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Full-Text Articles in Life Sciences

Providential Tides: The Double Low Water Of Narragansett Bay, D. G. Bowers, J. M. Brubaker May 2020

Providential Tides: The Double Low Water Of Narragansett Bay, D. G. Bowers, J. M. Brubaker

VIMS Articles

We investigate a mechanism for producing double-lows and double-highs in the semi-diurnal tide by selective amplification of higher harmonics in a resonant gulf. A double low water is observed at Providence, RI, near the head of Narragansett Bay on days when there is a flattening of the low water tidal curve at Newport, at the mouth of the bay. The flattening is caused by an unusually large quarter-diurnal component to the tide at Newport. The quarter diurnal component has the right phase (a maximum close to the time of the minimum in the semi-diurnal tide) to produce a prolonged flattening ...


Minimal Effects Of Oyster Aquaculture On Local Water Quality: Examples From Southern Chesapeake Bay, Jessica Turner, M. Lisa Kellogg, Grace M. Massey, Carl Friedrichs Nov 2019

Minimal Effects Of Oyster Aquaculture On Local Water Quality: Examples From Southern Chesapeake Bay, Jessica Turner, M. Lisa Kellogg, Grace M. Massey, Carl Friedrichs

VIMS Articles

As the oyster aquaculture industry grows and becomes incorporated into management practices, it is important to understand its effects on local environments. This study investigated how water quality and hydrodynamics varied among farms as well as inside versus outside the extent of caged grow-out areas located in southern Chesapeake Bay. Current speed and water quality variables (chlorophyll-a fluorescence, turbidity, and dissolved oxygen) were measured along multiple transects within and adjacent to four oyster farms during two seasons. At the scale of individual aquaculture sites, we were able to detect statistically significant differences in current speed and water quality variables between ...


Scientific Considerations For Acidification Monitoring In The Us Mid-Atlantic Region, Ka Goldsmith, S Lau, Et Al, Eh Shadwick, Et Al Sep 2019

Scientific Considerations For Acidification Monitoring In The Us Mid-Atlantic Region, Ka Goldsmith, S Lau, Et Al, Eh Shadwick, Et Al

VIMS Articles

Coastal and ocean acidification has the potential to cause significant environmental and societal impacts. Monitoring carbonate chemistry parameters over spatial and temporal scales is challenging, especially with limited resources. A lack of monitoring data can lead to a limited understanding of real-world conditions. Without such data, robust experimental and model design is challenging, and the identification and understanding of episodic acidification events is nearly impossible. We present considerations for resource managers, academia, and industry professionals who are currently developing acidification monitoring programs in the Mid-Atlantic region. We highlight the following considerations for deliberation: 1) leverage existing infrastructure to include multiple ...


Bacterial And Archaeal Specific-Predation In The North Atlantic Basin, Lm Seyler, S Tuorto, Lr Mcguinness, Dl Gong, Lj Kerkof Sep 2019

Bacterial And Archaeal Specific-Predation In The North Atlantic Basin, Lm Seyler, S Tuorto, Lr Mcguinness, Dl Gong, Lj Kerkof

VIMS Articles

Stable isotope probing (SIP) was used to track prokaryotic and eukaryotic carbon uptake along a meridional transect (Long. 52°W) in the North Atlantic to assess if 13C-resource partitioning between bacteria and archaea and 13C-labeled eukaryotic predators could be detected. One-liter SIP microcosms were amended with 13C-acetate or 13C-urea and incubated for 48 h. Our data indicated archaea often outcompeted bacteria for 13C-urea while both archaea and bacteria could incorporate 13C-acetate. This 13C label could also be tracked into eukaryotic microbes. The largest number of 13C-labeled eukaryotic OTUs, and the greatest percentage ...


