Click on the title of a talk to view the abstract.

Breakfast: 8:30 am- 9:00 am

Mural Room, Clark Hall

General Session: 9:00 am- 11:00 am

Clark Hall 107

9:00- 9:14 am Manduca sexta moths can learn ozone-altered floral plumes: implications for pollination in the Anthropocene. Brynn Cook1, T'ai Roulston1, Manuel Lerdau1, Alex Haverkamp2, Markus Knadden2
The communication between pollinators and their mutualist partners is the basis for global food diversity and security. One way in which plants communicate with pollinators is by releasing bouquets of floral volatiles into the atmosphere, which form “scent pathways” pollinators can follow to their target flower. However, anthropogenically derived oxidative atmospheric pollutants, such as ozone, can react with floral volatiles, degrading or altering these olfactory cues. While emerging research indicates that ozone-altered plumes may be innately less appealing to insect foragers, no studies have examined if pollinators’ prodigious olfactory learning capacities could help mediate the suspected deleterious effects of atmospheric pollutants on pollination success. Here we demonstrate that the model pollinator Manduca sexta (M. sexta), flying in a wind tunnel, can overcome an initial discrimination against an ozonated floral plume and learn to associate the ozone-altered plumes with a reward. Perhaps most significantly, M. Sexta demonstrate the ability to generalize from a pure plume to an ozone-altered one: after being trained on a pure floral scent, nearly 50% of M. sexta attempted to forage on an ozone-altered plume that they did not innately respond to. M. sexta were even more capable of learning ozonated scents in a more realistic scenario where they encountered an ozone-altered plume before foraging on a pure plume, indicatingthat the initial presence of ozonated scents enhance M. sexta’s ability to make the association between ozonated plume and reward. This ability to cue in and learn ozone-altered plumes one while on the wing may enable generalist pollinators like Manduca to maintain their status as efficient foragers even in polluted atmospheres.
Author affiliations: 1Department of Environmental Sciences, University of Virginia; 2Max Planck Chemical Ecology

9:14- 9:28 am Virginia seaside coastal plain habitat use by bees. Jessie Thuma, Linda Blum and T’ai Roulston
Wild native bees are importantinsect pollinators and are crucial in food production around the globe. However, habitat loss, human disturbance, and climate change pose major threats to native bee populations and their numbers are in decline, threatening agricultural productivity and local farmers’ livelihoods. On the Eastern Shore of Virginia, rising sea levelsare causing land cover along the shore to shift from crop land to old field to high marsh, whichmay have negative consequences for native bee communities that play an important role in such an agriculture-based community. My research aims to answer two questions: (1) Is the bee community in an old field more diverse than the bee community in a high salt marshand agricultural field, based on species abundance and richness? (2)Is the bee community in the salt marsh distinctfrom the bee community in the old fields and agricultural fields? Native bees were collected from 15 sites over the course of four weeks. The samples were then sorted, pinned, and identified to determine species abundance and richness, and to compare the bee communities in high marsh, old field, and agricultural field. A total of 6309beespecimensand 47 distinct species were sampled. There were 1481 specimenscollected from high marsh sites, 3068 collected fromagricultural sites, and 1760 collected from old field sites. The average number of species collected per marsh site was 18, per agricultural site was 24, and per old field site was 22. Data analysis is still ongoing. The results of this study will advance understanding of how bee communities respond to the effects of climate change and human activity, and will contribute important information about the ecological costs and benefits of shifting land cover between farm land, old field, and high salt marsh.
Author affiliations: Department of Environmental Sciences, University of Virginia

9:28- 9:42 am Effects of an Antihistamine and an Insecticide on Intraguild Predation in Aquatic Insects. