov (United States)

    Chmura, G. L.

    2004-05-01

    For decades researchers have concentrated on proving that C is exported from salt marshes to coastal waters, with limited success. Yet, the C retained in the marsh soils may be equally important. Presumptions that minor amounts of C are stored in salt marsh soils are based upon measurements of low percentages of C in many marshes. Simply measuring the organic matter content of marsh soils provides little indication of the amount or rate of C stored, as this parameter is based upon the percent by mass of the soil. The critical parameter to calculate is C density, derived from percent organic matter and bulk density. (The latter is often neglected in marsh soil studies.) Calculation of C density reveals that minerogenic soils with high bulk densities may have C densities or C storage rates equivalent to more organic soils with low bulk densities. A global average soil C density of 0.055 ± 0.004 g cm-3 has been calculated from 107 measurements reported for salt marshes around the world (Gulf of Mexico, NE and NW Atlantic, Mediterranean and NE Pacific). Assuming an average marsh soil depth of 0.5 m and using inventories of marsh area available for Europe, Scandinavia, Africa, Canada and the U.S., the C stored globally in salt marshes is greater than 430 ± 30 Tg C. The global carbon storage could be twice this as there are no marsh inventories available for Asia or South America. Rates of C storage can be calculated from 96 C density measurements where soil accretion rates also were measured. Globally, marshes sequester an average of 210 g CO2 m-2 yr-1, an order of magnitude greater than rates reported for peatlands. Salt marsh C storage can have regional importance. At a magnitude of 5 Tg C yr-1, tidal wetlands comprise 1--2 percent of the C sink (300--580 Tg C yr-1) estimated for the coterminous U.S. In the Bay of Fundy restoration of salt marshes reclaimed for agricultural land could enable sequestration of an additional 240 to 360 Gg C yr-1, equivalent to 4 to 6

  1. Overestimation of marsh vulnerability to sea level rise

    Science.gov (United States)

    Kirwan, Matthew L.; Temmerman, Stijn; Skeehan, Emily E.; Guntenspergen, Glenn R.; Fagherazzi, Sergio

    2016-01-01

    Coastal marshes are considered to be among the most valuable and vulnerable ecosystems on Earth, where the imminent loss of ecosystem services is a feared consequence of sea level rise. However, we show with a meta-analysis that global measurements of marsh elevation change indicate that marshes are generally building at rates similar to or exceeding historical sea level rise, and that process-based models predict survival under a wide range of future sea level scenarios. We argue that marsh vulnerability tends to be overstated because assessment methods often fail to consider biophysical feedback processes known to accelerate soil building with sea level rise, and the potential for marshes to migrate inland.

  2. Comparative study of methods to estimate hydraulic parameters in the hydraulically undisturbed Opalinus Clay (Switzerland)

    Energy Technology Data Exchange (ETDEWEB)

    Yu, C.; Matray, J.-M. [Institut de Radioprotection et de Sûreté Nucléaire, Fontenay-aux-Roses, (France); Yu, C.; Gonçalvès, J. [Aix Marseille Université UMR 6635 CEREGE Technopôle Environnement Arbois-Méditerranée Aix-en-Provence, Cedex 4 (France); and others

    2017-04-15

    The deep borehole (DB) experiment gave the opportunity to acquire hydraulic parameters in a hydraulically undisturbed zone of the Opalinus Clay at the Mont Terri rock laboratory (Switzerland). Three methods were used to estimate hydraulic conductivity and specific storage values of the Opalinus Clay formation and its bounding formations through the 248 m deep borehole BDB-1: application of a Poiseuille-type law involving petrophysical measurements, spectral analysis of pressure time series and in situ hydraulic tests. The hydraulic conductivity range in the Opalinus Clay given by the first method is 2 × 10{sup -14}-6 × 10{sup -13} m s{sup -1} for a cementation factor ranging between 2 and 3. These results show low vertical variability whereas in situ hydraulic tests suggest higher values up to 7 × 10{sup -12} m s{sup -1}. Core analysis provides economical estimates of the homogeneous matrix hydraulic properties but do not account for heterogeneities at larger scale such as potential tectonic conductive features. Specific storage values obtained by spectral analysis are consistent and in the order of 10{sup -6} m{sup -1}, while formulations using phase shift and gain between pore pressure signals were found to be inappropriate to evaluate hydraulic conductivity in the Opalinus Clay. The values obtained are globally in good agreement with the ones obtained previously at the rock laboratory. (authors)

  3. Production of alkaline cellulase by fungi isolated from an undisturbed rain forest of peru.

    Science.gov (United States)

    Vega, Karin; Villena, Gretty K; Sarmiento, Victor H; Ludeña, Yvette; Vera, Nadia; Gutiérrez-Correa, Marcel

    2012-01-01

    Alkaline cellulase producing fungi were isolated from soils of an undisturbed rain forest of Peru. The soil dilution plate method was used for the enumeration and isolation of fast growing cellulolytic fungi on an enriched selective medium. Eleven out of 50 different morphological colonies were finally selected by using the plate clearing assay with CMC as substrate at different pH values. All 11 strains produced cellulases in liquid culture with activities at alkaline pH values without an apparent decrease of them indicating that they are true alkaline cellulase producers. Aspergillus sp. LM-HP32, Penicillium sp. LM-HP33, and Penicillium sp. LM-HP37 were the best producers of FP cellulase (>3 U mL(-1)) with higher specific productivities (>30 U g(-1) h(-1)). Three strains have been found suitable for developing processes for alkaline cellulase production. Soils from Amazonian rain forests are good sources of industrial fungi with particular characteristics. The results of the present study are of commercial and biological interest. Alkaline cellulases may be used in the polishing and washing of denim processing of the textile industry.

  4. Production of Alkaline Cellulase by Fungi Isolated from an Undisturbed Rain Forest of Peru

    Directory of Open Access Journals (Sweden)

    Karin Vega

    2012-01-01

    Full Text Available Alkaline cellulase producing fungi were isolated from soils of an undisturbed rain forest of Peru. The soil dilution plate method was used for the enumeration and isolation of fast growing cellulolytic fungi on an enriched selective medium. Eleven out of 50 different morphological colonies were finally selected by using the plate clearing assay with CMC as substrate at different pH values. All 11 strains produced cellulases in liquid culture with activities at alkaline pH values without an apparent decrease of them indicating that they are true alkaline cellulase producers. Aspergillus sp. LM-HP32, Penicillium sp. LM-HP33, and Penicillium sp. LM-HP37 were the best producers of FP cellulase (>3 U mL−1 with higher specific productivities (>30 U g−1 h−1. Three strains have been found suitable for developing processes for alkaline cellulase production. Soils from Amazonian rain forests are good sources of industrial fungi with particular characteristics. The results of the present study are of commercial and biological interest. Alkaline cellulases may be used in the polishing and washing of denim processing of the textile industry.

  5. The ecological half-life of 137Cs in undisturbed silt soil

    International Nuclear Information System (INIS)

    Drosg, M.

    2012-01-01

    The time necessary to safely cultivate agricultural areas after they have been contaminated by radioactivity (e.g. after the Chernobyl accident) is not determined by the physical half-life of the radioactive isotopes in question but by their (usually much shorter) ecological half-life (). This half-life not only depends on the type of soil but also on whether the soil was fertilized or not. Therefore it is not possible to determine an ecological half-life that is universally valid. However, the value for undisturbed, unfertilized soil should provide a general indication for the duration of ecological half-life. In a silt soil in Vienna, Austria, the ecological half-life of 137 Cs was determined to be 0.8 years, which is much shorter than the physical half-life of 30 years. - Highlights: ► Absolute measurements of 137 Cs radioactivity in leaves of perennial plants. ► The natural 40 K radioactivity served as reference. ► The ecological half-life of 137 Cs in loamy soil was determined.

  6. Resistance of undisturbed soil microbiomes to ceftriaxone indicates extended spectrum β-lactamase activity

    Directory of Open Access Journals (Sweden)

    Joao eGatica

    2015-11-01

    Full Text Available Emergence and spread of antibiotic resistance, and specifically resistance to third generation cephalosporins associated with extended spectrum β-lactamase (ESBL activity, is one of the greatest epidemiological challenges of our time. In this study we addressed the impact of the third generation cephalosporin ceftriaxone on microbial activity and bacterial community composition of two physically and chemically distinct undisturbed soils in highly regulated microcosm experiments. Surprisingly, periodical irrigation of the soils with clinical doses of ceftriaxone did not affect their microbial activity; and only moderately impacted the microbial diversity (α and β of the two soils. Corresponding slurry experiments demonstrated that the antibiotic capacity of ceftriaxone rapidly diminished in the presence of soil, and approximately 70% of this inactivation could be explained by biological activity. The biological nature of ceftriaxone degradation in soil was supported by microcosm experiments that amended model Escherichia coli strains to sterile and non-sterile soils in the presence and absence of ceftriaxone and by the ubiquitous presence of ESBL genes (blaTEM, blaCTX-M and blaOXA in soil DNA extracts. Collectively, these results suggest that the resistance of soil microbiomes to ceftriaxone stems from biological activity and even more, from broad-spectrum β-lactamase activity; raising questions regarding the scope and clinical implications of ESBLs in soil microbiomes.

  7. Pore Space Statistics From the X-ray CT of Large Undisturbed Soil Columns

    Science.gov (United States)

    Martin, M. A.; Tuller, M.; Guber, A. K.; García-Gutiérrez, C.; San Jose Martinez, F.; Pachepsky, Y. A.; Caniego, J. F.

    2007-12-01

    Large soil columns need to be studied to infer geometric properties of macropores and their role in flow and transport phenomena, especially when colloid or colloid-facilitated transport is of interest. We have sampled and studied undisturbed columns (7.5 cm ID, 20 cm length) of the Taylor soil from a grassed floodplain. A FlashCTTM - 420 kV system (HYTEC Inc.) was used for X-ray computer tomography (CT) scanning. The FlashCT-DAQ, the FlashCT-DPS, and the FlashCT-VIZ software was used for reconstruction. A MatLab® software with GUI for processing, analyzing and visualizing of 3D X-ray CT scans was developed. It was used in the binarization process on each of 1480 cross-section images obtained for each column. The resolution of about 100 mkm was sufficient to distinguish macropores. The high-connectivity macropore space was reconstructed from the imagery, as well. The "porosity-depth" data series have been investigated. The R/S (rescale range) analysis indicated that these series did not have a simple structure that might be understood as a persistent or antipersistent fractional Brownian motion using the Hurst exponent. More complex behavior had been detected that could be characterized by means of multifractal analysis. The water retention data were obtained for column sections and were related to the CT characterization of these sections. Large columns present feasible objects for CT if macroporosity is of interest.

  8. Vertical migration of 85Sr, 137Cs and 131I in various arable and undisturbed soils

    International Nuclear Information System (INIS)

    Palagyi, S.; Palagyiova, J.

    2002-01-01

    Vertical migration of 85 Sr, 137 Cs and 131 I in some arable and undisturbed single-contaminated soils was studied by gamma-spectrometry measurements in lysimetric laboratory conditions applying irrigation of the soil profiles with wet atmospheric precipitation for about one year (except radioiodine). A new simple exponential compartment (box) model was derived, allowing us to calculate the migration rate constants and migration rates in the individual soil layers (vertical sections) as well as the total vertical migration rate constants and total vertical migration rates of radionuclides in the bulk soil horizon. The data from the time dependence of the depth activity distribution (radionuclide concentration along the vertical soil profile) were used to test the model. The migration rate constants and migration rates were found to be affected by the contaminating radionuclides as well as by the site, type and depth of the soil. The relaxation times of the radionuclides in the soil horizons were calculated. The effects on the rate parameters of the permanent grass cover and the zeolite applied onto the arable soil surfaces were also investigated

  9. The long-term variability of chemical structure of deep-water basins of the Caspian Sea

    Science.gov (United States)

    Serebrennikova, Ekaterina

    2017-04-01

    The Caspian Sea is a unique water object: the biggest lake on Earth, so large that it actually functions as a sea, but totally isolated from the World Ocean and extremely responsive to the climatic changes. The Caspian Sea is characterized by periodical large-scale sea level oscillations - it is one of the manifestations of multidecadal climatic fluctuations on East European Plain. In order to monitor the environmental conditions staff of the Laboratory of Hydrochemistry of Russian Federal Research Institution of Fisheries and Oceanography (FSBSI "VNIRO") in collaboration with other russian scientific institutions conducts annual research cruises to the Caspian Sea. For the last 40 years natural and anthropogenic climatic changes caused a stable stratification of the water column in both Caspian basins and the nourishment depletion of the photic layer, created and annually aggravated by the biological pump. The data, collected in annual expeditions since 1995, shows the progressing hypoxia below the depth of 400 meters and the formation of hydrogen sulfidic contamination in bottom waters. The cumulative effect of natural variability and extremely intensive anthropogenic stress creates a very depressing environment for all the aquatics, from phytoplankton to unique commercial species. In the last 20 years the level of the Caspian Sea has lowered for 2,5 meters. This is a result of changes in the water balance of the Caspian Sea, that includes the decrease of freshwater income. In long-term perspective this leads to an increase in surface water density and in winter convection depth. However up until 2016 the stratification of the water column stayed stable, so the deep waters were isolated form the atmosphere. Annual monitoring since 1995 has shown gradual oxygen depletion and intensive accumulation of biogenic elements. In 2016 concentrations of phosphate and nitrate were the highest ever registered for the Caspian Sea. The analysis of the research conducted in

  10. The multiple gas-liquid subsea separation system: development and qualification of a novel solution for deep water field production

    Energy Technology Data Exchange (ETDEWEB)

    Abrand, Stephanie; Butin, Nicolas; Shaiek, Sadia; Hallot, Raymond [Saipem S.p.A., Milano (Italy)

    2012-07-01

    Subsea processing is more and more considered as a viable solution for the development of deep and ultra deep water fields. SAIPEM has developed a deep water gas separation and liquid boosting system, based on its proprietary 'Multi pipe' separator concept, providing a good flexibility in handling a wide range of steady and un-steady multiphase input streams using a relatively simple mechanical arrangement. The Multi pipe Concept features an array of vertical pipes for gas/liquid separation by gravity and adequate liquid hold up volumes. The operating principle is the same as standard gravity vessels. Specific inlet pipe arrangements have been worked out to enhance the separation efficiency and internals can be implemented to further optimize the performances. The limited diameter and wall thickness of the vertical pipes make the Multi pipe Concept particularly suited for deep and ultra-deep water applications and/or high pressure conditions where the selection of a single separator vessel could lead to unpractical wall thicknesses. In most cases, standard API or ASME pipes can be utilized for the Multi pipe Separator, thus enabling conventional fabrication methods, and in turn reducing cost and delivery time and opening opportunities for local content. The qualification testing program has seen two subsequent phases. The first qualification phase aimed at the confirmation of the hydrodynamic behavior of the system. In particular, the homogeneous distribution of the multiphase stream into the pipes and the stability of the liquid levels under un-steady inlet conditions were continuously assessed during the tests. This first qualification phase gave confidence in the viability of the Multi pipe and in its good hydrodynamic behavior under the different inlet conditions that can be encountered during field production. It proved that, having the same liquid level in all the separator pipes, whatever the inlet conditions are, the Multi pipe separator can be

  11. Evidence of a modern deep water magmatic hydrothermal system in the Canary Basin (eastern central Atlantic Ocean)

    Science.gov (United States)

    Medialdea, T.; Somoza, L.; González, F. J.; Vázquez, J. T.; de Ignacio, C.; Sumino, H.; Sánchez-Guillamón, O.; Orihashi, Y.; León, R.; Palomino, D.

    2017-08-01

    New seismic profiles, bathymetric data, and sediment-rock sampling document for the first time the discovery of hydrothermal vent complexes and volcanic cones at 4800-5200 m depth related to recent volcanic and intrusive activity in an unexplored area of the Canary Basin (Eastern Atlantic Ocean, 500 km west of the Canary Islands). A complex of sill intrusions is imaged on seismic profiles showing saucer-shaped, parallel, or inclined geometries. Three main types of structures are related to these intrusions. Type I consists of cone-shaped depressions developed above inclined sills interpreted as hydrothermal vents. Type II is the most abundant and is represented by isolated or clustered hydrothermal domes bounded by faults rooted at the tips of saucer-shaped sills. Domes are interpreted as seabed expressions of reservoirs of CH4 and CO2-rich fluids formed by degassing and contact metamorphism of organic-rich sediments around sill intrusions. Type III are hydrothermal-volcanic complexes originated above stratified or branched inclined sills connected by a chimney to the seabed volcanic edifice. Parallel sills sourced from the magmatic chimney formed also domes surrounding the volcanic cones. Core and dredges revealed that these volcanoes, which must be among the deepest in the world, are constituted by OIB-type, basanites with an outer ring of blue-green hydrothermal Al-rich smectite muds. Magmatic activity is dated, based on lava samples, at 0.78 ± 0.05 and 1.61 ± 0.09 Ma (K/Ar methods) and on tephra layers within cores at 25-237 ky. The Subvent hydrothermal-volcanic complex constitutes the first modern system reported in deep water oceanic basins related to intraplate hotspot activity.type="synopsis">type="main">Plain Language SummarySubmarine volcanism and associated hydrothermal systems are relevant processes for the evolution of the ocean basins, due their impact on the geochemistry of the oceans, their potential to form significant ore deposits, and their

  12. Restoring Ecological Function to a Submerged Salt Marsh

    Science.gov (United States)

    Stagg, C.L.; Mendelssohn, I.A.

    2010-01-01

    Impacts of global climate change, such as sea level rise and severe drought, have altered the hydrology of coastal salt marshes resulting in submergence and subsequent degradation of ecosystem function. A potential method of rehabilitating these systems is the addition of sediment-slurries to increase marsh surface elevation, thus ameliorating effects of excessive inundation. Although this technique is growing in popularity, the restoration of ecological function after sediment addition has received little attention. To determine if sediment subsidized salt marshes are functionally equivalent to natural marshes, we examined above- and belowground primary production in replicated restored marshes receiving four levels of sediment addition (29-42 cm North American Vertical Datum of 1988 [NAVD 88]) and in degraded and natural ambient marshes (4-22 cm NAVD 88). Moderate intensities of sediment-slurry addition, resulting in elevations at the mid to high intertidal zone (29-36 cm NAVD 88), restored ecological function to degraded salt marshes. Sediment additions significantly decreased flood duration and frequency and increased bulk density, resulting in greater soil drainage and redox potential and significantly lower phytotoxic sulfide concentrations. However, ecological function in the restored salt marsh showed a sediment addition threshold that was characterized by a decline in primary productivity in areas of excessive sediment addition and high elevation (>36 cm NAVD 88). Hence, the addition of intermediate levels of sediment to submerging salt marshes increased marsh surface elevation, ameliorated impacts of prolonged inundation, and increased primary productivity. However, too much sediment resulted in diminished ecological function that was equivalent to the submerged or degraded system. ?? 2010 Society for Ecological Restoration International.

  13. Marshes on the Move: Testing effects of seawater intrusion on vegetation communities of the salt marsh-upland ecotone

    Science.gov (United States)

    The Northeastern United States is a hotspot for sea level rise (SLR), subjecting coastal salt marshes to erosive loss, shifts in vegetation communities, and altered biogeochemistry due to seawater intrusion. Salt marsh plant community zonation is driven by tradeoffs in stress to...

  14. Continuous and interval training programs using deep water running improves functional fitness and blood pressure in the older adults.

    Science.gov (United States)

    Reichert, Thaís; Kanitz, Ana Carolina; Delevatti, Rodrigo Sudatti; Bagatini, Natália Carvalho; Barroso, Bruna Machado; Kruel, Luiz Fernando Martins

    2016-02-01

    This study aimed to investigate the effects of two periodized training programs of deep water running on functional fitness and blood pressure in the older adults. Thirty-six individuals were divided into continuous group (CONT) and interval group (INT). Both groups were trained for 28 weeks (twice weekly). Measures were performed before the training period, after 12 weeks and training period. Two-way ANOVA and post hoc of Bonferroni were used (α = 0.05). There were no differences between groups in functional tests, with the exception of the flexibility of the upper limbs, in which the INT group showed the highest values. There was a significant improvement in both groups of foot up-and-go test (CONT 6.45 to 5.67; INT 6.59 to 5.78, in seconds), flexibility of lower limbs (CONT -4.76 to -0.61; INT 0.54 to 4.63, in centimeters), strength of upper (CONT 18.76 to 27.69; INT 18.66 to 26.58, in repetitions) and lower limbs (CONT 14.46 to 21.23; INT 14.40 to 21.58, in repetitions), and 6-min walk (CONT 567.50 to 591.16; INT 521.41 to 582.77, in meters). No differences were shown between groups for systolic blood pressure; however, diastolic blood pressure remained higher in CONT during all training. The blood pressure decreased significantly in both groups after the training (CONT 142 ± 16/88 ± 3 to 125 ± 14/77 ± 7 mmHg; INT 133 ± 15/75 ± 7 to 123 ± 17 and 69 ± 11 mmHg). Both programs of deep water running training promoted improvements of similar magnitude in all parameters of functional fitness, with the exception of flexibility of upper limbs, and decreased blood pressure in the older individuals.

  15. Nocturnal Foraging by Red-Legged Kittiwakes, a Surface Feeding Seabird That Relies on Deep Water Prey During Reproduction.

    Directory of Open Access Journals (Sweden)

    Nobuo Kokubun

    Full Text Available Narrow foraging specialization may increase the vulnerability of marine predators to climate change. The red-legged kittiwake (Rissa brevirostris is endemic to the Bering Sea and has experienced drastic population fluctuations in recent decades, presumably due to climate-driven changes in food resources. Red-legged kittiwakes are presumed to be a nocturnal surface-foraging seabird that feed almost entirely on deep water Myctophidae fishes. However, there is little empirical evidence confirming their nocturnal foraging activity during the breeding season. This study investigated the foraging behavior of red-legged kittiwakes by combining GPS tracking, accelerometry, and dietary analyses at the world's largest breeding colony of red-legged kittiwakes on St. George I. GPS tracking of 5 individuals revealed that 82.5% of non-flight behavior (including foraging and resting occurred over the ocean basin (bottom depth >1,000 m. Acceleration data from 4 birds showed three types of behaviors during foraging trips: (1 flight, characterized by regular wing flapping, (2 resting on water, characterized by non-active behavior, and (3 foraging, when wing flapping was irregular. The proportions of both foraging and resting behaviors were higher at night (14.1 ± 7.1% and 20.8 ± 14.3% compared to those during the day (6.5 ± 3.0% and 1.7 ± 2.7%. The mean duration of foraging (2.4 ± 2.9 min was shorter than that of flight between prey patches (24.2 ± 53.1 min. Dietary analyses confirmed myctophids as the dominant prey (100% by occurrence and 98.4 ± 2.4% by wet-weight. Although the sample size was limited, these results suggest that breeding red-legged kittiwakes concentrated their foraging on myctophids available at the surface during nighttime in deep water regions. We propose that the diel patterns and ephemeral nature of their foraging activity reflected the availability of myctophids. Such foraging specialization may exacerbate the vulnerability of red

  16. Modeling tidal marsh distribution with sea-level rise: evaluating the role of vegetation, sediment, and upland habitat in marsh resiliency.

    Science.gov (United States)

    Schile, Lisa M; Callaway, John C; Morris, James T; Stralberg, Diana; Parker, V Thomas; Kelly, Maggi

    2014-01-01

    Tidal marshes maintain elevation relative to sea level through accumulation of mineral and organic matter, yet this dynamic accumulation feedback mechanism has not been modeled widely in the context of accelerated sea-level rise. Uncertainties exist about tidal marsh resiliency to accelerated sea-level rise, reduced sediment supply, reduced plant productivity under increased inundation, and limited upland habitat for marsh migration. We examined marsh resiliency under these uncertainties using the Marsh Equilibrium Model, a mechanistic, elevation-based soil cohort model, using a rich data set of plant productivity and physical properties from sites across the estuarine salinity gradient. Four tidal marshes were chosen along this gradient: two islands and two with adjacent uplands. Varying century sea-level rise (52, 100, 165, 180 cm) and suspended sediment concentrations (100%, 50%, and 25% of current concentrations), we simulated marsh accretion across vegetated elevations for 100 years, applying the results to high spatial resolution digital elevation models to quantify potential changes in marsh distributions. At low rates of sea-level rise and mid-high sediment concentrations, all marshes maintained vegetated elevations indicative of mid/high marsh habitat. With century sea-level rise at 100 and 165 cm, marshes shifted to low marsh elevations; mid/high marsh elevations were found only in former uplands. At the highest century sea-level rise and lowest sediment concentrations, the island marshes became dominated by mudflat elevations. Under the same sediment concentrations, low salinity brackish marshes containing highly productive vegetation had slower elevation loss compared to more saline sites with lower productivity. A similar trend was documented when comparing against a marsh accretion model that did not model vegetation feedbacks. Elevation predictions using the Marsh Equilibrium Model highlight the importance of including vegetation responses to sea

  17. Assessing Salt Marsh Recovery Utilizing Improved Computer-Aided Tomography Technology (CTT)

    Science.gov (United States)

    In 2001 the Padanarum marsh, a small 7.2-acre marsh in Dartmouth, MA, was chosen as a Tidal Hydrology Restoration site. The site was initially characterized as a brackish mostly freshwater deteriorating marsh. In May 2003 the seawater input to this marsh was increased by replacin...

  18. Restoration of salt-marsh vegetation in relation to site suitability, species pool and dispersal traits

    NARCIS (Netherlands)

    Wolters, Mineke; Garbutt, Angus; Bekker, Renee M.; Bakker, Jan P.; Carey, Peter D.

    1. Restoration of salt marshes on previously reclaimed land provides an excellent opportunity to study plant colonization and subsequent development of salt-marsh vegetation. Insight into the process of salt-marsh development can guide the design, implementation and evaluation of salt-marsh

  19. Carbon transfer from plant roots to soil - NanoSIMS analyses of undisturbed rhizosphere samples

    Science.gov (United States)

    Vidal, Alix; Hirte, Juliane; Bender, S. Franz; Mayer, Jochen; Gattinger, Andreas; Mueller, Carsten W.

    2017-04-01

    Soils are composed of a wide diversity of organic and mineral compounds, interacting to form complex mosaics of microenvironments. Roots and microorganisms are both key sources of organic carbon (OC). The volume of soil around living roots, i.e. the rhizosphere, is a privileged area for soil microbial activity and diversity. The microscopic observation of embedded soil sections has been applied since the 1950´s and has enabled observation of the rhizosphere at the smallest scale of organism interaction, i.e. at the level of root cells and bacteria (Alexander and Jackson, 1954). However, the observation of microorganisms in their intact environment, especially in soil, remains challenging. Existing microscopic images do not provide clear evidence of the chemical composition of compounds observed in the rhizosphere. Nano-scale secondary ion mass spectrometry (NanoSIMS) is a high spatial resolution method providing elemental and isotopic maps of organic and mineral materials. This technic has been increasingly used in soil science during the last decade (Hermann et al., 2007; Vogel et al., 2014) and more specifically for undisturbed soil sample observations (Vidal et al., 2016). In the present study, NanoSIMS was used to illustrate the biological, physical and chemical processes occurring in the rhizosphere at the microscale. To meet this objective, undisturbed rhizosphere samples were collected from a field experiment in Switzerland where wheat plants were pulse-labelled with 99% 13C-CO2 in weekly intervals throughout the growing season and sampled at flowering. Samples were embedded, sectioned, polished and analyzed with NanoSIMS, obtaining secondary ion images of 12C, 13C, 12C14N, 16O, 31P16O2, and 32S. The δ13C maps were obtained thanks to 12C and 13C images. 13C labelled root cells were clearly distinguished on images and presented highly variable δ13C values. Labelled spots (soil particles, forming microaggregates tightly bound to root cells. Finally, some

  20. Stratigraphic hierarchy of organic carbon rich siltstones in deep-water facies, Brushy Canyon Formation (Guadalupian), Delaware Basin, West Texas

    Science.gov (United States)

    Sageman, Bradley B.; Gardner, Michael H.; Armentrout, John M.; Murphy, Adam E.

    1998-05-01

    The first systematic test for a predictive relationship between organic carbon content and stratigraphic hierarchy in a deep-water slope to basin-floor deposit was performed. The studied section includes the Pipeline Shale, the Brushy Canyon Formation, and the lower part of the Cherry Canyon Formation of the Delaware Mountain Group, West Texas. This interval represents one large-scale, 3rd-order genetic sequence within which 4th- and 5th-order stratigraphic cycles are recognized. Samples of fine-grained facies throughout the section were collected from outcrop and analyzed for organic carbon content and hydrogen index. Degree of pyritization was also determined for a subset of the samples. The results indicate that organic enrichment is closely correlated to the stratigraphic hierarchy at the 3rd-, 4th-, and 5th-order levels. The data suggest that quantity and quality of preserved organic matter are controlled by changes in bulk sedimentation rate (dilution vs. condensation), which affect organic matter inputs to the sediment, as well as the balance between (1) burial and preservation of organic matter and (2) its degradation on the sea floor during times of sediment starvation.

  1. Inter-annual variability and potential for selectivity in the diets of deep-water Antarctic echinoderms

    Science.gov (United States)

    Wigham, B. D.; Galley, E. A.; Smith, C. R.; Tyler, P. A.

    2008-11-01

    The continental shelf of the West Antarctic Peninsula (WAP) is a highly productive region but also unusually deep as a result of isostatic depression by the polar ice cap. The close coupling of surface processes with those of the benthos would be expected in such a seasonally variable environment; however, the cold, deep conditions of the WAP shelf may allow for the persistence of organic material in the sediments as a "food bank". Chlorophyll and carotenoid pigments were determined from the gut contents of seven species of echinoderm and from the surficial sediment on the bathyal continental shelf. Samples were collected as part of the FOODBANCS programme during successive cruises in austral spring (October 2000) and austral autumn (March 2001). Pigments were identified and quantified using reverse-phase high-performance liquid chromatography (HPLC). A lack of qualitative selectivity was observed among species, compared to that observed for deep-water assemblages at temperate latitudes, supporting the theory of a persistent "food bank". However, significant quantitative differences were observed among species and between years and sampling location on the shelf. Species differences were marked between those we classified as "true" deposit feeders and those species whose diet also may be supplemented by scavenging and/or grazing.

  2. CHARACTERIZING NATURAL GAS HYDRATES IN THE DEEP WATER GULF OF MEXICO: APPLICATIONS FOR SAFE EXPLORATION AND PRODUCTION ACTIVITIES

    Energy Technology Data Exchange (ETDEWEB)

    Steve Holditch; Emrys Jones

    2003-01-01

    In 2000, Chevron began a project to learn how to characterize the natural gas hydrate deposits in the deepwater portions of the Gulf of Mexico. A Joint Industry Participation (JIP) group was formed in 2001, and a project partially funded by the U.S. Department of Energy (DOE) began in October 2001. The primary objective of this project is to develop technology and data to assist in the characterization of naturally occurring gas hydrates in the deep water Gulf of Mexico (GOM). These naturally occurring gas hydrates can cause problems relating to drilling and production of oil and gas, as well as building and operating pipelines. Other objectives of this project are to better understand how natural gas hydrates can affect seafloor stability, to gather data that can be used to study climate change, and to determine how the results of this project can be used to assess if and how gas hydrates act as a trapping mechanism for shallow oil or gas reservoirs. During April-September 2002, the JIP concentrated on: Reviewing the tasks and subtasks on the basis of the information generated during the three workshops held in March and May 2002; Writing Requests for Proposals (RFPs) and Cost, Time and Resource (CTRs) estimates to accomplish the tasks and subtasks; Reviewing proposals sent in by prospective contractors; Selecting four contractors; Selecting six sites for detailed review; and Talking to drill ship owners and operators about potential work with the JIP.

  3. CHARACTERIZING NATURAL GAS HYDRATES IN THE DEEP WATER GULF OF MEXICO: APPLICATIONS FOR SAFE EXPLORATION AND PRODUCTION ACTIVITIES

    Energy Technology Data Exchange (ETDEWEB)

    Steve Holditch; Emrys Jones

    2003-01-01

    In 2000, Chevron began a project to learn how to characterize the natural gas hydrate deposits in the deepwater portions of the Gulf of Mexico. A Joint Industry Participation (JIP) group was formed in 2001, and a project partially funded by the U.S. Department of Energy (DOE) began in October 2001. The primary objective of this project is to develop technology and data to assist in the characterization of naturally occurring gas hydrates in the deep water Gulf of Mexico (GOM). These naturally occurring gas hydrates can cause problems relating to drilling and production of oil and gas, as well as building and operating pipelines. Other objectives of this project are to better understand how natural gas hydrates can affect seafloor stability, to gather data that can be used to study climate change, and to determine how the results of this project can be used to assess if and how gas hydrates act as a trapping mechanism for shallow oil or gas reservoirs. During the first six months of operation, the primary activities of the JIP were to conduct and plan Workshops, which were as follows: (1) Data Collection Workshop--March 2002 (2) Drilling, Coring and Core Analyses Workshop--May 2002 (3) Modeling, Measurement and Sensors Workshop--May 2002.

  4. Strategies for restoration of deep-water coral ecosystems based on a global survey of oil and gas regulations

    Science.gov (United States)

    Cordes, E. E.; Jones, D.; Levin, L. A.

    2016-02-01

    The oil and gas industry is one of the most active agents of the global industrialization of the deep sea. The wide array of impacts following the Deepwater Horizon oil spill highlighted the need for a systematic review of existing regulations both in US waters and internationally. Within different exclusive economic zones, there are a wide variety of regulations regarding the survey of deep-water areas prior to leasing and the acceptable set-back distances from vulnerable marine ecosystems once they are discovered. There are also varying mitigation strategies for accidental release of oil and gas, including active monitoring systems, temporary closings of oil and gas production, and marine protected areas. The majority of these regulations are based on previous studies of typical impacts from oil and gas drilling, rather than accidental releases. However, the probability of an accident from standard operations increases significantly with depth. The Oil & Gas working group of the Deep Ocean Stewardship Initiative is an international partnership of scientists, managers, non-governmental organizations, and industry professionals whose goal is to review existing regulations for the oil & gas industry and produce a best practices document to advise both developed and developing nations on their regulatory structure as energy development moves into deeper waters.

  5. Polychaete Annelid (segmented worms) Species Composition in the Deep Gulf of Mexico following the Deep Water Horizon (DWH) Oil Spill

    Science.gov (United States)

    QU, F.; Rowe, G.

