Marjorie A. M. Friedrichs

Marjorie A. M. Friedrichs
Virginia Institute of Marine Science

Ph.D.

About

121
Publications
24,339
Reads
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5,795
Citations
Citations since 2016
71 Research Items
3406 Citations
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20162017201820192020202120220100200300400500600
20162017201820192020202120220100200300400500600
Introduction
Dr. Marjorie Friedrichs is a Research Professor at the Virginia Institute of Marine Science of William & Mary. Her interdisciplinary research focuses on using numerical models to better understand how physical processes affect biogeochemistry in estuarine and coastal systems. Current projects focus specifically on hypoxia, acidification and harmful algal blooms, with an emphasis on both short-term forecasting and impacts of long-term change.

Publications

Publications (121)
Preprint
Full-text available
Multiple climate-driven stressors, including warming and increased nutrient delivery, are exacerbating hypoxia in coastal marine environments. Within coastal watersheds, environmental managers are particularly interested in climate impacts on terrestrial processes, which may undermine the efficacy of management actions designed to reduce eutrophica...
Article
Full-text available
Submarine canyons provide a conduit for shelf-slope exchange via topographically induced processes such as upwelling and downwelling. These processes in the Wilmington Canyon, located along the shelf-break of the Mid-Atlantic Bight (MAB), have not been previously studied, and the associated hydrographic variability inside the canyon and on the adja...
Article
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Plain Language Summary Thank you to the 1,371 reviewers who provided 2,661 reviews during 2021 to ensure the same quality and integrity of JGR‐O manuscripts.
Article
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While ecosystem health is improving in many estuaries worldwide following nutrient reductions, inconsistent trends in water clarity often remain. The Chesapeake Bay, a eutrophic estuary with a highly populated watershed, is a crucial testbed for these concerns. Improved efforts are needed to understand why some measurements of downstream estuarine...
Article
Full-text available
Seasonal hypoxia is a characteristic feature of the Chesapeake Bay due to anthropogenic nutrient input from agriculture and urbanization throughout the watershed. Although coordinated management efforts since 1985 have reduced nutrient inputs to the Bay, oxygen concentrations at depth in the summer still frequently fail to meet water quality standa...
Article
The Chesapeake Bay is the largest, most productive, and most biologically diverse estuary in the continental United States providing crucial habitat and natural resources for culturally and economically important species. Pressures from human population growth and associated development and agricultural intensification have led to excessive nutrien...
Article
Full-text available
Public awareness of microplastics and their widespread presence throughout most bodies of water are increasingly documented. The accumulation of microplastics in the ocean, however, appears to be far less than their riverine inputs, suggesting that there is a “missing sink” of plastics in the ocean. Estuaries have long been recognized as filters fo...
Article
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The accurate estimation of stream water temperature is essential for understanding environmental controls on the structure and functioning of aquatic ecosystems. Few studies have coupled soil and stream water temperatures to capture the synergy of thermal balances between terrestrial and riverine systems. As a result, little is known about how mult...
Article
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Research Impact Statement: Since 1985, the Chesapeake Bay has warmed three to four times faster in war-mer than cooler months; this has been driven primarily by atmospheric changes and by ocean warming in the lower Bay. ABSTRACT: Coastal environments such as the Chesapeake Bay have long been impacted by eutrophication stressors resulting from hum...
Article
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Understanding decadal changes in the coastal carbonate system is essential for predicting how the health of these waters responds to anthropogenic drivers, such as changing atmospheric conditions and riverine inputs. However, studies that quantify the relative impacts of these drivers are lacking. In this study, the primary drivers of decadal trend...
Article
Full-text available
Ecological forecasts are quantitative tools that can guide ecosystem management. The co‐emergence of extensive environmental monitoring and quantitative frameworks allows for widespread development and continued improvement of ecological forecasting systems. We use a relatively simple estuarine hypoxia model to demonstrate advances in addressing so...
