Emily S Bernhardt

Emily S Bernhardt
Duke University | DU · Department of Biology

Ph.D. Ecology and Evolutionary Biology, Cornell University

About

313
Publications
71,994
Reads
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23,823
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Introduction
I am a biogeochemist and ecosystem ecologist whose research is focused on understanding how human accelerated environmental change (global warming, rising CO2, urbanization) alters the biogeochemical cycling of elements within watersheds.
Additional affiliations
August 2004 - present
Duke University
Position
  • Professor (Full)
August 2002 - August 2004
University of Maryland, College Park
Position
  • PostDoc Position
August 1996 - May 2001
Education
August 1996 - May 2001
Cornell University
Field of study
  • Ecology and Evolutionary Biology
August 1992 - May 1996

Publications

Publications (313)
Article
Full-text available
Nonpoint source urban nutrient loading into streams and receiving water bodies is widely recognized as a major environmental management challenge. A dominant research and management paradigm assumes that loading primarily derives from elevated stormwater. However, baseflow can account for a large portion of total loading, especially for low develop...
Article
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Coastal forested wetlands support many endemic species, sequester substantial carbon stocks, and have been reduced in extent due to historic drainage and agricultural expansion. Many of these unique coastal ecosystems have been drained, while those that remain are now threatened by saltwater intrusion and sea level rise in hydrologically modified c...
Article
Full-text available
The effects of sea level rise and coastal saltwater intrusion on wetland plants can extend well above the high-tide line due to drought, hurricanes, and groundwater intrusion. Research has examined how coastal salt marsh plant communities respond to increased flooding and salinity, but more inland coastal systems have received less attention. The a...
Article
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Significance This paper provides a comprehensive analysis of the annual patterns of ecosystem productivity and respiration for more than 200 rivers, comparing the magnitude and phenology of river metabolic regimes with annual estimates from more than 150 terrestrial ecosystems. Although mean annual temperature and mean annual precipitation explain...
Article
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Artisanal and small‐scale gold mining (ASGM) is the primary global source of anthropogenic mercury (Hg) emissions and a large source of landscape change. ASGM occurs throughout the world, including in the Peruvian Amazon. This dataset contains measurements of surface water, precipitation, throughfall, leaves, sediment, soil, and air samples from ac...
Article
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Mercury emissions from artisanal and small-scale gold mining throughout the Global South exceed coal combustion as the largest global source of mercury. We examined mercury deposition and storage in an area of the Peruvian Amazon heavily impacted by artisanal gold mining. Intact forests in the Peruvian Amazon near gold mining receive extremely high...
Article
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A variety of antibiotics are ubiquitous in all freshwater ecosystems that receive wastewater. A wide variety of antibiotics have been developed to kill problematic bacteria and fungi through targeted application, and their use has contributed significantly to public health and livestock management. Unfortunately, a substantial fraction of the antib...
Article
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Salinization of freshwater ecosystems impacts carbon cycling, a particular concern for coastal wetlands, which are important agents of carbon sequestration. Previous experimental work using salt additions as a proxy for sea level rise, reveals widely divergent effects of salt on soil carbon processes. We performed a laboratory salt addition experim...
Article
With advances in eDNA metabarcoding, environmental microbiomes are increasingly used as cost-effective tools for monitoring ecosystem health. Stream ecosystems in Central Appalachia, heavily impacted by alkaline drainage from mountaintop coal mining, present ideal opportunities for biomonitoring using stream microbiomes, but the structural and func...
Article
Aquatic-terrestrial contaminant transport via emerging aquatic insects has been studied across contaminant classes and aquatic ecosystems, but few studies have quantified the magnitude of these insect-mediated contaminant fluxes, limiting our understanding of their drivers. Using a recent conceptual model, we identified watershed mining extent, set...
Preprint
Full-text available
The effects of sea level rise and coastal saltwater intrusion on wetland plants can extend well above the high-tide line due to drought, hurricanes, and groundwater intrusion. Research has examined how coastal salt marsh plant communities respond to increased flooding and salinity, but more inland coastal systems have received less attention. The a...