    2012-12-01

    Sediments 5 to 9 km from the Deep Water Horizon (DWH) Oil Spill site were sampled using a 0.2 m2 box corer 5 months after the event to assess the effects of the oil spill on polychaete annelid (segmented worms) community structure. Numbers of species, abundance, and biodiversity indices were all significantly lower than pre-spill values from similar depths in the eastern Gulf of Mexico (GoM). All of the five dominant species were different. Non-selective deposit feeders and selective deposit feeders were still the most frequent feeding guilds, but their abundances decreased significantly after the event. A large number of carnivorous Sigalionidae may be a response to an accumulation of PAHs on the sediment. Multivariate analyses (CLUSTER and multidimensional scaling (MDS)) illustrate the differences between assemblages near the DWH and those from prior studies in similar deep GoM habitats. In sum, the polychaete populations appeared to be at an early stage of succession in the recovery from the spill or they could be a resident assemblage that is the natural characteristic infauna in or adjacent to natural seeps of fossil hydrocarbons.

  6. Parametric study on the behavior of an innovative subsurface tension leg platform in ultra-deep water

    Science.gov (United States)

    Zhen, Xing-wei; Huang, Yi

    2017-10-01

    This study focuses on a new technology of Subsurface Tension Leg Platform (STLP), which utilizes the shallowwater rated well completion equipment and technology for the development of large oil and gas fields in ultra-deep water (UDW). Thus, the STLP concept offers attractive advantages over conventional field development concepts. STLP is basically a pre-installed Subsurface Sea-star Platform (SSP), which supports rigid risers and shallow-water rated well completion equipment. The paper details the results of the parametric study on the behavior of STLP at a water depth of 3000 m. At first, a general description of the STLP configuration and working principle is introduced. Then, the numerical models for the global analysis of the STLP in waves and current are presented. After that, extensive parametric studies are carried out with regarding to SSP/tethers system analysis, global dynamic analysis and riser interference analysis. Critical points are addressed on the mooring pattern and riser arrangement under the influence of ocean current, to ensure that the requirements on SSP stability and riser interference are well satisfied. Finally, conclusions and discussions are made. The results indicate that STLP is a competitive well and riser solution in up to 3000 m water depth for offshore petroleum production.

  7. Composition and diversity patterns of megafauna discards in the deep-water shrimp trawl fishery off Brazil.

    Science.gov (United States)

    Perez, J A A; Pereira, B N; Pereira, D A; Schroeder, R

    2013-10-01

    Composition and spatial diversity patterns of retained and discarded catches in the deep-water shrimp (family Aristeidae) trawling fishery off Brazil were assessed by observers on-board commercial operations in 2005 and 2006. These trawls caught 19,440 kg and 180,076 individuals of which 76·0 and 65·2%, respectively, were discarded at sea. Finfishes represented 54% of the numerical catch but were almost fully discarded (98%). Crustaceans represented 40% of the numerical catch and were mostly retained (80%). The scarlet shrimp Aristaeopsis edwardsiana comprised approximately half of the retained catch. The remainder of the retained proportion comprised mainly the red giant shrimp Aristaeomorpha foliacea, the alistado shrimp Aristeus antillensis and small quantities of Argentine hake Merluccius hubbsi and gulf hake Urophycis mystacea. Discards comprised 108 species including 72 fish species, 19 crustaceans and 10 cephalopods. The large-scaled lanternfish Neoscopelus macrolepidotus was dominant in the discards, followed by the benthopelagic fishes Monomitopus agassizii, Synagrops bellus, Dibranchus atlanticus and Gadella imberbis and various macrurid species. This fishery was restricted to a limited bathymetric range (700-800 m), where discrete megafauna assemblages exist and may have been significantly affected. © 2013 The Authors. Journal of Fish Biology © 2013 The Fisheries Society of the British Isles.

  8. Bythaelurus tenuicephalus n. sp., a new deep-water catshark (Carcharhiniformes, Scyliorhinidae) from the western Indian Ocean.

    Science.gov (United States)

    Kaschner, Carina Julia; Weigmann, Simon; Thiel, Ralf

    2015-09-07

    A new dwarf deep-water catshark, Bythaelurus tenuicephalus, is described based on one adult and one juvenile male specimen from off Tanzania and Mozambique in the western Indian Ocean. The new species differs from its congeners by its slender head and snout, which is only slightly bell-shaped in dorsoventral view without distinct lateral indention. All other Bythaelurus species have distinctly bell-shaped snouts with a strong lateral indention anterior to outer nostrils. Compared to its congeners in the western Indian Ocean, B. tenuicephalus n. sp. also has broader claspers in adult males (base width 2.1% TL vs. 1.5-1.8% TL). It further differs from B. clevai by attaining a smaller maximum size and having a color pattern of fewer and smaller blotches, larger oral papillae, a shorter snout, and broader claspers without knob-like apex and with a smaller envelope and a subtriangular (vs. subrectangular) exorhipidion. Compared to B. hispidus, the new species has a longer snout, a longer dorsal-caudal space, broader clasper without knob-like apex, and fewer vertebral centra. In contrast to B. lutarius, B. tenuicephalus attains a smaller maximum size and has a blotched (vs. largely plain) coloration, numerous (vs. lacking) oral papillae, shorter anterior nasal flaps, a longer caudal fin, a shorter pelvic anal space, and shorter and broader claspers.

  9. Bythaelurus vivaldii, a new deep-water catshark (Carcharhiniformes, Scyliorhinidae) from the northwestern Indian Ocean off Somalia.

    Science.gov (United States)

    Weigmann, Simon; Kaschner, Carina Julia

    2017-05-08

    A new very small deep-water catshark, Bythaelurus vivaldii, is described based on two female specimens caught off Somalia in the northwestern Indian Ocean during the German 'Valdivia' expedition in 1899. It is morphologically closest to the recently described B. bachi, which is the only other Bythaelurus species in the western Indian Ocean that shares a stout body of large specimens and the presence of oral papillae. It further resembles B. vivaldii in the broad mouth and broad posterior head, but differs in the presence of composite oral papillae and a higher diversity in dermal denticle morphology. Additionally, the new species differs from all congeners in the western Indian Ocean in a larger pre-second dorsal fin length, a longer head, a larger interdorsal space, a larger intergill length, a longer pectoral-fin posterior margin, a shorter caudal fin, an intermediate caudal fin preventral margin, and a larger internarial width. Furthermore, the second dorsal fin of the new species is smaller than in its congeners in the western Indian Ocean except for B. lutarius, which is easily distinguished by the slender body and virtual absence of oral papillae, as well as the aforementioned further characters. An updated key to all valid species of Bythaelurus is provided.

  10. Fecundity and embryo development of three Antarctic deep-water scleractinians: Flabellum thouarsii, F. curvatum and F. impensum

    Science.gov (United States)

    Waller, Rhian G.; Tyler, Paul A.; Smith, Craig R.

    2008-11-01

    The larval development of three species of deep-water scleractinian, Flabellum thouarsii, F. curvatum and F. impensum, was examined from samples collected from the deep continental shelf off the Western Antarctic Peninsula between 1999 and 2001. All three of these species were gonochoric, with females brooding multiple stages of planulae larvae. Mean fecundity was found to be high ( F. thouarsii, 2412 oocytes per polyp (opp) (±1554sd); F. curvatum 1618 opp (±1071sd); F. impensum, 1270 opp (±884sd)). F. thouarsii has a previtellogenic oocyte size of ˜500 μm and a maximum oocyte size of ˜4800 μm. F. curvatum has a previtellogenic oocyte size of ˜800 μm and a maximum oocytes size of ˜5120 μm, and F. impensum has the largest oocyte sizes with a previtellogenic oocyte size of ˜1000 μm and a maximum oocyte size of ˜5200 μm. Larvae were found free within the gastrovascular cavity and embedded within the mesenterial gastrodermis. Three tentative stages of larvae were observed within female individuals, with the final stages having prominent tentacle buds and oral areas. A maximum of two larvae were found per mesentery in F. thouarsii and F. impensum, and four larvae were found per mesentery for F. curvatum. Four stages of spermatogenesis also were observed using histological techniques. The observations are discussed in relation to modes of reproduction in Antarctic waters and the deep sea.

  11. Large-scale deep-water seafloor mapping from the Rockall to the Hatton basins, NE Atlantic

    Science.gov (United States)

    Monteys, X.; Thébaudeau, B.; Murcia, C.; Duncan, N.

    2016-02-01

    Multibeam data acquired in 2000 and 2001 during the Irish National Seabed Survey (INSS) are used for the first detailed investigation of the seabed geomorphology and sediment type in the Hatton-Rockall basin area of the North East Atlantic Ocean, covering an area of approximately 80,000 km². The original multibeam survey produced bathymetric and backscatter datasets that allowed the creation of a Digital Terrain Models of approximately 50 m in resolution in water depths between 500 and 3500 m. Near-surface sediments for the entire region haven been classified using features derived from multibeam angular backscatter data (12kHz) and robust unsupervised clustering techniques. Additionally, sub bottom data imaging the shallow stratigraphy and geomagnetic measurements collected at the time of the MBES survey are combined to further characterise some of the features identified. The features presented in detail include parts of the Hatton and Gardar contourite drifts, volcanic mounds identified by their morphology and magnetic signature, deep-water coral mounds, iceberg scours as well as canyons, gullies and escarpments along and down the slopes of the banks and mounds. This study highlights for the first time the variety and complexity of the seafloor present at the seabed in the Irish Hatton-Rockall basin area

  12. Control of flow structure in the wake region of circular cylinder with meshy wire in deep water

    Directory of Open Access Journals (Sweden)

    Burcu Oğuz

    2016-08-01

    Full Text Available In this study the aim is decreasing the effect and the intensity of the temporary loads resulted from vortex shedding that have an impact on the cylinder (chimneys, high buildings etc. located in deep water and the object or objects in the wake region and definition of the optimum values (wire thickness and porosity β With different thickness and different porosity ratios the effect of meshy wire that surrounded a circular cylinder of D=50 mm diameter was observed at Re_D=5000. The porosity ratios were four different values between a range of β=0.5-0.8 with an interval of 0.1. The thicknesses of wire were 1 mm, 2 mm, 3 mm and 4 mm. The flow structure in the wake region of circular cylinder was tried to be controlled by meshy wire that surrounded the cylinder. Experiments were carried out by using particle image velocimetry (PIV technique. Comparing with bare cylinder results, turbulence kinetic energy (TKE and Reynolds shear stress values increase with wire thicknesses of b=1 mm, 2 mm for all porosity ratios and decrease with b=3 mm, 4 mm. With porosity ratio of β=0.6 and wire thickness of b=4 mm TKE and Reynolds shear stress results show that meshy wire controls the flow in the wake region of the cylinder. Frequency value results also define that best flow control is obtained with β=0.6 and b=4 mm.

  13. Small scale temporal distribution of radiocesium in undisturbed coniferous forest soil: Radiocesium depth distribution profiles.

    Science.gov (United States)

    Teramage, Mengistu T; Onda, Yuichi; Kato, Hiroaki

    2016-04-01

    The depth distribution of pre-Fukushima and Fukushima-derived (137)Cs in undisturbed coniferous forest soil was investigated at four sampling dates from nine months to 18 months after the Fukushima nuclear power plant accident. The migration rate and short-term temporal variability among the sampling profiles were evaluated. Taking the time elapsed since the peak deposition of pre-Fukushima (137)Cs and the median depth of the peaks, its downward displacement rates ranged from 0.15 to 0.67 mm yr(-1) with a mean of 0.46 ± 0.25 mm yr(-1). On the other hand, in each examined profile considerable amount of the Fukushima-derived (137)Cs was found in the organic layer (51%-92%). At this moment, the effect of time-distance on the downward distribution of Fukushima-derived (137)Cs seems invisible as its large portion is still found in layers where organic matter is maximal. This indicates that organic matter seems the primary and preferential sorbent of radiocesium that could be associated with the physical blockage of the exchanging sites by organic-rich dusts that act as a buffer against downward propagation of radiocesium, implying radiocesium to be remained in the root zone for considerable time period. As a result, this soil section can be a potential source of radiation dose largely due to high radiocesium concentration coupled with its low density. Generally, such kind of information will be useful to establish a dynamic safety-focused decision support system to ease and assist management actions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Nitrate Leaching from Winter Cereal Cover Crops Using Undisturbed Soil-Column Lysimeters.

    Science.gov (United States)

    Meisinger, John J; Ricigliano, Kristin A

    2017-05-01

    Cover crops are important management practices for reducing nitrogen (N) leaching, especially in the Chesapeake Bay watershed, which is under total maximum daily load (TMDL) restraints. Winter cereals are common cool-season crops in the Bay watershed, but studies have not directly compared nitrate-N (NO-N) leaching losses from these species. A 3-yr cover crop lysimeter study was conducted in Beltsville, MD, to directly compare NO-N leaching from a commonly grown cultivar of barley ( L.), rye ( L.), and wheat ( L.), along with a no-cover control, using eight tension-drained undisturbed soil column lysimeters in a completely randomized design with two replicates. The lysimeters were configured to exclude runoff and to estimate NO-N leaching and flow-weighted NO-N concentration (FWNC). The temporal pattern of NO-N leaching showed a consistent highly significant ( < 0.001) effect of lower NO-N leaching with cover crops compared with no cover but showed only small and periodically significant ( < 0.05) effects among the cultivars of barley, rye, and wheat covers. Nitrate-N leaching was more affected by the quantity of establishment-season (mid-October to mid-December) precipitation than by cover crop species. For example, compared with no cover, winter cereal covers reduced NO-N leaching 95% in a dry year and 50% in wet years, with corresponding reductions in FWNC of 92 and 43%, respectively. These results are important for scientists, nutrient managers, and policymakers because they directly compare NO-N leaching from winter cereal covers and expand knowledge for developing management practices for winter cereals that can improve water quality and increase N efficiency in cropping systems. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  15. Long-term changes in liana abundance and forest dynamics in undisturbed Amazonian forests.

    Science.gov (United States)

    Laurance, William F; Andrade, Ana S; Magrach, Ainhoa; Camargo, José L C; Valsko, Jefferson J; Campbell, Mason; Fearnside, Philip M; Edwards, Will; Lovejoy, Thomas E; Laurance, Susan G

    2014-06-01

    Lianas (climbing woody vines) are important structural parasites of tropical trees and may be increasing in abundance in response to global-change drivers. We assessed long-term (-14-year) changes in liana abundance and forest dynamics within 36 1-ha permanent plots spanning -600 km2 of undisturbed rainforest in central Amazonia. Within each plot, we counted each liana stem (> or = 2 cm diameter) and measured its diameter at 1.3 m height, and then used these data to estimate liana aboveground biomass. An initial liana survey was completed in 1997-1999 and then repeated in 2012, using identical methods. Liana abundance in the plots increased by an average of 1.00% +/- 0.88% per year, leading to a highly significant (t = 6.58, df = 35, P rainfall and forest dynamics from our study site to test hypotheses about potential drivers of change in liana communities. Lianas generally increase with rainfall seasonality, but we found no significant trends over time (1997-2012) in five rainfall parameters (total annual rainfall, dry-season rainfall, wet-season rainfall, number of very dry months, CV of monthly rainfall). However, rates of tree mortality and recruitment have increased significantly over time in our plots, and general linear mixed-effect models suggested that lianas were more abundant at sites with higher tree mortality and flatter topography. Rising concentrations of atmospheric CO2, which may stimulate liana growth, might also have promoted liana increases. Our findings clearly support the view that lianas are increasing in abundance in old-growth tropical forests, possibly in response to accelerating forest dynamics and rising CO2 concentrations. The aboveground biomass of trees was lowest in plots with abundant lianas, suggesting that lianas could reduce forest carbon storage and potentially alter forest dynamics if they continue to proliferate.

  16. Retention and remobilization of stabilized silver nanoparticles in an undisturbed loamy sand soil.

    Science.gov (United States)

    Liang, Yan; Bradford, Scott A; Simunek, Jiri; Heggen, Marc; Vereecken, Harry; Klumpp, Erwin

    2013-01-01

    Column experiments were conducted with undisturbed loamy sand soil under unsaturated conditions (around 90% saturation degree) to investigate the retention of surfactant stabilized silver nanoparticles (AgNPs) with various input concentration (Co), flow velocity, and ionic strength (IS), and the remobilization of AgNPs by changing the cation type and IS. The mobility of AgNPs in soil was enhanced with decreasing solution IS, increasing flow rate and input concentration. Significant retardation of AgNP breakthrough and hyperexponential retention profiles (RPs) were observed in almost all the transport experiments. The retention of AgNPs was successfully analyzed using a numerical model that accounted for time- and depth-dependent retention. The simulated retention rate coefficient (k1) and maximum retained concentration on the solid phase (Smax) increased with increasing IS and decreasing Co. The high k1 resulted in retarded breakthrough curves (BTCs) until Smax was filled and then high effluent concentrations were obtained. Hyperexponential RPs were likely caused by the hydrodynamics at the column inlet which produced a concentrated AgNP flux to the solid surface. Higher IS and lower Co produced more hyperexponential RPs because of larger values of Smax. Retention of AgNPs was much more pronounced in the presence of Ca(2+) than K(+) at the same IS, and the amount of AgNP released with a reduction in IS was larger for K(+) than Ca(2+) systems. These stronger AgNP interactions in the presence of Ca(2+) were attributed to cation bridging. Further release of AgNPs and clay from the soil was induced by cation exchange (K(+) for Ca(2+)) that reduced the bridging interaction and IS reduction that expanded the electrical double layer. Transmission electron microscopy, energy-dispersive X-ray spectroscopy, and correlations between released soil colloids and AgNPs indicated that some of the released AgNPs were associated with the released clay fraction.

  17. Marsh canopy structure changes and the Deepwater Horizon oil spill

    Science.gov (United States)

    Ramsey, Elijah W.; Rangoonwala, Amina; Jones, Cathleen E.

    2016-01-01

    Marsh canopy structure was mapped yearly from 2009 to 2012 in the Barataria Bay, Louisiana coastal region that was impacted by the 2010 Deepwater Horizon (DWH) oil spill. Based on the previously demonstrated capability of NASA's UAVSAR polarimetric synthetic aperture radar (PolSAR) image data to map Spartina alterniflora marsh canopy structure, structure maps combining the leaf area index (LAI) and leaf angle distribution (LAD, orientation) were constructed for yearly intervals that were directly relatable to the 2010 LAI-LAD classification. The yearly LAI-LAD and LAI difference maps were used to investigate causes for the previously revealed dramatic change in marsh structure from prespill (2009) to postspill (2010, spill cessation), and the occurrence of structure features that exhibited abnormal spatial and temporal patterns. Water level and salinity records showed that freshwater releases used to keep the oil offshore did not cause the rapid growth from 2009 to 2010 in marsh surrounding the inner Bay. Photointerpretation of optical image data determined that interior marsh patches exhibiting rapid change were caused by burns and burn recovery, and that the pattern of 2010 to 2011 LAI decreases in backshore marsh and extending along some tidal channels into the interior marsh were not associated with burns. Instead, the majority of 2010 to 2011 shoreline features aligned with vectors displaying the severity of 2010 shoreline oiling from the DWH spill. Although the association is not conclusive of a causal oil impact, the coexistent pattern is a significant discovery. PolSAR marsh structure mapping provided a unique perspective of marsh biophysical status that enhanced detection of change and monitoring of trends important to management effectiveness.

  18. Environmental controls on multiscale spatial patterns of salt marsh vegetation

    DEFF Research Database (Denmark)

    Kim, Daehyun; Cairns, David; Bartholdy, Jesper

    2010-01-01

    physical processes operate. This study investigated such a topography-vegetation relationship in a Danish salt marsh, focusing upon two scales: a macro-scale (ca. 500 m) across the marsh platform, encompassing seaward and landward areas, and a meso-scale ( ca. 25 m) across tidal creeks. While long-term sea...... represented an ecological sequence from early to late succession, and strongly correlated with surface elevation. However, the gradient did not show any significant relationship with distance from shoreline or tidal channels. Our results suggest that, in salt marshes, elevation plays a still more important...

  19. Sedimentation, accretion, and subsidence in marshes of Barataria Basin, Louisiana

    International Nuclear Information System (INIS)

    Hatton, R.S.; DeLaune, R.D.; Patrick, W.H. Jr.

    1983-01-01

    Vertical accretion and sediment accumulation rates were determined from the distribution of 137 Cs in cores collected from fresh water, intermediate, brackish, and salt marshes in the Barataria Basin, Louisiana. Vertical accretion rates vary from about 1.3 cm.yr -1 in levee areas to 0.7 in backmarshes. Mineral sediment content of the marsh soil profile decreased with distance from the coast. Except in natural levee areas, marsh accretion rates are less than subsidence measured by water level data, however this alone cannot account for observed land-loss patterns in the basin area

  20. Recent Advances in Studies of Coastal Marsh Sedimentation

    Science.gov (United States)

    Pasternack, G. B.; Leonard, L. A.

    2001-05-01

    Limited understanding of sedimentation processes in coastal marshes is a key constraint on the management of environmental impacts associated with sea level rise, degrading quality and quantity of aquatic habitats, and downstream impacts of watershed land use. The problem is exacerbated by complex interactions among physical, ecological, and chemical variables that impact sedimentation over a large range of spatio-temporal scales. These challenges are being met by increasingly sophisticated approaches which cross-fertilize from other disciplines or go even further to integrate multidisciplinary perspectives. One example of the former has been improved precision of fine scale measurements of fluid mechanics and sediment transport over marsh plains and application of those measurements in geomorphologic and coastal engineering models. This advancement has improved our understanding of marsh dynamics at a mechanistic level, which is key for improving the predictive capabilities of wetland models. An example of a multidisciplinary approach that has become very common is the combined usage of multiple monitoring, isotopic, and palynological methods for estimating sedimentation and erosion at a site over a range of time scales. By applying such combinations, it has been possible to piece apart the relative roles of natural processes such as sea level rise and storms from human impacts such as flow constrictions, channel dredging, and sediment supply changes. Beyond improving approaches used to study marshes, past work has led to new questions about marsh morphodynamics and how coastal marshes interact with upland watersheds. With the aid of chaos theory, some recent studies have asserted that coastal marsh channels are fractal and thus must follow universal laws in common with watershed drainages and other dendritic systems. Also, where marshes exist among a mosaic of habitats on a delta, research has revealed the relative roles of watershed versus coastal processes in

  1. Marsh Loss Due to Cumulative Impacts of Hurricane Isaac and the Deepwater Horizon Oil Spill in Louisiana

    Directory of Open Access Journals (Sweden)

    Shruti Khanna

    2017-02-01

    Full Text Available Coastal ecosystems are greatly endangered due to anthropogenic development and climate change. Multiple disturbances may erode the ability of a system to recover from stress if there is little time between disturbance events. We evaluated the ability of the saltmarshes in Barataria Bay, Louisiana, USA, to recover from two successive disturbances, the DeepWater Horizon oil spill in 2010 and Hurricane Isaac in 2012. We measured recovery using vegetation indices and land cover change metrics. We found that after the hurricane, land loss along oiled shorelines was 17.8%, while along oil-free shorelines, it was 13.6% within the first 7 m. At a distance of 7–14 m, land loss from oiled regions was 11.6%, but only 6.3% in oil-free regions. We found no differences in vulnerability to land loss between narrow and wide shorelines; however, vegetation in narrow sites was significantly more stressed, potentially leading to future land loss. Treated oiled regions also lost more land due to the hurricane than untreated regions. These results suggest that ecosystem recovery after the two disturbances is compromised, as the observed high rates of land loss may prevent salt marsh from establishing in the same areas where it existed prior to the oil spill.

  2. Carbon Exchange Processes In A Old-Growth Undisturbed Boreal Forest In Northern Sweden

    Science.gov (United States)

    Lindroth, A.; Heliasz, M.; Mölder, M.; Holst, J.

    2015-12-01

    It has been a common and long lasting view that old-growth forests are carbon neutral, i.e., the uptake of CO2 by gross photosynthesis is equal to the release of the same amount through ecosystem respiration. This hypothesis was originally developed by Odum based on theoretical reasoning on the balance between stability and diversity in ecosystems and how this relationship shifted with succession over time. At that time, the theory was underpinned by a relatively scarce empirical material but later supported by the observed decline in net primary productivity (NPP) with increasing stand age. More recently, based on direct measurements of net ecosystem exchange (NEE) Luyssaert et al. showed that old-growth forests still were significant sinks for atmospheric carbon dioxide thus challenging the hypothesis that old forests are in balance with respect to uptake and emission of CO2. Most of the forests in Luyssaert et al. analyses were temperate and semi-arid boreal forests and only few were located in the humid boreal zone. In order to shed light on this issue we initiated in 2011 carbon exchange studies in an old (>200 years) undisturbed humid boreal forest in Northern Sweden using EC measurements of NEE and chamber measurements of soil effluxes. The results indicate that the forest is a small sink of CO2 in the order of 20 g C m-2 y-1. The forest floor vegetation contributes significantly to GPP, in the order of 25-40%, depending on time of season. The nighttime ecosystem respiration showed a weak increase with air temperature up to about 15 ºC and then it started to decrease. The reason for this decrease that occurred at a relatively low temperature is still unclear. The small annual sink of -20 g C m-2 observed here is similar in magnitude to changes in soil carbon content on nearby much older forests located on small islands which has not been disturbed for several hundreds of years. Our study thus confirms that old forests can continue to take up carbon although

  3. Quantitative imaging of the 3-D distribution of cation adsorption sites in undisturbed soil

    Science.gov (United States)

    Keck, Hannes; Strobel, Bjarne W.; Petter Gustafsson, Jon; Koestel, John

    2017-10-01

    Several studies have shown that the distribution of cation adsorption sites (CASs) is patchy at a millimetre to centimetre scale. Often, larger concentrations of CASs in biopores or aggregate coatings have been reported in the literature. This heterogeneity has implications on the accessibility of CASs and may influence the performance of soil system models that assume a spatially homogeneous distribution of CASs. In this study, we present a new method to quantify the abundance and 3-D distribution of CASs in undisturbed soil that allows for investigating CAS densities with distance to the soil macropores. We used X-ray imaging with Ba2+ as a contrast agent. Ba2+ has a high adsorption affinity to CASs and is widely used as an index cation to measure the cation exchange capacity (CEC). Eight soil cores (approx. 10 cm3) were sampled from three locations with contrasting texture and organic matter contents. The CASs of our samples were saturated with Ba2+ in the laboratory using BaCl2 (0.3 mol L-1). Afterwards, KCl (0.1 mol L-1) was used to rinse out Ba2+ ions that were not bound to CASs. Before and after this process the samples were scanned using an industrial X-ray scanner. Ba2+ bound to CASs was then visualized in 3-D by the difference image technique. The resulting difference images were interpreted as depicting the Ba2+ bound to CASs only. The X-ray image-derived CEC correlated significantly with results of the commonly used ammonium acetate method to determine CEC in well-mixed samples. The CEC of organic-matter-rich samples seemed to be systematically overestimated and in the case of the clay-rich samples with less organic matter the CEC seemed to be systematically underestimated. The results showed that the distribution of the CASs varied spatially within most of our samples down to a millimetre scale. There was no systematic relation between the location of CASs and the soil macropore structure. We are convinced that the approach proposed here will strongly

  4. Deep Water Ocean Acoustics

    Science.gov (United States)

    2016-12-22

    analysis was conducted on the North Pacific Acoustics Laboratory Philippine Sea tests 2009 and 2010, both of which Dr. Heaney participated as a co-chief...obtained from the ambient noise field. In underwater acoustics , this travel time strongly depends on the depth and temperature and to a lesser extent...et al. 2012) and underwater volcanoes (Green at al. 2013). Guided wave propagation contributes to the limited acoustical attenuation by the SOFAR

  5. Swimming in Deep Waters

    Science.gov (United States)

    Schussler, Deborah; Feiman-Nemser, Sharon; Diez, Mary E.; Murrell, Peter

    2012-01-01

    The authors respond to a review of their book, "Teaching as a Moral Practice: Defining, Developing, and Assessing Dispositions". The authors emphasize a vision of shared commitments for quality teaching whereby teacher-educators instill and nurture the wisdom and virtue that a moral teacher must possess in order to teach in a variety of…

  6. Deep Water Ocean Acoustics

    Science.gov (United States)

    2015-07-17

    Ocean Acoustics 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER...paper and presented on global acoustic propagation (including on Europa, a small moon of Jupiter ) at the International Conference of Sound and

  7. Deep Water Ocean Acoustics

    Science.gov (United States)

    2015-10-19

    to a maximum of 143.1°. The back- azimuth as a function of frequency does show coherent behavior, at least within the observed 0.3° small time...level vs. Phone Number (similar to depth) as function of time as the source moved from 10-20 km away. The structure of this interference pattern...dimensional long-range acoustic propagation for improved localisation methods” Dr. Heaney visited Emanuel Coelho at CMRE in La Spezia Italy and

  8. Water Quality Assessment for Deep-water Channel area of Guangzhou Port based on the Comprehensive Water Quality Identification Index Method

    Science.gov (United States)

    Chen, Yi

    2018-03-01

    The comprehensive water quality identification index method is able to assess the general water quality situation comprehensively and represent the water quality classification; water environment functional zone achieves pollution level and standard objectively and systematically. This paper selects 3 representative zones along deep-water channel of Guangzhou port and applies comprehensive water quality identification index method to calculate sea water quality monitoring data for different selected zones from year 2006 to 2014, in order to investigate the temporal variation of water quality along deep-water channel of Guangzhou port. The comprehensive water quality level from north to south presents an increased trend, and the water quality of the three zones in 2014 is much better than in 2006. This paper puts forward environmental protection measurements and suggestions for Pearl River Estuary, provides data support and theoretical basis for studied sea area pollution prevention and control.

  9. Is Ekman pumping responsible for the seasonal variation of warm circumpolar deep water in the Amundsen Sea?

    Science.gov (United States)

    Kim, T. W.; Ha, H. K.; Wåhlin, A. K.; Lee, S. H.; Kim, C. S.; Lee, J. H.; Cho, Y. K.

    2017-01-01

    Ekman pumping induced by horizontally varying wind and sea ice drift is examined as an explanation for observed seasonal variation of the warm layer thickness of circumpolar deep water on the Amundsen Sea continental shelf. Spatial and temporal variation of the warm layer thickness in one of the deep troughs on the shelf (Dotson Trough) was measured during two oceanographic surveys and a two-year mooring deployment. A hydrographic transect from the deep ocean, across the shelf break, and into the trough shows a local elevation of the warm layer at the shelf break. On the shelf, the water flows south-east along the trough, gradually becoming colder and fresher due to mixing with cold water masses. A mooring placed in the trough shows a thicker and warmer layer in February and March (late summer/early autumn) and thinner and colder layer in September, October and November (late winter/early spring). The amplitude of this seasonal variation is up to 60 m. In order to investigate the effects of Ekman pumping, remotely sensed wind (Antarctic Mesoscale Prediction System wind data) and sea ice velocity and concentration (EASE Polar Pathfinder) were used. From the estimated surface stress field, the Ekman transport and Ekman pumping were calculated. At the shelf break, where the warm layer is elevated, the Ekman pumping shows a seasonal variation correlating with the mooring data. Previous studies have not been able to show a correlation between observed wind and bottom temperature, but it is shown here that when sea ice drift is taken into account the Ekman pumping at the outer shelf correlates with bottom temperature in Dotson Trough. The reason why the Ekman pumping varies seasonally at the shelf break appears to be the migration of the ice edge in the expanding polynya in combination with the wind field which on average is westward south of the shelf break.

  10. The Morphometry of the Deep-Water Sinuous Mendocino Channel and the Immediate Environs, Northeastern Pacific Ocean

    Directory of Open Access Journals (Sweden)

    James V. Gardner

    2017-11-01

    Full Text Available Mendocino Channel, a deep-water sinuous channel located along the base of Gorda Escarpment, was for the first time completely mapped with a multibeam echosounder. This study uses newly acquired multibeam bathymetry and backscatter, together with supporting multichannel seismic and sediment core data to quantitatively describe the morphometry of the entire Mendocino Channel and to explore the age and possible causes that may have contributed to the formation and maintenance of the channel. The first 42 km of the channel is a linear reach followed for the next 83.8 km by a sinuous reach. The sinuous reach has a sinuosity index of 1.66 before it changes back to a linear reach for the next 22.2 km. A second sinuous reach is 40.2 km long and the two reaches are separated by a crevasse splay and a large landslide that deflected the channel northwest towards Gorda Basin. Both sinuous reaches have oxbow bends, cut-off meanders, interior and exterior terraces and extensive levee systems. The lower sinuous reach becomes more linear for the next 22.2 km before the channel relief falls below the resolution of the data. Levees suddenly decrease in height above the channel floor mid-way along the lower linear reach close to where the channel makes a 90° turn to the southwest. The entire channel floor is smooth at the resolution of the data and only two large mounds and one large sediment pile were found on the channel floor. The bathymetry and acoustic backscatter, together with previously collected seismic data and box and piston cores provide details to suggest Mendocino Channel may be no older than early Quaternary. A combination of significant and numerous earthquakes and wave-loading resuspension by storms are the most likely processes that generated turbidity currents that have formed and modified Mendocino Channel.

  11. Lessons learnt from the Indian Ocean Tsunami 2004: the role of surface and subsurface topography in deep water tsunami propagation

    Science.gov (United States)

    Pattiaratchi, C. B.