A Data-Driven Modeling Approach For Simulating Algal Blooms In The Tidal Freshwater Of James River In Response To Riverine Nutrient Loading, Jian Shen, Qubin Qin, Ya Wang, Mac Sisson Apr 2019

A Data-Driven Modeling Approach For Simulating Algal Blooms In The Tidal Freshwater Of James River In Response To Riverine Nutrient Loading, Jian Shen, Qubin Qin, Ya Wang, Mac Sisson

VIMS Articles

Algal blooms often occur in the tidal freshwater (TF) of the James River estuary, a tributary of the Chesapeake Bay. The timing of algal blooms correlates highly to a summer low-flow period when residence time is long and nutrients are available. Because of complex interactions between physical transport and algal dynamics, it is challenging to predict interannual variations of bloom correctly using a complex eutrophication model without having ahigh-resolution model gridto resolve complexgeometryand anaccurate estimate of nutrientloading to drive the model. In this study, an approach using long-term observational data (from 1990 to 2013) and the Support vector machine (LS-SVM ...


Advancing Marine Biogeochemical And Ecosystem Reanalyses And Forecasts As Tools For Monitoring And Managing Ecosystem Health, K Fennel, M Gehlen, P Brasseur, Cw Brown, C Ciavatta, G Cossarini, A Crise, Ca Edwards, D Ford, Marjorie A.M. Friedrichs, Et Al Mar 2019

Advancing Marine Biogeochemical And Ecosystem Reanalyses And Forecasts As Tools For Monitoring And Managing Ecosystem Health, K Fennel, M Gehlen, P Brasseur, Cw Brown, C Ciavatta, G Cossarini, A Crise, Ca Edwards, D Ford, Marjorie A.M. Friedrichs, Et Al

VIMS Articles

Ocean ecosystems are subject to a multitude of stressors, including changes in ocean physics and biogeochemistry, and direct anthropogenic influences. Implementation of protective and adaptive measures for ocean ecosystems requires a combination of ocean observations with analysis and prediction tools. These can guide assessments of the current state of ocean ecosystems, elucidate ongoing trends and shifts, and anticipate impacts of climate change and management policies. Analysis and prediction tools are defined here as ocean circulation models that are coupled to biogeochemical or ecological models. The range of potential applications for these systems is broad, ranging from reanalyses for the assessment ...


The Effect Of A Small Vegetation Dieback Event On Salt Marsh Sediment Transport, Daniel J. Coleman, Matthew L. Kirwan Jan 2019

The Effect Of A Small Vegetation Dieback Event On Salt Marsh Sediment Transport, Daniel J. Coleman, Matthew L. Kirwan

VIMS Articles

Vegetation is a critical component of the ecogeomorphic feedbacks that allow a salt marsh to build soil and accrete vertically. Vegetation dieback can therefore have detrimental effects on marsh stability, especially under conditions of rising sea levels. Here, we report a variety of sediment transport measurements associated with an unexpected, natural dieback in a rapidly prograding marsh in the Altamaha River Estuary, Georgia. We find that vegetation mortality led to a significant loss in elevation at the dieback site as evidenced by measurements of vertical accretion, erosion, and surface topography compared to vegetated refer- ence areas. Below-ground vegetation mortality led ...


Symbiotic Unicellular Cyanobacteria Fix Nitrogen In The Arctic Ocean, K. Harding, K. A. Turk-Kubo, Re Sipler, M. M. Mills, D. A. Bronk Dec 2018

Symbiotic Unicellular Cyanobacteria Fix Nitrogen In The Arctic Ocean, K. Harding, K. A. Turk-Kubo, Re Sipler, M. M. Mills, D. A. Bronk

VIMS Articles

Biological dinitrogen (N2) fixation is an important source of nitrogen (N) in low-latitude open oceans. The unusual N2-fixing unicellular cyanobacteria (UCYN-A)/haptophyte symbiosis has been found in an increasing number of unexpected environments, including northern waters of the Danish Straight and Bering and Chukchi Seas. We used nanoscale secondary ion mass spectrometry (nanoSIMS) to measure 15N2 uptake into UCYN-A/haptophyte symbiosis and found that UCYN-A strains identical to low-latitude strains are fixing N2 in the Bering and Chukchi Seas, at rates comparable to subtropical waters. These results show definitively that cyanobacterial N2 fixation is not constrained to subtropical waters, challenging ...