Article
Current land‐use classifications used to assess urbanization effects on stream water quality date back to the 1980s when limited information was available to characterize watershed attributes that mediate non‐point source pollution. With high resolution remote sensing and widely used GIS tools, there has been a vast increase in the availability and...
Article
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Mountaintop mining, like all forms of surface mining, fundamentally alters the landscape to extract resources that lie 10-100 ms below the land surface. Despite these deep, critical zone alterations, post-mining landscapes are required by United States law to be restored to ecosystems of equal or greater value than the ones they replace. Yet, remot...
Article
The rivers of Appalachia (USA) are among the most biologically diverse freshwater ecosystems in the temperate zone and are home to numerous endemic aquatic organisms. Throughout the Central Appalachian ecoregion, extensive surface coal mines generate alkaline mine drainage that raises the pH, salinity and trace element concentrations in downstream...
Article
Ecosystems constantly adjust to altered biogeochemical inputs, changes in vegetation and climate, and previous physical disturbances. Such disturbances create overlapping ‘biogeochemical legacies’ affecting modern nutrient mass balances. To understand how “legacies” affected watershed-ecosystem biogeochemistry during five decades of studies within...
Article
Mercury (Hg), a potent neurotoxic element, can biomagnify through food webs once converted into methylmercury (MeHg). Some studies have found that selenium (Se) exposure may reduce MeHg bioaccumulation and toxicity, though this pattern is not universal. Se itself can also be toxic at elevated levels. We experimentally manipulated the relative conce...
Article
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Climate change is driving ecological shifts in coastal regions of the world, where low topographic relief makes ecosystems particularly vulnerable to sea level rise, salinization, storm surge, and other effects of global climate change. The consequences of rising water tables and salinity can penetrate well inland, and lead to particularly dramatic...
Article
Deoxygenation of aquatic ecosystems is a key feature of the Anthropocene. Studies are increasingly reporting low oxygen conditions in rivers and headwater streams even in the absence of high nutrient loads. We examined the frequency of river hypoxia (dissolved oxygen [DO] < 50% saturated in O2) in the North Carolina Piedmont by examining monitoring...
Article
The Hubbard Brook Experimental Forest (HBEF) was established in 1955 by the U.S. Department of Agriculture, Forest Service out of concerns about the effects of logging increasing flooding and erosion. To address this issue, within the HBEF hydrological and micrometeorological monitoring was initiated in small watersheds designated for harvesting ex...
Article
Stream solute monitoring has produced many insights into ecosystem and Earth system functions. Although new sensors have provided novel information about the fine‐scale temporal variation of some stream water solutes, we lack adequate sensor technology to gain the same insights for many other solutes. We used two machine learning algorithms – Suppo...
Article
Full-text available
Artisanal and small-scale gold mining (ASGM) is the largest global source of anthropogenic mercury emissions. However, little is known about how effectively mercury released from ASGM is converted into the bioavailable form of methylmercury in ASGM-altered landscapes. Through examination of ASGM-impacted river basins in Peru, we show that lake area...
Article
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The increasing availability of high‐frequency freshwater ecosystem metabolism data provides an opportunity to identify links between metabolic regimes, as gross primary production and ecosystem respiration patterns, and consumer energetics with the potential to improve our current understanding of consumer dynamics (e.g., population dynamics, commu...
Article
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Coal is naturally enriched in trace elements, including mercury (Hg) and selenium (Se). Alkaline mine drainage from mountaintop mining valley fill (MTM-VF)—the dominant form of surface coal mining in Appalachia, USA—releases large quantities of Se into streams draining mined catchments, resulting in elevated bioaccumulation of Se in aquatic and rip...
Article
Freshwater ecosystems are exposed to engineered nanoparticles through municipal and industrial wastewater-effluent discharges and agricultural non-point source runoff. Because previous work has shown that engineered nanoparticles from these sources can accumulate in freshwater algal assemblages, we hypothesized that nanoparticles may affect the bio...
Article
Mercury (Hg) is a pervasive environmental pollutant and contaminant of concern for both people and wildlife that has been a focus of environmental remediation efforts for decades. A growing body of literature has motivated calls for revising Hg consumption advisories to co-consider selenium (Se) levels in seafood and implies that remediating aquati...