    2014-12-01

    The Indian Ocean experienced its most devastating natural disaster through the action of a Tsunami, resulting from of an earthquake off the coast of Sumatra on 26th of December 2004. This resulted in widespread damage both to property and human lives with over 250,000 deaths in the region and many millions homeless. Our understanding of tsunami generation and propagation has increased significantly over the past decade. In this presentation, results obtained from detailed analysis of sea level data from Western Australia and Sri Lanka together with numerical modelling are presented to highlight the effects of topography both at the surface and subsurface. The major effects are due to wave reflection and refraction. Examples of wave reflection include: impacts on Malaysia/Thailand, Sri Lanka and Western Australia due to wave reflection from Sri Lanka, Maldives and Mascarene Ridge, respectively. In the case of Sri Lanka, the maximum wave height recorded along the west coast during the 2004 tsunami was due to the reflected wave from Maldives impacting 3 hours after the arrival of the initial waves. Similarly, along the West coast of Australia highest waves occurred 15 hours after the arrival of the first wave. Here, based on travel times, we postulate that the waves were reflected from the Mascarene Ridge and/or the island of Madagascar (Figure 1b). The conclusions based on observations were verified using numerical model simulations using the MOST and ComMIT models. Numerical modelling using the MOST model indicated the role of offshore susurface topography on tsunami propagation through wave wave refraction. Examples of wave refraction included the effects of deep water seamounts (Venin Meinesz) and plateaus (Wallaby, Cuvier and Exmouth) on tsunami propagation along the West Australian coast. The tsunami waves are first scattered by the Venin Meinesz seamounts and were then refracted by the Wallaby and Cuvier plateaus resulting in waves being deflected onto the

  12. Flume Experiments for Optimizing the Hydraulic Performance of a Deep-Water Wetland Utilizing Emergent Vegetation and Obstructions

    Directory of Open Access Journals (Sweden)

    Shang-Shu Shih

    2016-06-01

    Full Text Available Constructed ponds and wetlands are widely used in urban areas for stormwater management, ecological conservation, and pollution treatment. The treatment efficiency of these systems is strongly related to the hydrodynamics and hydraulic residence time. In this study, we developed a physical model and used rhodamine-WT as a tracer to conduct flume experiments. An equivalent Reynolds number was assumed, and the flume was a 1/25-scale model. Emergent obstructions (EOs, submerged obstructions (SOs, and high- and low-density emergent vegetation were placed along the sides of the flume, and 49 tracer tests were performed. We altered the density, spatial extent, aspect ratio, and configurations of the obstructions and emergent vegetation to observe changes in the hydraulic efficiency of a deep-water wetland. In the cases of low-aspect-ratio obstructions, the effects of the EOs on the hydraulic efficiency were significantly stronger than those of the SOs. In contrast, in the cases of high-aspect-ratio obstructions, the improvement effects of the EOs were weaker than those of the SOs. The high-aspect-ratio EOs altered the flow direction and constrained the water conveyance area, which apparently caused a short-circuited flow phenomenon, resulting in a decrease in hydraulic efficiency. Most cases revealed that the emergent vegetation improved the hydraulic efficiency more than the EOs. The high-density emergent vegetation (HEV improved the hydraulic efficiency more than the low-density emergent vegetation (LEV. Three cases involving HEV, two cases involving LEV, and one case involving EOs attained a good hydraulic efficiency (λ > 0.75. To achieve greater water purification, aquatic planting in constructed wetlands should not be overly dense. The HEV configuration in case 3-1 achieved optimum hydraulic performance for compliance with applicable water treatment standards.

  13. Sears Point Tidal Marsh Restoration Project: Phase I

    Science.gov (United States)

    Information about the SFBWQP Sears Point Tidal Marsh Restoration Project: Phase I project, part of an EPA competitive grant program to improve SF Bay water quality focused on restoring impaired waters and enhancing aquatic resources.

  14. Sears Point Tidal Marsh Restoration Project: Phase II

    Science.gov (United States)

    Information about the SFBWQP Sears Point Tidal Marsh Restoration Project: Phase II, part of an EPA competitive grant program to improve SF Bay water quality focused on restoring impaired waters and enhancing aquatic resources.

  15. Vegetation - Suisun Marsh, Change 1999 to 2000 [ds163

    Data.gov (United States)

    California Natural Resource Agency — This vegetation mapping project of Suisun Marsh blends ground-based classification, aerial photo interpretation, and GIS editing and processing. The method is based...

  16. Vegetation - Suisun Marsh, Change 1999 to 2003 [ds164

    Data.gov (United States)

    California Natural Resource Agency — This vegetation mapping project of Suisun Marsh blends ground-based classification, aerial photo interpretation, and GIS editing and processing. The method is based...

  17. Unsupervised detection of salt marsh platforms: a topographic method

    Directory of Open Access Journals (Sweden)

    G. C. H. Goodwin

    2018-03-01

    Full Text Available Salt marshes filter pollutants, protect coastlines against storm surges, and sequester carbon, yet are under threat from sea level rise and anthropogenic modification. The sustained existence of the salt marsh ecosystem depends on the topographic evolution of marsh platforms. Quantifying marsh platform topography is vital for improving the management of these valuable landscapes. The determination of platform boundaries currently relies on supervised classification methods requiring near-infrared data to detect vegetation, or demands labour-intensive field surveys and digitisation. We propose a novel, unsupervised method to reproducibly isolate salt marsh scarps and platforms from a digital elevation model (DEM, referred to as Topographic Identification of Platforms (TIP. Field observations and numerical models show that salt marshes mature into subhorizontal platforms delineated by subvertical scarps. Based on this premise, we identify scarps as lines of local maxima on a slope raster, then fill landmasses from the scarps upward, thus isolating mature marsh platforms. We test the TIP method using lidar-derived DEMs from six salt marshes in England with varying tidal ranges and geometries, for which topographic platforms were manually isolated from tidal flats. Agreement between manual and unsupervised classification exceeds 94 % for DEM resolutions of 1 m, with all but one site maintaining an accuracy superior to 90 % for resolutions up to 3 m. For resolutions of 1 m, platforms detected with the TIP method are comparable in surface area to digitised platforms and have similar elevation distributions. We also find that our method allows for the accurate detection of local block failures as small as 3 times the DEM resolution. Detailed inspection reveals that although tidal creeks were digitised as part of the marsh platform, unsupervised classification categorises them as part of the tidal flat, causing an increase in false negatives

  18. Unsupervised detection of salt marsh platforms: a topographic method

    Science.gov (United States)

    Goodwin, Guillaume C. H.; Mudd, Simon M.; Clubb, Fiona J.

    2018-03-01

    Salt marshes filter pollutants, protect coastlines against storm surges, and sequester carbon, yet are under threat from sea level rise and anthropogenic modification. The sustained existence of the salt marsh ecosystem depends on the topographic evolution of marsh platforms. Quantifying marsh platform topography is vital for improving the management of these valuable landscapes. The determination of platform boundaries currently relies on supervised classification methods requiring near-infrared data to detect vegetation, or demands labour-intensive field surveys and digitisation. We propose a novel, unsupervised method to reproducibly isolate salt marsh scarps and platforms from a digital elevation model (DEM), referred to as Topographic Identification of Platforms (TIP). Field observations and numerical models show that salt marshes mature into subhorizontal platforms delineated by subvertical scarps. Based on this premise, we identify scarps as lines of local maxima on a slope raster, then fill landmasses from the scarps upward, thus isolating mature marsh platforms. We test the TIP method using lidar-derived DEMs from six salt marshes in England with varying tidal ranges and geometries, for which topographic platforms were manually isolated from tidal flats. Agreement between manual and unsupervised classification exceeds 94 % for DEM resolutions of 1 m, with all but one site maintaining an accuracy superior to 90 % for resolutions up to 3 m. For resolutions of 1 m, platforms detected with the TIP method are comparable in surface area to digitised platforms and have similar elevation distributions. We also find that our method allows for the accurate detection of local block failures as small as 3 times the DEM resolution. Detailed inspection reveals that although tidal creeks were digitised as part of the marsh platform, unsupervised classification categorises them as part of the tidal flat, causing an increase in false negatives and overall platform

  19. Characteristics of the deep ocean carbon system during the past 150,000 years: ΣCO2 distributions, deep water flow patterns, and abrupt climate change

    Science.gov (United States)

    Boyle, Edward A.

    1997-01-01

    Studies of carbon isotopes and cadmium in bottom-dwelling foraminifera from ocean sediment cores have advanced our knowledge of ocean chemical distributions during the late Pleistocene. Last Glacial Maximum data are consistent with a persistent high-ΣCO2 state for eastern Pacific deep water. Both tracers indicate that the mid-depth North and tropical Atlantic Ocean almost always has lower ΣCO2 levels than those in the Pacific. Upper waters of the Last Glacial Maximum Atlantic are more ΣCO2-depleted and deep waters are ΣCO2-enriched compared with the waters of the present. In the northern Indian Ocean, δ13C and Cd data are consistent with upper water ΣCO2 depletion relative to the present. There is no evident proximate source of this ΣCO2-depleted water, so I suggest that ΣCO2-depleted North Atlantic intermediate/deep water turns northward around the southern tip of Africa and moves toward the equator as a western boundary current. At long periods (>15,000 years), Milankovitch cycle variability is evident in paleochemical time series. But rapid millennial-scale variability can be seen in cores from high accumulation rate series. Atlantic deep water chemical properties are seen to change in as little as a few hundred years or less. An extraordinary new 52.7-m-long core from the Bermuda Rise contains a faithful record of climate variability with century-scale resolution. Sediment composition can be linked in detail with the isotope stage 3 interstadials recorded in Greenland ice cores. This new record shows at least 12 major climate fluctuations within marine isotope stage 5 (about 70,000–130,000 years before the present). PMID:11607737

  20. Characteristics of the deep ocean carbon system during the past 150,000 years: SigmaCO2 distributions, deep water flow patterns, and abrupt climate change.

    Science.gov (United States)

    Boyle, E A

    1997-08-05

    Studies of carbon isotopes and cadmium in bottom-dwelling foraminifera from ocean sediment cores have advanced our knowledge of ocean chemical distributions during the late Pleistocene. Last Glacial Maximum data are consistent with a persistent high-SigmaCO2 state for eastern Pacific deep water. Both tracers indicate that the mid-depth North and tropical Atlantic Ocean almost always has lower SigmaCO2 levels than those in the Pacific. Upper waters of the Last Glacial Maximum Atlantic are more SigmaCO2-depleted and deep waters are SigmaCO2-enriched compared with the waters of the present. In the northern Indian Ocean, delta13C and Cd data are consistent with upper water SigmaCO2 depletion relative to the present. There is no evident proximate source of this SigmaCO2-depleted water, so I suggest that SigmaCO2-depleted North Atlantic intermediate/deep water turns northward around the southern tip of Africa and moves toward the equator as a western boundary current. At long periods (>15,000 years), Milankovitch cycle variability is evident in paleochemical time series. But rapid millennial-scale variability can be seen in cores from high accumulation rate series. Atlantic deep water chemical properties are seen to change in as little as a few hundred years or less. An extraordinary new 52.7-m-long core from the Bermuda Rise contains a faithful record of climate variability with century-scale resolution. Sediment composition can be linked in detail with the isotope stage 3 interstadials recorded in Greenland ice cores. This new record shows at least 12 major climate fluctuations within marine isotope stage 5 (about 70,000-130,000 years before the present).

  1. Risk-based work optimization for deep water drilling operations: Integration of risk analysis, maintenance and human factors on BOP operation

    OpenAIRE

    Liu, Honggang

    2013-01-01

    Master's thesis in Offshore technology The offshore deep water drilling has attracted global attention since the Macando blowout. It raised worldwide concern on the safety level of oil & gas industry and resulted in directly influence on offshore drilling activity. The thesis start from the introduction of offshore drilling, and the development of global oil & gas market, then come back to China, and generally described the history of offshore petroleum exploration and production in South ...

  2. Breeding biology and conservation of the Marsh Seedeater Sporophila palustris

    OpenAIRE

    Vizentin-Bugoni, J; Areta, JI; Di Giacomo, AG; Di Giacomo, AS; Jacobs, F; Coimbra, MAA; Dias, RA

    2013-01-01

    The Marsh Seedeater Sporophila palustris is one of the most endangered and least known of the capuchino seedeaters. Breeding populations are patchy, occurring in north-east Argentina, southern Brazil, and Uruguay. We present data on the breeding biology of the species, and describe nests and eggs, behaviour (including courtship, nesting, incubation and parental care), breeding sites and food items. Marsh Seedeaters breed in well-preserved grasslands with wet soils and tall vegetation. In gene...

  3. Modelling deep-water formation in the north-west Mediterranean Sea with a new air-sea coupled model: sensitivity to turbulent flux parameterizations

    Science.gov (United States)

    Seyfried, Léo; Marsaleix, Patrick; Richard, Evelyne; Estournel, Claude

    2017-12-01

    In the north-western Mediterranean, the strong, dry, cold winds, the Tramontane and Mistral, produce intense heat and moisture exchange at the interface between the ocean and the atmosphere leading to the formation of deep dense waters, a process that occurs only in certain regions of the world. The purpose of this study is to demonstrate the ability of a new coupled ocean-atmosphere modelling system based on MESONH-SURFEX-SYMPHONIE to simulate a deep-water formation event in real conditions. The study focuses on summer 2012 to spring 2013, a favourable period that is well documented by previous studies and for which many observations are available. Model results are assessed through detailed comparisons with different observation data sets, including measurements from buoys, moorings and floats. The good overall agreement between observations and model results shows that the new coupled system satisfactorily simulates the formation of deep dense water and can be used with confidence to study ocean-atmosphere coupling in the north-western Mediterranean. In addition, to evaluate the uncertainty associated with the representation of turbulent fluxes in strong wind conditions, several simulations were carried out based on different parameterizations of the flux bulk formulas. The results point out that the choice of turbulent flux parameterization strongly influences the simulation of the deep-water convection and can modify the volume of the newly formed deep water by a factor of 2.

  4. Origin and biogeography of the deep-water Mediterranean Hydromedusae including the description of two new species collected in submarine canyons of Northwestern Mediterranean

    Directory of Open Access Journals (Sweden)

    J. M. Gili

    1998-06-01

    Full Text Available Two new species of hydromedusae (Foersteria antoniae and Cunina simplex are described from plankton collected in sediment traps placed in the Lacaze-Duthiers Submarine Canyon and along Banyuls-sur-Mer coast (northwestern Mediterranean. The Mediterranean hydromedusan deep-water fauna contains 41 species which represent 45.5 % of the world-wide deep-sea hydromedusae fauna (90 and 20% of the total number of Mediterranean hydromedusae (204. The Mediterranean deep-water hydromedusan fauna is characterised by a large percentage of holoplanktonic species (61%, mainly Trachymedusae. Nevertheless, contrary to the general opinion, the percentage of meroplanktonic species is equally high. The most original features of this fauna lies however in the importance of the number of endemic species (22% and in the fact that the majority of them are meroplanktonic Leptomedusae with a supposed bathybenthic stage. Some of the endemic species could still represent relics of the primitive Tethys fauna having survived to the Messinian crisis. The origin of the Mediterranean deep-water hydromedusan fauna is discussed and a general hypothesis is proposed.

  5. Herbivory drives the spread of salt marsh die-off.

    Directory of Open Access Journals (Sweden)

    Mark D Bertness

    Full Text Available Salt marsh die-off is a Western Atlantic conservation problem that has recently spread into Narragansett Bay, Rhode Island, USA. It has been hypothesized to be driven by: 1 eutrophication decreasing plant investment into belowground biomass causing plant collapse, 2 boat wakes eroding creek banks, 3 pollution or disease affecting plant health, 4 substrate hardness controlling herbivorous crab distributions and 5 trophic dysfunction releasing herbivorous crabs from predator control. To distinguish between these hypotheses we quantified these variables at 14 Narragansett Bay salt marshes where die-off intensity ranged from <5% to nearly 98%. Nitrogen availability, wave intensity and plant growth did not explain any variation in die-off. Herbivory explained 73% of inter-site variation in die-off and predator control of herbivores and substrate hardness also varied significantly with die-off. This suggests that salt marsh die-off is being largely driven by intense herbivory via the release of herbivorous crabs from predator control. Our results and those from other marsh systems suggest that consumer control may not simply be a factor to consider in marsh conservation, but with widespread predator depletion impacting near shore habitats globally, trophic dysfunction and runaway consumption may be the largest and most urgent management challenge for salt marsh conservation.

  6. Sedimentation and response to sea-level rise of a restored marsh with reduced tidal exchange: Comparison with a natural tidal marsh

    Science.gov (United States)

    Vandenbruwaene, W.; Maris, T.; Cahoon, D.R.; Meire, P.; Temmerman, S.

    2011-01-01

    Along coasts and estuaries, formerly embanked land is increasingly restored into tidal marshes in order to re-establish valuable ecosystem services, such as buffering against flooding. Along the Scheldt estuary (Belgium), tidal marshes are restored on embanked land by allowing a controlled reduced tide (CRT) into a constructed basin, through a culvert in the embankment. In this way tidal water levels are significantly lowered (ca. 3 m) so that a CRT marsh can develop on formerly embanked land with a ca. 3 m lower elevation than the natural tidal marshes. In this study we compared the long-term change in elevation (ΔE) within a CRT marsh and adjacent natural tidal marsh. Over a period of 4 years, the observed spatio-temporal variations in ΔE rate were related to variations in inundation depth, and this relationship was not significantly different for the CRT marsh and natural tidal marsh. A model was developed to simulate the ΔE over the next century. (1) Under a scenario without mean high water level (MHWL) rise in the estuary, the model shows that the marsh elevation-ΔE feedback that is typical for a natural tidal marsh (i.e. rising marsh elevation results in decreasing inundation depth and therefore a decreasing increase in elevation) is absent in the basin of the CRT marsh. This is because tidal exchange of water volumes between the estuary and CRT marsh are independent from the CRT marsh elevation but dependent on the culvert dimensions. Thus the volume of water entering the CRT remains constant regardless of the marsh elevation. Consequently the CRT MHWL follows the increase in CRT surface elevation, resulting after 75 years in a 2–2.5 times larger elevation gain in the CRT marsh, and a faster reduction of spatial elevation differences. (2) Under a scenario of constant MHWL rise (historical rate of 1.5 cm a-1), the equilibrium elevation (relative to MHWL) is 0.13 m lower in the CRT marsh and is reached almost 2 times faster. (3) Under a scenario of

  7. Plant community composition and biomass in Gulf Coast Chenier Plain marshes: Responses to winter burning and structural marsh management

    Science.gov (United States)

    Gabrey, S.W.; Afton, A.D.

    2001-01-01

    Many marshes in the Gulf Coast Chenier Plain, USA, are managed through a combination of fall or winter burning and structural marsh management (i.e., levees and water control structures; hereafter SMM). The goals of winter burning and SMM include improvement of waterfowl and furbearer habitat, maintenance of historic isohaline lines, and creation and maintenance of emergent wetlands. Although management practices are intended to influence the plant community, effects of these practices on primary productivity have not been investigated. Marsh processes, such as vertical accretion and nutrient cycles, which depend on primary productivity may be affected directly or indirectly by winter burning or SMM. We compared Chenier Plain plant community characteristics (species composition and above- and belowground biomass) in experimentally burned and unburned control plots within impounded and unimpounded marshes at 7 months (1996), 19 months (1997), and 31 months (1998) after burning. Burning and SMM did not affect number of plant species or species composition in our experiment. For all three years combined, burned plots had higher live above-ground biomass than did unburned plots. Total above-ground and dead above-ground biomasses were reduced in burned plots for two and three years, respectively, compared to those in unburned control plots. During all three years, belowground biomass was lower in impounded than in unimpounded marshes but did not differ between burn treatments. Our results clearly indicate that current marsh management practices influence marsh primary productivity and may impact other marsh processes, such as vertical accretion, that are dependent on organic matter accumulation and decay.

  8. Intermediate to deep water hydrographic changes of the Japan Sea over the past 10 Myr, inferred from radiolarian data (IODP Exp. 346, Site U1425)

    Science.gov (United States)

    Matsuzaki, Kenji M.; Itaki, Takuya; Tada, Ryuji; Kurokawa, Shunsuke

    2017-04-01

    The Japan Sea is a back-arc basin opened under a continental rifting during the Early to Middle Miocene (ca. 25-13 Ma). This area is characterized by active tectonism, which drastically modified the Japan Sea paleogeography such as the sill depth of its key straits. In modern condition, the Japan Sea is connected to adjacent marginal seas and the Pacific Ocean by four straits shallower than 130 m. These straits are the Tsushima Strait connecting to the East China Sea, the Tsugaru Strait connecting to the Pacific, and the Soya and Mamiya Straits connecting to the Sea of Okhotsk. Therefore, the intermediate and deep water of the Japan Sea is isolated, leading the formation of a unique and regional deep sea water, known as the Japan Sea Proper Water. However, past studies show that during the late Miocene and Pliocene, only the Tsugaru Strait connecting to the North Pacific was opened. This strait was deeper during Plio-Miocene and have likely enable inflow of deep to intermediate water of the North Pacific in the Japan Sea. Radiolarians are one of the planktic micro-organisms group bearing siliceous skeletons. Their species comprise shallow to deep water dwellers, sensitive to changes in sea water physical/ecological properties forced by climate changes. Their fossils are known for be well preserved in the deep-sea sediments of the North Pacific. Therefore, in this study we propose to monitor changes in intermediate to deep water hydrography of the Japan Sea since the late Miocene, using radiolarian as an environmental proxy. In 2013 the IODP Expedition 346 retrieved sediment cores at different sites in the Japan Sea. In this study, we have analyzed 139 core sediments samples collected at Site U1425. This site is situated in the middle of the Yamato Bank. We selected this site because the past 10 Myr could be recovered continuously without hiatuses. Changes in radiolarian assemblages reveal that the oceanographic setting of the Japan Sea changed drastically at ca. 2

  9. Foraminiferal Zn/Ca: New Insights as to Glacial-Interglacial Changes in North Atlantic Deep Water Fluxes to the Southern Ocean

    Science.gov (United States)

    James, R. H.; Austin, W.; Rogers, N. W.

    2002-12-01

    The subantarctic section of the Southern Ocean is particularly suited to monitoring fluctuations in the global influence of North Atlantic Deep Water (NADW), but proxy data for past NADW fluxes into this region taken from sediment cores have yielded conflicting information. Variations in benthic foraminiferal δ13C and Nd isotope ratios in the Fe-Mn oxide component of sediments support the idea of a weakening or shutdown of NADW production during glacial times, whereas other proxies, such as Cd/Ca, Ba/Ca and 231Pa/230Th ratios, show little change from the Last Glacial Maximum (LGM) to the Holocene epoch. Because of the potential importance of deep water circulation for global climate change, it is imperative to find new tracers for reconstructing changes in water mass composition. One such tracer is Zn. Firstly, there is a particularly large (~sevenfold) increase in Zn between the deep North Atlantic and the deep South Atlantic, so Zn will be a sensitive tracer of the glacial-interglacial interactions between NADW and southern source deep waters such as Circumpolar Deep Water (CPDW). Secondly, Zn is associated with the refractory parts of planktonic material produced in surface waters, so the Zn concentration of deep waters will be less sensitive to changes in surface productivity than other proxy data (Cd and δ13C). Finally, because Zn has a long residence time in the oceans (a few thousand to tens of thousand years) relative to the estimated residence time of CPDW (~120 years), then bottom water Zn concentrations respond to changes in NADW fluxes on a sub-millenial timescale. In order to test this idea, we have measured the glacial-interglacial variation of Zn/Ca (and also Mg/Ca, Sr/Ca and Cd/Ca) in benthic foraminifera recovered from the subantarctic Southern Ocean (ODP Site 1089). Preliminary results obtained to date suggest that Zn/Ca is lower during interglacials and this is thought to reflect stronger influence of NADW (with low Zn) at this site. In

  10. A method for simulating transient ground-water recharge in deep water-table settings in central Florida by using a simple water-balance/transfer-function model

    Science.gov (United States)

    O'Reilly, Andrew M.

    2004-01-01

    A relatively simple method is needed that provides estimates of transient ground-water recharge in deep water-table settings that can be incorporated into other hydrologic models. Deep water-table settings are areas where the water table is below the reach of plant roots and virtually all water that is not lost to surface runoff, evaporation at land surface, or evapotranspiration in the root zone eventually becomes ground-water recharge. Areas in central Florida with a deep water table generally are high recharge areas; consequently, simulation of recharge in these areas is of particular interest to water-resource managers. Yet the complexities of meteorological variations and unsaturated flow processes make it difficult to estimate short-term recharge rates, thereby confounding calibration and predictive use of transient hydrologic models. A simple water-balance/transfer-function (WBTF) model was developed for simulating transient ground-water recharge in deep water-table settings. The WBTF model represents a one-dimensional column from the top of the vegetative canopy to the water table and consists of two components: (1) a water-balance module that simulates the water storage capacity of the vegetative canopy and root zone; and (2) a transfer-function module that simulates the traveltime of water as it percolates from the bottom of the root zone to the water table. Data requirements include two time series for the period of interest?precipitation (or precipitation minus surface runoff, if surface runoff is not negligible) and evapotranspiration?and values for five parameters that represent water storage capacity or soil-drainage characteristics. A limiting assumption of the WBTF model is that the percolation of water below the root zone is a linear process. That is, percolating water is assumed to have the same traveltime characteristics, experiencing the same delay and attenuation, as it moves through the unsaturated zone. This assumption is more accurate if

  11. Salt Marsh Formation in the Lower Hudson River Estuary

    Science.gov (United States)

    Merley, Michael; Peteet, Dorothy; Hansen, James E. (Technical Monitor)

    2001-01-01

    Salt marshes are constant depositional environments and as a result contain accurate indicators of past relative sea level rise and salinity. The Hudson River marshes are at least twice as deep when compared to coastal marshes on either side of the mouth of the Hudson. The reason for this difference in sedimentation is unclear. This study uses macrofossil data as well as sediment stratigraphy in order to understand the formation and evolution of these marshes. The composition of seeds, roots, shoots and foraminifera, are used to indicate past sea levels. The four sites involved in this study are, from south to north, the Arthur Kill Marsh in Staten Island (40 36 N, 74 77W), Piermont marsh (N 4100; 73 55W) Croton Point (41 14 N; 73 50W) and Iona Island (41 18N, 73 58W). These are all tidally influenced but with increasing distances from the New York Bight, which gives a good spectrum of tidal influence. AMS-C14 dates on basal macrofossils will document the time of each marsh formation. Basal material from Arthur Kill (8 m) includes freshwater seeds such as Viola, Potomageton and Alnus along with Salix buds. Basal material from Croton Point (10 m) includes fibrous woody material, foraminifera and Zanichellia seeds and other brackish vegetational components. The basal material from Piermont (13.77 m) is lacking any identifiable macrofossils between 150 and 500 microns. The basal material from Iona Island (10 m) has vegetation such as Scirpus and Cyperus seeds, probably implying a brackish environment. The freshwater origin of the Arthur Kill marsh in Staten Island is significant because it predates either sea level rise or the western channel incision. Additional implications for this study include evidence for changes in river channel geomorphology. Reasons for the relatively deeper river marshes include possible basal clay compaction, high production due to river and marine nutrients as well as tectonic activity. This study provides the groundwork for more high

  12. Modelling the long-term vertical dynamics of salt marshes

    Science.gov (United States)

    Zoccarato, Claudia; Teatini, Pietro

    2017-04-01

    Salt marshes are vulnerable environments hosting complex interactions between physical and biological processes with a strong influence on the dynamics of the marsh evolution. The estimation and prediction of the elevation of a salt-marsh platform is crucial to forecast the marsh growth or regression under different scenarios considering, for example, the potential climate changes. The long-term vertical dynamics of a salt marsh is predicted with the aid of an original finite-element (FE) numerical model accounting for the marsh accretion and compaction and for the variation rates of the relative sea level rise, i.e., land subsidence of the marsh basement and eustatic rise of the sea level. The accretion term considers the vertical sedimentation of organic and inorganic material over the marsh surface, whereas the compaction reflects the progressive consolidation of the porous medium under the increasing load of the overlying younger deposits. The modelling approach is based on a 2D groundwater flow simulator, which provides the pressure evolution within a compacting/accreting vertical cross-section of the marsh assuming that the groundwater flow obeys the relative Darcy's law, coupled to a 1D vertical geomechanical module following Terzaghi's principle of effective intergranular stress. Soil porosity, permeability, and compressibility may vary with the effective intergranular stress according to empirically based relationships. The model also takes into account the geometric non-linearity arising from the consideration of large solid grain movements by using a Lagrangian approach with an adaptive FE mesh. The element geometry changes in time to follow the deposit consolidation and the element number increases in time to follow the sedimentation of new material. The numerical model is tested on different realistic configurations considering the influence of (i) the spatial distribution of the sedimentation rate in relation to the distance from the marsh margin, (ii

  13. Environmental impacts of the deep-water oil and gas industry: a review to guide management strategies

    Directory of Open Access Journals (Sweden)

    Erik E. Cordes

    2016-09-01

    impacts: at least 2 km from any discharge points and surface infrastructure and 200 m from seafloor infrastructure with no expected discharges. Although managing natural resources is, arguably, more challenging in deep-water environments, inclusion of these proven conservation tools contributes to robust environmental management strategies for oil and gas extraction in the deep sea.

  14. Australia's deep-water octocoral fauna: historical account and checklist, distributions and regional affinities of recent collections.

    Science.gov (United States)

    Alderslade, Philip; Althaus, Franziska; Mcennulty, Felicity; Gowlett-Holmes, Karen; Williams, Alan

    2014-05-20

    The number of deep-water (>80 m) octocoral species recorded from Australian waters has more than tripled from 135 to 457 following six surveys undertaken between 1997 and 2008 on the deep continental margin of south-eastern, western and north-western Australia and the Tasman Sea.  This rapid increase in knowledge follows a slow accumulation of records since the earliest collections were made by vessels such as the Géographe and the Naturaliste in the early years of the 19 century. Consistent identification and alpha-labelling of the octocoral fauna between surveys has permitted a multi-region description and comparison.  We detail the identities, distributions and regional affinities of 457 octocoral species in 131 genera and 28 families from the orders Alcyonacea and Pennatulacea, including 69 new species, 17 new genera and 43 first records for Australia. Five of the more common genera were widely distributed (present at 35 and 66 sampling stations spanning all of the 4 survey regions), but two were restricted to south-eastern Australia-Pleurogorgia Versluys, 1902 and Tokoprymno Bayer, 1996-and were only sampled from depths below 700 m.  The great majority of species (81%) and nearly half of all genera (47%) were only sampled once or twice.  The highest average number of species per sampling station (3.2) was reported from the outer shelf. The proportion of new species was highest (22%) on the upper and lower slope bathomes, intermediate (13-15%) on the mid-slope bathome and lowest (8%) on the outer shelf bathome.  Species overlap between bathomes was low, but all families were shared across bathomes. Most described species (55 of 69) have an Indo-West Pacific affinity, 20 have an Indian Ocean affinity, while three were previously recorded from the Atlantic Ocean only; 20 appear to be Australian endemics. Octocorals can now be added to an emerging set of taxon-specific data sets-including fishes, ophiuroids and galatheids-that permit regional-scale analysis

  15. The radiation monitoring at 'The Marsh'

    International Nuclear Information System (INIS)

    Manushev, B.; Bonchev, Ts.; Minev, L.; Burin, K.; Kolev, D.; Vasilev, D.; Boshkova, T.; Gurev, V.; Asenov, I.; Mateev, A.; Georgiev, G.; Marinov, V.; Najdenov, M.; Kolchakov, I.; Manushev, E.; Gelev, M.; Koleva, K.; Gylybov, M.; Iliev, S.

    1995-01-01

    Since 1979 the Kozloduy NPP has been dumping radioactive waste waters into a canal system situated on a lowland close to the Danube river and known as 'The Marsh'. Contaminated soil strips had been located along the canals. The sites have been marked and the exposure rates on-surface and in-depth have been measured. Soil samples have been investigated by gamma-ray spectrometry and selected samples evaluated for Pt and Sr-90 content and alpha and beta radioactivity. Data on exposure rates from 4430 points have been processed. On the canal bottom the exposure rates vary from 30 to 100 μR/h and on the canal sides they exceed 100 μR/h. The main sources of activity have been identified as Cs-137 and Co-60. Results from agro-ecological characterization of the soils have been presented. The following possible ways of soil treatment and decontamination are discussed: burying the polluted earth; chemical tilling and treating with zeolites; deriving the artificial radionuclides by an appropriate crop-rotation; creating an experimental field-range; creating an wood massive; no special treatment. 16 refs., 2 tabs

  16. Coherent Microwave Scattering Model of Marsh Grass

    Science.gov (United States)

    Duan, Xueyang; Jones, Cathleen E.

    2017-12-01

    In this work, we developed an electromagnetic scattering model to analyze radar scattering from tall-grass-covered lands such as wetlands and marshes. The model adopts the generalized iterative extended boundary condition method (GIEBCM) algorithm, previously developed for buried cylindrical media such as vegetation roots, to simulate the scattering from the grass layer. The major challenge of applying GIEBCM to tall grass is the extremely time-consuming iteration among the large number of short subcylinders building up the grass. To overcome this issue, we extended the GIEBCM to multilevel GIEBCM, or M-GIEBCM, in which we first use GIEBCM to calculate a T matrix (transition matrix) database of "straws" with various lengths, thicknesses, orientations, curvatures, and dielectric properties; we then construct the grass with a group of straws from the database and apply GIEBCM again to calculate the T matrix of the overall grass scene. The grass T matrix is transferred to S matrix (scattering matrix) and combined with the ground S matrix, which is computed using the stabilized extended boundary condition method, to obtain the total scattering. In this article, we will demonstrate the capability of the model by simulating scattering from scenes with different grass densities, different grass structures, different grass water contents, and different ground moisture contents. This model will help with radar experiment design and image interpretation for marshland and wetland observations.

  17. Wave attenuation across a tidal marsh in San Francisco Bay

    Science.gov (United States)

    Foster-Martinez, Madeline R.; Lacy, Jessica; Ferner, Matthew C.; Variano, Evan A.

    2018-01-01

    Wave attenuation is a central process in the mechanics of a healthy salt marsh. Understanding how wave attenuation varies with vegetation and hydrodynamic conditions informs models of other marsh processes that are a function of wave energy (e.g. sediment transport) and allows for the incorporation of marshes into coastal protection plans. Here, we examine the evolution of wave height across a tidal salt marsh in San Francisco Bay. Instruments were deployed along a cross-shore transect, starting on the mudflat and crossing through zones dominated by Spartina foliosa and Salicornia pacifica. This dataset is the first to quantify wave attenuation for these vegetation species, which are abundant in the intertidal zone of California estuaries. Measurements were collected in the summer and winter to assess seasonal variation in wave attenuation. Calculated drag coefficients of S. foliosa and S. pacifica were similar, indicating equal amounts of vegetation would lead to similar energy dissipation; however, S. pacifica has much greater biomass close to the bed (<20 cm) and retains biomass throughout the year, and therefore, it causes more total attenuation. S. foliosa dies back in the winter, and waves often grow across this section of the marsh. For both vegetation types, attenuation was greatest for low water depths, when the vegetation was emergent. For both seasons, attenuation rates across S. pacifica were the highest and were greater than published attenuation rates across similar (Spartina alterniflora) salt marshes for the comparable depths. These results can inform designs for marsh restorations and management plans in San Francisco Bay and other estuaries containing these species.

  18. Salt-Marsh Landscapes and the Signatures of Biogeomorphic Feedbacks

    Science.gov (United States)

    D'Alpaos, A.; Marani, M.