Discerning Autotrophy, Mixotrophy And Heterotrophyin Marine Tack Archaea From The North Atlantic, L M. Seyler, L. R. Mcguinness, J. A. Gilbert, J. F. Biddle, Donglai Gong, L. J. Kerkhof Jan 2018

Discerning Autotrophy, Mixotrophy And Heterotrophyin Marine Tack Archaea From The North Atlantic, L M. Seyler, L. R. Mcguinness, J. A. Gilbert, J. F. Biddle, Donglai Gong, L. J. Kerkhof

VIMS Articles

DNA stable isotope probing (SIP) was used to track the uptake of organic and inorganic carbon sources for TACK archaea(Thaumarchaeota/Aigarchaeota/Crenarchaeota/Korarchaeota) on a cruise of opportunity in the North Atlantic. Due to water limitations, duplicate samples from the deep photic (60–115 m), the mesopelagic zones (local oxygen minimum; 215–835 m)and the bathypelagic zone (2085–2835 m) were amended with various combinations of12C- or13C-acetate/urea/bicarbonate to assess cellular carbon acquisition. The SIP results indicated the majority of TACK archaeal operational taxonomic units(OTUs) incorporated13C from acetate and/or urea into newly synthesized DNA within ...


Accuracy And Precision Of Tidal Wetland Soil Carbon Mapping In The Conterminous United States, Jr Holmquist, L Windham-Myers, N Bliss, S Crooks, Jt Morris, W. G. Reay, Et Al. Jan 2018

Accuracy And Precision Of Tidal Wetland Soil Carbon Mapping In The Conterminous United States, Jr Holmquist, L Windham-Myers, N Bliss, S Crooks, Jt Morris, W. G. Reay, Et Al.

VIMS Articles

Tidal wetlands produce long-term soil organic carbon (C) stocks. Thus for carbon accounting purposes, we need accurate and precise information on the magnitude and spatial distribution of those stocks. We assembled and analyzed an unprecedented soil core dataset, and tested three strategies for mapping carbon stocks: applying the average value from the synthesis to mapped tidal wetlands, applying models fit using empirical data and applied using soil, vegetation and salinity maps, and relying on independently generated soil carbon maps. Soil carbon stocks were far lower on average and varied less spatially and with depth than stocks calculated from available soils ...


Millennial Soil Retention Of Terrestrial Organic Matter Deposited In The Bengal Fan, Kl French, Christopher J. Hein, N Haghipour, L Wacker, Hr Kudrass Jan 2018

Millennial Soil Retention Of Terrestrial Organic Matter Deposited In The Bengal Fan, Kl French, Christopher J. Hein, N Haghipour, L Wacker, Hr Kudrass

VIMS Articles

The abundance of organic carbon (OC) in vegetation and soils (similar to 2,600 PgC) compared to carbon in the atmosphere (similar to 830 PgC) highlights the importance of terrestrial OC in global carbon budgets. The residence time of OC in continental reservoirs, which sets the rates of carbon exchange between land and atmosphere, represents a key uncertainty in global carbon cycle dynamics. Retention of terrestrial OC can also distort bulk OC- and biomarker-based paleorecords, yet continental storage timescales remain poorly quantified. Using "bomb" radiocarbon (C-14) from thermonuclear weapons testing as a tracer, we model leaf-wax fatty acid and bulk ...


Predicting Marsh Vulnerability To Sea-Level Rise Using Holocene Relative Sea-Level Data, Bp Horton, I Shennan, Sl Bradley, N Cahill, Matthew L. Kirwan, Re Kopp, Ta Shaw Jan 2018

Predicting Marsh Vulnerability To Sea-Level Rise Using Holocene Relative Sea-Level Data, Bp Horton, I Shennan, Sl Bradley, N Cahill, Matthew L. Kirwan, Re Kopp, Ta Shaw

VIMS Articles

Tidal marshes rank among Earth's vulnerable ecosystems, which will retreat if future rates of relative sea-level rise (RSLR) exceed marshes' ability to accrete vertically. Here, we assess the limits to marsh vulnerability by analyzing >780 Holocene reconstructions of tidal marsh evolution in Great Britain. These reconstructions include both transgressive (tidal marsh retreat) and regressive (tidal marsh expansion) contacts. The probability of a marsh retreat was conditional upon Holocene rates of RSLR, which varied between -7.7 and 15.2 mm/yr. Holocene records indicate that marshes are nine times more likely to retreat than expand when RSLR rates are ...