Article
Full-text available
Excessive nutrient inputs from land, particularly nitrogen (N), have been found to increase the occurrence of hypoxia and harmful algal blooms in coastal ecosystems. To identify the main contributors of increased N loading and evaluate the efficacy of water pollution control policies, it is essential to quantify and attribute the long‐term changes...
Article
During the last decade, oyster aquaculture has rebounded in Virginia and has been associated with an increase in subaqueous leased area. Production levels remain historically low, however, and many leases are thought to be underutilized. This study uses a novel approach leveraging high-resolution environmental data to evaluate lease utilization and...
Article
Full-text available
The lateral transport and degassing of carbon in riverine ecosystems is difficult to quantify on large spatial and long temporal scales due to the relatively poor representation of carbon processes in many models. Here, we coupled a scale-adaptive hydrological model with the Dynamic Land Ecosystem Model to simulate key riverine carbon processes acr...
Conference Paper
Full-text available
While ecosystem health is improving in many estuaries worldwide following nutrient reductions, ambiguous trends in water clarity often remain. The Chesapeake Bay, a highly populated eutrophic estuary, is a crucial testbed for this issue. Efforts are needed to understand why downstream estuarine water clarity appears uncorrelated with watershed mana...
Article
Full-text available
Key Point The editors thank the 2020 peer reviewers
Article
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Daily real-time nowcasts (current conditions) and 2-day forecasts of environmental conditions in the Chesapeake Bay have been continuously available for 4 years. The forecasts use a 3-D hydrodynamic-biogeochemical model with 1 to 2 km resolution and 3-D output every 6 hours that includes salinity, water temperature, pH, aragonite saturation state,...
Article
Shoreline erosion supplies sediments to estuaries and coastal waters, influencing water clarity and primary production. Globally, shoreline erosion sediment inputs are changing with anthropogenic alteration of coastlines in populated regions. Chesapeake Bay, a prime example of such a system where shoreline erosion accounts for a large proportion of...
Data
This data repository is a permanent archive of the results presented in the associated publication (Turner et al. 2020, Science of the Total Environment, doi: 10.1016/j.scitotenv.2021.145157). The objective of this study was to investigate the effects of shoreline erosion on water clarity in the Chesapeake Bay. To this end, we used the Chesapeake B...
Article
Full-text available
Cobia (Rachycentron canadum) is a large coastal pelagic fish species that represents an important fishery in many coastal Atlantic states of the U.S. They are heavily fished in Virginia when they migrate into Chesapeake Bay during the summer to spawn and feed. These coastal habitats have been subjected to warming and increased hypoxia which in turn...
Article
Full-text available
ABSTRACT: Nursery area habitats such as estuaries are vital for the success of many fish populations. Climate change is altering conditions in these areas, which can thus impact the availability of suitable nursery habitat. The sandbar shark Carcharhinus plumbeus uses Chesapeake Bay (USA) as a nursery habitat during the summer months from birth up...
Article
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Abstract Most present forecast systems for estuaries predict conditions for only a few days into the future. However, there are many reasons to expect that skillful estuarine forecasts are possible for longer time periods, including increasingly skillful extended atmospheric forecasts, the potential for lasting impacts of atmospheric forcing on est...
Article
Full-text available
Estuarine water clarity depends on the concentrations of aquatic constituents, such as colored dissolved organic matter, phytoplankton, inorganic suspended solids, and detritus, which are influenced by variations in riverine inputs. These constituents directly affect temperature because when water is opaque, sunlight heats a shallower layer of the...
Article
Full-text available
The Chesapeake Bay is a large coastal-plain estuary that has experienced considerable anthropogenic change over the past century. At the regional scale, land-use change has doubled the nutrient input from rivers and led to an increase in riverine carbon and alkalinity. The bay has also experienced global changes, including the rise of atmospheric t...