    2014-12-01

    Salt marshes are coastal ecosystems which play a large role in the bio-geomorphological evolution of intertidal areas. The dense stands of halophytic plants which populate salt-marsh systems largely contribute to govern their dynamics, influencing marsh hydrodynamics and sediment transport through enhanced flow resistance and settling, and direct particle capture by plant stems. In addition, plants are known to increase vertical accretion through direct organic accretion. Looking across the salt-marsh landscape can one see the signatures of feedbacks between landscape and biota? Field evidence and the results of biomorphodynamic models indeed show that the interplay between physical and biological processes generates some striking biological and morphological patterns at different scales. One such pattern, vegetation zonation, consists in a mosaic of vegetation patches, of approximately uniform composition, displaying sharp transitions in the presence of extremely small topographic gradients. Here we extend the model proposed by Marani et al. (2013) to a two-dimensional framework, furthermore including the effect of direct capture of sediment particles by plant stems. This allows us to account for the effect of the drainage density of tidal networks on the observed biogeomorphic patterns and to model the coupled evolution of marsh platforms and channel networks cutting through them. A number of different scenarios have been modelled to analyze the changes induced in bio-geomorphic patterns by plants with different characteristics, within marshes characterized by different drainage densities, or subjected to changing environmental forcing such as rates of relative sea level rise and sediment supply. Model results emphasize that zonation patterns are a signature of bio-geomorphic feedbacks with vegetation acting as a landscape constructor which feeds back on, directly alters, and contributes to shape tidal environments. In addition, model results show that

  19. Oceanographic data collected during the Deep Water Corals of the Davidson Seamount 2006 expedition aboard the R/V WESTERN FLYER in the North Pacific from January 26, 2006 - February 4, 2006 (NODC Accession 0052881)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Building off the successes of an Office of Ocean Exploration (OE) expedition to Davidson Seamount in 2002, this project will focus on deep-water corals. The...

  20. Oceanographic Data collected during the Bermuda: Search for Deep Water Caves expedition on the RV Endurance in the North Atlantic Ocean between September 5, 2009 - September 30, 2009 (NODC Accession 0111205)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Deep-water marine caves are one of the Earth's last largely unexplored frontiers of undiscovered fauna (animal life). More than 150 limestone caves are known to...

  1. Vertical growth of a young back barrier salt marsh, Skallingen, SW Denmark

    DEFF Research Database (Denmark)

    Nielsen, Niels; Nielsen, Jørgen

    2002-01-01

    salt marsh, rate of sediment accretion, sea-level rise, storm surge frequency, Danish wadden sea......salt marsh, rate of sediment accretion, sea-level rise, storm surge frequency, Danish wadden sea...

  2. Salt marsh stability and patterns of sedimentation across a backbarrier platform

    DEFF Research Database (Denmark)

    Bartholdy, Anders; Bartholdy, Jesper; Kroon, Aart

    2010-01-01

    ) was measured at 32 locations across the studied salt marsh platform. It was found to correlate with two independent variables: (1) distance to marsh edge and (2) distance to creeks of 2nd or higher order. They explained in combination 71% of the variation. The derived algorithms for estimating the salt marsh...... deposition made it possible to tune in a model in a 4 by 4 m grid covering the studied salt marsh area of app 3 km2. This was used to describe the general pattern of deposition on the salt marsh platform. Running the model with a constant sea level revealed that balance between the inner and the outer salt...... marsh deposition cannot be achieved within a time scale of 1000s of years. Modeling salt marsh sedimentation under rising sea level scenarios revealed that only one specific sea level rise provides equilibrium for a given location. With a higher sea level rise, the marsh at the specific location...

  3. A Climate Change Adaptation Strategy for Management of Coastal Marsh Systems

    Science.gov (United States)

    Sea level rise is causing shoreline erosion, increased coastal flooding, and marsh vulnerability to the impact of storms. Coastal marshes provide flood abatement, carbon and nutrient sequestration, water quality maintenance, and habitat for fish, shellfish, and wildlife, includin...

  4. The 7Be profiles in the undisturbed soil used for reference site to estimate the soil erosion

    Science.gov (United States)

    Raksawong, S.; Krmar, M.; Bhongsuwan, T.

    2017-06-01

    The cosmogenic radionuclide 7Be is increasingly used to obtain information on event-related soil erosion rates within agricultural landscapes. In this study, we select two undisturbed and flat areas to calculate the reference inventory and relaxation mass depth by using 7Be technique to document short-term erosion. Our results showed that the depth distribution of 7Be in undisturbed soil profiles was 1.0 cm in sites S02 and S03; the initial activities were 31.6 and 38.8 Bq.kg-1, respectively. The relaxation mass depths were 5.4 and 7.2 kg.m-2 and the measured reference 7Be inventories were 71 and 110 Bq.m-2 for sites S02 and S03, respectively. The difference values of the relaxation mass depth and the reference inventory of both sites implied that for determining a short term soil erosion using 7Be, the reference site was suggested to be selected as close as possible to the study site.

  5. Along-dip variations of structural style in the Somali Basin deep-water fold and thrust belt (East Africa)

    Science.gov (United States)

    Cruciani, Francesco; Rinaldo Barchi, Massimiliano

    2014-05-01

    Continental passive margins are place of extended slope-failure phenomena, which can lead to the formation of gravity-driven deep-water fold and thrust belts (DW-FTBs), in regions where no far-field compressional stress is active. These giant geological features, which are confined to the sedimentary section, consist of extensional-compressional linked systems detached over a common décollement, generally salt or shales. The continental passive margin of northern Kenya and southern Somalia is an excellent and relatively unexplored site for recognizing and understanding the DW-FTBs originated over a regional shale décollement. In this study we have interpreted a 2D seismic data-set of the 1980s, hosted by Marine Geoscience Data System at Lamont-Doherty Earth Observatory of Columbia University (http://www.marine-geo.org), and recently reprocessed by ENI, in order to investigate the structural style of a DW-FTB developed offshore of northern Kenya and southern Somalia (Somali Basin). This region records the oldest sedimentary section of the Indian Ocean since the breakup of Gondwana began in the Middle-Lower Jurassic separating Madagascar from Africa. From the Upper Cretaceous to at least the Lower Miocene, the margin has been characterized by gravitational collapse leading to the formation of a DW-FTB extending more than 400 km along-strike. The northern portion of the DW-FTB is about 150 km wide, whilst in the southern portion is few tens of km wide. We analysed the northern portion along a regional seismic section. Our study represents the first detailed structural interpretation of this DW-FTB since its discovery in the 1980s. The good quality of the available reprocessed seismic data has allowed us to identify remarkable along-dip variations in the structural style. The basal detachment constantly deepens landward, in agreement with a prevailing gravity-spreading deformation process (as in the case of the Niger Delta). On the seismic data are not visible, as

  6. The persistence of endangered Florida Salt Marsh Voles in salt marshes of the central Florida Gulf Coast

    Science.gov (United States)

    Hotaling, A.S.; Percival, H.F.; Kitchens, W.M.; Kasbohm, J.W.

    2010-01-01

    Two endangered Microtus pennsylvanicus dukecampbelli (Florida Salt Marsh Vole) were captured at a new location, in February of 2009, at Lower Suwannee National Wildlife Refuge. Since the species discovery in 1979, only 43 Florida Salt Marsh Voles (hereafter FSM Vole) have been captured. Outside of the type locality, this is only the second documented location for the FSM Vole. Given the difficulty in trapping this species and the lack of information about its life history, its discovery in a new location lends itself to the possibility that it is more widespread in the Central Florida Gulf Coast than previously thought. Although much of the salt marsh in the area is in public ownership, a good deal of it has already been altered by logging or development and is threatened by global climate change. More research is needed to adequately protect and manage the habitat for the FSM Vole. A study of FSM Vole coastal salt marsh habitat could also serve as a valuable monitoring tool for subtle changes in salt marsh habitats as global climate change progresses.

  7. Lung anatomy and histology of the extant coelacanth shed light on the loss of air-breathing during deep-water adaptation in actinistians.

    Science.gov (United States)

    Cupello, Camila; Meunier, François J; Herbin, Marc; Clément, Gaël; Brito, Paulo M

    2017-03-01

    Lungs are specialized organs originated from the posterior pharyngeal cavity and considered as plesiomorphic for osteichthyans, as they are found in extant basal actinopterygians (i.e. Polypterus ) and in all major groups of extant sarcopterygians. The presence of a vestigial lung in adult stages of the extant coelacanth Latimeria chalumnae is the result of allometric growth during ontogeny, in relation with long-time adaptation to deep water. Here, we present the first detailed histological and anatomical description of the lung of Latimeria chalumnae , providing new insights into its arrested differentiation in an air-breathing complex, mainly represented by the absence of pneumocytes and of compartmentalization in the latest ontogenetic stages.

  8. Diatreme-forming volcanism in a deep-water faulted basin margin: Lower Cretaceous outcrops from the Basque-Cantabrian Basin, western Pyrenees

    Science.gov (United States)

    Agirrezabala, L. M.; Sarrionandia, F.; Carracedo-Sánchez, M.

    2017-05-01

    Deep-water diatremes and related eruption products are rare and they have been mainly interpreted from seismic-based data. We present lithofacies and geochemistry analysis of two Lower Cretaceous (Albian) deep-water diatremes and associated extra-diatreme volcaniclastic deposits at a well-exposed outcrop of the northern margin of the Basque-Cantabrian Basin (north Iberia). The studied diatremes are located along a N-S trending Albian fault and present sub-circular to elongate sections, inward-dipping steep walls and smooth to very irregular contacts with the host rocks. They are filled by un-bedded mixed breccias constituted by juvenile and lithic (sedimentary, igneous and metamorphic) clasts. Their textural and structural characteristics indicate that they represent lower diatreme and root zones of the volcanic system. Mapping, geochemical and petrologic data from diatreme-fills support their genetic relationship with the extra-diatreme volcaniclastic beds, which would be generated by the eruption of an incipiently vesicular trachytic magma. Studied diatremes result from multiple explosions that lasted over an estimated period of 65 k.y. during the Late Albian (H. varicosum ammonite Zone, pro parte), and reached up to a maximum subsurface depth of ca. 370 m, whereas extra-diatreme volcaniclastic beds were formed by eruption-fed gravity-driven flows on the deep-water (200-500 m) paleoseabed. Petrological features suggest that these diatremes and related extra-diatreme deposits resulted mainly from phreatomagmatic explosions. In addition, organic geochemistry data indicate that the thermal effect of the trachytic melts on the sedimentary host caused the conversion of the abundant organic matter to methane and CO2 gases, which could also contribute significantly to the overpressure necessary for the explosive fragmentation of the magma and the host rocks. Considering the inferred confining pressures (ca. 8-11 MPa) and the possible participation of unvesiculated (or

  9. Environmental assessment of Al-Hammar Marsh, Southern Iraq

    Directory of Open Access Journals (Sweden)

    Hind Fadhil Abdullah Al-Gburi

    2017-02-01

    Discussion and conclusions: Decreasing of Tigris and Euphrates discharges during the past decades due to drought conditions and upstream damming, as well as the increasing stress of wastewater effluents from anthropogenic activities, led to degradation of the downstream Al-Hammar Marsh water quality in terms of physical, chemical, and biological properties. As such properties were found to consistently exceed the historical and global quality objectives. However, element concentration decreasing trend at the marsh outlet station compared to other stations indicate that the marsh plays an important role as a natural filtration and bioremediation system. Higher element concentrations in winter were due to runoff from the washing of the surrounding Sabkha during flooding by winter rainstorms. Finally, the high concentrations of heavy metals in fish samples can be attributed to bioaccumulation and biomagnification processes.

  10. Does vegetation prevent wave erosion of salt marsh edges?

    Science.gov (United States)

    Feagin, R A; Lozada-Bernard, S M; Ravens, T M; Möller, I; Yeager, K M; Baird, A H

    2009-06-23

    This study challenges the paradigm that salt marsh plants prevent lateral wave-induced erosion along wetland edges by binding soil with live roots and clarifies the role of vegetation in protecting the coast. In both laboratory flume studies and controlled field experiments, we show that common salt marsh plants do not significantly mitigate the total amount of erosion along a wetland edge. We found that the soil type is the primary variable that influences the lateral erosion rate and although plants do not directly reduce wetland edge erosion, they may do so indirectly via modification of soil parameters. We conclude that coastal vegetation is best-suited to modify and control sedimentary dynamics in response to gradual phenomena like sea-level rise or tidal forces, but is less well-suited to resist punctuated disturbances at the seaward margin of salt marshes, specifically breaking waves.

  11. Radiocarbon dating of plant macrofossils from tidal-marsh sediment

    Science.gov (United States)

    Kemp, A.C.; Nelson, Alan R.; Horton, B.P.

    2013-01-01

    Tidal-marsh sediment is an archive of Holocene environmental changes, including movements of sea and land levels, and extreme events such as hurricanes, earthquakes, and tsunamis. Accurate and precise radiocarbon dating of environmental changes is necessary to estimate rates of change and the recurrence interval (frequency) of events. Plant macrofossils preserved in growth position (or deposited soon after death) in tidal-marsh sediment are ideal samples for dating such changes. In this chapter, we focus on the selection of plant macrofossils for radiocarbon dating and the application of ages from different types of macrofossils to varied research projects, and make recommendations for selection and preparation of tidal-marsh samples for dating.

  12. The impact of sheep grazing on net nitrogen mineralization rate in two temperate salt marshes

    NARCIS (Netherlands)

    Kiehl, K.; Esselink, Peter; Gettner, S; Bakker, J. P.

    Nitrogen mineralization rate was studied in grazing trials with three different stocking rates (0, 3, 10 sheep ha(-1)) in two man-made salt marshes, viz. a Puccinellia maritima-dominated low salt marsh and a high salt marsh dominated by Festuca rubra. Mineralization rates were derived from the

  13. Effects of livestock species and stocking density on accretion rates in grazed salt marshes

    NARCIS (Netherlands)

    Nolte, Stefanie; Esselink, Peter; Bakker, Jan P.; Smit, Christian

    2015-01-01

    Coastal ecosystems, such as salt marshes, are threatened by accelerated sea-level rise (SLR). Salt marshes deliver valuable ecosystem services such as coastal protection and the provision of habitat for a unique flora and fauna. Whether salt marshes in the Wadden Sea area are able to survive

  14. Tidal Creek Morphology and Sediment Type Influence Spatial Trends in Salt Marsh Vegetation

    DEFF Research Database (Denmark)

    Kim, Daehyun; Cairns, David M.; Bartholdy, Jesper

    2013-01-01

    Zonal patterns of salt marsh plants and physical conditions have been addressed primarily across the elevation gradient from inland to coastline rather than across tidal creeks in relation to their hydro-geomorphic processes such as bar formation and bank erosion. We found at a Danish marsh...... to fully understand the underlying structure and geographic variability in salt marshes....

  15. Nitrogen processing in a tidal freshwater marsh: a whole ecosystem 15N labeling study

    NARCIS (Netherlands)

    Gribsholt, B.; Boschker, H.T.S.; Struyf, E.; Andersson, M.G.I.; Tramper, A.; de Brabandere, L.; van Damme, S.; Brion, N.; Meire, P.; Dehairs, F.; Middelburg, J.J.; Heip, C.H.R.

    2005-01-01

    We quantified the fate and transport of watershed-derived ammonium in a tidal freshwater marsh fringing the nutrientrich Scheldt River in a whole-ecosystem 15N labeling experiment. 15N-NH4+ was added to the floodwater entering a 3,477 14 m2 tidal marsh area, and marsh ammonium processing and

  16. 78 FR 27989 - Bandon Marsh, Nestucca Bay, and Siletz Bay National Wildlife Refuges, Coos, Tillamook, and...

    Science.gov (United States)

    2013-05-13

    ... comments regarding the separate Bandon Marsh NWR Land Protection Planning (LPP) process will be considered...] Bandon Marsh, Nestucca Bay, and Siletz Bay National Wildlife Refuges, Coos, Tillamook, and Lincoln... Assessments (EAs) for three Oregon refuges--Bandon Marsh, Nestucca Bay, and Siletz Bay National Wildlife...

  17. Impacts of adjacent land use and isolation on marsh bird communities.

    Science.gov (United States)

    Smith, Lyndsay A; Chow-Fraser, Patricia

    2010-05-01

    Over the next half century the human population is expected to grow rapidly, resulting in the conversion of rural areas into cities. Wetlands in these regions are therefore under threat, even though they have important ecosystem services and functions. Many obligate marsh-nesting birds in North America have shown declines over the past 40 years, and it is important to evaluate marsh bird community response to increased urbanization. We surveyed 20 coastal marshes in southern Ontario, Canada, and found that obligate marsh-nesting birds preferred rural over urban wetlands, generalist marsh-nesting birds showed no preference, while synanthropic species showed a trend towards increased richness and abundance in urban marshes. The Index of Marsh Bird Community Integrity (IMBCI) was calculated for each wetland and we found significantly higher scores in rural compared to urban wetlands. The presence of a forested buffer surrounding the marsh was not an important factor in predicting the distribution of generalists, obligates, synanthropic species, or the IMBCI. More isolated marshes had a lower species richness of obligate marsh-nesters and a lower IMBCI than less isolated marshes. Based on our results, we recommend that urban land use is not the dominant land use within 1000 m from any wetland, as it negatively affects the abundance and richness of obligate marsh-nesters, and the overall integrity of the avian community. We also recommend that all existing wetlands be conserved to mitigate against isolation effects and to preserve biodiversity.

  18. Ecological structure and function in a restored versus natural salt marsh.

    Science.gov (United States)

    Rezek, Ryan J; Lebreton, Benoit; Sterba-Boatwright, Blair; Beseres Pollack, Jennifer

    2017-01-01

    Habitat reconstruction is commonly employed to restore degraded estuarine habitats and lost ecological functions. In this study, we use a combination of stable isotope analyses and macrofauna community analysis to compare the ecological structure and function between a recently constructed Spartina alterniflora salt marsh and a natural reference habitat over a 2-year period. The restored marsh was successful in providing habitat for economically and ecologically important macrofauna taxa; supporting similar or greater density, biomass, and species richness to the natural reference during all but one sampling period. Stable isotope analyses revealed that communities from the natural and the restored marshes relied on a similar diversity of food resources and that decapods had similar trophic levels. However, some generalist consumers (Palaemonetes spp. and Penaeus aztecus) were more 13C-enriched in the natural marsh, indicating a greater use of macrophyte derived organic matter relative to restored marsh counterparts. This difference was attributed to the higher quantities of macrophyte detritus and organic carbon in natural marsh sediments. Reduced marsh flooding frequency was associated with a reduction in macrofaunal biomass and decapod trophic levels. The restored marsh edge occurred at lower elevations than natural marsh edge, apparently due to reduced fetch and wind-wave exposure provided by the protective berm structures. The lower elevation of the restored marsh edge mitigated negative impacts in sampling periods with low tidal elevations that affected the natural marsh. The results of this study highlight the importance of considering sediment characteristics and elevation in salt marsh constructions.

  19. Ecological structure and function in a restored versus natural salt marsh.

    Directory of Open Access Journals (Sweden)

    Ryan J Rezek

    Full Text Available Habitat reconstruction is commonly employed to restore degraded estuarine habitats and lost ecological functions. In this study, we use a combination of stable isotope analyses and macrofauna community analysis to compare the ecological structure and function between a recently constructed Spartina alterniflora salt marsh and a natural reference habitat over a 2-year period. The restored marsh was successful in providing habitat for economically and ecologically important macrofauna taxa; supporting similar or greater density, biomass, and species richness to the natural reference during all but one sampling period. Stable isotope analyses revealed that communities from the natural and the restored marshes relied on a similar diversity of food resources and that decapods had similar trophic levels. However, some generalist consumers (Palaemonetes spp. and Penaeus aztecus were more 13C-enriched in the natural marsh, indicating a greater use of macrophyte derived organic matter relative to restored marsh counterparts. This difference was attributed to the higher quantities of macrophyte detritus and organic carbon in natural marsh sediments. Reduced marsh flooding frequency was associated with a reduction in macrofaunal biomass and decapod trophic levels. The restored marsh edge occurred at lower elevations than natural marsh edge, apparently due to reduced fetch and wind-wave exposure provided by the protective berm structures. The lower elevation of the restored marsh edge mitigated negative impacts in sampling periods with low tidal elevations that affected the natural marsh. The results of this study highlight the importance of considering sediment characteristics and elevation in salt marsh constructions.

  20. Physical and Biological Regulation of Carbon Sequestration in Tidal Marshes

    Science.gov (United States)

    Morris, J. T.; Callaway, J.

    2017-12-01

    The rate of carbon sequestration in tidal marshes is regulated by complex feedbacks among biological and physical factors including the rate of sea-level rise (SLR), biomass production, tidal amplitude, and the concentration of suspended sediment. We used the Marsh Equilibrium Model (MEM) to explore the effects on C-sequestration across a wide range of permutations of these variables. C-sequestration increased with the rate of SLR to a maximum, then down to a vanishing point at higher SLR when marshes convert to mudflats. An acceleration in SLR will increase C-sequestration in marshes that can keep pace, but at high rates of SLR this is only possible with high biomass and suspended sediment concentrations. We found that there were no feasible solutions at SLR >13 mm/yr for permutations of variables that characterize the great majority of tidal marshes, i.e., the equilibrium elevation exists below the lower vertical limit for survival of marsh vegetation. The rate of SLR resulting in maximum C-sequestration varies with biomass production. C-sequestration rates at SLR=1 mm/yr averaged only 36 g C m-2 yr-1, but at the highest maximum biomass tested (5000 g/m2) the mean C-sequestration reached 399 g C m-2 yr-1 at SLR = 14 mm/yr. The empirical estimate of C-sequestration in a core dated 50-years overestimates the theoretical long-term rate by 34% for realistic values of decomposition rate and belowground production. The overestimate of the empirical method arises from the live and decaying biomass contained within the carbon inventory above the marker horizon, and overestimates were even greater for shorter surface cores.

  1. Signatures of Biogeomorphic Feedbacks in Salt-Marsh Systems

    Science.gov (United States)

    D'Alpaos, Andrea; Marani, Marco

    2015-04-01

    Salt-marsh ecosystems which play a large role in the bio-geomorphological evolution of intertidal areas. Dense stands of halophytic vegetations which populate salt marshes largely control the dynamics of these ecosystems influencing marsh hydrodynamics and sediment transport through enhanced flow resistance and settling, and direct particle capture by plant stems. Moreover, plants are also known to increase vertical accretion through direct organic accretion. Field evidence and the results of biomorphodynamic models indeed show that the interplay between physical and biological processes generates some striking biological and morphological patterns at different scales. One such pattern, vegetation zonation, consists in a mosaic of vegetation patches, of approximately uniform composition, displaying sharp transitions in the presence of extremely small topographic gradients. Here we develop a two-dimensional model which describes the mutual interaction and adjustment between tidal flows, sediment transport and morphology mediated by vegetation influence. The model allows us describe the coupled evolution of marsh platforms and channel networks cutting through them. A number of different scenarios were modelled to analyze the changes induced in bio-geomorphic patterns by plants with different characteristics, within marshes characterized by different drainage densities, or subjected to changing environmental forcing such as rates of relative sea level rise and sediment supply. Model results emphasize that zonation patterns are a signature of bio-geomorphic feedbacks with vegetation acting as a landscape constructor which feeds back on, directly alters, and contributes to shape tidal environments. In addition, model results show that biogeomorphic feedbacks critically affect the response and the resilience of salt-marsh landscapes to changes in the environmental forcing.

  2. Assessing the Potential for Inland Migration of a Northeastern Salt Marsh

    Science.gov (United States)

    Farron, S.; FitzGerald, D.; Hughes, Z. J.

    2017-12-01

    It is often assumed that as sea level rises, salt marshes will expand inland. If the slope of the upland is relatively flat and sufficient sediment is available, marshes should be able to spread horizontally and grow vertically in order to maintain their areal extent. However, in cases where marshes are backed by steeper slopes, or sediment supply is limited, rising sea level will produce minimal gains along the landward edge insufficient to offset potential losses along the seaward edge. This study uses future sea level rise scenarios to project areal losses for the Great Marsh in Massachusetts, the largest continuous salt marsh in New England. Land area covered by salt marsh is defined by surface elevation. Annual sediment input to the system is estimated based on the areal extent of high and low marsh, historical accretion rates for each, and known organic/inorganic ratios. Unlike other studies, sediment availability is considered to be finite, and future accretion rates are limited based on the assumption that the system is presently receiving the maximum sediment input available. The Great Marsh is dominated by high marsh; as sea level rises, it will convert to low marsh, vastly altering the ecological and sedimentological dynamics of the system. If it is assumed that former high marsh areas will build vertically at the increased rate associated with low marsh, then much of the total marsh area will be maintained. However, this may be an unrealistic assumption due to the low levels of suspended sediment within the Great Marsh system. Modeling the evolution of the Great Marsh by assuming that the current accretion rate is the maximum possible for this system reveals much greater losses than models assuming an unlimited sediment supply would predict (17% less marsh by 2115). In addition, uplands surrounding the Great Marsh have been shaped by glaciation, leaving numerous drumlins and other glacial landforms. Compared to the flat backbarrier, the surrounding

  3. Groundwater controls ecological zonation of salt marsh macrophytes.

    Science.gov (United States)

    Wilson, Alicia M; Evans, Tyler; Moore, Willard; Schutte, Charles A; Joye, Samantha B; Hughes, Andrea H; Anderson, Joseph L

    2015-03-01

    Ecological zonation of salt marsh macrophytes is strongly influenced by hydrologic factors, but these factors are poorly understood. We examined groundwater flow patterns through surficial sediments in two saltmarshes in the southeastern United States to quantify hydrologic differences between distinct ecological zones. Both sites included tall- or medium-form Spartina alterniflora near the creek bank; short-form Spartina alterniflora in the mid-marsh; salt flats and Salicornia virginica in the high marsh; and Juncus roemarianus in brackish-to-fresh areas adjacent to uplands. Both sites had relatively small, sandy uplands and similar stratigraphy consisting of marsh muds overlying a deeper sand layer. We found significant hydrologic differences between the four ecological zones. In the zones colonized by S. alterniflora, the vertical flow direction oscillated with semi-diurnal tides. Net flow (14-day average) through the tall S. alterniflora zones was downward, whereas the short S. alterniflora zones included significant periods of net upward groundwater flow. An examination of tidal efficiency at these sites suggested that the net flow patterns rather than tidal damping controlled the width of the tall S. alterniflora zone. In contrast to the S. alterniflora zones, hypersaline zones populated by S. virginica were characterized by sustained periods (days) of continuous upward flow of saline water during neap tides. The fresher zone populated by J. roemarianus showed physical flow patterns that were similar to the hypersaline zones, but the upwelling porewaters were fresh rather than saline. These flow patterns were influenced by the hydrogeologic framework of the marshes, particularly differences in hydraulic head between the upland water table and the tidal creeks. We observed increases in hydraulic head of approximately 40 cm from the creek to the upland in the sand layers below both marshes, which is consistent with previous observations that sandy aquifers

  4. Salt marsh stability modelled in relation to sea level rise

    DEFF Research Database (Denmark)

    Bartholdy, Jesper; Bartholdy, Anders; Kroon, Aart

    2010-01-01

    Accretion on a natural backbarrier salt marsh was modeled as a function of high tide level, initial salt marsh level and distance to the source. Calibration of the model was based on up to ca 80 year old marker horizons, supplemented by 210Pb/137Cs datings and subsequent measurements of clay...... that mass depth down core can be directly related to the bulk dry density of the surface layer by means of a logarithmic function. The results allow for an evaluation of the use of marker horizons in the topmost layers and show that it is important to know the level of the marker in relation to the salt...

  5. Salt Marsh Ecosystem Responses to Restored Tidal Connectivity across a 14y Chronosequence

    Science.gov (United States)

    Capooci, M.; Spivak, A. C.; Gosselin, K.

    2016-02-01

    Salt marshes support valuable ecosystem services. Yet, human activities negatively impact salt marsh function and contribute to their loss at a global scale. On Cape Cod, MA, culverts and impoundments under roads and railways restricted tidal exchange and resulted in salt marsh conversion to freshwater wetlands. Over the past 14 y, these structures have been removed or replaced, restoring tidal connectivity between marshes and a saltwater bay. We evaluated differences in plant community composition, sediment properties, and pore water chemistry in marshes where tidal connectivity was restored using a space-for-time, or chronosequence approach. Each restored marsh was paired with a nearby, natural salt marsh to control for variability between marshes. In each restored and natural salt marsh we evaluated the plant community by measuring species-specific percent cover and biomass and collected sediment cores for bulk density and pore water analyses. Plant communities responded rapidly: salt-tolerant species, such as Spartina alterniflora, became established while freshwater species, including Phragmites australis, were less abundant within 3 y of restoration. The number of plant species was generally greater in marshes restored within 10 y, compared to older and natural marshes. Sediment bulk density varied with depth and across sites. This likely reflects differences in site history and local conditions. Deeper horizons (24-30cm) generally had higher values in restored sites while surface values (0-3cm) were similar in restored and natural marshes. Porewater pH and sulfide were similar in restored and natural marshes, suggesting rapid microbial responses to seawater reintroduction. Overall, marsh properties and processes reflecting biological communities responded rapidly to tidal restoration. However, variability between study locations underscores the potential importance of site history, local hydrology, and geomorphology in shaping marsh biogeochemistry.

  6. Phenological Impacts of Hurricane Katrina (2005) and Gustav (2008) on Louisiana Coastal Marshes

    Science.gov (United States)

    Mo, Y.; Kearney, M.; Riter, A.

    2015-12-01

    Coastal marshes provide indispensable ecological functions, such as offering habitat for economic fish and wildlife, improving water quality, protecting inland areas from floods, and stabilizing the shoreline. Hurricanes—though helping to maintain the elevation of coastal wetlands by depositing large amounts of sediments—pose one of the largest threats for coastal marshes in terms of eroding shorelines, scouring marsh surfaces, and resuspending sediments. Coastal marshes phenologies can be important for understanding broad response of marshes to stressors, like hurricanes. We investigated the phenological impacts of Katrina and Gustav (Category 3 and 2 hurricanes at landfall in southeast Louisiana on 29 August, 2005, and 1 September, 2008, respectively) on freshwater, intermediate, brackish, and saline marshes in southeastern Louisiana. Landsat-derived Normalized Difference Vegetation Index data were processed using ENVI 4.8. Phenological patterns of the marshes were modeled using a nonlinear mixed model using SAS 9.4. We created and compared marsh phenologies of 1994 and 2014, the reference years, to those of 2005 and 2008, the hurricane years. Preliminary results show that in normal years: (1) the NDVI of four marsh types peaked in July; (2) freshwater marshes had the highest peak NDVI, followed by intermediate, brackish, and saline marshes; and (3) the growth durations of the marshes are around three to six months. In 2005, the major phenological change was shortening of growth duration, which was most obvious for intermediate and brackish marshes. The peak NDVI values of the four marsh types were not affected because the hurricane occurred at the end of August, one month after the peak NDVI time. By comparison, there was no obvious phenological impact on the marshes by Gustav (2008) with respect to peak NDVI, peak NDVI day, and growth duration.

  7. North Atlantic Deep Water export to the Southern Ocean over the past 14 Myr: Evidence from Nd and Pb isotopes in ferromanganese crusts

    Science.gov (United States)

    Frank, M.; Whiteley, N.; Kasten, S.; Hein, J.R.; O'Nions, K.

    2002-01-01

    The intensity of North Atlantic Deep Water (NADW) production has been one of the most important parameters controlling the global thermohaline ocean circulation system and climate. Here we present a new approach to reconstruct the overall strength of NADW export from the North Atlantic to the Southern Ocean over the past 14 Myr applying the deep water Nd and Pb isotope composition as recorded by ferromanganese crusts and nodules. We present the first long-term Nd and Pb isotope time series for deep Southern Ocean water masses, which are compared with previously published time series for NADW from the NW Atlantic Ocean. These data suggest a continuous and strong export of NADW, or a precursor of it, into the Southern Ocean between 14 and 3 Ma. An increasing difference in Nd and Pb isotope compositions between the NW Atlantic and the Southern Ocean over the past 3 Myr gives evidence for a progressive overall reduction of NADW export since the onset of Northern Hemisphere glaciation (NHG). The Nd isotope data allow us to assess at least semiquantitatively that the amount of this reduction has been in the range between 14 and 37% depending on location.

  8. An approach to operational risk modeling and estimation of safety levels for deep water work class remotely operated vehicle—A case study with reference to ROSUB 6000

    Directory of Open Access Journals (Sweden)

    N. Vedachalam

    2016-04-01

    Full Text Available This paper presents a quantitative approach to operational risk modeling and estimation of safety integrity levels, required for the deep water electric work class remotely operated vehicle with reference to ROSUB6000 developed by the National Institute of Ocean Technology, India. ROSUB6000 is used for carrying out bathymetric surveys, gas hydrate surveys, poly-metallic nodule exploration, salvage operations, and meeting emergency response situations. The system is expected to be in operation for a period of 300h per year, and has to be extremely safe and reliable. Methods and models for the quantitative assessment of operational safety and estimation of safety integrity levels for ROV are seldom available in the deep water intervention industry. The safety instrumented functions implemented in the ROV should be able to meet the SIL requirements of specific mission. This study indicates that the required safety factors are implemented into the design of the state-of-the-art ROV ROSUB 6000, considering IEC 61508/61511 recommendations on Health, Safety and Environment and it is found that the system is able to meet the required SIL for seven identified functions. This paper gives the design and safety engineers in the ROV industry, an overview of the numerical operational risk assessment methods and safety-centered ROV engineering.

  9. Observation of oxygen ventilation into deep waters through targeted deployment of multiple Argo-O2 floats in the north-western Mediterranean Sea in 2013

    Science.gov (United States)

    Coppola, L.; Prieur, L.; Taupier-Letage, I.; Estournel, C.; Testor, P.; Lefevre, D.; Belamari, S.; LeReste, S.; Taillandier, V.

    2017-08-01

    During the winter 2013, an intense observation and monitoring was performed in the north-western Mediterranean Sea to study deep water formation process that drives thermohaline circulation and biogeochemical processes (HYMEX SOP2 and DEWEX projects). To observe intensively and continuously the impact of deep convection on oxygen (O2) ventilation, an observation strategy was based on the enhancement of the Argo-O2 floats to monitor the offshore dense water formation area (DWF) in the Gulf of Lion prior to and at the end of the convective period (December 2012 to April 2013). The intense O2 measurements performed through shipborne CTD casts and Argo-O2 floats deployment revealed an O2 inventory rapidly impacted by mixed layer (ML) deepening on the month scale. The open-sea convection in winter 2013 ventilated the deep waters from mid-February to the end of May 2013. The newly ventilated dense water volume, based on an Apparent Oxygen Utilization (AOU) threshold, was estimated to be about 1.5 × 1013 m3 during the DWF episode, increasing the deep O2 concentrations from 196 to 205 µmol kg-1 in the north-western basin.