Spatial Distribution And Morphological Responses To Predation In The Salt Marsh Periwinkle, Aj Rietl, Mg Sorrentino, Bj Roberts Jan 2018

Spatial Distribution And Morphological Responses To Predation In The Salt Marsh Periwinkle, Aj Rietl, Mg Sorrentino, Bj Roberts

VIMS Articles

The salt marsh periwinkle (Littoraria irrorata) is a common and often abundant mollusk in marshes of the Gulf and Atlantic coasts of the United States. Several studies have focused on the effects of periwinkles on Spartina alterniflora production and the effects of oil on periwinkle survivability, yet the general ecology of the snail has been underreported. In this study, we measured spatial distributions, biomass, shell repair frequency, and a suite of morphological characteristics of L. irrorata at three sites in each of five regions spanning the southeastern Louisiana Coast between the Atchafalaya and Mississippi rivers. Sampling was conducted along 50 ...


Time Trends Of Polybrominated Diphenyl Ethers (Pbdes) In Antarctic Biota, E Markham, Ek Brault, M Khairy, Ar Robuck, Me Goebel, Mg Cantwell, Rm Dickhut, R Lohmann Jan 2018

Time Trends Of Polybrominated Diphenyl Ethers (Pbdes) In Antarctic Biota, E Markham, Ek Brault, M Khairy, Ar Robuck, Me Goebel, Mg Cantwell, Rm Dickhut, R Lohmann

VIMS Articles

Polybrominated diphenyl ethers (PBDEs) are "emerged" contaminants that were produced and used as flame retardants in numerous consumer and industrial applications for decades until banned. They remain ubiquitously present in the environment today. Here, a unique set of >200 biotic samples from the Antarctic was analyzed for PBDEs, including phytoplankton, krill, fish, and fur seal milk, spanning several sampling seasons over 14 years. PBDE-47 and -99 were the dominant congeners determined in all samples, constituting > 60% of total PBDEs. A temporal trend was observed for Sigma 7PBDE concentrations in fur seal milk, where concentrations significantly increased (R-2 = 0.57, p < 0.05) over time (2000-2014). Results for krill and phytoplankton also suggested increasing PBDE concentrations over time. Trends of PBDEs in fur seal milk of individual seals sampled 1 or more years apart showed no clear temporal trends. Overall, there was no indication of PBDEs decreasing in Antarctic biota yet, whereas numerous studies have reported decreasing trends in the northern hemisphere. Similar PBDE concentrations in perinatal versus nonperinatal milk implied the importance of local PBDE sources for bioaccumulation. These results indicate the need for continued assessment of contaminant trends, such as PBDEs, and their replacements, in Antarctica.


Cohesive And Mixed Sediment In The Regional Ocean Modeling System (Roms V3.6) Implemented In The Coupled Ocean-Atmosphere-Wave-Sediment Transport Modeling System (Coawst R1234), Cr Sherwood, Al Aretxabaleta, Courtney K. Harris, Jp Rinehimer, R Verney, B Ferre Jan 2018

Cohesive And Mixed Sediment In The Regional Ocean Modeling System (Roms V3.6) Implemented In The Coupled Ocean-Atmosphere-Wave-Sediment Transport Modeling System (Coawst R1234), Cr Sherwood, Al Aretxabaleta, Courtney K. Harris, Jp Rinehimer, R Verney, B Ferre

VIMS Articles

We describe and demonstrate algorithms for treating cohesive and mixed sediment that have been added to the Regional Ocean Modeling System (ROMS version 3.6), as implemented in the Coupled Ocean-Atmosphere-Wave- Sediment Transport Modeling System (COAWST Subversion repository revision 1234). These include the following: floc dynamics (aggregation and disaggregation in the water column); changes in floc characteristics in the seabed; erosion and deposition of cohesive and mixed (combination of cohesive and non-cohesive) sediment; and biodiffusive mixing of bed sediment. These routines supplement existing noncohesive sediment modules, thereby increasing our ability to model fine-grained and mixed-sediment environments. Additionally, we describe changes ...