Article
Full-text available
Selenium is highly elevated in Appalachian streams and stream organisms that receive alkaline mine drainage from mountaintop removal coal mining compared to unimpacted streams in the region. Adult aquatic insects can be important vectors of waterborne contaminants to riparian food webs, yet pathways of Se transport and exposure of riparian organism...
Article
Background and aims: Coastal plant communities globally are highly vulnerable to future sea-level rise and storm damage, but the extent to which these habitats are affected by the various environmental perturbations associated with chronic salinization remains unclear. In this study, we examine the relationship between North Carolina wetland tree...
Article
Reliable predictions of the environmental fate and risk of engineered nanomaterials (ENMs) require a better understanding of ENM reactivity in complex, biologically active systems for chronic low-concentration exposure scenarios. Here, simulated freshwater wetland mesocosms were dosed with ENMs to assess how their reactivity and seasonal changes in...
Article
Full-text available
Throughout the Central Appalachian ecoregion, mountaintop removal coal mining (MTM) is the predominant form of land use change. The streams draining MTM impacted watersheds have been reported to contain high stream nitrate (NO3⁻) concentrations, yet the source and persistence of elevated NO3⁻ remains unknown. Here we compiled data from multiple sou...
Article
Whole microbial communities regularly merge with one another, often in tandem with their environments, in a process called community coalescence. Such events impose substantial changes: abiotic perturbation from environmental blending and biotic perturbation of community merging. We used an aquatic mixing experiment to independently unravel the eff...
Article
The chemical composition and properties of environmental media determine nanomaterial (NM) transport, fate, biouptake, and organism response. To compare and interpret experimental data, it is essential that sufficient context be provided for describing the physical and chemical characteristics of the setting in which a nanomaterial may be present....
Presentation
Wetlands in the coastal plain of the southeastern United States are biodiversity hotspots that are vulnerable to ecosystem changes driven by increasing salinization due to more frequent storm surges and drought events. Salinization of freshwater wetlands is further exacerbated by human alteration of hydrologic flow. Our work aims to document the ch...
Article
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High‐resolution data are improving our ability to resolve temporal patterns and controls on river productivity, but we still know little about the emergent patterns of primary production at river‐network scales. Here, we estimate daily and annual river‐network gross primary production (GPP) by applying characteristic temporal patterns of GPP (i.e.,...
Article
Full-text available
Changes in sea-level rise and precipitation are altering patterns of coastal wetland hydrology and salinization. We conducted paired laboratory (20 weeks) and field (15 weeks) marine salt addition experiments to disentangle the effects of hydrology (permanent versus intermittent flooding) and elevated marine salts (sulfate versus other salt ions) o...
Article
Chemical pollution mixtures enter aquatic environments and interact with microorganisms in eclectic ways with disparate consequences for microbial ecosystem services. Can using a thermodynamic framework help to determine the net influence of a chemical mixture on the functional capacity of benthic microbial communities? We examined this question by...
Article
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Diel variability in nutrient concentrations is common but not universal in aquatic ecosystems. Theoretical models of photoautotrophic systems attribute the absence of diel uptake variation to nutrient scarcity, such that diel variability in nutrient uptake disappears as nutrients becomes limiting. We tested this prediction in a mesocosm experiment,...
Article
Full-text available
Watershed urbanization increases the concentrations of major ions in downstream freshwater ecosystems. Non-point source ions from human activities and the chemical weathering of infrastructure are efficiently transported by stormwater runoff through subsurface pipes directly into streams. While the increase in mean streamwater solute concentrations...
Presentation
Coastal wetlands are highly vulnerable to rapid changes associated with climate change, including more frequent storm events, fire, drought, and saltwater intrusion. Trees are a crucial component to maintaining ecosystem structure by controlling light availability to the soil and influencing biogeochemical cycling of nutrients and water. Our study...
Article
A majority of environmental studies describe microbiomes at coarse scales of taxonomic resolution (bacterial community, phylum), ignoring key ecological knowledge gained from finer‐scales and microbial indicator taxa. Here, we characterized the distribution of 940 bacterial taxa from 41 streams along an urbanization gradient (0‐83% developed waters...