  10. Persistence and movement of atrazine in a salt marsh sediment microecosystem

    International Nuclear Information System (INIS)

    Isensee, A.R.

    1987-01-01

    Pesticides enter salt marshes in runoff from agricultural lands or through direct or near-by application. Concern has been raised that the tidal action in the salt marsh that functions to trap sediment and nutrients may also function to concentrate pesticides to harmful levels. Studies have been conducted to evaluate the effect of pesticides on representative species of salt marsh ecosystems. This paper describes the use of a modified salt marsh microecosystem to evaluate persistence and movement of atrazine in salt marsh sediment under simulated tidal flux and continuous flooding conditions. Atrazine persistence was also compared under normal field conditions

  11. Determination Of Reference-Site Based On The Cs-137 Distribution At Soil Layer From A Few Undisturbed Location

    International Nuclear Information System (INIS)

    Suhartini, Nita; Darman; Haryono; Djarot, A.S.

    2000-01-01

    Radiogenic 137 Cs content of a soil used to estimate the amount of erosion in area, with respect to a reference site. The investigation aimed to determined the reference-site from several of undisturbed locations based on the 137 Cs distribution of the soil layer. The location are a forest at West Java, namely Gn Pangrango - Cibodas, Gn. Masigit Kareumbi and Gn. Kamojang Garut. The points sampling were chosen at an open and very flat area where the possibility of erosion is very low. The samples were taken using Scrapper (20x50) cm, and the layer thickness is 2 cm with sampling depth is 20 cm. The result showed that the best location which could be used as a reference-site is the forest ata Gn. Pangranggo - Cibodas, having the men value of 137 Cs activity is 520 Bq/m 2

  12. Sedimentation and response to sea-level rise of a restored marsh with reduced tidal exchange: Comparison with a natural tidal marsh

    OpenAIRE

    Vandenbruwaene, W.; Maris, T.; Cox, T.J.S.; Cahoon, D.R.; Meire, P.; Temmerman, S.

    2011-01-01

    Along coasts and estuaries, formerly embanked land is increasingly restored into tidal marshes in order to re-establish valuable ecosystem services, such as buffering against flooding. Along the Scheldt estuary (Belgium), tidal marshes are restored on embanked land by allowing a controlled reduced tide (CRT) into a constructed basin, through a culvert in the embankment. In this way tidal water levels are significantly lowered (ca. 3 m) so that a CRT marsh can develop on formerly embanked land...

  13. Effect of pore water velocities and solute input methods on chloride transport in the undisturbed soil columns of Loess Plateau

    Science.gov (United States)

    Zhou, BeiBei; Wang, QuanJiu

    2017-09-01

    Studies on solute transport under different pore water velocity and solute input methods in undisturbed soil could play instructive roles for crop production. Based on the experiments in the laboratory, the effect of solute input methods with small pulse input and large pulse input, as well as four pore water velocities, on chloride transport in the undisturbed soil columns obtained from the Loess Plateau under controlled condition was studied. Chloride breakthrough curves (BTCs) were generated using the miscible displacement method under water-saturated, steady flow conditions. Using the 0.15 mol L-1 CaCl2 solution as a tracer, a small pulse (0.1 pore volumes) was first induced, and then, after all the solution was wash off, a large pulse (0.5 pore volumes) was conducted. The convection-dispersion equation (CDE) and the two-region model (T-R) were used to describe the BTCs, and their prediction accuracies and fitted parameters were compared as well. All the BTCs obtained for the different input methods and the four pore water velocities were all smooth. However, the shapes of the BTCs varied greatly; small pulse inputs resulted in more rapid attainment of peak values that appeared earlier with increases in pore water velocity, whereas large pulse inputs resulted in an opposite trend. Both models could fit the experimental data well, but the prediction accuracy of the T-R was better. The values of the dispersivity, λ, calculated from the dispersion coefficient obtained from the CDE were about one order of magnitude larger than those calculated from the dispersion coefficient given by the T-R, but the calculated Peclet number, Pe, was lower. The mobile-immobile partition coefficient, β, decreased, while the mass exchange coefficient increased with increases in pore water velocity.

  14. Inventories and concentration profiles of 137Cs in undisturbed soils in the northeast of Buenos Aires Province, Argentina

    International Nuclear Information System (INIS)

    Montes, M.L.; Silva, L.M.S.; Sá, C.S.A.; Runco, J.; Taylor, M.A.; Desimoni, J.

    2013-01-01

    Inventories and vertical distribution of 137 Cs were determined in La Plata region undisturbed soils, Argentina. A mean inventory value of 891 ± 220 Bq/m 2 was established, which is compatible with the values expected from atmospheric weapon tests fallout. The study was complemented with pH, organic carbon fraction, texture and mineralogical soil analyses. Putting together Southern Hemisphere 137 Cs inventory data, it is possible to correlate these data with the mean annual precipitations. The large differences in 137 Cs concentration profiles were attributed to soil properties, especially the clay content and the pH values. A convection–dispersion model with irreversible retention was used to fit the activity concentration profiles. The obtained effective diffusion coefficient and effective convection velocity parameters values were in the range from 0.2 cm 2 /y to 0.4 cm 2 /y and from 0.23 cm/y to 0.43 cm/y, respectively. These data are in agreement with values reported in literature. In general, with the growth of clay content in the soil, there was an increase in the transfer rate from free to bound state. Finally, the highest transfer rate from free to bound state was obtained for soil pH value equal to 8. - Highlights: ► Inventories and vertical distribution of 137 Cs were determined in undisturbed soils of La Plata city region, Argentina. ► The study was complemented with soil analyses of pH, organic carbon, texture and mineralogy. ► Inventory data were correlated with the mean annual precipitations. ► Concentration profile differences were attributed to soil properties, especially the clay content and the pH value. ► A convection–dispersion model with irreversible retention was used to fit the measured 137 Cs concentration profiles.

  15. Dissolved rainfall inputs and streamwater outputs in an undisturbed watershed on highly weathered soils in the Brazilian cerrado

    Science.gov (United States)

    Markewitz, Daniel; Resende, Julio C. F.; Parron, Lucilia; Bustamante, Mercedes; Klink, Carlos A.; Figueiredo, Ricardo De O.; Davidson, Eric A.

    2006-08-01

    The cerrados of Brazil cover 2 million km2. Despite the extent of these seasonally dry ecosystems, little watershed research has been focused in this region, particularly relative to the watersheds of the Amazon Basin. The cerrado shares pedogenic characteristics with the Amazon Basin in draining portions of the Brazilian shield and in possessing Oxisols over much of the landscape. The objective of this research was to quantify the stream water geochemical relationships of an undisturbed 1200 ha cerrado watershed for comparison to river geochemistry in the Amazon. Furthermore, this undisturbed watershed was used to evaluate stream discharge versus dissolved ion concentration relationships. This research was conducted in the Córrego Roncador watershed of the Reserva Ecológica do Roncador (RECOR) of the Instituto Brasileiro Geografia e Estatística (IBGE) near Brasilia, Brazil. Bulk precipitation and stream water chemistry were analysed between May 1998 and May 2000. The upland soils of this watershed are nutrient poor possessing total stocks of exchangeable elements in the upper 1 m of 81 +/- 13, 77 +/- 4, 25 +/- 3, and 1 +/- 1 kg ha-1 of K, Ca, Mg, and P, respectively. Bulk precipitation inputs of dissolved nutrients for this watershed are low and consistent with previous estimates. The nutrient-poor soils of this watershed, however, increase the relative importance of precipitation for nutrient replenishment to vegetation during episodes of ecosystem disturbance. Stream water dissolved loads were extremely dilute with conductivities ranging from 4 to 10 μS cm-1 during periods of high- and low-flow, respectively. Despite the low concentrations in this stream, geochemical relationships were similar to other Amazonian streams draining shield geologies. Discharge-concentration relationships for Ca and Mg in these highly weathered soils developed from igneous rocks of the Brazilian shield demonstrated a significant negative relationship indicating a continued

  16. Deep-water turbidites as Holocene earthquake proxies: the Cascadia subduction zone and Northern San Andreas Fault systems

    Directory of Open Access Journals (Sweden)

    J. E. Johnson

    2003-06-01

    Full Text Available New stratigraphic evidence from the Cascadia margin demonstrates that 13 earthquakes ruptured the margin from Vancouver Island to at least the California border following the catastrophic eruption of Mount Mazama. These 13 events have occurred with an average repeat time of ?? 600 years since the first post-Mazama event ?? 7500 years ago. The youngest event ?? 300 years ago probably coincides with widespread evidence of coastal subsidence and tsunami inundation in buried marshes along the Cascadia coast. We can extend the Holocene record to at least 9850 years, during which 18 events correlate along the same region. The pattern of repeat times is consistent with the pattern observed at most (but not all localities onshore, strengthening the contention that both were produced by plate-wide earthquakes. We also observe that the sequence of Holocene events in Cascadia may contain a repeating pattern, a tantalizing look at what may be the long-term behavior of a major fault system. Over the last ?? 7500 years, the pattern appears to have repeated at least three times, with the most recent A.D. 1700 event being the third of three events following a long interval of 845 years between events T4 and T5. This long interval is one that is also recognized in many of the coastal records, and may serve as an anchor point between the offshore and onshore records. Similar stratigraphic records are found in two piston cores and one box core from Noyo Channel, adjacent to the Northern San Andreas Fault, which show a cyclic record of turbidite beds, with thirty- one turbidite beds above a Holocene/.Pleistocene faunal «datum». Thus far, we have determined ages for 20 events including the uppermost 5 events from these cores. The uppermost event returns a «modern» age, which we interpret is likely the 1906 San Andreas earthquake. The penultimate event returns an intercept age of A.D. 1664 (2 ?? range 1505- 1822. The third event and fourth event

  17. Gulf-Wide Information System, Environmental Sensitivity Index Intermediate Marsh, Geographic NAD83, LDWF (2001) [esi_intermediate_marsh_LDWF_2001

    Data.gov (United States)

    Louisiana Geographic Information Center — This data set contains Environmental Sensitivity Index (ESI) intermediate marshes data of coastal Louisiana. The ESI is a classification and ranking system, which...

  18. Gulf-Wide Information System, Environmental Sensitivity Index Brackish Marsh, Geographic NAD83, LDWF (2001) [esi_brackish_marsh_LDWF_2001

    Data.gov (United States)

    Louisiana Geographic Information Center — This data set contains Environmental Sensitivity Index (ESI) brackish marshes data of coastal Louisiana. The ESI is a classification and ranking system, which...

  19. Numerical models of salt marsh evolution: ecological, geomorphic, and climatic factors

    Science.gov (United States)

    Fagherazzi, Sergio; Kirwan, Matthew L.; Mudd, Simon M.; Guntenspergen, Glenn R.; Temmerman, Stijn; D'Alpaos, Andrea; van de Koppel, Johan; Rybczyk, John; Reyes, Enrique; Craft, Chris; Clough, Jonathan

    2012-01-01

    Salt marshes are delicate landforms at the boundary between the sea and land. These ecosystems support a diverse biota that modifies the erosive characteristics of the substrate and mediates sediment transport processes. Here we present a broad overview of recent numerical models that quantify the formation and evolution of salt marshes under different physical and ecological drivers. In particular, we focus on the coupling between geomorphological and ecological processes and on how these feedbacks are included in predictive models of landform evolution. We describe in detail models that simulate fluxes of water, organic matter, and sediments in salt marshes. The interplay between biological and morphological processes often produces a distinct scarp between salt marshes and tidal flats. Numerical models can capture the dynamics of this boundary and the progradation or regression of the marsh in time. Tidal channels are also key features of the marsh landscape, flooding and draining the marsh platform and providing a source of sediments and nutrients to the marsh ecosystem. In recent years, several numerical models have been developed to describe the morphogenesis and long-term dynamics of salt marsh channels. Finally, salt marshes are highly sensitive to the effects of long-term climatic change. We therefore discuss in detail how numerical models have been used to determine salt marsh survival under different scenarios of sea level rise.

  20. Critical width of tidal flats triggers marsh collapse in the absence of sea-level rise.

    Science.gov (United States)

    Mariotti, Giulio; Fagherazzi, Sergio

    2013-04-02

    High rates of wave-induced erosion along salt marsh boundaries challenge the idea that marsh survival is dictated by the competition between vertical sediment accretion and relative sea-level rise. Because waves pounding marshes are often locally generated in enclosed basins, the depth and width of surrounding tidal flats have a pivoting control on marsh erosion. Here, we show the existence of a threshold width for tidal flats bordering salt marshes. Once this threshold is exceeded, irreversible marsh erosion takes place even in the absence of sea-level rise. This catastrophic collapse occurs because of the positive feedbacks among tidal flat widening by wave-induced marsh erosion, tidal flat deepening driven by wave bed shear stress, and local wind wave generation. The threshold width is determined by analyzing the 50-y evolution of 54 marsh basins along the US Atlantic Coast. The presence of a critical basin width is predicted by a dynamic model that accounts for both horizontal marsh migration and vertical adjustment of marshes and tidal flats. Variability in sediment supply, rather than in relative sea-level rise or wind regime, explains the different critical width, and hence erosion vulnerability, found at different sites. We conclude that sediment starvation of coastlines produced by river dredging and damming is a major anthropogenic driver of marsh loss at the study sites and generates effects at least comparable to the accelerating sea-level rise due to global warming.

  1. Regeneration of plants from Fraxinus nigra Marsh. hypocotyls

    Science.gov (United States)

    Rochelle R. Beasley; Paula M. Pijut

    2013-01-01

    Fraxinus nigra Marsh. (black ash) is a native North American hardwood tree species that is ecologically important and has ethnobotanical significance to American Indian communities of the eastern United States. Black ash has immature embryos at seed set, combined with complex stratification requirements, making natural regeneration difficult. This,...

  2. Impacts of intensified agriculture developments on marsh wetlands.

    Science.gov (United States)

    Luan, Zhaoqing; Zhou, Demin

    2013-01-01

    A spatiotemporal analysis on the changes in the marsh landscape in the Honghe National Nature Reserve, a Ramsar reserve, and the surrounding farms in the core area of the Sanjiang Plain during the past 30 years was conducted by integrating field survey work with remote sensing techniques. The results indicated that intensified agricultural development had transformed a unique natural marsh landscape into an agricultural landscape during the past 30 years. Ninety percent of the natural marsh wetlands have been lost, and the areas of the other natural landscapes have decreased very rapidly. Most dry farmland had been replaced by paddy fields during the progressive change of the natural landscape to a farm landscape. Attempts of current Chinese institutions in preserving natural wetlands have achieved limited success. Few marsh wetlands have remained healthy, even after the establishment of the nature reserve. Their ecological qualities have been declining in response to the increasing threats to the remaining wetland habitats. Irrigation projects play a key role in such threats. Therefore, the sustainability of the natural wetland ecosystems is being threatened by increased regional agricultural development which reduced the number of wetland ecotypes and damaged the ecological quality.

  3. Responses of Salt Marsh Plant Rhizosphere Diazotroph Assemblages to Drought

    Directory of Open Access Journals (Sweden)

    Debra A. Davis

    2018-03-01

    Full Text Available Drought has many consequences in the tidally dominated Spartina sp. salt marshes of the southeastern US; including major dieback events, changes in sediment chemistry and obvious changes in the landscape. These coastal systems tend to be highly productive, yet many salt marshes are also nitrogen limited and depend on plant associated diazotrophs as their source of ‘new’ nitrogen. A 4-year study was conducted to investigate the structure and composition of the rhizosphere diazotroph assemblages associated with 5 distinct plant zones in one such salt marsh. A period of greatly restricted tidal inundation and precipitation, as well as two periods of drought (June–July 2004, and May 2007 occurred during the study. DGGE of nifH PCR amplicons from rhizosphere samples, Principal Components Analysis of the resulting banding patterns, and unconstrained ordination analysis of taxonomic data and environmental parameters were conducted. Diazotroph assemblages were organized into 5 distinct groups (R2 = 0.41, p value < 0.001 whose presence varied with the environmental conditions of the marsh. Diazotroph assemblage group detection differed during and after the drought event, indicating that persistent diazotrophs maintained populations that provided reduced supplies of new nitrogen for vegetation during the periods of drought.

  4. Avifauna of Vwaza Marsh Wildlife Reserve, Malawi | Engel | Journal ...

    African Journals Online (AJOL)

    Despite having a well-documented avifauna, some areas of Malawi, such as Vwaza Marsh Wildlife Reserve (986 km²), are still poorly known ornithologically. We spent 12 days in October 2009, before the wet season, and two days in November 2009, after the first rains, documenting the birds of Vwaza. We found six new ...

  5. Impacts of Intensified Agriculture Developments on Marsh Wetlands

    Directory of Open Access Journals (Sweden)

    Zhaoqing Luan

    2013-01-01

    Full Text Available A spatiotemporal analysis on the changes in the marsh landscape in the Honghe National Nature Reserve, a Ramsar reserve, and the surrounding farms in the core area of the Sanjiang Plain during the past 30 years was conducted by integrating field survey work with remote sensing techniques. The results indicated that intensified agricultural development had transformed a unique natural marsh landscape into an agricultural landscape during the past 30 years. Ninety percent of the natural marsh wetlands have been lost, and the areas of the other natural landscapes have decreased very rapidly. Most dry farmland had been replaced by paddy fields during the progressive change of the natural landscape to a farm landscape. Attempts of current Chinese institutions in preserving natural wetlands have achieved limited success. Few marsh wetlands have remained healthy, even after the establishment of the nature reserve. Their ecological qualities have been declining in response to the increasing threats to the remaining wetland habitats. Irrigation projects play a key role in such threats. Therefore, the sustainability of the natural wetland ecosystems is being threatened by increased regional agricultural development which reduced the number of wetland ecotypes and damaged the ecological quality.

  6. Burrowing and foraging activity of marsh crabs under different ...

    Science.gov (United States)

    New England salt marshes are susceptible to degradation and habitat loss as a result of increased periods of inundation as sea levels rise. Increased inundation may exacerbate marsh degradation that can result from crab burrowing and foraging. Most studies to date have focused on how crab burrowing and foraging can impact the dominant low marsh plant species, Spartina alterniflora. Here we used a mesocosm experiment to examine the relationship of foraging and burrowing activity in two dominant New England crab species, Sesarma reticulatum and Uca pugilator, and the combined effect of inundation, on the dominant high marsh plant species Spartina patens using a 3 × 2 factorial design with three crab treatments (Sesarma, Uca, control) at two levels of inundation (low, high). Plants were labeled with a nitrogen (N) stable isotope tracer to estimate plant consumption by the two crab species. At both levels of inundation, we found that S. reticulatum had a significant negative impact on both above- and below-ground biomass by physically clipping and uprooting the plants, whereas U. pugilator had no significant impact. Low inundation treatments for both crab species had significantly greater aboveground biomass than high inundation. Stable N isotope tracer levels were roughly the same for both S. reticulatum and U. pugilator tissue, suggesting that the impact of S. reticulatum on S. patens was not through consumption of the plants. Overall, our results suggest the pot

  7. Medieval reclamation and colonization of marginal land on Romney Marsh

    Directory of Open Access Journals (Sweden)

    Luke Barber

    1999-11-01

    Full Text Available Since 1991 the UCL Field Archaeology Unit (UCLFAU has been investigating the settlement pattern and landscape history of part of Romney Marsh in Kent, revealed by gravel extraction at Lydd Quarry. The project manager describes the work and shows how it is contributing to our knowledge of rural life in medieval England.

  8. Medieval reclamation and colonization of marginal land on Romney Marsh

    OpenAIRE

    Luke Barber

    1999-01-01

    Since 1991 the UCL Field Archaeology Unit (UCLFAU) has been investigating the settlement pattern and landscape history of part of Romney Marsh in Kent, revealed by gravel extraction at Lydd Quarry. The project manager describes the work and shows how it is contributing to our knowledge of rural life in medieval England.

  9. A simple, dynamic, hydrological model of a mesotidal salt marsh

    Science.gov (United States)

    Salt marsh hydrology presents many difficulties from a modeling standpoint: the bi-directional flows of tidal waters, variable water densities due to mixing of fresh and salt water, significant influences from vegetation, and complex stream morphologies. Because of these difficu...

  10. Temperature sensitivity of organic-matter decay in tidal marshes

    Science.gov (United States)

    Kirwan, Matthew L.; Guntenspergen, Glenn R.; Langley, J.A.

    2014-01-01

    Approximately half of marine carbon sequestration takes place in coastal wetlands, including tidal marshes, where organic matter contributes to soil elevation and ecosystem persistence in the face of sea-level rise. The long-term viability of marshes and their carbon pools depends, in part, on how the balance between productivity and decay responds to climate change. Here, we report the sensitivity of labile soil organic-matter decay in tidal marshes to seasonal and latitudinal variations in temperature measured over a 3-year period. We find a moderate increase in decay rate at warmer temperatures (3-6% per °C, Q10 = 1.3-1.5). Despite the profound differences between microbial metabolism in wetlands and uplands, our results indicate a strong conservation of temperature sensitivity. Moreover, simple comparisons with organic-matter production suggest that elevated atmospheric CO2 and warmer temperatures will accelerate carbon accumulation in marsh soils, and potentially enhance their ability to survive sea-level rise.

  11. Meiobenthos of Saphala salt marsh, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Ingole, B.S.; Ansari, Z.A.; Parulekar, A.H.

    Benthic fauna of the salt marsh comprised 10 taxonomic groups, dominated by nematodes (63.9%), harpacticoids (18.5%), turbellaria (5.6%), crustacean nauplii (5.4%) and polychaetes (4.1%). The population density varied from 282 to 17300 (10 cm)-2...

  12. Natural gas geological characteristics and great discovery of large gas fields in deep-water area of the western South China Sea

    Directory of Open Access Journals (Sweden)

    Zhenfeng Wang

    2015-12-01

    Full Text Available To accelerate the petroleum exploration in deep sea of China, since the period of “the 11th Five-Year Plan”, the sedimentary process, source rock formation and hydrocarbon generation and expulsion process in deep-water area of the Qiongdongnan Basin in the western South China Sea have been studied systematically using the data like large-area 3D seismic survey, logging, drill core (cuttings and geochemical analysis, providing three innovative understandings, i.e. excellent hydrocarbon source conditions, good accumulation conditions, and grouping and zonal distribution of large exploration targets. From the study, the following conclusions are drawn. First, the deep-water area located in the southern and central parts of the Qiongdongnan Basin was formed under the control of such tectonic events as Indosinian–Eurasian Plate collision, Himalayan uplifting and South China Sea expansion, and experienced Paleogene lift and Neogene depression stages. Second, accompanied by lacustrine deposition, faulting activity was violent in Eocene; whereas in Early Oligocene, rift continued to develop under a sedimentary environment of marine–terrestrial transitional facies and littoral-neritic facies. Third, oil generation predominated Eocene lacustrine mudstone and gas generation predominated Lower Oligocene marine–terrestrial transitional facies coal-measure strata compose two sets of major source rocks. Fourth, analysis in respect of thermal evolution level, hydrocarbon generation volume and hydrocarbon generation intensity shows that Ledong, Lingshui, Baodao and Changchang sags belong to potential hydrocarbon-rich kitchens, among which Ledong and Lingshui sags have been proved to have great hydrocarbon generation potential by drilling. Fifth, researches of deep-water sedimentology and hydrocarbon accumulation dynamics reveal that Paleogene and Neogene plays are developed vertically, and favorable hydrocarbon accumulation zones like the Central

  13. Modeling Stratigraphic Architecture of Deep-water Deposits Using a Small Unmanned Aircraft: Neogene Thin-bedded Turbidites, East Coast Basin, New Zealand

    Science.gov (United States)

    Nieminski, N.; Graham, S. A.

    2014-12-01

    One of the outstanding challenges of field geology is inaccessibility of exposure. The ability to view and characterize outcrops that are difficult to study from the ground is greatly improved by aerial investigation. Detailed stratigraphic architecture of such exposures is best addressed by using advances and availability of small unmanned aircraft systems (sUAS) that can safely navigate from high-altitude overviews of study areas to within a meter of the exposure of interest. High-resolution photographs acquired at various elevations and azimuths by sUAS are then used to convert field measurements to digital representations in three-dimensions at a fine scale. Photogrammetric software is used to capture complex, detailed topography by creating digital surface models with a range imaging technique that estimates three-dimensional structures from two-dimensional image sequences. The digital surface model is overlain by detailed, high-resolution photography. Pairing sUAS technology with readily available photogrammetry software that requires little processing time and resources offers a revolutionary and cost-effective methodology for geoscientists to investigate and quantify stratigraphic and structural complexity of field studies from the convenience of the office. These methods of imaging and modeling remote outcrops are demonstrated in the East Coast Basin, New Zealand, where wave-cut platform exposures of Miocene deep-water deposits offer a unique opportunity to investigate the flow processes and resulting characteristics of thin-bedded turbidite deposits. Stratigraphic architecture of wavecut platform and vertically-dipping exposures of these thin-bedded turbidites is investigated with sUAS coupled with Structure from Motion (SfM) photogrammetry software. This approach allows the geometric and spatial variation of deep-water architecture to be characterized continuously along 2,000 meters of lateral exposure, as well as to measure and quantify cyclic

  14. Lower Paleozoic deep-water facies of the Medfra area, central Alaska: A section in Geologic studies in Alaska by the U.S. Geological Survey, 1997

    Science.gov (United States)

    Dumoulin, Julie A.; Bradley, Dwight C.; Harris, Anita G.; Repetski, John E.

    1999-01-01

    Deep-water facies, chiefly hemipelagic deposits and turbidites, of Cambrian through Devonian age are widely exposed in the Medfra and Mt. McKinley quadrangles. These strata include the upper part of the Telsitna Formation (Middle-Upper Ordovician) and the Paradise Fork Formation (Lower Silurian-Lower Devonian) in the Nixon Fork terrane, the East Fork Hills Formation (Upper Cambrian-Lower Devonian) in the East Fork subterrane of the Minchumina terrane, and the chert and argillite unit (Ordovician) and the argillite and quartzite unit (Silurian- Devonian? and possibly older) in the Telida subterrane of the Minchumina terrane.In the western part of the study area (Medfra quadrangle), both hemipelagic deposits and turbidites are largely calcareous and were derived from the Nixon Fork carbonate platform. East- ern exposures (Mt. McKinley quadrangle; eastern part of the Telida subterrane) contain much less carbonate; hemipelagic strata are mostly chert, and turbidites contain abundant rounded quartz and lesser plagioclase and potassium feldspar. Deep-water facies in the Medfra quadrangle correlate well with rocks of the Dillinger terrane exposed to the south (McGrath quadrangle), but coeval strata in the Mt. McKinley quadrangle are compositionally similar to rocks to the northeast (Livengood quadrangle). Petrographic data thus suggest that the Telida subterranes presently defined is an artificial construct made up of two distinct sequences of disparate provenance.Restoration of 90 and 150 km of dextral strike-slip on the Iditarod and Farewell faults, respectively, aligns the deep-water strata of the Minchumina and Dillinger terranes in a position east of the Nixon Fork carbonate platform. This restoration supports the interpretation that lower Paleozoic rocks in the Nixon Fork and Dillinger terranes, and in the western part of the Minchumina terrane (East Fork subterrane and western part of the Telida subterrane), formed along a single continental margin. Rocks in the

  15. Evidence of discontinuous and continuous gas migration through undisturbed and self-sealed Cox clay-stone

    International Nuclear Information System (INIS)

    Davy, C. A.; M'Jahad, S.; Skoczylas, F.; Talandier, J.; Ghayaza, M.

    2012-01-01

    it is a long-lasting procedure, it allows to assess both gas migration modes at the sample outlet (i.e. discontinuous or continuous). In our laboratory, by using the step-by-step method under in situ confining stresses (5 to 12 MPa), and argon as gas, former studies have mainly investigated discontinuous gas passage for vertical, horizontal or inclined cores from the Bure site. A number of samples was self-sealed, mainly those from horizontal or inclined cores. Variations by one order of magnitude have been recorded between results on horizontal and inclined cores or vertical cores. While GBP values range from 1.26 MPa and up to 3 MPa for the first test series on vertical cores, it is almost an order of magnitude lower for the second test series (horizontal or inclined cores), with values ranging from 0.2 to 1.3 MPa. This difference is mainly associated to gas passage through self-sealed fractures, in relation with clay transverse anisotropy. Indeed, COx clay-stone is a sedimentary indurated clay, composed of sub-horizontal diagenetic bedding planes: whenever GBP tests are performed along the bedding planes, lower values may be expected (due to a greater number of sealed cracks, created during sample preparation) rather than when performing GBP experiments perpendicularly to the bedding planes. Despite this extensive research, which was backed by numerical simulations of homogeneous media with LML and EDF-ASTER codes, several scientific questions remain. In particular, argillite self-sealing or undisturbed states may display different gas migration properties: it is expected that undisturbed matter will let gas pass at higher pressure than if self-sealed. Also, the discontinuous gas migration mode may be related to diffusion or capillary snap off, or to both phenomena. And discontinuous breakthrough does not suffice to describe fully the gas migration phenomena through undisturbed or self-sealed argillite, for it occurs distinctly from continuous passage and gas

  16. Marsh Creation in a Northern Pacific Estuary: Is Thirteen Years of Monitoring Vegetation Dynamics Enough?

    Directory of Open Access Journals (Sweden)

    Neil K. Dawe

    2000-12-01

    Full Text Available Vegetation changes were monitored over a 13-yr period (1982-1994 in the Campbell River estuary following the development of marshes on four intertidal islands. The marshes were created to mitigate the loss of a natural estuarine marsh resulting from the construction of a dry land log-sorting facility. Plant species coverage was measured along 23 permanent transects in planted and unplanted blocks on the constructed islands, and in naturally occurring low-marsh and mid-to-high marsh reference communities on nearby Nunn's Island. Five dominant species, Carex lyngbyei, Juncus balticus, Potentilla pacifica, Deschampsia caespitosa, and Eleocharis palustris established successfully and increased in cover in both planted and unplanted areas. The planted, unplanted, and Nunn's Island low-marsh sites had similar total plant cover and species richness by the 13th year. Principal components analysis of the transects through time indicated successful establishment of mid-to-low marsh communities on the constructed islands by the fourth year. Vegetation fluctuations on the constructed islands were greater than in the mid-to-high and low-marsh reference communities on Nunn's Island. Results showed that substrate elevation and island configuration were major influences on the successful establishment and subsequent dynamics of created marsh communities. Aboveground biomass estimates of marshes on the created islands attained those of the reference marshes on Nunn's Island between years 6 and 13. However, Carex lyngbyei biomass on the created islands had not reached that of the reference marshes by year 13. Despite the establishment of what appeared to be a productive marsh, with species composition and cover similar to those of the reference marshes on Nunn's Island, vegetation on the created islands was still undergoing changes that, in some cases, were cause for concern. On three of the islands, large areas devoid of vegetation formed between years 6 and 13

  17. Coupled Wave Energy and Erosion Dynamics along a Salt Marsh Boundary, Hog Island Bay, Virginia, USA

    Directory of Open Access Journals (Sweden)

    Anthony M. Priestas

    2015-09-01

    Full Text Available The relationship between lateral erosion of salt marshes and wind waves is studied in Hog Island Bay, Virginia USA, with high-resolution field measurements and aerial photographs. Marsh retreat is compared to wave climate calculated in the bay using the spectral wave-model Simulating Waves Nearshore (SWAN. We confirm the existence of a linear relationship between long-term salt marsh erosion and wave energy, and show that wave power can serve as a good proxy for average salt-marsh erosion rates. At each site, erosion rates are consistent across several temporal scales, ranging from months to decades, and are strongly related to wave power. On the contrary, erosion rates vary in space and weakly depend on the spatial distribution of wave energy. We ascribe this variability to spatial variations in geotechnical, biological, and morphological marsh attributes. Our detailed field measurements indicate that at a small spatial scale (tens of meters, a positive feedback between salt marsh geometry and wave action causes erosion rates to increase with boundary sinuosity. However, at the scale of the entire marsh boundary (hundreds of meters, this relationship is reversed: those sites that are more rapidly eroding have a marsh boundary which is significantly smoother than the marsh boundary of sheltered and slowly eroding marshes.

  18. Zooming in and out: Scale dependence of extrinsic and intrinsic factors affecting salt marsh erosion

    Science.gov (United States)

    Wang, Heng; van der Wal, Daphne; Li, Xiangyu; van Belzen, Jim; Herman, Peter M. J.; Hu, Zhan; Ge, Zhenming; Zhang, Liquan; Bouma, Tjeerd J.

    2017-07-01

    Salt marshes are valuable ecosystems that provide important ecosystem services. Given the global scale of marsh loss due to climate change and coastal squeeze, there is a pressing need to identify the critical extrinsic (wind exposure and foreshore morphology) and intrinsic factors (soil and vegetation properties) affecting the erosion of salt marsh edges. In this study, we quantified rates of cliff lateral retreat (i.e., the eroding edge of a salt marsh plateau) using a time series of aerial photographs taken over four salt marsh sites in the Westerschelde estuary, the Netherlands. In addition, we experimentally quantified the erodibility of sediment cores collected from the marsh edge of these four marshes using wave tanks. Our results revealed the following: (i) at the large scale, wind exposure and the presence of pioneer vegetation in front of the cliff were the key factors governing cliff retreat rates; (ii) at the intermediate scale, foreshore morphology was partially related to cliff retreat; (iii) at the local scale, the erodibility of the sediment itself at the marsh edge played a large role in determining the cliff retreat rate; and (iv) at the mesocosm scale, cliff erodibility was determined by soil properties and belowground root biomass. Thus, both extrinsic and intrinsic factors determined the fate of the salt marsh but at different scales. Our study highlights the importance of understanding the scale dependence of the factors driving the evolution of salt marsh landscapes.

  19. Nitrous oxide emissions could reduce the blue carbon value of marshes on eutrophic estuaries

    Science.gov (United States)

    Roughan, Brittney L.; Kellman, Lisa; Smith, Erin; Chmura, Gail L.