The Competing Impacts Of Climate Change And Nutrient Reductions On Dissolved Oxygen In Chesapeake Bay, Id Irby, Marjorie A.M. Friedrichs, F Da, Ke Hinson Jan 2018

The Competing Impacts Of Climate Change And Nutrient Reductions On Dissolved Oxygen In Chesapeake Bay, Id Irby, Marjorie A.M. Friedrichs, F Da, Ke Hinson

VIMS Articles

The Chesapeake Bay region is projected to experience changes in temperature, sea level, and precipitation as a result of climate change. This research uses an estuarine-watershed hydrodynamic-biogeochemical modeling system along with projected mid-21st-century changes in temperature, freshwater flow, and sea level rise to explore the impact climate change may have on future Chesapeake Bay dissolved-oxygen (DO) concentrations and the potential success of nutrient reductions in attaining mandated estuarine water quality improvements. Results indicate that warming bay waters will decrease oxygen solubility year-round, while also increasing oxygen utilization via respiration and remineralization, primarily impacting bottom oxygen in the spring. Rising sea ...


Numerical Model Of Geochronological Tracers For Deposition And Reworking Applied To The Mississippi Subaqueous Delta, Jj Birchler, Courtney K. Harris, Ta Kniskern, Cr Sherwood Jan 2018

Numerical Model Of Geochronological Tracers For Deposition And Reworking Applied To The Mississippi Subaqueous Delta, Jj Birchler, Courtney K. Harris, Ta Kniskern, Cr Sherwood

VIMS Articles

Measurements of naturally occurring, short-lived radioisotopes from sediment cores on the Mississippi subaqueous delta have been used to infer event bed characteristics such as depositional thicknesses and accumulation rates. Specifically, the presence of Beryllium-7 (Be-7) indicates recent riverine-derived terrestrial sediment deposition; while Thorium-234 (Th-234) provides evidence of recent suspension in marine waters. Sediment transport models typically represent coastal flood and storm deposition via estimated grain size patterns and deposit thicknesses, however, and do not directly calculate radioisotope activities and profiles, which leads to a disconnect between the numerical model and field observations. Here, observed radioisotopic profiles from the Mississippi subaqueous ...


Cross-Scale Baroclinic Simulation Of The Effect Of Channel Dredging In An Estuarine Setting, Fei Ye, Harry V. Wang, H Huang, Zg Wang, Z Liu, X Li Jan 2018

Cross-Scale Baroclinic Simulation Of The Effect Of Channel Dredging In An Estuarine Setting, Fei Ye, Harry V. Wang, H Huang, Zg Wang, Z Liu, X Li

VIMS Articles

Holistic simulation approaches are often required to assess human impacts on a river-estuary-coastal system, due to the intrinsically linked processes of contrasting spatial scales. In this paper, a Semi-implicit Cross-scale Hydroscience Integrated System Model (SCHISM) is applied in quantifying the impact of a proposed hydraulic engineering project on the estuarine hydrodynamics. The project involves channel dredging and land expansion that traverse several spatial scales on an ocean-estuary-river-tributary axis. SCHISM is suitable for this undertaking due to its flexible horizontal and vertical grid design and, more importantly, its efficient high-order implicit schemes applied in both the momentum and transport calculations. These ...


Assimilating Bio-Optical Glider Data During A Phytoplankton Bloom In The Southern Ross Sea, De Kaufman, Marjorie A.M. Friedrichs, Jcp Hemmings, Walker O. Smith Jr. Jan 2018

Assimilating Bio-Optical Glider Data During A Phytoplankton Bloom In The Southern Ross Sea, De Kaufman, Marjorie A.M. Friedrichs, Jcp Hemmings, Walker O. Smith Jr.

VIMS Articles

The Ross Sea is a region characterized by high primary productivity in comparison to other Antarctic coastal regions, and its productivity is marked by considerable variability both spatially (1-50 km) and temporally (days to weeks). This variability presents a challenge for inferring phytoplankton dynamics from observations that are limited in time or space, which is often the case due to logistical limitations of sampling. To better understand the spatio-temporal variability in Ross Sea phytoplankton dynamics and to determine how restricted sampling may skew dynamical interpretations, high-resolution bio-optical glider measurements were assimilated into a one-dimensional biogeochemical model adapted for the Ross ...