Article
Full-text available
Saltwater intrusion is the leading edge of sea-level rise, preceding tidal inundation, but leaving its salty signature far inland. With climate change, saltwater is shifting landward into regions that previously have not experienced or adapted to salinity, leading to novel transitions in biogeochemistry, ecology, and human land uses. We explore the...
Article
Widespread saltwater intrusion into freshwater coastal ecosystems could dramatically alter the fate of stored carbon as well as the rate of future soil carbon (C) sequestration. We carried out a large survey of soil C at 51 freshwater wetland sites across the coastal plain of North Carolina. We then conducted a microcosm experiment with soils from...
Article
Effluents from coal-fired power plant ash ponds are a major source of environmental contamination, annually loading more than a million metric tons of pollutants to aquatic ecosystems in the U.S. alone. Though this waste stream is characterized by elevated concentrations of numerous inorganic constituents, decades of previous research effort has fo...
Article
Full-text available
Although seasonal patterns of ecosystem productivity have been extensively described and analyzed with respect to their primary forcings in terrestrial and marine systems, comparatively little is known about these same processes in rivers. However, it is now possible to perform a large‐scale synthesis on the patterns and drivers of river productivi...
Preprint
Whole microbial communities regularly merge with one another, often in tandem with their environments, in a process called community coalescence. Such events allow us to address a central question in ecology — what processes shape community assembly. We used a reciprocal transplant and mixing experiment to directly and independently unravel the eff...
Article
Full-text available
A national-scale quantification of metabolic energy flow in streams and rivers can improve understanding of the temporal dynamics of in-stream activity, links between energy cycling and ecosystem services, and the effects of human activities on aquatic metabolism. The two dominant terms in aquatic metabolism, gross primary production (GPP) and aero...
Article
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Headwater streams draining urbanized watersheds are subject to frequent and intense storm flows. These floods can disrupt metabolic processes occurring in benthic biofilms via the removal of biomass (i.e., scouring flows, bed mobilization) or light attenuation due to turbidity. Furthermore, channel incision caused by frequent hydraulic disturbance...
Article
Simulating multiple linked elemental cycles is a frontier in the field of biogeochemistry. The Generalized Algorithm for Nutrient, Growth, Stoichiometric and Thermodynamic Analysis (GANGSTA) is a software framework that automates the instantiation of formalized, user-defined conceptual models of linked elemental cycles as simulation model code. The...
Article
Permitted and accidental releases of contaminants from coal combustion residual (CCR) storage facilities pose environmental and ecological risks for associated freshwater ecosystems around the world. Previous studies have applied isotope ratios in CCRs as environmental tracers to delineate and quantify the impact of CCRs and other fossil fuel waste...
Article
Full-text available
Predicting nanoparticle fate in aquatic environments requires mimicking of ecosystem complexity to observe the geochemical processes affecting their behaviour. Here, 12 nm Au nanoparticles were added weekly to large-scale freshwater wetland mesocosms. After six months, ~70% of Au was associated with the macrophyte Egeria densa, where, despite the t...
Article
In many temperate forested watersheds, hydrologic nitrogen export has declined substantially in recent decades, and many of these watersheds show enduring effects from historic acid deposition. A watershed acid remediation experiment in New Hampshire, U.S.A. reversed many of these legacy effects of acid deposition and also increased watershed nitro...
Article
Full-text available
The exposure of freshwater-dependent coastal ecosystems to saltwater is a present-day impact of climate and land-use changes in many coastal regions, with the potential to harm freshwater and terrestrial biota, alter biogeochemical cycles and reduce agricultural yields. Land-use activities associated with artificial drainage infrastructure (canals,...
Article
Full-text available
Coastal forested wetlands provide important ecosystem services such as carbon sequestration, nutrient retention, and flood protection, but they are also important sources of greenhouse gas emissions. Human appropriation of surface water and extensive ditching and draining of coastal plain landscapes are interacting with rising sea levels to increas...
Article
Translating the ever-increasing wealth of information on microbiomes (environment, host or built environment) to advance our understanding of system-level processes is proving to be an exceptional research challenge. One reason for this challenge is that relationships between characteristics of microbiomes and the system-level processes that they i...