    2018-04-01

    The supply of nitrogen to ecosystems has surpassed the Earth’s Planetary Boundary and its input to the marine environment has caused estuarine waters to become eutrophic. Excessive supply of nitrogen to salt marshes has been associated with shifts in species’ distribution and production, as well as marsh degradation and loss. Our study of salt marshes in agriculturally intensive watersheds shows that coastal eutrophication can have an additional impact. We measured gas fluxes from marsh soils and verified emissions of nitrous oxide (N2O) in nitrogen-loaded marshes while the reference marsh was a sink for this gas. Salt marsh soils are extremely efficient carbon sinks, but emissions of N2O, a greenhouse gas 298 times more potent than CO2, reduces the value of the carbon sink, and in some marshes, may counterbalance any value of stored carbon towards mitigation of climate change. Although more research is merited on the nitrogen transformations and carbon storage in eutrophic marshes, the possibility of significant N2O emissions should be considered when evaluating the market value of carbon in salt marshes subject to high levels of nitrogen loading.

  20. Cenozoic deep-water sedimentary basin formation at the Australia-Pacific plate boundary, southern New Caledonia Trough and Taranaki Basin, New Zealand

    Science.gov (United States)

    Baur, J. R.; Sutherland, R.; Stern, T. A.

    2010-12-01

    Investigation of four petroleum exploration wells and seismic-reflection interpretation reveal >2 km of tectonic subsidence related to Cretaceous rift structures, and 2-3km of Cenozoic subsidence with little faulting of the upper crust. Comparisons to thermal cooling models require stretching factors that are incompatible with the continental foundations of the basin. In addition, up to 50 % of the subsidence signal occurred in the Mid-Cenozoic, hundreds of kilometres from potential contemporary plate boundaries. Thus, upper crustal faulting, thermal relaxation or flexure cannot explain the 300-500 km wide and 2000 km long sedimentary basin system. We suggest that not all deep-water basins are the evolved products of processes that form shallow-water sedimentary basins, but instead they may be influenced by different processes such as convection in the asthenospheric mantle, instabilities in the mantle lithosphere and/or detachment fault zones that inevitably lead to deeper water.

  1. Comparative Reproduction Aspects of the Deep-water Shrimps Aristaeomorpha foliacea and Aristeus antennatus (Decapoda, Aristeidae in the Greek Ionian Sea (Eastern Mediterranean

    Directory of Open Access Journals (Sweden)

    K. Kapiris

    2009-01-01

    Full Text Available In the eastern Ionian Sea, the deep-water shrimps Aristaeomorpha foliacea and Aristeus antennatus constitute a virgin fishing resource, since their maximum abundance depth exceeds commercial exploitation depths. The two sympatric species share a number of common reproductive features, such as summer reproduction. A slight temporal shift in mating activity, ovarian maturation, and spawning period was observed between species. The most notable difference was the more pronounced seasonality in reproductive activity of Aristeus antennatus compared to that of A. foliacea as evidenced by the frequency of inseminated females and functionally mature males, as well as by the shorter ovarian maturation period. Nevertheless, regarding the whole life span, both sexes of Aristeus antennatus exhibit a more extended reproductive activity in comparison to A. foliacea. No notable differentiation of both species existed in comparison to other Mediterranean regions.

  2. Features of the propagation of pseudorandom pulse signals from the shelf to deep water in the presence of gyre formation on the acoustic track

    Science.gov (United States)

    Akulichev, V. A.; Burenin, A. V.; Ladychenko, S. Yu.; Lobanov, V. B.; Morgunov, Yu. N.

    2017-08-01

    The paper discusses the results of an experiment conducted in the Sea of Japan in March 2016 on an acoustic track 194 km long in winter hydrological conditions. The most complex case of propagation of pseudorandom pulse signals from the shelf to deep water in the presence of gyre formation on the acoustic track. An analysis of the experimentally obtained pulse characteristics show that at all points, a maximum, in terms of amplitude, first arrival of acoustic energy is recorded. This is evidence that at a given depth horizon, pulses that have passed the shortest distance through a near-surface sound channel at small angles close to zero are received first. The calculation method of mean sound velocity on the track, based on the satellite data of surface temperature monitoring, is proposed. We expect that the results obtained with this method can be successfully used for the purposes of acoustic range finding and navigation.

  3. Deep-water fisheries in Brazil: history, status and perspectives Pesquerías de aguas profundas en Brasil: historia, situación actual y perspectivas

    Directory of Open Access Journals (Sweden)

    José Angel Alvarez Perez

    2009-01-01

    Full Text Available The recent development of deep-water fisheries off Brazil is reviewed from biological, eco-nomic, and political perspectives. This process has been centered in the southeastem and southern sectors of the Brazilian coast (19°-34°S and was motivated by the overfishing of the main coastal resources and a government-induced vessel-chartering program. Shelf break (100-250 m operations by national hook-and-line and trawl vessels intensified in the 1990s. Around 2000-2001, however, foreign-chartered longliners, gillnetters, potters, and trawlers started to operate in Brazilian waters, leading the occupation of the upper slope (250-500 m, mostly targeting monkfish (Lophyus gastrophysus, the Argentine hake (Merluccius hubbsi, the Brazilian codling (Urophycis mystacea, the wreckfish (Polyprion americanus, the Argentine short-fin squid (Illex argentinus, the red crab (Chaceon notialis, and the royal crab (Chaceon ramosae. Between 2004 and 2007, chartered trawlers established a valuable fishery on deep-water shrimps (family Aristeidae, heavily exploiting the lower slope (500-1000 m. Total catches of deep-water resources varied annually from 5,756 ton in 2000 to a maximum of 19,923 ton in 2002, decreasing to nearly 11,000 ton in 2006. Despite intensive data collection, the availability of timely stock assessments, and a formal participatory process for the discussion of management plans, deep-water stocks are already considered to be overexploited due to limitations of governance. .El reciente desarrollo de la pesca profunda en Brasil fue revisado desde perspectivas biológicas, econômicas y políticas. Este proceso se ha centrado en los sectores sureste y sur de la costa de Brasil (19°-34°S y fue motivado por la sobrepesca de los principales recursos costeros en conjunto con una política gubernamental de arriendo de buques pesqueros. Las operaciones de pesca sobre el borde de la plataforma (100-250 m por buques palangreros y arrastreros se

  4. Deep-water profiling of 137Cs and 90Sr in the Black Sea. A further insight into dynamics of the post-Chernobyl radioactive contamination

    International Nuclear Information System (INIS)

    Gulin, S.B.; Egorov, V.N.; Duka, M.S.; Sidorov, I.G.; Proskurnin, V.Yu.; Mirzoyeva, N.Yu.; Bey, O.N.; Gulina, L.V.

    2015-01-01

    The first post-Chernobyl measurements of vertical distribution of 137 Cs in the abyssal Black Sea waters have been conducted in the vicinity of submarine canyon Viteaz together with profiling of 90 Sr. This allowed showing an increase in 137 Cs concentration and the low 90 Sr/ 137 Cs activity ratio (≈0.2) at 1,000 m water depth, suggesting the long-distance influence of the Danube River runoff through the Viteaz Canyon. Calculation of inventories of 90 Sr and 137 Cs in oxic and anoxic Black Sea waters and their comparison with the total input of these radionuclides to the Black Sea after the Chernobyl accident have revealed considerable accumulation of them in the deep water column. (author)

  5. Technology strategy for deepwater and subsea production systems 2008 update; Technology Target Areas; TTA7 - Deep water and subsea prodution technology

    Energy Technology Data Exchange (ETDEWEB)

    2008-07-01

    Executive summary 'Deepwater and Subsea Production Systems' has been identified as one of the eight new Technology Target Areas (TTAs) in Norway's technology strategy for the Oil and Gas sector. This TTA covers deepwater floating production systems, subsea systems (except subsea processing technologies which are addressed by TTA6) and arctic development systems (in both shallow and deepwater). The total hydrocarbon reserves worldwide, which are enabled by the technologies under this TTA exceed 400 billion boe which, itself exceeds the proven reserves of Saudi Arabia. For deepwater developments the long term technical challenge is to develop flexible and adaptive systems which are better able to cope with subsurface uncertainties e.g. compartmentalisation and provide required access to the reservoir to enable successful recovery. More specific medium term challenges relate to developing solutions for harsh environmental conditions such as those offshore Norway and to develop cost effective methods of installing subsea hardware in deep and ultra deep water without requiring expensive crane vessels. For subsea systems the challenge is to develop solutions for ultra deepwater without increasing costs, so that Norway's leading export position in this area can be maintained and strengthened. Considering developments in the arctic, Norwegian industry is already well placed through its familiarity with arctic climate, close relationship with Russia and involvement in Sakhalin II. As we move to water depth beyond about 150m use of Gravity Base Structures (GBS) becomes very expensive or non-feasible and we need to consider other solutions. Subsea-to-beach could be an attractive solution but we need to resolve challenges related to long distance tie backs, flow assurance, uneven terrain, etc. There is also a specific need to develop floating systems capable of drilling and production in an arctic environment. To address the above technical challenges the

  6. Implications of reduced turbidity current and landslide activity for the Initial Eocene Thermal Maximum - evidence from two distal, deep-water sites

    Science.gov (United States)

    Clare, Michael A.; Talling, Peter J.; Hunt, James E.

    2015-06-01

    Previous studies propose that submarine landslides and turbidity currents may become more likely due to future rapid global warming. Determining whether global warming increases likelihood assists in assessment of landslide-triggered tsunami hazards and risk to seafloor structures. Other studies propose that landslides helped to trigger past rapid climate change due to sudden release of gas hydrates. Two deep-water turbidite records show prolonged hiatuses in turbidity current activity during the Initial Eocene Thermal Maximum (IETM) at ∼55 Ma. The IETM represents a possible proxy for future anthropogenically-induced climate change. It is likely that our records mainly represent large and fast moving disintegrative submarine landslides. Statistical analysis of long term (>2.3 Myr) records shows that turbidity current frequency significantly decreased after the IETM. Our results indicate that rapid climate change does not necessarily cause increased turbidity current activity, and do not provide evidence for landslides as a primary trigger for the IETM.

  7. High Spatial resolution remote sensing for salt marsh change detection on Fire Island National Seashore

    Science.gov (United States)

    Campbell, A.; Wang, Y.

    2017-12-01

    Salt marshes are under increasing pressure due to anthropogenic stressors including sea level rise, nutrient enrichment, herbivory and disturbances. Salt marsh losses risk the important ecosystem services they provide including biodiversity, water filtration, wave attenuation, and carbon sequestration. This study determines salt marsh change on Fire Island National Seashore, a barrier island along the south shore of Long Island, New York. Object-based image analysis was used to classifying Worldview-2, high resolution satellite, and topobathymetric LiDAR. The site was impacted by Hurricane Sandy in October of 2012 causing a breach in the Barrier Island and extensive overwash. In situ training data from vegetation plots were used to train the Random Forest classifier. The object-based Worldview-2 classification achieved an overall classification accuracy of 92.75. Salt marsh change for the study site was determined by comparing the 2015 classification with a 1997 classification. The study found a shift from high marsh to low marsh and a reduction in Phragmites on Fire Island. Vegetation losses were observed along the edge of the marsh and in the marsh interior. The analysis agreed with many of the trends found throughout the region including the reduction of high marsh and decline of salt marsh. The reduction in Phragmites could be due to the species shrinking niche between rising seas and dune vegetation on barrier islands. The complex management issues facing salt marsh across the United States including sea level rise and eutrophication necessitate very high resolution classification and change detection of salt marsh to inform management decisions such as restoration, salt marsh migration, and nutrient inputs.

  8. Sedimentation and response to sea-level rise of a restored marsh with reduced tidal exchange: Comparison with a natural tidal marsh

    NARCIS (Netherlands)

    Vandenbruwaene, W.; Maris, T.; Cox, T.J.S.; Cahoon, D.R.; Meire, P.; Temmerman, S.

    2011-01-01

    Along coasts and estuaries, formerly embanked land is increasingly restored into tidal marshes in order to re-establish valuable ecosystem services, such as buffering against flooding. Along the Scheldt estuary (Belgium), tidal marshes are restored on embanked land by allowing a controlled reduced

  9. Catch and post-release mortalities of deep-water sharks caught by bottom longlines in the Cantabrian Sea (NE Atlantic)

    Science.gov (United States)

    Rodríguez-Cabello, Cristina; Sánchez, Francisco

    2017-12-01

    The majority of deep-water fish have very low capacity to survive discarding as fishery bycatch due to their biological characteristics and adaptation to depth. This study explores the catch and post-release mortalities of several deep-water shark species caught by bottom longline in the El Cachucho (Le Danois Bank) MPA in northern Spanish waters (NE Atlantic). Survivorship was qualitatively evaluated according to health condition and responses of individuals after capture and subsequent release. A total of 15 species were caught, of which the most abundant were leafscale gulper shark Centrophorus squamosus (39%), birdbeak dogfish Deania calcea (39%) and Portuguese dogfish Centroscymnus coelolepis (10%). Catch or at-vessel mortality (AVM) for these species was lower than expected, 1.2%, 8.8% and 4.5%, respectively but 18.9%, 37.4% and 38.6% including both those specimens dead on retrieval and those scored in poor condition). The species with the highest vitality rate was C. squamosus (37.3% in good condition; 43.8% in moderate condition), followed by D. calcea (22.8% in good condition; 39.8% in moderate condition) and C. coelolepis (6.8% and 54.5%). Post-release mortality (PRM) was examined using electronic tags (PSATs, n = 14). Of the nine C. squamosus tagged successfully, three died within 5-10 weeks after release, whereas the other six survived for periods of at least 45-120 days, when tags were programmed to release). In the case of C. coelolepis, two of the four tagged specimens died almost immediately after release, whereas the other two tags indicated that the fish survived immediate release, but data were too limited to gauge survival due to tag failure.

  10. Deep-water Reservoir Modelling Using a volume-based approach on Full-Offset Seismic Data: Etim Field, Offshore Nigeria

    International Nuclear Information System (INIS)

    Nwaeri, E.; Zimbrick, G.; Proett, B.

    2002-01-01

    Reservoir characterization of deep-water deposits is a challenging task. Major issues to address include: (1) prediction of sand distribution away from well control, (2) definition of reservoir geometry and size, and (3) spatial placement of sand bodies in the geologic model. In a typical deep-water setting, lithostratigraphic correlation using well logs has been found to be unreliable. Seismic correlation is critical, but complications from mixed-impedance reservoir, and variations in frequency/phase content of available full stack data can arise.We describe a reservoir description workflow that utilizes both volume-and map-based conditioning tools, in the absence of AVO products. A good density of interpreted horizons was used to provide stratigraphic control on the volume interpretation techniques. Map pattern analysis of horizon slices helped focus environment of deposition (EOD) interpretations on key areas of reservoir development.A seismic wedge model helped develop an interpretation strategy and assess seismic data quality. Results showed that seed detection of trough-peak pairs gave a reasonable prediction of reservoir distribution at Etim.Seismic attributes were used to calibrate and predict net sand thickness. The predictions were integrated with EOD maps and well control to provide final net sand maps. Extracted geobodies from the sculpted seismic data were used to place sands in their proper position in the geologic model.The resulting geologic model preserves spatial positioning of the seismically derived reservoir elements and provides better definition of reservoir connectivity. This workflow is appropriate for fields where multi-volume (AVO) seismic data are unavailable and 3-D positioning of reservoir elements is required

  11. Deep-water stands of Cystoseira zosteroides C. Agardh (Fucales, Ochrophyta) in the Northwestern Mediterranean: Insights into assemblage structure and population dynamics

    Science.gov (United States)

    Ballesteros, Enric; Garrabou, Joaquim; Hereu, Bernat; Zabala, Mikel; Cebrian, Emma; Sala, Enric

    2009-04-01

    Populations dominated by Cystoseira zosteroides, an endemic and threatened Mediterranean seaweed, colonize deep-water rocky habitats down to more than 50 m depth. Assemblages dominated by this species display high algal and invertebrate species richness. Algal biomass averages 1134 g dw m -2. Erect and turf algae account for only 25% of total algal dry weight, while encrusting corallines are responsible for the remaining 75%. Sponges, bryozoans and ascidians constitute the dominant sessile macrofauna. Cystoseira zosteroides is the dominant erect algae, with a mean biomass of 60.6 g dw m -2, and densities ranging from 4 to 7 plants m -2. The alien turf alga Womersleyella setacea has a biomass of 104.2 g dw m -2 and covers most of the understory substrate. The size-frequency distribution of C. zosteroides populations shows differences over time. Mean annual growth of the main axis is around 0.5 cm and mean annual mortality rate is lower than 2%. Recruitment was almost nil during the studied period of time (10 years). Processes structuring these deep-water Cystoseira stands must be driven by episodic disturbances, after-disturbance recruitment pulses, and long periods of steady growth that last at least 10 years. However, it is also possible that recruitment is irreversibly inhibited by the alien alga W. setacea in which case these old-growth stands are faced with extinction. The highly diversified assemblages and the low growth and low mortality rates of C. zosteroides indicate high vulnerability to natural and anthropogenic disturbances, and call for effective measures to ensure their conservation.

  12. Modeling of seismic amplitude to discriminate the effects of lithology and fluids in AVO anomalies in deep water of the Gulf of Mexico Basin.

    Science.gov (United States)

    Kerdan, T.; Ramirez Ortega, C.; Gonzalez Ibarra, A.

    2007-05-01

    Recently the interest in deep water hydrocarbon exploration of the Gulf of Mexico Basin has increased. Hydrocarbon detection with AVO method in deep water presents greater ambiguity than at shallow depth. For this reason it is necessary to establish an strategy that reduces the risk of perforation associated with the interpretation of AVO anomalies. For the case of sandstone and shale, their petrophysical properties vary widely in the Gulf of Mexico Basin. For example, sandstones located at depths greater than 2-3 km can loose porosity due to cementation and hence this affect rock properties as impedance and Poisson coefficient, producing changes in seismic amplitudes. Reservoir sandstones can produce positive, negative o null reflections in the seismic sections. Throughout the Tertiary basins in the Gulf of México there are areas where acoustic impedance values of shales and gas sandstones are approximately equal. This means that those zones with hydrocarbon can appear as dim spot and are difficult to detect with conventional 3D seismic data. Hydrocarbon saturation affected the velocity of soft rocks at shallow depths, where sandstones is not cemented, but at greater depth when cementation increases susceptibility of rocks to fluid diminishes. For that reason it is important before AVO to make the elastic modeling to study the influence of different factors like mineralogy (obtained from analysis of well core and well logs), pore pressure, attenuation, illumination, anisotropy, etc. The studied elastic models show that it is often difficult to isolate the lithologic and fluid contribution to seismic response. To discriminate lithology from hydrocarbon it is necessary to make anelastic modeling (including attenuation), based on the fact that sands with gas produce attenuation anomaly whereas mineralogical changes do not. A detailed study of attenuation will allow to evaluate if the volume of gas in reservoir is commercial or not.

  13. Discard composition associated with the deep water rose shrimp fisheries (Parapenaeus longirostris, Lucas 1846 in the south-central Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    G. MILISENDA

    2017-02-01

    Full Text Available Discarding in fisheries is believed to be a waste of natural resources, as it is the part of the total catch brought on board but then returned to the sea dead or alive for any reason. This study aims to advance knowledge of the discards associated with the deep water rose shrimp fisheries in the south-central Mediterranean Sea. We address this issue by examining the data collected within the module of commercial catch monitoring (Campbiol of European data collection framework (DCF between January 2009 and December 2013. Multivariate data analysis and the generalized additive model (GAMs were used to assess the spatio-temporal composition of the discard and factors influencing its distribution. Overall, discard represented 32.9±15.4% of the total catch. Multiple analysis of variance highlighted the significant effect on discard assemblage only for the factor of depth (p-value <0.05. In general, bony fish were the most discarded organisms (23.5±14.4%. Cartilaginous fish, crustaceans and other invertebrates represented approximately 13% of the total catch. The fraction of discard in the catch presented significant variation regarding the years, depth and fishing ground. Our results showed that most of the discards in the deep water rose shrimp (DPS fisheries are due to species that have a minimum legal size (Hake, DPS, Trachurus spp., and are consequently subjected to the discard ban (art. 15 of the reg. EU 1380/2013. To avoid the landing of discards, specific measures aimed to minimize the unwanted catches of undersized species should be implemented.

  14. A Multi-Band Analytical Algorithm for Deriving Absorption and Backscattering Coefficients from Remote-Sensing Reflectance of Optically Deep Waters

    Science.gov (United States)

    Lee, Zhong-Ping; Carder, Kendall L.

    2001-01-01

    A multi-band analytical (MBA) algorithm is developed to retrieve absorption and backscattering coefficients for optically deep waters, which can be applied to data from past and current satellite sensors, as well as data from hyperspectral sensors. This MBA algorithm applies a remote-sensing reflectance model derived from the Radiative Transfer Equation, and values of absorption and backscattering coefficients are analytically calculated from values of remote-sensing reflectance. There are only limited empirical relationships involved in the algorithm, which implies that this MBA algorithm could be applied to a wide dynamic range of waters. Applying the algorithm to a simulated non-"Case 1" data set, which has no relation to the development of the algorithm, the percentage error for the total absorption coefficient at 440 nm a (sub 440) is approximately 12% for a range of 0.012 - 2.1 per meter (approximately 6% for a (sub 440) less than approximately 0.3 per meter), while a traditional band-ratio approach returns a percentage error of approximately 30%. Applying it to a field data set ranging from 0.025 to 2.0 per meter, the result for a (sub 440) is very close to that using a full spectrum optimization technique (9.6% difference). Compared to the optimization approach, the MBA algorithm cuts the computation time dramatically with only a small sacrifice in accuracy, making it suitable for processing large data sets such as satellite images. Significant improvements over empirical algorithms have also been achieved in retrieving the optical properties of optically deep waters.

  15. Southwest Pacific deep water carbonate chemistry linked to high southern latitude climate and atmospheric CO2 during the Last Glacial Termination

    Science.gov (United States)

    Allen, Katherine A.; Sikes, Elisabeth L.; Hönisch, Bärbel; Elmore, Aurora C.; Guilderson, Thomas P.; Rosenthal, Yair; Anderson, Robert F.

    2015-08-01

    A greater amount of CO2 was stored in the deep sea during glacial periods, likely via greater efficiency of the biologic pump and increased uptake by a more alkaline ocean. Reconstructing past variations in seawater carbonate ion concentration (a major component of alkalinity) enables quantification of the relative roles of different oceanic CO2 storage mechanisms and also places constraints on the timing, magnitude, and location of subsequent deep ocean ventilation. Here, we present a record of deep-water inorganic carbon chemistry since the Last Glacial Maximum (LGM; ∼19-23 ka BP), derived from sediment core RR0503-83 raised from 1627 m in New Zealand's Bay of Plenty. The core site lies within the upper limit of southern-sourced Circumpolar Deep Water (CDW), just below the lower boundary of Antarctic Intermediate Water (AAIW). We reconstruct past changes in bottom water inorganic carbon chemistry from the trace element and stable isotopic composition of calcite shells of the epibenthic foraminifer Cibicidoides wuellerstorfi. A record of ΔCO32-(ΔCO32- = [COCO32-] in situ - [CO32-] saturation) derived from the foraminiferal boron to calcium ratio (B/Ca) provides evidence for greater ice-age storage of respired CO2 and reveals abrupt deglacial shifts in [CO32-] in situ of up to 30 μmol/kg (5 times larger than the difference between average LGM and Holocene values). The rapidity of these changes suggests the influence of changing water mass structure and atmospheric circulation in addition to a decrease in CO2 content of interior waters.

  16. The big squeeze: ecosystem change and contraction of habitat for newly discovered deep-water reefs off the U.S. West Coast

    Science.gov (United States)

    Wickes, L.; Etnoyer, P. J.; Lauermann, A.; Rosen, D.

    2016-02-01

    Cold-water reefs are fragile, complex ecosystems that extend into the bathyal depths of the ocean, creating three dimensional structure and habitat for a diversity of deep-water invertebrates and fishes. The cold waters of the California Current support a diverse assemblage of these corals at relatively shallow depths close to shore. At these depths and locations the communities face a multitude of stressors, including low carbonate saturations, hypoxia, changing temperature, and coastal pollution. The current study employed ROV surveys (n=588, 2003-2015) to document the distribution of deep-sea corals in the Southern California Bight, including the first description of a widespread reef-building coral in the naturally acidified waters off the U.S. West Coast. We provide empirical evidence of species survival in the corrosive waters (Ωarag 0.67-1.86), but find loss of reef integrity. Recent publications have implied acclimation, resistance, and resilience of cold-water reef-building corals to ocean acidification, but results of this study indicate a cost to skeletal framework development with a subsequent loss of coral habitat. While ocean acidification and declines in oxygen are expected to further impinge on Lophelia at depth (𝑥̅=190 m), surface warming and coastal polution may affect shallower populations and mesophotic reef assemblages, resulting in a contraction of available coral habitat. Recent observations of die offs of gorgonians and antipatharians from surveys in shallow (50 m) and deep water (500 m) provide compelling evidence of ongoing ecosystem changes. Concurrent losses in habitat quality in deep and mesophotic waters suggest that corals may be "squeezed" into a more restricted depth range. New monitoring efforts aim to characterize the health and condition of deep corals with respect to gradients in carbonate chemistry, coastal pollution and changing temperatures, to assess vulnerability and both current and future habitat suitability.

  17. The effectiveness of a deep water aquatic exercise program in cancer-related fatigue in breast cancer survivors: a randomized controlled trial.

    Science.gov (United States)

    Cantarero-Villanueva, Irene; Fernández-Lao, Carolina; Cuesta-Vargas, Antonio I; Del Moral-Avila, Rosario; Fernández-de-Las-Peñas, César; Arroyo-Morales, Manuel

    2013-02-01

    To investigate the effectiveness of an 8-week aquatic program on cancer-related fatigue, as well as physical and psychological outcomes in breast cancer survivors. A randomized controlled trial. Outpatient clinic, urban, academic medical center, and a sport university swimming pool. Breast cancer survivors (N=68) were randomly assigned to either an experimental (aquatic exercise group in deep water pool) group or a control (usual care) group. The intervention group attended aquatic exercise sessions 3 times per week for 8 weeks in a heated deep swimming pool. Sessions lasted 60 minutes in duration: 10 minutes of warm-up, 40 minutes of aerobic and endurance exercises, and 10 minutes of cool-down exercises. Patients allocated to the usual care group followed the oncologist's recommendations in relation to a healthy lifestyle. Values for fatigue (Piper Fatigue Scale), mood state (Profile of Mood States), and abdominal (trunk curl static endurance test) and leg (multiple sit-to-stand test) strength were collected at baseline, after the last treatment session, and at a 6-month follow-up. Immediately after discharge, the aquatic exercise group showed a large effect size in total fatigue score (d=.87; 95% confidence interval, .48-1.26), trunk curl endurance (d=.92; 95% confidence interval, 1.97-3.83), and leg strength (d=1.10; .55-2.76), but negligible effects in vigor, confusion, and disturbance of mood (daquatic exercise group maintained large to small effect sizes in fatigue scores, multiple sit-to-stand test, and trunk curl static endurance (.25>d>.90) and negligible effects for the fatigue-severity dimension and different scales of the Profile of Mood States (daquatic exercise program conducted in deep water was effective for improving cancer-related fatigue and strength in breast cancer survivors. Copyright © 2013 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  18. Recommendations for computer code selection of a flow and transport code to be used in undisturbed vadose zone calculations for TWRS immobilized wastes environmental analyses

    International Nuclear Information System (INIS)

    VOOGD, J.A.

    1999-01-01

    An analysis of three software proposals is performed to recommend a computer code for immobilized low activity waste flow and transport modeling. The document uses criteria restablished in HNF-1839, ''Computer Code Selection Criteria for Flow and Transport Codes to be Used in Undisturbed Vadose Zone Calculation for TWRS Environmental Analyses'' as the basis for this analysis

  19. Marsh collapse thresholds for coastal Louisiana estimated using elevation and vegetation index data

    Science.gov (United States)

    Couvillion, Brady R.; Beck, Holly

    2013-01-01

    Forecasting marsh collapse in coastal Louisiana as a result of changes in sea-level rise, subsidence, and accretion deficits necessitates an understanding of thresholds beyond which inundation stress impedes marsh survival. The variability in thresholds at which different marsh types cease to occur (i.e., marsh collapse) is not well understood. We utilized remotely sensed imagery, field data, and elevation data to help gain insight into the relationships between vegetation health and inundation. A Normalized Difference Vegetation Index (NDVI) dataset was calculated using remotely sensed data at peak biomass (August) and used as a proxy for vegetation health and productivity. Statistics were calculated for NDVI values by marsh type for intermediate, brackish, and saline marsh in coastal Louisiana. Marsh-type specific NDVI values of 1.5 and 2 standard deviations below the mean were used as upper and lower limits to identify conditions indicative of collapse. As marshes seldom occur beyond these values, they are believed to represent a range within which marsh collapse is likely to occur. Inundation depth was selected as the primary candidate for evaluation of marsh collapse thresholds. Elevation relative to mean water level (MWL) was calculated by subtracting MWL from an elevation dataset compiled from multiple data types including light detection and ranging (lidar) and bathymetry. A polynomial cubic regression was used to examine a random subset of pixels to determine the relationship between elevation (relative to MWL) and NDVI. The marsh collapse uncertainty range values were found by locating the intercept of the regression line with the 1.5 and 2 standard deviations below the mean NDVI value for each marsh type. Results indicate marsh collapse uncertainty ranges of 30.7–35.8 cm below MWL for intermediate marsh, 20–25.6 cm below MWL for brackish marsh, and 16.9–23.5 cm below MWL for saline marsh. These values are thought to represent the ranges of

  20. Coastal marsh degradation: modeling the influence of vegetation die-off patterns on flow and sedimentation

    Science.gov (United States)

    Schepers, Lennert; Wang, Chen; Kirwan, Matthew; Belluco, Enrica; D'Alpaos, Andrea; Temmerman, Stijn

    2014-05-01

    Coastal marshes are vulnerable ecosystems that provide ecosystem functions such as storm protection and carbon sequestration. However, degradation of vegetated marshes into bare tidal flats or open water has been reported as a worldwide phenomenon, threatening their valuable wetland functions. Moreover, tidal marshes and bare flats are considered as alternative stable ecosystem states, which implies that, once vegetated marshes have degraded to bare flats, the (re)conversion from bare flats to marsh vegetation may be very difficult. Recent aerial photo analysis has demonstrated that the degradation or die-off of a marsh area is a spatial process, whereby vegetation is typically replaced by non-vegetated areas in the form of interior marsh pools, also known as ponds or marsh basins. On a small scale, these pools have similar characteristics among different marshes worldwide: pools that are located further away from tidal channels and with broad channel connections to the tidal channel system appear to have low surface elevations and a low probability for marsh recovery (this is re-establishment of vegetation on the surface). Interior pools located closer to, but that are not connected to channels on the other hand, are positioned on higher elevations and are more likely to recover. These findings may have important implications for the restoration potential of degraded marshes and their functions. We hypothesize that bio-geomorphologic interactions are the main mechanisms causing these differences in elevation and recovery potential of interior marsh pools: pools that are not connected to the channel system, are separated from the channel by vegetation, which reduces the flow velocity, increases sedimentation and may explain our observation of higher surface elevation of this type of pools. In contrast, pools that are connected with the channel system are not protected by vegetation and will experience higher flow velocities and lower sedimentation rates or even

  1. Environmental controls on multiscale spatial patterns of salt marsh vegetation

    DEFF Research Database (Denmark)

    Kim, Daehyun; Cairns, David; Bartholdy, Jesper

    2010-01-01

    In coastal environments, biogeographic patterns are generally influenced by surface elevation and horizontal distance from sea water. However, it is still unclear whether these major topographic factors are significant controls of vegetation patterns across spatial scales at which different...... physical processes operate. This study investigated such a topography-vegetation relationship in a Danish salt marsh, focusing upon two scales: a macro-scale (ca. 500 m) across the marsh platform, encompassing seaward and landward areas, and a meso-scale ( ca. 25 m) across tidal creeks. While long-term sea......-level variation and grazing influenced the macro-scale pattern, short-term fluvial-geomorphic processes drove the meso-scale pattern. Despite these different underlying processes, similar floristic gradient structures between the two scales were identified by nonmetric multidimensional scaling. The gradient...

  2. Conditions for Sustainability of the Elephant Marsh Fishery in Malawi

    Directory of Open Access Journals (Sweden)

    Ishmael B. M. Kosamu

    2014-06-01

    Full Text Available The Elephant Marsh, a wetland in Southern Malawi, is important for small-scale fisheries. It is managed by local institutions, which are not formally linked to any state institutions. This paper uses qualitative comparative analysis (QCA to examine factors for sustainability at 24 fishing villages around the wetland using a hypothesis that “If strong local institutions (with or without government support exist in an environment where resource users take collective action, and there is no or minimal conflictive interference, small-scale fisheries become sustainable”. It was revealed that the sustainability of small-scale fisheries management at Elephant Marsh relies heavily on the strength of local fisheries’ committees. Future interventions on fisheries management at the resource should, therefore, pay particular attention to protecting and (rebuilding collective social capital, especially in the leadership of fisheries committees.

  3. Assessment of metolachlor and diuron leaching in a tropical soil using undisturbed soil columns under laboratory conditions.

    Science.gov (United States)

    Dores, Eliana F G C; De Souza, Luana; Villa, Ricardo D; Pinto, Alicio Alves

    2013-01-01

    In the present study, diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-metoxi-1-methylethyl)acetamide] leaching was studied in undisturbed soil columns collected in a cotton crop area in Mato Grosso State, Brazil. The pesticides were applied to the soil surface in dosages similar to those used in a cotton plantation. To assess the leaching process, soil columns were submitted to simulated rain under laboratory conditions at 25 ± 3°C, in the absence of wind and direct solar radiation. During the rain simulations, leachate solutions were collected and herbicide concentrations were determined. At the end of the experiment, the soil columns were cut into 10 cm sections to determine the remaining herbicide concentrations through the soil profile. Metolachlor was detected in all soil sections, and approximately 4% of the applied mass was leached. Diuron was detected only in the upper two soil sections and was not detected in the leachate. A linear correlation (r > 0.94) between the metolachlor soil concentrations and the organic contents of the soil sections was observed. Mass balance suggests that around 56% of diuron and 40% of metolachlor were degraded during the experiments. Measurements of the water table depth in the area where the samples were collected showed that it varied from 2 to 6 m and is therefore vulnerable to contamination by the studied herbicides, particularly metolachlor, which demonstrated a higher leaching potential.

  4. Influence of organic amendments on diuron leaching through an acidic and a calcareous vineyard soil using undisturbed lysimeters

    International Nuclear Information System (INIS)

    Thevenot, M.; Dousset, S.; Rousseaux, S.; Andreux, F.