Early-Holocene Greening Of The Afro-Asian Dust Belt Changed Sources Of Mineral Dust In West Asia, A Sharifi, Ln Murphy, A Pourmand, Ac Clement, Elizabeth A. Canuel Jan 2018

Early-Holocene Greening Of The Afro-Asian Dust Belt Changed Sources Of Mineral Dust In West Asia, A Sharifi, Ln Murphy, A Pourmand, Ac Clement, Elizabeth A. Canuel

VIMS Articles

Production, transport and deposition of mineral dust have significant impacts on different components of the Earth systems through time and space. In modern times, dust plumes are associated with their source region(s) using satellite and land -based measurements and trajectory analysis of air masses through time. Reconstruction of past changes in the sources of mineral dust as related to changes in climate, however, must rely on the knowledge of the geochemical and mineralogical composition of modern and paleodust, and that of their potential source origins. In this contribution, we present a 13,000-yr record of variations in radiogenic Sr-Nd-Hf ...


A Communal Catalogue Reveals Earth’S Multiscale Microbial Diversity, Luke R. Thompson, Jon G. Saunders, Et Al, Earth Microbiome Project Consortium, Donglai Gong Nov 2017

A Communal Catalogue Reveals Earth’S Multiscale Microbial Diversity, Luke R. Thompson, Jon G. Saunders, Et Al, Earth Microbiome Project Consortium, Donglai Gong

VIMS Articles

Our growing awareness of the microbial world's importance and diversity contrasts starkly with our limited understanding of its fundamental structure. Despite recent advances in DNA sequencing, a lack of standardized protocols and common analytical frameworks impedes comparisons among studies, hindering the development of global inferences about microbial life on Earth. Here we present a meta-analysis of microbial community samples collected by hundreds of researchers for the Earth Microbiome Project. Coordinated protocols and new analytical methods, particularly the use of exact sequences instead of clustered operational taxonomic units, enable bacterial and archaeal ribosomal RNA gene sequences to be followed across ...


Comparisons Of Different Instruments For Measuring Suspended Cohesive Sediment Concentrations, Yy Shao, Jpy Maa Jan 2017

Comparisons Of Different Instruments For Measuring Suspended Cohesive Sediment Concentrations, Yy Shao, Jpy Maa

VIMS Articles

Laboratory experiments were conducted to compare the performances of four different instruments for measuring suspended cohesive sediment concentrations (SSCs). Among these instruments, two were different models of optical backscatter sensor (i.e., OBS3+ and OBS5+), one was an acoustic Doppler velocimeter (MicroADV), and the last was a laser infrared optical sensor developed at Hohai University, China (HHU-LIOS). Sediments collected from the Yangtze River Estuary and a commercially available kaolinite were selected to check the responses of these four instruments. They were placed in an aqueous solution, and the SSCs were changed within a range from about 10 mg/L to ...


Chemical And Photophysiological Impact Of Terrestrially-Derived Dissolved Organic Matter On Nitrate Uptake In The Coastal Western Arctic, Re Sipler, Se Baer, Tl Connelly, Me Frischer, Qn Roberts, Pl Yager, Da Bronk Jan 2017

Chemical And Photophysiological Impact Of Terrestrially-Derived Dissolved Organic Matter On Nitrate Uptake In The Coastal Western Arctic, Re Sipler, Se Baer, Tl Connelly, Me Frischer, Qn Roberts, Pl Yager, Da Bronk

VIMS Articles

The Arctic is warming at a rate nearly twice the global average, leading to thawing permafrost, increased coastal erosion, and enhanced delivery of riverine terrestrially-derived dissolved organic matter (tDOM) to coastal waters. This humic-rich tDOM has the ability to attenuate light required for photosynthesis and stimulate heterotrophic growth by supplying a source of labile organic carbon. Due to tDOM's high carbon to nitrogen (C : N) ratio, additional nitrogen is required for microorganisms to utilize this excess carbon for growth, thus exacerbating competition between autotrophs and heterotrophs for limiting nutrients and potentially reducing primary production. The effect of Arctic tDOM ...


