Marjorie A. M. Friedrichs

Virginia Institute of Marine Science

Coastal acidification, warming, and nutrient management actions all alter water quality conditions that marine species experience, with potential impacts to their physiological processes. Decreases in calcite saturation state (ΩCa) and food availability, combined with warming water temperatures, pose a threat to calcifying organisms; however, the m...

Intra-annual patterns of hypoxia in Chesapeake Bay have been recorded since the mid-1900s, but anthropogenic inputs and climate change have exacerbated the volume and extent of hypoxic waters, which mobile marine fishes avoid. This estuary provides important habitat for many seasonally resident species but declines in relative abundance and relativ...

Variations in estuarine carbonate chemistry can have critical impacts on marine calcifying organisms, yet the drivers of this variability are difficult to quantify from observations alone, due to the strong spatiotemporal variability of these systems. Terrestrial runoff and wetland processes vary year to year based on local precipitation, and estua...

Climate-induced changes in hypoxia are among the most serious threats facing estuaries, which are among the most productive ecosystems on Earth. Future projections of estuarine hypoxia typically involve long-term multi-decadal continuous simulations or more computationally efficient time slice and delta methods that are restricted to short historic...

Thank you to the 1396 reviewers who provided 2328 reviews during 2023 to ensure the quality and integrity of JGR‐Oceans manuscripts.

Seasonal hypoxia is a recurring threat to ecosystems and fisheries in the Chesapeake Bay. Hypoxia forecasting based on coupled hydrodynamic and biogeochemical models has proven useful for many stakeholders, as these models excel in accounting for the effects of physical forcing on oxygen supply, but may fall short in replicating the more complex bi...

The development of low‐oxygen zones threatening marine life (hypoxia) occurs annually in multiple coastal regions of the world. The largest estuary of the continental United States, the Chesapeake Bay, typically has ≈10 km³ of water with dioxygen concentrations <3 mg L⁻¹ in July. As numerical methods for refining model resolutions in targeted areas...

Plain Language Summary Despite occupying only 1% of the Earth's surface, inland waters (rivers, lakes, and reservoirs) play a critical role in global carbon (C) cycling by linking two of the Earth's largest C pools, terrestrial and marine ecosystems, as well as by exchanging CO2 with the atmosphere. Inland waters emit and bury C before it reaches t...

Key Points The editors thank the 2022 peer reviewers New editorial practices reduce pressure on reviewers Co‐reviewer tool allows collaboration with students and postdocs

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...

Aquaculturists, local beach managers, and other stakeholders require forecasts of harmful biotic events, so they can assess and respond to health threats when harmful algal blooms (HABs) are present. Based on this need, we are developing empirical habitat suitability models for a variety of Chesapeake Bay HABs to forecast their occurrence based on...

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...

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...

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.

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...

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...

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...

While ecosystem health is improving in many estuaries worldwide following nutrient reductions, inconsistent trends in water clarity measurements 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 downstre...

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...

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...

Ecological forecasts are quantitative tools that can guide ecosystem management. The coemergence 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 som...

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...

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...

While water quality is improving in many estuaries worldwide following nutrient reductions, ambiguous trends in water clarity often follow despite declining nutrient concentrations. 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 i...

While ecosystem health is improving in many estuaries worldwide following nutrient reductions, inconsistent trends in water clarity measurements 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 downstre...

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...

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...

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...

The Chesapeake Bay is the largest estuary in the United States, and its watershed is home to more than 18 million people. 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 river...

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...

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...

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. Chesapeake Bay serves as a case study for investigating the effects of changing sediment inputs on water clarity. Long-term incr...

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...

Key Point The editors thank the 2020 peer reviewers

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,...

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...

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...

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...

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...

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...

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...

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...

Key Points The editors thank the 2019 peer reviewers

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...

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...

Despite long-term reductions in riverine sediment and nutrient loading, the mainstem of the Chesapeake Bay has shown a lack of improvement in water clarity as measured by Secchi depth. Shoreline erosion may account for part of this discrepancy, as it provides a significant source of fine sediment loading to the Bay. This study examined the relative...

Abstract. 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 atm...

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...

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...

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...

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...

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...

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...

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...

This study uses a neural network model trained with in situ data, combined with satellite data and hydrodynamic model products, to compute the daily estuarine export of dissolved organic carbon (DOC) at the mouths of Chesapeake Bay (CB) and Delaware Bay (DB) from 2007 to 2011. Both bays show large flux variability with highest fluxes in spring and...

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...

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...

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...

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.