Article
Full-text available
Estuaries play an uncertain but potentially important role in the global carbon cycle via CO2 outgassing. The uncertainty mainly stems from the paucity of studies that document the full spatial and temporal variability of estuarine surface water partial pressure of carbon dioxide ( pCO2). Here, we explore the potential of utilizing the abundance of...
Article
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Key Points The editors thank the 2019 peer reviewers
Article
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Sediment processes, including resuspension and transport, affect water quality in estuaries by altering light attenuation, primary productivity, and organic matter remineralization, which then influence oxygen and nitrogen dynamics. The relative importance of these processes on oxygen and nitrogen dynamics varies in space and time due to multiple f...
Poster
Full-text available
The Chesapeake Bay is the largest estuary in the U.S. with the highest land-to-water ratio of any estuarine watershed in the world. Management policies actively limit watershed inputs of nutrients and sediments to the estuary. In this heavily-populated, highly-managed system, it is imperative to understand water clarity change over time. Remote sen...
Presentation
Over the last several decades, the Chesapeake Bay has experienced a significant net decline in estuarine water clarity in conjunction with rapid human population growth within its watershed. Despite long-term reductions in riverine sediment loading, the main stem of the Bay has shown a lack of improvement in water clarity as measured by Secchi dept...
Article
Full-text available
Despite the important role of alkalinity in estuarine carbon cycling, the seasonal and decadal variability of alkalinity, particularly within multiple tidal tributaries of the same estuary, is poorly understood. Here we analyze more than 25,000 alkalinity measurements, mostly from the 1980s and 1990s, in the major tidal tributaries of the Chesapeak...
Technical Report
Full-text available
This report is intended as part of the important dialogue between the ocean colour and the biogeochemical/ecosystem/climate modelling communities. Numerical modellers are frequent users of ocean colour products, but many modellers remain unsure of the best way to use these products, and are often unaware of the uncertainties associated with them. O...
Article
Full-text available
The Chesapeake Bay, a large coastal plain estuary, has been studied extensively in terms of its water quality, and yet, comparatively less is known about its carbonate system. Here we present discrete observations of dissolved inorganic carbon (DIC) and total alkalinity from four seasonal cruises in 2016–2017. These new observations are used to cha...
Article
Full-text available
Understanding the vulnerability of estuarine ecosystems to anthropogenic impacts requires a quantitative assessment of the dynamic drivers of change to the carbonate (CO2) system. Here we present new high‐frequency pH data from a moored sensor. These data are combined with discrete observations to create continuous time series of total dissolved in...
Poster
Full-text available
Over the last several decades, the Chesapeake Bay has experienced a significant net decline in estuarine water clarity in conjunction with rapid human population growth within its watershed. Despite long-term reductions in riverine sediment loading, the main stem of the Bay has shown a lack of improvement in water clarity as measured by Secchi dept...
Article
Full-text available
AbstractThis study uses a neural network model trained with in situ data, combined with satellitedata and hydrodynamic model products, to compute the daily estuarine export of dissolved organiccarbon (DOC) at the mouths of Chesapeake Bay (CB) and Delaware Bay (DB) from 2007 to 2011. Bothbays show largeflux variability with highestfluxes in spring a...
Article
Full-text available
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 sta...
Article
Full-text available
Understanding of nitrogen cycling on continental shelves, a critical component of global nutrient cycling, is hampered by limited observations compared to the strong variability on a wide range of time and space scales. Numerical models have the potential to partially alleviate this issue by filling spatiotemporal data gaps and hence resolving annu...
Chapter
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Over the past quarter century, biogeochemical modeling efforts for research and operational oceanographic programs have increasingly used data assimilation methods to improve the models and their hindcasts, nowcasts, or forecasts. A useful classification of assimilation methods distinguishes between those methods used for state estimation and for p...
Poster
Full-text available
Investigated the effects of inorganic-organic particle ballasting on water clarity, the transfer of organic matter to depth, and the spatial patterns of primary production using a Chesapeake Bay ROMS-based biogeochemical model.