Ensemble Modeling Informs Hypoxia Management In The Northern Gulf Of Mexico, D Scavia, I Bertani, Dr Obenour, Re Turner, David R. Forrest, A Katin Jan 2017

Ensemble Modeling Informs Hypoxia Management In The Northern Gulf Of Mexico, D Scavia, I Bertani, Dr Obenour, Re Turner, David R. Forrest, A Katin

VIMS Articles

A large region of low-dissolved-oxygen bottom waters (hypoxia) forms nearly every summer in the northern Gulf of Mexico because of nutrient inputs from theMississippi River Basin andwater column stratification. Policymakers developed goals to reduce the area of hypoxic extent because of its ecological, economic, and commercial fisheries impacts. However, the goals remain elusive after 30 y of research and monitoring and 15 y of goal-setting and assessment because there has been little change in river nitrogen concentrations. An intergovernmental Task Force recently extended to 2035 the deadline for achieving the goal of a 5,000-km(2) 5-y average hypoxic zone ...


Lateral Vegetation Growth Rates Exert Control On Coastal Foredune "Hummockiness" And Coalescing Time, Eb Goldstein, Lj Moore, Od Vinent Jan 2017

Lateral Vegetation Growth Rates Exert Control On Coastal Foredune "Hummockiness" And Coalescing Time, Eb Goldstein, Lj Moore, Od Vinent

VIMS Articles

Coastal foredunes form along sandy, low-sloped coastlines and range in shape from continuous dune ridges to hummocky features, which are characterized by alongshore-variable dune crest elevations. Initially scattered dune-building plants and species that grow slowly in the lateral direction have been implicated as a cause of foredune "hummockiness". Our goal in this work is to explore how the initial configuration of vegetation and vegetation growth characteristics control the development of hummocky coastal dunes including the maximum hummockiness of a given dune field. We find that given sufficient time and absent external forcing, hummocky foredunes coalesce to form continuous dune ridges ...


Assessing Water Quality Of The Chesapeake Bay By The Impact Of Sea Level Rise And Warming, P Wang, L Linker, Harry V. Wang, G Bhatt, G Yactayo, K Hinson, R Tian Jan 2017

Assessing Water Quality Of The Chesapeake Bay By The Impact Of Sea Level Rise And Warming, P Wang, L Linker, Harry V. Wang, G Bhatt, G Yactayo, K Hinson, R Tian

VIMS Articles

The influence of sea level rise and warming on circulation and water quality of the Chesapeake Bay under projected climate conditions in 2050 were estimated by computer simulation. Four estuarine circulation scenarios in the estuary were run using the same watershed load in 1991-2000 period. They are, 1) the Base Scenario, which represents the current climate condition, 2) a Sea Level Rise Scenario, 3) a Warming Scenario, and 4) a combined Sea Level Rise and Warming Scenario. With a 1.6-1.9 degrees C increase in monthly air temperatures in the Warming Scenario, water temperature in the Bay is estimated ...


Microbial Community Response To Terrestrially Derived Dissolved Organic Matter In The Coastal Arctic, Re Sipler, Colleen T. E. Kellogg, Tara L. Connelly, Qn Roberts, Patricia L. Yager, Deborah A. Bronk Jan 2017

Microbial Community Response To Terrestrially Derived Dissolved Organic Matter In The Coastal Arctic, Re Sipler, Colleen T. E. Kellogg, Tara L. Connelly, Qn Roberts, Patricia L. Yager, Deborah A. Bronk

VIMS Articles

Warming at nearly twice the global rate, higher than average air temperatures are the new 'normal' for Arctic ecosystems. This rise in temperature has triggered hydrological and geochemical changes that increasingly release carbon-rich water into the coastal ocean via increased riverine discharge, coastal erosion, and the thawing of the semipermanent permafrost ubiquitous in the region. To determine the biogeochemical impacts of terrestrially derived dissolved organic matter (tDOM) on marine ecosystems we compared the nutrient stocks and bacterial communities present under ice-covered and ice-free conditions, assessed the lability of Arctic tDOM to coastal microbial communities from the Chukchi Sea, and identified ...