    2008-01-01

    The influence of different organic amendments on diuron leaching was studied through undisturbed vineyard soil columns. Two composts (A and D), the second at two stages of maturity, and two soils (VR and Bj) were sampled. After 1 year, the amount of residues (diuron + metabolites) in the leachates of the VR soil (0.19-0.71%) was lower than in the Bj soil (4.27-8.23%), which could be explained by stronger diuron adsorption on VR. An increase in the amount of diuron leached through the amended soil columns, compared to the blank, was observed for the Bj soil only. This result may be explained by the formation of mobile complexes between diuron and water-extractable organic matter (WEOM) through the Bj soil, or by competition between diuron and WEOM for the adsorption sites in the soil. For both soils, the nature of the composts and their degree of maturity did not significantly influence diuron leaching. - The application of organic amendments increased diuron leaching through a sandy-loam soil, in contrast to a clay-loam soil

  5. Influence of organic amendments on diuron leaching through an acidic and a calcareous vineyard soil using undisturbed lysimeters

    Energy Technology Data Exchange (ETDEWEB)

    Thevenot, M. [UMR 1229 Microbiologie et Geochimie des Sols, CMSE, INRA - Universite de Bourgogne, UFR des Sciences de la Terre et de l' Environnement, 6 Boulevard Gabriel, 21000 Dijon (France)], E-mail: mathieu.thevenot@u-bourgogne.fr; Dousset, S. [UMR 5561 Biogeosciences, CNRS - Universite de Bourgogne, UFR des Sciences de la Terre et de l' Environnement, 6 Boulevard Gabriel, 21000 Dijon (France); Rousseaux, S. [EA 4149 Laboratoire de Recherche en Vigne et Vin, Institut Universitaire de la Vigne et du Vin, rue Claude Ladrey, 21000 Dijon (France); Andreux, F. [UMR 1229 Microbiologie et Geochimie des Sols, CMSE, INRA - Universite de Bourgogne, UFR des Sciences de la Terre et de l' Environnement, 6 Boulevard Gabriel, 21000 Dijon (France)

    2008-05-15

    The influence of different organic amendments on diuron leaching was studied through undisturbed vineyard soil columns. Two composts (A and D), the second at two stages of maturity, and two soils (VR and Bj) were sampled. After 1 year, the amount of residues (diuron + metabolites) in the leachates of the VR soil (0.19-0.71%) was lower than in the Bj soil (4.27-8.23%), which could be explained by stronger diuron adsorption on VR. An increase in the amount of diuron leached through the amended soil columns, compared to the blank, was observed for the Bj soil only. This result may be explained by the formation of mobile complexes between diuron and water-extractable organic matter (WEOM) through the Bj soil, or by competition between diuron and WEOM for the adsorption sites in the soil. For both soils, the nature of the composts and their degree of maturity did not significantly influence diuron leaching. - The application of organic amendments increased diuron leaching through a sandy-loam soil, in contrast to a clay-loam soil.

  6. Effect of grass cover on water and pesticide transport through undisturbed soil columns, comparison with field study (Morcille watershed, Beaujolais)

    International Nuclear Information System (INIS)

    Dousset, S.; Thevenot, M.; Schrack, D.; Gouy, V.; Carluer, N.

    2010-01-01

    The purpose of this work is to assess the effectiveness of two grass covers (buffer zone and grass-covered inter-row), to reduce pesticide leaching, and subsequently to preserve groundwater quality. Lower amounts of pesticides leached through grass-cover soil columns (2.7-24.3% of the initial amount) than the bare soil columns (8.0-55.1%), in correspondence with their sorption coefficients. Diuron was recovered in higher amounts in leachates (8.9-32.2%) than tebuconazole (2.7-12.9%), in agreement with their sorption coefficients. However, despite having a sorption coefficient similar to that of diuron, more procymidone was recovered in the leachates (10.2-55.1%), probably due to its facilitated transport by dissolved organic matter. Thus even in this very permeable soil, higher organic matter contents associated with grass-cover reduce the amount of pesticide leaching and limit the risk of groundwater contamination by the pesticides. The results of diuron and tebuconazole transfer through undisturbed buffer zone soil columns are in agreement with field observations on the buffer zone. - Grass-covered soils reduce the amount of pesticide leaching, due mainly to their higher organic matter contents, thereby reducing the risk of groundwater contamination.

  7. Effect of grass cover on water and pesticide transport through undisturbed soil columns, comparison with field study (Morcille watershed, Beaujolais)

    Energy Technology Data Exchange (ETDEWEB)

    Dousset, S., E-mail: sylvie.dousset@limos.uhp-nancy.f [Nancy-Universite, CNRS, LIMOS, BP 70239, 54506 Vandoeuvre-les-Nancy (France); Thevenot, M. [Universite de Lille 1, CNRS, Geosystemes, 59655 Villeneuve d' Ascq (France); Schrack, D. [INRA-SAD ASTER, 88500 Mirecourt (France); AFSSA, Laboratoire d' Etudes et de Recherches en Hydrologie, 54000 Nancy (France); Gouy, V.; Carluer, N. [UR Milieux Aquatiques, Ecologie et Pollution, Cemagref, 69336 Lyon Cedex (France)

    2010-07-15

    The purpose of this work is to assess the effectiveness of two grass covers (buffer zone and grass-covered inter-row), to reduce pesticide leaching, and subsequently to preserve groundwater quality. Lower amounts of pesticides leached through grass-cover soil columns (2.7-24.3% of the initial amount) than the bare soil columns (8.0-55.1%), in correspondence with their sorption coefficients. Diuron was recovered in higher amounts in leachates (8.9-32.2%) than tebuconazole (2.7-12.9%), in agreement with their sorption coefficients. However, despite having a sorption coefficient similar to that of diuron, more procymidone was recovered in the leachates (10.2-55.1%), probably due to its facilitated transport by dissolved organic matter. Thus even in this very permeable soil, higher organic matter contents associated with grass-cover reduce the amount of pesticide leaching and limit the risk of groundwater contamination by the pesticides. The results of diuron and tebuconazole transfer through undisturbed buffer zone soil columns are in agreement with field observations on the buffer zone. - Grass-covered soils reduce the amount of pesticide leaching, due mainly to their higher organic matter contents, thereby reducing the risk of groundwater contamination.

  8. Effect of grass cover on water and pesticide transport through undisturbed soil columns, comparison with field study (Morcille watershed, Beaujolais).

    Science.gov (United States)

    Dousset, S; Thévenot, M; Schrack, D; Gouy, V; Carluer, N

    2010-07-01

    The purpose of this work is to assess the effectiveness of two grass covers (buffer zone and grass-covered inter-row), to reduce pesticide leaching, and subsequently to preserve groundwater quality. Lower amounts of pesticides leached through grass-cover soil columns (2.7-24.3% of the initial amount) than the bare soil columns (8.0-55.1%), in correspondence with their sorption coefficients. Diuron was recovered in higher amounts in leachates (8.9-32.2%) than tebuconazole (2.7-12.9%), in agreement with their sorption coefficients. However, despite having a sorption coefficient similar to that of diuron, more procymidone was recovered in the leachates (10.2-55.1%), probably due to its facilitated transport by dissolved organic matter. Thus even in this very permeable soil, higher organic matter contents associated with grass-cover reduce the amount of pesticide leaching and limit the risk of groundwater contamination by the pesticides. The results of diuron and tebuconazole transfer through undisturbed buffer zone soil columns are in agreement with field observations on the buffer zone. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  9. SOM and Biomass C Stocks in Degraded and Undisturbed Andean and Coastal Nothofagus Forests of Southwestern South America

    Directory of Open Access Journals (Sweden)

    Francis Dube

    2016-12-01

    Full Text Available Grazing and over-exploitation can severely degrade soil in native forests. Considering that productivity in ecosystems is related to soil organic matter (SOM content and quality, the objectives of this study were to: (1 determine the influence of degraded (DEF, partly-degraded (PDF, and undisturbed (UNF Nothofagus forests on the stocks of carbon (C in tree biomass and SOM; (2 evaluate fractions of SOM as indicators of sustainable management; and (3 use the Century model to determine the potential gains of soil organic C (SOC. The forests are located in the Andes and Coastal mountains of southern Chile. The SOM was fractionated to separate the light fraction (LF, macroaggregates (>212 µm, mesoaggregates (212–53 µm, and microaggregates (<53 µm. In two measurement periods, the SOC stocks at 0–20 cm and 20–40 cm depths in macroaggregates were on average 100% higher in the Andean UNF, and SOC was over twice as much at 20–40 cm depth in Andean DEF. Century simulations showed that improved silvopastoral management would gradually increase total SOC in degraded soils of both sites, especially the Ultisol with a 15% increase between 2016 and 2216 (vs. 7% in the Andisol. Greater SOC in macroaggregates (p < 0.05 of UNF indicate a condition of higher sustainability and better management over the years.

  10. Dynamics of Leishmania chagasi infection in small mammals of the undisturbed and degraded tropical dry forests of northern Colombia.

    Science.gov (United States)

    Travi, B L; Osorio, Y; Becerra, M T; Adler, G H

    1998-01-01

    The infection rate with Leishmania chagasi and the population dynamics of small mammals were studied in an undisturbed forest reserve (Colosó) and an area of highly degraded forest (San Andrés de Sotavento [SAS]) in northern Colombia, both endemic for visceral leishmaniasis. Live trapping of mammals was done every month, and species, age, sex and reproductive status determined. L. chagasi was detected in samples of skin or spleen by the polymerase chain reaction, after extraction of deoxyribonucleic acid using specific primers (DB8/AJS3), and dot blood hybridization. Didelphis marsupialis was found to be infected in Colosó (3/21, 14.3%) and SAS (13/137, 9.5%); its relative abundance was higher in SAS (93/113, 82% of the captures). Although Proechimys canicollis was also found to be infected in Colosó (3/34, 8.8%) and SAS (2/4), its relative abundance was much lower (4%) in SAS than in Colosó (56% of 77 animals captured). Sciurus granatensis, Marmosa robinsoni, Heteromys anomalus, Zygodontomys brevicauda and Metachirus nudicaudatus were less common, and no L. chagasi infection was detected in them.

  11. Geodetic Imaging of Marsh Surface Elevation with Terrestrial Laser Scanning

    Science.gov (United States)

    Nguyen, C. T.; Starek, M. J.; Gibeaut, J. C.; Lord, A.

    2015-12-01

    The resilience of marshes to a rising sea is dependent on their elevation response. Given the level of precision required to measure minute changes in marsh elevation over time, survey methods have to be adapted to minimize impacts to the sediment surface. Current approaches include Surface Elevation Tables (SETs), which are used to monitor wetland surface change with respect to an in situ vertical benchmark. Although SETs have been proven as an effective technique to track subtle sedimentation rates (RTK GPS for comparison. Grand Bay in Mississippi USA is one of the most biologically productive estuarine ecosystems in the Gulf of Mexico. The study region is covered by dense and tall saw-grass that makes it a challenging environment for bare-earth mapping. For this survey, a Riegl VZ-400 TLS (1550 nm wavelength) was utilized. The system is capable of recording multiple returns per a transmitted pulse (up to 15) and provides full-waveform output for signal post-processing to extract returns. The objectives of the study are twofold: 1) examine impacts of TLS survey design, scan angle and scan density on marsh elevation mapping; 2) assess the capabilities of multiple-echo and full-waveform TLS data to extract the bare-earth surface below the dense vegetation. This presentation will present results of the study including the developed TLS survey protocol and data processing workflow, details on waveform and multi-echo approaches for ground point detection, and a discussion on error analysis and challenges for measuring marsh surface elevation with TLS.

  12. Oiling accelerates loss of salt marshes, southeastern Louisiana.

    Directory of Open Access Journals (Sweden)

    Michael Beland

    Full Text Available The 2010 BP Deepwater Horizon (DWH oil spill damaged thousands of km2 of intertidal marsh along shorelines that had been experiencing elevated rates of erosion for decades. Yet, the contribution of marsh oiling to landscape-scale degradation and subsequent land loss has been difficult to quantify. Here, we applied advanced remote sensing techniques to map changes in marsh land cover and open water before and after oiling. We segmented the marsh shorelines into non-oiled and oiled reaches and calculated the land loss rates for each 10% increase in oil cover (e.g. 0% to >70%, to determine if land loss rates for each reach oiling category were significantly different before and after oiling. Finally, we calculated background land-loss rates to separate natural and oil-related erosion and land loss. Oiling caused significant increases in land losses, particularly along reaches of heavy oiling (>20% oil cover. For reaches with ≥20% oiling, land loss rates increased abruptly during the 2010-2013 period, and the loss rates during this period are significantly different from both the pre-oiling (p < 0.0001 and 2013-2016 post-oiling periods (p < 0.0001. The pre-oiling and 2013-2016 post-oiling periods exhibit no significant differences in land loss rates across oiled and non-oiled reaches (p = 0.557. We conclude that oiling increased land loss by more than 50%, but that land loss rates returned to background levels within 3-6 years after oiling, suggesting that oiling results in a large but temporary increase in land loss rates along the shoreline.

  13. Cyanobacterial diversity in alkaline marshes of northern Belize (Central America)

    Czech Academy of Sciences Publication Activity Database

    Komárek, Jiří; Ventura, S.; Turicchia, S.; Komárková, Jaroslava; Mascalchi, C.; Soldati, E.

    2005-01-01

    Roč. 158, č. 117 (2005), s. 265-278 ISSN 0342-1120. [Symposium of the International Association for Cyanophyte Research /16./. Luxembourg, 30.08.2004-03.09.2004] R&D Projects: GA AV ČR(CZ) IAA6005309; GA AV ČR KSK6005114; GA MŠk(CZ) ME 653 Institutional research plan: CEZ:AV0Z6005908 Keywords : Cyanobacteria * alkaline marshes * Central Amerika Subject RIV: EF - Botanics

  14. Updated estimates of carbon accumulation rates in coastal marsh sediments

    OpenAIRE

    Ouyang, X.; Lee, S. Y.

    2014-01-01

    Studies on carbon stock in salt marsh sediments have increased since the review by Chmura et al. (2003). However, uncertainties exist in estimating global carbon storage in these vulnerable coastal habitats, thus hindering the assessment of their importance. Combining direct data and indirect estimation, this study compiled studies involving 143 sites across the Southern and Northern hemispheres, and provides an updated estimate of the global average carbon accumulation rate...

  15. Elders Point East Marsh Island Restoration Monitoring Data Analysis

    Science.gov (United States)

    2017-09-21

    Abstract Chronic loss of intertidal salt marsh island habitat in Jamaica Bay, New York, has led to efforts by multi-agency partnerships to reduce... partnerships to reduce loss through habitat restoration. In response to these losses, under the U.S. Army Corps of Engineers’ Continuing Authorities...consideration is the definition of “long-term.” For the Elders East Project, multiple years of post-construction monitoring certainly adds confidence to a

  16. Distribution patterns of salt marsh vegetation on Parramore Island, Virginia Coast Reserve

    Energy Technology Data Exchange (ETDEWEB)

    Hegnauer, E.A.; Furman, T. (Univ. of Virginia, Charlottesville, VA (United States). Dept. of Environmental Sciences)

    1994-03-01

    The Virginia Coast Reserve is a classic example of an estuarine-barrier island complex, and is dominated physiographically by tidal salt marshes. Marsh vegetation includes Spartina alterniflora and patens, Juncus romerianus, Disticlis spicata and Salicornia virginica; these species occur in a random mosaic pattern throughout the salt marsh. Previous work has shown that porewater salinity and flooding frequency control plant distributions at a gross scale (daily tidal inundation versus occasional flooding), but variations in these parameters are extremely subtle in the Parramore marshes. The goal of this research is to document and monitor small-scale physical factors that control spatial distribution of marsh species. The results of this study have serious implications for development of artificial wetlands. Topographic variations on the order of < 10 cm are significant in determining both flooding history and water table salinity, and therefore affect the colonization and growth of marsh plant species dramatically.

  17. Traits of estuarine marsh plants affect wave dissipation

    Science.gov (United States)

    Schulte Ostermann, Tilla; Heuner, Maike; Bouma, Tjeerd

    2017-04-01

    Estuarine vegetation can attenuate hydrodynamic forces such as waves or flow velocities and therefore has an important role in natural tidal bank protection. This function depends on the degree of hydrodynamic forces, bank morphology and on plant traits of the dominant species. The traits vary between the species but also between different marsh sites. Biomass, stem density and biomechanical properties are crucial factors that influence the rate of wave dissipation. These properties illustrate the trade-offs a species is facing in such a dynamic habitat and highlight the ability of dominant species such as Bolboschoenus maritimus and Schoenoplectus tabernaemontani to protect the tidal bank. Along the Elbe estuary, traits of dominant marsh plant species were measured on different sites. The sites vary e.g. in their elevation, salt levels and inundation periods. To analyse the role that plant traits can play in wave dissipation, the structure of the vegetation as well as the composition was recorded. Biomechanical tests helped to understand the species traits regarding stem flexibility and to determine the effects of plant traits on wave dynamics and vice versa. On the conference, we will present how plant traits affect the wave dissipation on tidal marshes and why they vary.

  18. Monitoring for bioremediation efficacy: The marrow marsh experience

    International Nuclear Information System (INIS)

    Nadeau, R.; Singhvi, R.; Ryabik, J.; Lin, Yihua; Syslo, J.

    1993-01-01

    The US Environmental Protection Agency's Environmental Response Team analyzed samples taken from Marrow Marsh, Galveston Bay, Texas, to assess the efficacy of a bioremediation effort in the marsh following the Apex barges spill on July 28, 1990. Samples from the marsh had been collected over a 96-hour period following the first application of the bioremediation agent and then 25 days after the second application, which occurred 8 days after the first. Results of sample analyses to evaluate changes in the chemical characteristics of spilled oil failed to show evidence of oil degradation during the 96 hours after the initial treatment, but did show evidence of degradation 25 days after the second treatment-although differences between samples from treated and untreated sites were not evident. Because control areas had not been maintained after the second application, contamination by the bioremediation agent of previously untreated (control) areas may have occurred, perhaps negating the possibility of detecting differences between treated and control areas. Better preparedness to implement bioremediation and conduct monitoring might have increased the effectiveness of the monitoring effort

  19. Vegetation engineers marsh morphology through multiple competing stable states

    Science.gov (United States)

    Marani, Marco; Da Lio, Cristina; D’Alpaos, Andrea

    2013-01-01

    Marshes display impressive biogeomorphic features, such as zonation, a mosaic of extensive vegetation patches of rather uniform composition, exhibiting sharp transitions in the presence of extremely small topographic gradients. Although generally associated with the accretion processes necessary for marshes to keep up with relative sea level rise, competing environmental constraints, and ecologic controls, zonation is still poorly understood in terms of the underlying biogeomorphic mechanisms. Here we find, through observations and modeling interpretation, that zonation is the result of coupled geomorphological–biological dynamics and that it stems from the ability of vegetation to actively engineer the landscape by tuning soil elevation within preferential ranges of optimal adaptation. We find multiple peaks in the frequency distribution of observed topographic elevation and identify them as the signature of biologic controls on geomorphodynamics through competing stable states modulated by the interplay of inorganic and organic deposition. Interestingly, the stable biogeomorphic equilibria correspond to suboptimal rates of biomass production, a result coherent with recent observations. The emerging biogeomorphic structures may display varying degrees of robustness to changes in the rate of sea level rise and sediment availability, with implications for the overall resilience of marsh ecosystems to climatic changes. PMID:23401529

  20. Remote sensing of wetland conditions in West Coast salt marshes

    Science.gov (United States)

    Ustin, Susan L.; Lay, Mui C.; Li, Lin

    2004-11-01

    The objective of the PEEIR (Pacific Estuarine Ecosystem Indicator Research Consortium) program is to develop new indicators for assessing wetland health or condition. As part of PEEIR program we are investigating the use of imaging spectrometry to map and characterize marsh vegetation of several estuarine systems in California. We obtained airborne Advanced Visible Infrared Imaging Spectrometer (AVIRIS) data, an instrument which measures a detailed reflectance spectrum (400-2500nm) for each pixel, over paired tidal marshes, having either a history of exposure to pollution or no known exposure. AVIRIS image data was analyzed based on comparison to field measurements and reflectance changes measured in hydroponic experiments. We report leaf and canopy reflectance measurements of several common plant species of Pacific coast salt marshes exposed to different concentrations of heavy metals (Cd, V) and crude oil contaminants. Species exhibited differential sensitivities to specific contaminants, however in general, Salicornia virginica, the most salt tolerant species and the dominant species in these wetlands (70-90% cover) was most sensitive to metal and petroleum contaminants. Field measurements of canopy reflectance, biomass and vegetation structure were acquired across GPS-located transects at each field site. The AVIRIS data were calibrated to surface reflectance using the FLAASH radiative transfer code and geometrically registered to coordinates using the 1m USGS digital orthophoto quads. AVIRIS results show spatial patterns of plant stress indicators (e.g., reduced chlorophyll and water contents) are consistent with known patterns of contamination in these tidal wetlands.

  1. Recovery of freshwater marsh vegetation after a saltwater intrusion event.

    Science.gov (United States)

    Flynn, K M; McKee, K L; Mendelssohn, I A

    1995-07-01

    Greenhouse mesocosms of freshwater marsh vegetation were exposed to a simulated saltwater intrusion event followed by a recovery period during which water levels and interstitial water salinity were adjusted over a range of conditions. Virtually all above-ground vegetation, including the three dominant species, Sagittaria lancifolia L., Leersia oryzoides (L.) Swartz, and Panicum hemitomon Schultes, was killed by the initial saltwater intrusion event. P. hemitomon did not recover, but S. lancifolia and L. oryzoides, as well as many of the other species initially present, exhibited some ability to recover depending on post-saltwater intrusion conditions. Increasingly harsh recovery conditions (for freshwater marsh vegetation), including more reduced soil conditions, higher interstitial salinities, and higher interstitial sulfide concentrations were associated with decreased live above-ground biomass and species richness. The effect of elevated salinity on vegetative recovery became more pronounced under flooded conditions. This experiment illustrates that the response of a freshwater marsh community to the long-term disturbance effect of a transient saltwater intrusion event will be strongly influenced by post-intrusion salinity and water levels.

  2. Otter Hunting and Trapping, a Traditional Practice of Marsh Arabs of Iraq

    OpenAIRE

    Omar F. Al-Sheikhly; Mukhtar K. Haba; Filippo Barbanera

    2015-01-01

    Two species of otter inhabit the marshes of southern Iraq: the European otter (Lutra lutra) and the smooth-coated otter (endemic subspecies: Lutrogale perspicillata maxwelli). Marsh Arabs have targeted otters since at least the 1950s. Nowadays, local marsh inhabitants are still heavily hunting otters for their fur or trapping their cubs to be raised as pets. These practices, together with habitat destruction (i.e., marshland drainage), represent primary threats to the otters’ survival in Iraq...

  3. Elevation dynamics in a restored versus a submerging salt marsh in Long Island Sound

    Science.gov (United States)

    Anisfeld, Shimon C.; Hill, Troy D.; Cahoon, Donald R.

    2016-01-01

    Accelerated sea-level rise (SLR) poses the threat of salt marsh submergence, especially in marshes that are relatively low-lying. At the same time, restoration efforts are producing new low-lying marshes, many of which are thriving and avoiding submergence. To understand the causes of these different fates, we studied two Long Island Sound marshes: one that is experiencing submergence and mudflat expansion, and one that is undergoing successful restoration. We examined sedimentation using a variety of methods, each of which captures different time periods and different aspects of marsh elevation change: surface-elevation tables, marker horizons, sediment cores, and sediment traps. We also studied marsh hydrology, productivity, respiration, nutrient content, and suspended sediment. We found that, despite the expansion of mudflat in the submerging marsh, the areas that remain vegetated have been gaining elevation at roughly the rate of SLR over the last 10 years. However, this elevation gain was only possible thanks to an increase in belowground volume, which may be a temporary response to waterlogging. In addition, accretion rates in the first half of the twentieth century were much lower than current rates, so century-scale accretion in the submerging marsh was lower than SLR. In contrast, at the restored marsh, accretion rates are now averaging about 10 mm yr−1 (several times the rate of SLR), much higher than before restoration. The main cause of the different trajectories at the two marshes appeared to be the availability of suspended sediment, which was much higher in the restored marsh. We considered and rejected alternative hypotheses, including differences in tidal flooding, plant productivity, and nutrient loading. In the submerging marsh, suspended and deposited sediment had relatively high organic content, which may be a useful indicator of sediment starvation.

  4. Lignocellulose-responsive bacteria in a southern California salt marsh identified by stable isotope probing

    OpenAIRE

    Darjany, Lindsay E.; Whitcraft, Christine R.; Dillon, Jesse G.

    2014-01-01

    Carbon cycling by microbes has been recognized as the main mechanism of organic matter decomposition and export in coastal wetlands, yet very little is known about the functional diversity of specific groups of decomposers (e.g., bacteria) in salt marsh benthic trophic structure. Indeed, salt marsh sediment bacteria remain largely in a black box in terms of their diversity and functional roles within salt marsh benthic food web pathways. We used DNA stable isotope probing (SIP) utilizing 13C-...

  5. The protective role of coastal marshes: a systematic review and meta-analysis.

    Directory of Open Access Journals (Sweden)

    Christine C Shepard

    Full Text Available BACKGROUND: Salt marshes lie between many human communities and the coast and have been presumed to protect these communities from coastal hazards by providing important ecosystem services. However, previous characterizations of these ecosystem services have typically been based on a small number of historical studies, and the consistency and extent to which marshes provide these services has not been investigated. Here, we review the current evidence for the specific processes of wave attenuation, shoreline stabilization and floodwater attenuation to determine if and under what conditions salt marshes offer these coastal protection services. METHODOLOGY/PRINCIPAL FINDINGS: We conducted a thorough search and synthesis of the literature with reference to these processes. Seventy-five publications met our selection criteria, and we conducted meta-analyses for publications with sufficient data available for quantitative analysis. We found that combined across all studies (n = 7, salt marsh vegetation had a significant positive effect on wave attenuation as measured by reductions in wave height per unit distance across marsh vegetation. Salt marsh vegetation also had a significant positive effect on shoreline stabilization as measured by accretion, lateral erosion reduction, and marsh surface elevation change (n = 30. Salt marsh characteristics that were positively correlated to both wave attenuation and shoreline stabilization were vegetation density, biomass production, and marsh size. Although we could not find studies quantitatively evaluating floodwater attenuation within salt marshes, there are several studies noting the negative effects of wetland alteration on water quantity regulation within coastal areas. CONCLUSIONS/SIGNIFICANCE: Our results show that salt marshes have value for coastal hazard mitigation and climate change adaptation. Because we do not yet fully understand the magnitude of this value, we propose that decision

  6. Tidal marsh stability in the face of human impacts and sea level rise

    Science.gov (United States)

    Kirwan, M. L.

    2014-12-01

    Coastal populations and marshes have been intertwined for centuries, where humans both influence and depend on the enormous ecosystem services that marshes provide. Although marshes have long been considered vulnerable to climate change, recent work identifies fascinating feedbacks between plant growth and geomorphology that enable them to actively resist sea level rise. Here, we will review existing literature and provide new data to examine how humans alter these feedbacks. Measurements of accretion and elevation change suggest that most marshes will survive present day sea level rise rates by building vertically. Numerical models predict that these marshes will survive moderate accelerations in the rate of sea level in places where dams do not limit sediment delivery to the coast. However, these results also suggest that marsh survival under faster accelerations in sea level will depend on their ability to migrate inland. Marsh transgression into uplands is influenced not only by topography, but also by human land use and decisions to harden shorelines. Preliminary numerical model experiments will be used to explore how basic biophysical and anthropogenic drivers determine whether sea level change will lead to marsh loss (erosion+drowning > transgression), marsh expansion (transgression > erosion), or dynamic equilibrium (transgression = erosion).

  7. Estuaries as filters: the role of tidal marshes in trace metal removal.

    Directory of Open Access Journals (Sweden)

    Johannes Teuchies

    Full Text Available Flux calculations demonstrate that many estuaries are natural filters for trace metals. Yet, the underlying processes are poorly investigated. In the present study, it was hypothesized that intertidal marshes contribute significantly to the contaminant filter function of estuaries. Trace metal concentrations and sediment characteristics were measured along a transect from the subtidal, over an intertidal flat and marsh to a restored marsh with controlled reduced tide. Metal concentrations in the intertidal and restored marsh were found to be a factor two to five higher than values in the subtidal and intertidal flat sediments. High metal concentrations and high accretion rates indicate a high metal accumulation capacity of the intertidal marshes. Overbank sedimentation in the tidal marshes of the entire estuary was calculated to remove 25% to 50% of the riverine metal influx, even though marshes comprise less than 8% of the total surface of the estuary. In addition, the large-scale implementation of planned tidal marsh restoration projects was estimated to almost double the trace metal storage capacity of the present natural tidal marshes in the estuary.

  8. Mosquitoes Associated with Ditch-Plugged and Control Tidal Salt Marshes on the Delmarva Peninsula

    Directory of Open Access Journals (Sweden)

    Paul T. Leisnham

    2011-07-01

    Full Text Available A study was conducted during the summer of 2009 (from July to September to characterize mosquito communities among different habitats in five historically ditched tidal salt marshes and three adjacent wooded areas in the E.A. Vaughn Wetland Management Area on the Maryland Delmarva Peninsula, USA. Study marshes are characteristic of Atlantic coastal salt marshes that had undergone grid ditching from the 1930s to 1950s. In the autumn of 2008 (October and November ditches were plugged near their outlets in two (‘experimental’ marshes with the aim to restore their natural tidal hydrology. The three other marshes were not plugged. Marshes were sampled from July to September in 2009 by using standard dip count method. A total of 2,457 mosquito larvae representing six species were collected on 15.4% (86/557 of all sample occasions and 399 adults representing four mosquito species were collected from landing counts. Aedes sollicitans, Anopheles bradleyi and Culex salinarius were the most common species collected in larval habitats, and Ae. sollicitans was the most common adult collected. Wooded habitats had more total mosquitoes, were also more frequently occupied by mosquitoes and had higher densities of mosquitoes than marsh habitats. Almost all larvae collected from marshes were from one experimental and one control site. The majority of larvae at the control site were Ae. sollicitans in marsh pannes while Cx. salinarius, An. bradleyi, Ae. cantator, and Ae. sollicitans were collected in high numbers from ditches at the experimental site. We found a difference in the proportion of marsh pannes occupied by Ae. sollicitans but not total mosquitoes sampled 4–5 days after spring tide events than on other occasions. Salinity measures of 42 larval habitats showed lower median salinity in mosquito-occupied habitats (11.5 ppt than unoccupied habitats (20.1 ppt, and in habitats in wooded areas followed by ditches and pannes in marsh areas. The results of

  9. Delineation of marsh types from Corpus Christi Bay, Texas, to Perdido Bay, Alabama, in 2010

    Science.gov (United States)

    Enwright, Nicholas M.; Hartley, Stephen B.; Couvillion, Brady R.; Michael G. Brasher,; Jenneke M. Visser,; Michael K. Mitchell,; Bart M. Ballard,; Mark W. Parr,; Barry C. Wilson,

    2015-07-23

    Coastal zone managers and researchers often require detailed information regarding emergent marsh vegetation types (that is, fresh, intermediate, brackish, and saline) for modeling habitat capacities and needs of marsh dependent taxa (such as waterfowl and alligator). Detailed information on the extent and distribution of emergent marsh vegetation types throughout the northern Gulf of Mexico coast has been historically unavailable. In response, the U.S. Geological Survey, in collaboration with the Gulf Coast Joint Venture, the University of Louisiana at Lafayette, Ducks Unlimited, Inc., and the Texas A&M University-Kingsville, produced a classification of emergent marsh vegetation types from Corpus Christi Bay, Texas, to Perdido Bay, Alabama.

  10. Carbon Sequestration in Tidal Salt Marshes of the Northeast United States.

    Science.gov (United States)

    Drake, Katherine; Halifax, Holly; Adamowicz, Susan C; Craft, Christopher

    2015-10-01

    Tidal salt marshes provide important ecological services, habitat, disturbance regulation, water quality improvement, and biodiversity, as well as accumulation and sequestration of carbon dioxide (CO2) in vegetation and soil organic matter. Different management practices may alter their capacity to provide these ecosystem services. We examined soil properties (bulk density, percent organic C, percent N), C and N pools, C sequestration and N accumulation at four marshes managed with open marsh water management (OMWM) and four marshes that were not at U.S. Fish and Wildlife National Wildlife Refuges (NWRs) on the East Coast of the United States. Soil properties (bulk density, percent organic C, percent N) exhibited no consistent differences among managed and non-OMWM marshes. Soil organic carbon pools (0-60-cm depth) also did not differ. Managed marshes contained 15.9 kg C/m(2) compared to 16.2 kg C/m(2) in non-OMWM marshes. Proportionately, more C (per unit volume) was stored in surface than in subsurface soils. The rate of C sequestration, based on (137)Cs and (210)Pb dating of soil cores, ranged from 41 to 152 g/m(2)/year. Because of the low emissions of CH4 from salt marshes relative to freshwater wetlands and the ability to sequester C in soil, protection and restoration of salt marshes can be a vital tool for delivering key ecosystem services, while at the same time, reducing the C footprint associated with managing these wetlands.

  11. Habitat Characteristics and Eggshell Distribution of the Salt Marsh Mosquito, Aedes vigilax, in Marshes in Subtropical Eastern Australia

    OpenAIRE

    Dale, Pat E. R.; Knight, Jon; Kay, Brian H.; Chapman, Heather; Ritchie, Scott A.; Brown, Michael D.

    2008-01-01

    Research at 10 locations in coastal subtropical Queensland, Australia, has shown that salt marshes contained heterogeneous distributions of eggshells of the pest and vector mosquito Aedes vigilax (Skuse) (Diptera:Culicidae). The eggshell distribution was related to specific vegetation assemblages, with a mix of the grass, Sporobolus virginicus (L.) Kunth (Poales: Poaceae), and the beaded glasswort, Sarcocornia quinqueflora (Bunge ex (Ung.-Stern) A.J. Scott (Caryophyllales: Chenopodiaceae), as...

  12. Automated Detection of Salt Marsh Platforms : a Topographic Method

    Science.gov (United States)

    Goodwin, G.; Mudd, S. M.; Clubb, F. J.