Article
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Resuspension affects water quality in coastal environments by entraining seabed organic matter into the water column, which can increase remineralization, alter seabed fluxes, decrease water clarity, and affect oxygen and nutrient dynamics. Nearly all numerical models of water column biogeochemistry, however, simplify seabed and bottom boundary lay...
Article
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Temperature is hypothesized to alter disease dynamics, particularly when species are living at or near their thermal limits. When disease occurs in marine systems, this can go undetected, particularly if the disease is chronic and progresses slowly. As a result, population‐level impacts of diseases can be grossly underestimated. Complex migratory p...
Article
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Low levels of dissolved oxygen (DO) occur in many embayments throughout the world and have numerous detrimental effects on biota. Although measurement of in situ DO is straightforward with modern instrumentation, quantifying the volume of water in a given embayment that is hypoxic (hypoxic volume (HV)) is a more difficult task; however, this inform...
Article
Full-text available
Excess nutrients derived from anthropogenic activity have resulted in the degradation of coastal water quality and an increase in low-oxygen and hypoxic events worldwide. In an effort to curb these impacts and restore water quality in the Chesapeake Bay, a maximum load of nutrients has been established based on a framework of regulatory standards a...
Article
Full-text available
Although rivers are the primary source of dissolved inorganic nitrogen (DIN) inputs to the Chesapeake Bay, direct atmospheric DIN deposition and coastal DIN concentrations on the continental shelf can also significantly influence hypoxia; however, the relative impact of these additional sources of DIN on Chesapeake Bay hypoxia has not previously be...
Article
Full-text available
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...
Article
We extend the 3D unstructured-grid model previously developed for the Upper Chesapeake Bay to cover the entire Bay and its adjacent shelf, and assess its skill in simulating saltwater intrusion and the coastal plume. Recently developed techniques, including a flexible vertical grid system and a 2nd-order, monotone and implicit transport solver are...
Article
Carbon cycling in the coastal zone affects global carbon budgets and is critical for understanding the urgent issues of hypoxia, acidification, and tidal wetland loss. However, there are no regional carbon budgets spanning the three main ecosystems in coastal waters: tidal wetlands, estuaries, and shelf waters. Here, we construct such a budget for...
Technical Report
Full-text available
Suggested Citation: Brady, D.C., J.V. DePinto, S.C. Chapra, D.M. Di Toro, M.A.M. Friedrichs, M.W. Gray, T. Jordan, M. Xia. 2018. Scientific and Technical Advisory Committee Chesapeake Bay Water Quality and Sediment Transport Model (WQSTM) Review. STAC Publication Number 18-002, Edgewater, MD. 40 pp.
Article
Full-text available
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 tim...
Article
Sea turtle strandings provide important mortality information, yet knowledge of turtle carcass at-sea drift and decomposition characteristics are needed to better understand and manage where these mortalities occur. We used empirical sea turtle carcass decomposition and drift experiments in the Chesapeake Bay, Virginia, USA to estimate probable car...
Technical Report
Full-text available
This report was written to encourage good data management among COMT collaborators. The report describes the life cycle of observation and model data collected and processed during the COMT program that ran from September 1, 2013 to August 31, 2018. This report is accessable from the U.S. IOOS Coastal and Ocean Modeling Testbed website (see https:/...
Article
Full-text available
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 changes in temperature, freshwater flow, and sea level rise for a 2050 scenario to explore the impact cli...
Article
Full-text available
The impacts of atmospheric nitrogen deposition (AND) on the chlorophyll and nitrogen dynamics of surface waters in the western North Atlantic (25°N-45°N, 65°W-80°W) are examined with a biogeochemical ocean model forced with a regional atmospheric chemistry model (Community Multiscale Air Quality, CMAQ). CMAQ simulations with year-specific emissions...
Article
Full-text available
An ocean modeling program is improving our ability to predict circulation along the U.S. West Coast, dead zones and other coastal ecosystem responses, and storm surges in island environments.
Preprint
Full-text available
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 tim...