Vegetation Recovery In Tidal Marshes Reveals Critical Slowing Down Under Increased Inundation, Jim Van Belzen, Johan Van De Koppel, Matthew L. Kirwan, Daphne Van Der Wal, Peter M.J. Herman, Vasilis Dakos, Sonia Kefi, Marten Scheffer, Glenn R. Guntenspergen, Tjeerd J. Bouma Jan 2017

Vegetation Recovery In Tidal Marshes Reveals Critical Slowing Down Under Increased Inundation, Jim Van Belzen, Johan Van De Koppel, Matthew L. Kirwan, Daphne Van Der Wal, Peter M.J. Herman, Vasilis Dakos, Sonia Kefi, Marten Scheffer, Glenn R. Guntenspergen, Tjeerd J. Bouma

VIMS Articles

A declining rate of recovery following disturbance has been proposed as an important early warning for impending tipping points in complex systems. Despite extensive theoretical and laboratory studies, this 'critical slowing down' remains largely untested in the complex settings of real-world ecosystems. Here, we provide both observational and experimental support of critical slowing down along natural stress gradients in tidal marsh ecosystems. Time series of aerial images of European marsh development reveal a consistent lengthening of recovery time as inundation stress increases. We corroborate this finding with transplantation experiments in European and North American tidal marshes. In particular, our results ...


Created Mangrove Wetlands Store Belowground Carbon And Surface Elevation Change Enables Them To Adjust To Sea-Level Rise, Ken W. Krauss, Nicole Cormier, Michael J. Osland, Matthew L. Kirwan, Camille L. Stagg, Janet A. Nestlerode, Marc J. Russell, Andrew S. From, Amanda C. Spivak, Darrin D. Dantin, James E. Harvey, Alejandro E. Almario Jan 2017

Created Mangrove Wetlands Store Belowground Carbon And Surface Elevation Change Enables Them To Adjust To Sea-Level Rise, Ken W. Krauss, Nicole Cormier, Michael J. Osland, Matthew L. Kirwan, Camille L. Stagg, Janet A. Nestlerode, Marc J. Russell, Andrew S. From, Amanda C. Spivak, Darrin D. Dantin, James E. Harvey, Alejandro E. Almario

VIMS Articles

Mangrove wetlands provide ecosystem services for millions of people, most prominently by providing storm protection, food and fodder. Mangrove wetlands are also valuable ecosystems for promoting carbon (C) sequestration and storage. However, loss of mangrove wetlands and these ecosystem services are a global concern, prompting the restoration and creation of mangrove wetlands as a potential solution. Here, we investigate soil surface elevation change, and its components, in created mangrove wetlands over a 25 year developmental gradient. All created mangrove wetlands were exceeding current relative sea-level rise rates (2.6 mm yr(-1)), with surface elevation change of 4.2-11.0 ...


The Roles Of Resuspension, Diffusion And Biogeochemical Processes On Oxygen Dynamics Offshore Of The Rhone River, France: A Numerical Modeling Study, Julia Moriarty, Courtney K. Harris, Katja Fennel, Marjorie A.M. Friedrichs, Kehui Xu, Christophe Rabouille Jan 2017

The Roles Of Resuspension, Diffusion And Biogeochemical Processes On Oxygen Dynamics Offshore Of The Rhone River, France: A Numerical Modeling Study, Julia Moriarty, Courtney K. Harris, Katja Fennel, Marjorie A.M. Friedrichs, Kehui Xu, Christophe Rabouille

VIMS Articles

Observations indicate that resuspension and associated fluxes of organic material and porewater between the seabed and overlying water can alter biogeochemical dynamics in some environments, but measuring the role of sediment processes on oxygen and nutrient dynamics is challenging. A modeling approach offers a means of quantifying these fluxes for a range of conditions, but models have typically relied on simplifying assumptions regarding seabed-water-column interactions. Thus, to evaluate the role of resuspension on biogeochemical dynamics, we developed a coupled hydrodynamic, sediment transport, and biogeochemical model (HydroBioSed) within the Regional Ocean Modeling System (ROMS). This coupled model accounts for processes including ...