    2017-12-01

    Monitoring the topographic evolution of coastal marshes is a crucial step toward improving the management of these valuable landscapes under the pressure of relative sea level rise and anthropogenic modification. However, determining their geometrically complex boundaries currently relies on spectral vegetation detection methods or requires labour-intensive field surveys and digitisation.We propose a novel method to reproducibly isolate saltmarsh scarps and platforms from a DEM. Field observations and numerical models show that saltmarshes mature into sub-horizontal platforms delineated by sub-vertical scarps: based on this premise, we identify scarps as lines of local maxima on a slope*relief raster, then fill landmasses from the scarps upward, thus isolating mature marsh platforms. Non-dimensional search parameters allow batch-processing of data without recalibration. We test our method using lidar-derived DEMs of six saltmarshes in England with varying tidal ranges and geometries, for which topographic platforms were manually isolated from tidal flats. Agreement between manual and automatic segregation exceeds 90% for resolutions of 1m, with all but one sites maintaining this performance for resolutions up to 3.5m. For resolutions of 1m, automatically detected platforms are comparable in surface area and elevation distribution to digitised platforms. We also find that our method allows the accurate detection of local bloc failures 3 times larger than the DEM resolution.Detailed inspection reveals that although tidal creeks were digitised as part of the marsh platform, automatic detection classifies them as part of the tidal flat, causing an increase in false negatives and overall platform perimeter. This suggests our method would benefit from a combination with existing creek detection algorithms. Fallen blocs and pioneer zones are inconsistently identified, particularly in macro-tidal marshes, leading to differences between digitisation and the automated method

  13. Genesis and distribution pattern of carbonate cements in lacustrine deep-water gravity-flow sandstone reservoirs in the third member of the Shahejie Formation in the Dongying Sag, Jiyang Depression, Eastern China

    DEFF Research Database (Denmark)

    Yang, Tian; Cao, Yingchang; Friis, Henrik

    2017-01-01

    The lacustrine deep-water gravity-flow sandstone reservoirs in the third member of the Shahejie Formation are the main exploration target for hydrocarbons in the Dongying Sag, Eastern China. Carbonate cementation is responsible for much of the porosity and permeability reduction in the lacustrine...

  14. Assessing wildlife benefits and carbon storage from restored and natural coastal marshes in the Nisqually River Delta: Determining marsh net ecosystem carbon balance

    Science.gov (United States)

    Anderson, Frank; Bergamaschi, Brian; Windham-Myers, Lisamarie; Woo, Isa; De La Cruz, Susan; Drexler, Judith; Byrd, Kristin; Thorne, Karen M.

    2016-06-24

    Working in partnership since 1996, the U.S. Fish and Wildlife Service and the Nisqually Indian Tribe have restored 902 acres of tidally influenced coastal marsh in the Nisqually River Delta (NRD), making it the largest estuary-restoration project in the Pacific Northwest to date. Marsh restoration increases the capacity of the estuary to support a diversity of wildlife species. Restoration also increases carbon (C) production of marsh plant communities that support food webs for wildlife and can help mitigate climate change through long-term C storage in marsh soils.In 2015, an interdisciplinary team of U.S. Geological Survey (USGS) researchers began to study the benefits of carbon for wetland wildlife and storage in the NRD. Our primary goals are (1) to identify the relative importance of the different carbon sources that support juvenile chinook (Oncorhynchus tshawytscha) food webs and contribute to current and historic peat formation, (2) to determine the net ecosystem carbon balance (NECB) in a reference marsh and a restoration marsh site, and (3) to model the sustainability of the reference and restoration marshes under projected sea-level rise conditions along with historical vegetation change. In this fact sheet, we focus on the main C sources and exchanges to determine NECB, including carbon dioxide (CO2) uptake through plant photosynthesis, the loss of CO2 through plant and soil respiration, emissions of methane (CH4), and the lateral movement or leaching loss of C in tidal waters.

  15. Acid-base buffering of soils in transitional and transitional-accumulative positions of undisturbed southern-taiga landscapes

    Science.gov (United States)

    Rusakova, E. S.; Ishkova, I. V.; Tolpeshta, I. I.; Sokolova, T. A.

    2012-05-01

    The method of continuous potentiometric titration (CPT) of soil water suspensions was used to evaluate the acid-base buffering of samples from the major genetic horizons of podzolic soils on a slope and soddy gley soils on the adjacent floodplain of a rivulet. In the soils of the slope, the buffering to acid upon titration from the pH of the initial titration point (ITP) to pH 3 in all the horizons was 1.5-2.0 times lower than that in the podzolic soils of the leveled interfluve, which could be due to the active leaching of exchangeable bases and oxalate-soluble aluminum and iron compounds with the later soil flows. In the soddy gley soils, the buffering to acid in the mineral horizons was 2-10 times higher than that in the podzolic soils. A direct dependence of the soil buffering to acid on the total content of exchangeable bases and on the content of oxalate-soluble aluminum compounds was found. A direct dependence of the buffering to basic upon titration from the ITP to pH 10 on the contents of the oxalate-soluble aluminum and organic matter was observed in the mineral horizons of all the studied soils. The soil treatment with Tamm's reagent resulted in the decrease of the buffering to acid in the soddy gley soils of the floodplain, as well as in the decrease of the buffering to basic in the soils on the slopes and in the soddy gley soils. It was also found that the redistribution of the mobile aluminum compounds between the eluvial, transitional, and transitional-accumulative positions in the undisturbed southern taiga landscapes leads to significant spatial differentiation of the acid-base buffering of the mineral soil horizons with a considerable increase in the buffer capacity of the soils within the transitional-accumulative terrain positions.

  16. Changes in Marsh Vegetation, Stability and Dissolved Organic Carbon in Barataria Bay Marshes Following the Deepwater Horizon Oil Spill

    Science.gov (United States)

    Holloway, J. M.; Aiken, G.; Kokaly, R. F.; Heckman, D.; Butler, K.; Mills, C. T.; Hoefen, T. M.; Piazza, S.

    2010-12-01

    Coastal wetlands in Southern Louisiana were contaminated by the release of record volumes of oil between April and July 2010. Barataria Bay was extensively impacted, resulting in the oiling and dieback of marsh grasses along a discontinuous margin up to 30m into the marshes. Shoreline stability and biogeochemistry have been monitored over three site visits between between July 10 and August 25, 2010. Initial observations in early July were that grasses, dominantly shape Spartina alterniflora and shape Juncus roemerianus, were bent over under the weight of a thick oil coating. The bent-over grasses were broken off along some reaches, leaving a stubbled shoreline more susceptible to erosion. Repeated site visits in mid and late August found visible erosion along some of the effected shorelines. Water samples were collected from the shoreline marsh remnants and from visibly unaffected marshes to characterize dissolved organic carbon (DOC) and total dissolved nitrogen (TDN). In spite of visible oil sheens in unfiltered water from contaminated shorelines and no visible sign of impact on vegetation in the “control” sites with no visible oil on vegetation, DOC concentrations were similar in impacted and visibly unimpacted sites in Barataria Bay. Subsequent samples in mid- and late-August had increased DOC concentrations relative to previous sample events regardless of whether the site was visibly impacted. There was a general increase in specific UV absorbance (SUVA), an index of aromaticity, with increasing DOC concentrations, either due to seasonal effects or continued dissolution of petroleum compounds. Further chemical characterization using fluorescence and gas chromatography will be used to confirm the presence of petroleum compounds. The ratio of DOC to TDN also increased over time, which may have implications for vegetation regrowth and plant community structure, including the shift of grass species dominating effected marshes. These initial findings suggest

  17. Deep-water seamounts in the NE Atlantic, sources of landslides-induced tsunamis: Slope stability analysis and tsunami numerical modelling

    Science.gov (United States)

    Baptista, M. A.; Omira, R.; Ramalho, I.; Vales, D.; Matias, L. M.; Terrinha, P.

    2015-12-01

    Submarine mass failures (SMFs) present one of the significant marine Geo-hazards. Their importance as contributors to tsunami hazard has been recognized over the last 20-30 years, but they are seldom considered in the evaluation of quantitative tsunami impact or in the design of warning strategies. This study aims to investigate the slope stability of the SMFs in the NE Atlantic, their companion tsunami and the associated hazard at the target coasts. It focuses on two major deep-water seamounts of the NE Atlantic, the Gorringe Bank and the Hirondelle, where evidences of large SMFs have been found. Slope stability analysis is often based on relationships between landslides and earthquakes. Here, within each considered seamount, slope failure potential is investigated through the pseudo-static method. This analysis allows establishing a relationship between the size of the SMF and the critical earthquake peak ground acceleration necessary to initiate it and therefore define the possible SMF scenarios. Numerical modelling of SMF-induced tsunami generation is then employed to test the tsunamigenic potential of each defined scenario. It is performed using a multi-layers viscous shallow-water model, where the lower layer represents the deformable slide that is assumed to be a viscous-incompressible fluid, and bounded by the upper layer of seawater assumed to be inviscid and incompressible. The propagation of tsunami waves is simulated employing non-linear shallow water equations. Results are presented in terms of: 1) slope stability curves that establish the relationship between the probable earthquake magnitudes and the possible sizes of SMFs, 2) possible SMF scenarios within each seamount, 3) potential of tsunami generation for each SMF, 4) tsunami coastal impact at target coasts. Results show that SMFs in the NE Atlantic have the potential of generating large tsunamis with significant impact along the surrounding coasts. Therefore, more attention must be accorded to

  18. Tidal marsh susceptibility to sea-level rise: importance of local-scale models

    Science.gov (United States)

    Thorne, Karen M.; Buffington, Kevin J.; Elliott-Fisk, Deborah L.; Takekawa, John Y.

    2015-01-01

    Increasing concern over sea-level rise impacts to coastal tidal marsh ecosystems has led to modeling efforts to anticipate outcomes for resource management decision making. Few studies on the Pacific coast of North America have modeled sea-level rise marsh susceptibility at a scale relevant to local wildlife populations and plant communities. Here, we use a novel approach in developing an empirical sea-level rise ecological response model that can be applied to key management questions. Calculated elevation change over 13 y for a 324-ha portion of San Pablo Bay National Wildlife Refuge, California, USA, was used to represent local accretion and subsidence processes. Next, we coupled detailed plant community and elevation surveys with measured rates of inundation frequency to model marsh state changes to 2100. By grouping plant communities into low, mid, and high marsh habitats, we were able to assess wildlife species vulnerability and to better understand outcomes for habitat resiliency. Starting study-site conditions were comprised of 78% (253-ha) high marsh, 7% (30-ha) mid marsh, and 4% (18-ha) low marsh habitats, dominated by pickleweed Sarcocornia pacifica and cordgrass Spartina spp. Only under the low sea-level rise scenario (44 cm by 2100) did our models show persistence of some marsh habitats to 2100, with the area dominated by low marsh habitats. Under mid (93 cm by 2100) and high sea-level rise scenarios (166 cm by 2100), most mid and high marsh habitat was lost by 2070, with only 15% (65 ha) remaining, and a complete loss of these habitats by 2080. Low marsh habitat increased temporarily under all three sea-level rise scenarios, with the peak (286 ha) in 2070, adding habitat for the endemic endangered California Ridgway’s rail Rallus obsoletus obsoletus. Under mid and high sea-level rise scenarios, an almost complete conversion to mudflat occurred, with most of the area below mean sea level. Our modeling assumed no marsh migration upslope due to human

  19. Expansive Tidal Marshes on the North American Eastern Seaboard: Relics of Colonial Deforestation?

    Science.gov (United States)

    Murray, A.; Kirwan, M.

    2013-12-01

    Experiments using a numerical model of tidal marsh ecomorphodynamic evolution suggest that changes in sediment supply (suspended sediment concentrations) reaching tidal marshes can play a role as strong as sea-level-rise rate in determining the extent and elevation of coastal wetlands. Testing a model-generated hypothesis, sediment coring and radiocarbon dating in the Plum Island Estuary marshes, Massachusetts, USA, suggested that marshes prograded rapidly and substantially following colonial deforestation (Kirwan et al., Geology, 2011). This controversial claim has been questioned, in part because historical maps from 1780 and 1830 show that the marsh had already attained most of its modern extent by that time--which is earlier than some of the of the radiocarbon mid-point dates (Priestas et al., Geology Forum, Dec. 2012). However, given the uncertainties in the radiocarbon dates, and in identifying the earliest marsh-derived layers in sediment cores, the maps and the dating are broadly consistent (Kirwan and Murray, Geology Forum, Dec. 2012). In addition, previous studies have shown that considerable land-use change had already occurred in this small coastal watershed by the late 17th Century, with local laws against tree cutting in place by 1660, and evidence for regional deforestation by 1700. Our field evidence, combined with the historical maps, indicates that this early colonial development lead to an expansion of marshes by approximately 50 percent within the studied area. Given the widespread and pervasive nature of subsequent land-use changes on the Eastern Seaboard from colonial through civil war periods, many of the currently expansive marshes on the East Coast may be relict. Numerical modeling suggests that when sediment concentrations fall below the values required to form a marsh, the marsh will be metastable, with vegetation feedbacks able to maintain the relict morphology and ecology, but susceptible to irreversible loss in response to disturbances

  20. Intertidal salt marshes as an important source of inorganic carbon to the coastal ocean

    Science.gov (United States)

    Wang, Zhaohui Aleck; Kroeger, Kevin D.; Ganju, Neil K.; Gonneea, Meagan; Chu, Sophie N.

    2016-01-01

    Dynamic tidal export of dissolved inorganic carbon (DIC) to the coastal ocean from highly productive intertidal marshes and its effects on seawater carbonate chemistry are thoroughly evaluated. The study uses a comprehensive approach by combining tidal water sampling of CO2parameters across seasons, continuous in situ measurements of biogeochemically-relevant parameters and water fluxes, with high-resolution modeling in an intertidal salt marsh of the U.S. northeast region. Salt marshes can acidify and alkalize tidal water by injecting CO2 (DIC) and total alkalinity (TA). DIC and TA generation may also be decoupled due to differential effects of marsh aerobic and anaerobic respiration on DIC and TA. As marsh DIC is added to tidal water, the buffering capacity first decreases to a minimum and then increases quickly. Large additions of marsh DIC can result in higher buffering capacity in ebbing tide than incoming tide. Alkalization of tidal water, which mostly occurs in the summer due to anaerobic respiration, can further modify buffering capacity. Marsh exports of DIC and alkalinity may have complex implications for the future, more acidified ocean. Marsh DIC export exhibits high variability over tidal and seasonal cycles, which is modulated by both marsh DIC generation and by water fluxes. The marsh DIC export of 414 g C m−2 yr−1, based on high-resolution measurements and modeling, is more than twice the previous estimates. It is a major term in the marsh carbon budget and translates to one of the largest carbon fluxes along the U.S. East Coast.

  1. Development of a Climate Change Adaptation Strategy for Management of Coastal Marsh Systems in Southern New England USA

    Science.gov (United States)

    Sea level rise is accelerating throughout the U.S. Northeast causing shoreline erosion, increased coastal flooding, and marsh vulnerability to the impact of storms. Coastal marshes provide flood abatement, carbon and nutrient sequestration, water quality maintenance, and habitat ...

  2. Development of a Climate-Change Adaptation Strategy for Management of Coastal Marsh Systems in Southern New England USA

    Science.gov (United States)

    Sea level rise is accelerating throughout the U.S. Northeast causing shoreline erosion, increased coastal flooding, and marsh vulnerability to the impact of storms. Coastal marshes provide flood abatement, carbon and nutrient sequestration, water quality maintenance, and habitat ...

  3. The density of feral honey bee (Apis mellifera) colonies in South East Australia is greater in undisturbed than in disturbed habitats

    OpenAIRE

    Hinson, Eloise M.; Duncan, Michael; Lim, Julianne; Arundel, Jonathan; Oldroyd, Benjamin P.

    2015-01-01

    International audience; AbstractApis mellifera is an important pollinator but is sometimes associated with adverse effects on natural ecosystems. We surveyed pairs of disturbed and undisturbed sites across three biomes in South East Australia. We used pheromone lures to trap drones, genotyped the drones to infer the number of colonies within flight range and then estimated colony densities using synthetic sampling distributions. Estimated colony densities ranged from 0.1 to 1.5 colonies km−2 ...

  4. Comparison of absolute biochemical parameters of undisturbed soils in Mediterranean environments (NE Spain) with corresponding parameters relative to soil organic carbon

    OpenAIRE

    Jiménez de Ridder, Patrícia; Marando, Graciela; Josa March, Ramon; Ginovart Gisbert, Marta; Ras Sabido, Antoni; Bonmati Pont, Manuel

    2017-01-01

    The study of soil quality requires the establishment of quality standards. To this end, several authors have highlighted the need to create databases of quality indicators, such as biochemical properties, for different types of undisturbed soils under various climates and to establish standardised methodologies for their development. In Spain, studies of the quality of native soils were initiated > 15 years ago by several groups of authors from differing locations, but little is known regardi...

  5. A New Approach to Monitoring Coastal Marshes for Persistent Flooding

    Science.gov (United States)

    Kalcic, M. T.; Underwood, L. W.; Fletcher, R. M.

    2012-12-01

    Many areas in coastal Louisiana are below sea level and protected from flooding by a system of natural and man-made levees. Flooding is common when the levees are overtopped by storm surge or rising rivers. Many levees in this region are further stressed by erosion and subsidence. The floodwaters can become constricted by levees and trapped, causing prolonged inundation. Vegetative communities in coastal regions, from fresh swamp forest to saline marsh, can be negatively affected by inundation and changes in salinity. As saltwater persists, it can have a toxic effect upon marsh vegetation causing die off and conversion to open water types, destroying valuable species habitats. The length of time the water persists and the average annual salinity are important variables in modeling habitat switching (cover type change). Marsh type habitat switching affects fish, shellfish, and wildlife inhabitants, and can affect the regional ecosystem and economy. There are numerous restoration and revitalization projects underway in the coastal region, and their effects on the entire ecosystem need to be understood. For these reasons, monitoring persistent saltwater intrusion and inundation is important. For this study, persistent flooding in Louisiana coastal marshes was mapped using MODIS (Moderate Resolution Imaging Spectroradiometer) time series of a Normalized Difference Water Index (NDWI). The time series data were derived for 2000 through 2009, including flooding due to Hurricane Rita in 2005 and Hurricane Ike in 2008. Using the NDWI, duration and extent of flooding can be inferred. The Time Series Product Tool (TSPT), developed at NASA SSC, is a suite of software developed in MATLAB® that enables improved-quality time series images to be computed using advanced temporal processing techniques. This software has been used to compute time series for monitoring temporal changes in environmental phenomena, (e.g. NDVI times series from MODIS), and was modified and used to

  6. Geostatistical evaluation of integrated marsh management impact on mosquito vectors using before-after-control-impact (BACI) design

    OpenAIRE

    Rochlin, Ilia; Iwanejko, Tom; Dempsey, Mary E; Ninivaggi, Dominick V

    2009-01-01

    Abstract Background In many parts of the world, salt marshes play a key ecological role as the interface between the marine and the terrestrial environments. Salt marshes are also exceedingly important for public health as larval habitat for mosquitoes that are vectors of disease and significant biting pests. Although grid ditching and pesticides have been effective in salt marsh mosquito control, marsh degradation and other environmental considerations compel a different approach. Targeted h...

  7. Aquatic Insects of New York Salt Marsh Associated with Mosquito Larval Habitat and their Potential Utility as Bioindicators

    OpenAIRE

    Rochlin, Ilia; Dempsey, Mary E.; Iwanejko, Tom; Ninivaggi, Dominick V.

    2011-01-01

    The aquatic insect fauna of salt marshes is poorly characterized, with the possible exception of biting Diptera. Aquatic insects play a vital role in salt marsh ecology, and have great potential importance as biological indicators for assessing marsh health. In addition, they may be impacted by measures to control mosquitoes such as changes to the marsh habitat, altered hydrology, or the application of pesticides. Given these concerns, the goals of this study were to conduct the first taxonom...

  8. Challenges for the heavy oil exportation though pipelines in deep waters; Desafios da exportacao de oleos pesados atraves de oleodutos em aguas profundas

    Energy Technology Data Exchange (ETDEWEB)

    Andreolli, Ivanilto; Borges Filho, Jonas P.; Gaspari, Eduardo F. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

    2008-07-01

    Due to the high pressures, low temperatures, and high viscosities involved, the heavy oil exportation in deep waters through pipelines imposes a number of challenges to be feasible. The viscosities involved in such scenarios are usually very high, which brings most of the system to a laminar flow even for the higher flow rates. In a laminar flow the viscosity is linearly and directly related to the frictional pressure drop and so its precise determination is crucial for the correct results from simulations in transient or in steady state, including the modeling thermal. This work presents some results in steady state and transient simulations of heavy oil of deg API around 16 and pipe length of approximately 20km. For the analyses in the steady state was concluded that in low outflows the required pressures can surpass the pressures in high outflows. In the transient regimen was concluded that in case of long stop, the return to the full outflow surpasses 6 days and the replacement of the fluids from the pipe by diesel is a solution to reduce significantly this time. (author)

  9. Piranema Field: developing economically small reserves in deep waters; Campo de Piracema: o desafio de desenvolver economicamente pequenas reservas em aguas profundas

    Energy Technology Data Exchange (ETDEWEB)

    Brandao, Renilton M. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

    2008-07-01

    Piranema Field is located southeast of the city of Aracaju, in deep waters, sub-basin of Sergipe, about 25 km from the coast, with water depth varying from 200 and 2,000 meters. The biggest challenges for the production of this field, with high quality oil (41 to 44 API), were small reserves, the presence of large submarine canyons separating various geological structures and difficulty installation of pipelines and wax formation in production lines, which could cause its blocking. After several studies, we decided to exploit in two phases, using an FPSO (Floating Production Storage and Offloading), cylindrical, completely innovative, whose cost of construction could make the project economically attractive and gas produced entirely re-injected, which would increase considerably recovery factor. The development will be in two phases, with the first one lasting about 7 years and the second 4 years. It is expected a recovery factor of around 40% over the eleven years of production, with a peak production of around 30,000 bbl/d. The total project cost will be $ 1.1 bi, including investments, operating costs and taxes. (author)

  10. Consequences of long-distance swimming and travel over deep-water pack ice for a female polar bear during a year of extreme sea ice retreat

    Science.gov (United States)

    Durner, G.M.; Whiteman, J.P.; Harlow, H.J.; Amstrup, Steven C.; Regehr, E.V.; Ben-David, M.

    2011-01-01

    Polar bears (Ursus maritimus) prefer to live on Arctic sea ice but may swim between ice floes or between sea ice and land. Although anecdotal observations suggest that polar bears are capable of swimming long distances, no data have been available to describe in detail long distance swimming events or the physiological and reproductive consequences of such behavior. Between an initial capture in late August and a recapture in late October 2008, a radio-collared adult female polar bear in the Beaufort Sea made a continuous swim of 687 km over 9 days and then intermittently swam and walked on the sea ice surface an additional 1,800 km. Measures of movement rate, hourly activity, and subcutaneous and external temperature revealed distinct profiles of swimming and walking. Between captures, this polar bear lost 22% of her body mass and her yearling cub. The extraordinary long distance swimming ability of polar bears, which we confirm here, may help them cope with reduced Arctic sea ice. Our observation, however, indicates that long distance swimming in Arctic waters, and travel over deep water pack ice, may result in high energetic costs and compromise reproductive fitness. ?? 2011 US Government.

  11. Trace elements and stable isotopes (δ13C and δ15N) in shallow and deep-water organisms from the East China Sea

    International Nuclear Information System (INIS)

    Asante, Kwadwo Ansong; Agusa, Tetsuro; Mochizuki, Hiroko; Ramu, Karri; Inoue, Suguru; Kubodera, Tsunemi; Takahashi, Shin; Subramanian, Annamalai; Tanabe, Shinsuke

    2008-01-01

    Trace elements (22) and stable isotope ratios (δ 15 N and δ 13 C) were analyzed in marine organisms from shallow (SW) and deep-water (DW) of the East China Sea to understand biomagnification and prey source of trace elements. In the benthic marine organisms from DW, δ 15 N values were negatively correlated with Ba, Cu, Ag, Mo, Sr, As, and Co concentrations. This may be due to the specific accumulation in lower trophic animals and/or the biodilution through the food web in DW. Relationships between δ 15 N and concentrations of Co, Cr, Bi, and Tl in fish and Ag, Bi, V, Hg, and Tl in crustaceans showed positive correlations, suggesting that trophic position was affecting the concentrations of those elements in phyla, with higher trophic animals retaining higher concentrations than the lower trophic animals. Positive correlations between δ 13 C and Rb were observed in marine organisms. Therefore, Rb may be a possible substitute of δ 13 C as tracer of prey source in the East China Sea although further investigation is required. - This is the first study on trophic transfer and prey source of trace elements in marine organisms from the East China Sea

  12. New case of lateral asymmetry in fishes: A new subfamily, genus and species of deep water clingfishes from Papua New Guinea, western Pacific Ocean.

    Science.gov (United States)

    Fricke, Ronald; Chen, Jhen-Nien; Chen, Wei-Jen

    2017-01-01

    The unusual clingfish Protogobiesox asymmetricus n. gen, n. sp. is described on the basis of four specimens collected in deep water off the north coast of Papua New Guinea in 2012. The species is characterized by its 9-10 dorsal rays, 8 anal rays, 17-24 pectoral-fin rays, 15 principal caudal-fin rays, 3 gills, third arch with 3 gill rakers, 34-35 total vertebrae, with asymmetrical lateral bending starting behind the skull, bent at an angle of 85°-92°; skull asymmetrical in frontal view; skin naked, surface of head and body without striae; disc without adhesive papillae. A new subfamily Protogobiesocinae is described for this species and Lepadicyathus mendeleevi Prokofiev, 2005, which is redescribed. The new subfamily is compared within the family; keys to the subfamilies of Gobiesocidae and the species within the new subfamily are presented; its phylogenetic relationship to other gobiesocids is inferred based on a multi-locus DNA dataset. Copyright © 2016 Académie des sciences. Published by Elsevier SAS. All rights reserved.

  13. Thermal-history reconstruction of the Baiyun Sag in the deep-water area of the Pearl River Mouth Basin, northern South China Sea

    Science.gov (United States)

    Tang, Xiaoyin; Yang, Shuchun; Hu, Shengbiao

    2017-11-01

    The Baiyun Sag, located in the deep-water area of the northern South China Sea, is the largest and deepest subbasin in the Pearl River Mouth Basin and one of the most important hydrocarbon-accumulation depression areas in China. Thermal history is widely thought to be of great importance in oil and gas potential assessment of a basin as it controls the timing of hydrocarbon generation and expulsion from the source rock. In order to unravel the paleo-heat flow of the Baiyun Sag, we first analyzed tectonic subsidence of 55 pseudo-wells constructed based on newly interpreted seismic profiles, along with three drilled wells. We then carried out thermal modeling using the multi-stage finite stretching method and calibrated the results using collected present-day vitrinite reflectance data and temperature data. Results indicate that the first and second heating of the Baiyun Sag after 49 Ma ceased at 33.9 Ma and 23 Ma. Reconstructed average basal paleoheat flow values at the end of the rifting periods are 57.7-86.2 mW/m2 and 66.7-97.3 mW/m2, respectively. Following the last heating period at 23 Ma, the study area has undergone a persistent thermal attenuation phase, and basal heat flow has cooled down to 64.0-79.2 mW/m2 at present.

  14. Assessing the potential impact of water-based drill cuttings on deep-water calcareous red algae using species specific impact categories and measured oceanographic and discharge data.

    Science.gov (United States)

    Nilssen, Ingunn; dos Santos, Francisco; Coutinho, Ricardo; Gomes, Natalia; Cabral, Marcelo Montenegro; Eide, Ingvar; Figueiredo, Marcia A O; Johnsen, Geir; Johnsen, Ståle

    2015-12-01

    The potential impact of drill cuttings on the two deep water calcareous red algae Mesophyllum engelhartii and Lithothamnion sp. from the Peregrino oil field was assessed. Dispersion modelling of drill cuttings was performed for a two year period using measured oceanographic and discharge data with 24 h resolution. The model was also used to assess the impact on the two algae species using four species specific impact categories: No, minor, medium and severe impact. The corresponding intervals for photosynthetic efficiency (ΦPSIImax) and sediment coverage were obtained from exposure-response relationship for photosynthetic efficiency as function of sediment coverage for the two algae species. The temporal resolution enabled more accurate model predictions as short-term changes in discharges and environmental conditions could be detected. The assessment shows that there is a patchy risk for severe impact on the calcareous algae stretching across the transitional zone and into the calcareous algae bed at Peregrino. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Diversity and taphonomic gradients from shoreface to deep water: Case studies based on sea urchin assemblages from the Miocene of Sardinia

    Science.gov (United States)

    Nebelsick, James; Mancosu, Andrea

    2016-04-01

    Echinoid faunas from Miocene sediments from Sardinia allow diversity to be correlated to variations in depositional environments as well as taphonomic pathways. Taxonomic richness and preservation potentials vary among both carbonate and siliciclastic dominated shelf environments. Studies include detailed investigation of stratigraphy, sedimentology, palaeontology and taphonomy in both the field and in the laboratory. Environmental Interpretations are based on composition and diversity of taxa, functional morphological interpretation of life habits as well as taphonomic signatures. These investigations have revealed: 1) various mass accumulations of clypeasteroid echinoids ranging from autochthonous assemblages to multiple in situ reworked accumulations in shore face environments, 2) the distribution of morphotypes of the common genus Clypeaster, 3) echinoid assemblages dominated by both irregular and regular echinoids in siliciclastic and carbonate shelf environments, 4) spatangoid assemblages in heavily bioturbated coarse sands, and 5) monotypic shell beds of well-preserved regular echinoids and spatangoid from deeper siliciclastic environments. Variations in the diversity of echinoid taxa are correlated to biotic and abiotic ecological factors in specific depositional environments. Preservation potentials vary highly as determined by ambient environmental conditions and skeletal architectures. A synthesis of faunal diversities and preservation potentials along shelf gradient ranging from shoreface to deep water is presented.

  16. Integrated TLWP-FPSO (Tension Leg Wellhead Platform-Floating Production, Storage and Offloading Vessel) solution for deep water field development offshore Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Neil; Heidari, Homayoun; Large, Sean [SBM Atlantia, Houston, TX (United States)

    2008-07-01

    A development strategy for some deep water fields offshore Brazil consists of a TLWP (Tension-Leg Wellhead Platform) connected by a fluid transfer line to a nearby FPSO. The TLWP provides dry tree riser support, drilling capability, manifolding, test separation, and multiphase pumping, while all other functions including full processing, accommodations, gas compression, power generation, water and chemical injection, storage and offloading, and gas export are provided by the FPSO. In one such scenario, the TLWP and FPSO could be connected using SBM's GAP mid-water fluid transfer line technology, with SBM Atlantia's FourStar{sup TM} hull concept for the TLWP. The FourStar{sup TM} is designed to be quayside- or float over-integrable, thus eliminating the need for a heavy lift installation vessel; while being structurally and hydrodynamically superior to other TLP alternatives. This paper presents a description of the technical development of the FourStar{sup TM} TLP and an overview of the GAP technology, and discusses the characteristics of an integrated TLWP-GAP-FPSO field development solution for a typical application offshore Brazil (author)

  17. Heavy and viscous oil evaluation in a deep water environment: an integrated evaluation process; Avaliacao de oleo pesado e viscoso em aguas profundas: um processo integrado de avaliacao

    Energy Technology Data Exchange (ETDEWEB)

    Barreto, Wesley S.; Armacanqui, Gina [Schlumberger, Rio de Janeiro, RJ (United States)

    2004-07-01

    There are many challenges related to heavy and viscous oil reserves evaluation. When this includes a deep-water offshore environment the challenges, including safety issues, increase in complexity. In this paper we share some experiences obtained during the preparation and execution of heavy oil evaluation activities. The process uses the petrophysical and fluid characterization preliminary results obtained during the logging phase as well as prior information from correlation field/wells in order to design the appropriate ESP configuration and location in the DST string as well as the sampler location which should allow monophasic sampling. During the operation a real time interpretation is performed validating the data obtained and sensitizing parameters such as pump frequency, bubble point pressure, GOR and viscosities, allowing the diagnostic of the operation and consequent appropriated flow conditions in order to provide a optimum picture supporting decisions regarding sampling time and other specific evaluation objectives. The examples presented illustrate the methodology proposed of integrated evaluation applied to heavy oil and its benefits. (author)

  18. Consumer trait variation influences tritrophic interactions in salt marsh communities.

    Science.gov (United States)

    Hughes, Anne Randall; Hanley, Torrance C; Orozco, Nohelia P; Zerebecki, Robyn A

    2015-07-01

    The importance of intraspecific variation has emerged as a key question in community ecology, helping to bridge the gap between ecology and evolution. Although much of this work has focused on plant species, recent syntheses have highlighted the prevalence and potential importance of morphological, behavioral, and life history variation within animals for ecological and evolutionary processes. Many small-bodied consumers live on the plant that they consume, often resulting in host plant-associated trait variation within and across consumer species. Given the central position of consumer species within tritrophic food webs, such consumer trait variation may play a particularly important role in mediating trophic dynamics, including trophic cascades. In this study, we used a series of field surveys and laboratory experiments to document intraspecific trait variation in a key consumer species, the marsh periwinkle Littoraria irrorata, based on its host plant species (Spartina alterniflora or Juncus roemerianus) in a mixed species assemblage. We then conducted a 12-week mesocosm experiment to examine the effects of Littoraria trait variation on plant community structure and dynamics in a tritrophic salt marsh food web. Littoraria from different host plant species varied across a suite of morphological and behavioral traits. These consumer trait differences interacted with plant community composition and predator presence to affect overall plant stem height, as well as differentially alter the density and biomass of the two key plant species in this system. Whether due to genetic differences or phenotypic plasticity, trait differences between consumer types had significant ecological consequences for the tritrophic marsh food web over seasonal time scales. By altering the cascading effects of the top predator on plant community structure and dynamics, consumer differences may generate a feedback over longer time scales, which in turn influences the degree of trait

  19. Guide to Common Tidal Marsh Invertebrates of the Northeastern Gulf of Mexico.

    Science.gov (United States)

    Heard, Richard W.

    The major groups of marine and estuarine macroinvertebrates of the tidal marshes of the northern Gulf of Mexico are described in this guide for students, taxonomists and generalists. Information on the recognition characteristics, distribution, habitat, and biology of salt marsh species from the coelenterate, annelid, mollusk and arthropod phyla…

  20. Marsh soil responses to tidal water nitrogen additions contribute to creek bank fracturing and slumping

    Science.gov (United States)

    Large-scale dissolved nutrient enrichment can cause a reduction in belowground biomass, increased water content of soils, and increased microbial decomposition, which has been linked with slumping of low marsh Spartina vegetation into creeks, and ultimately marsh loss. Our study ...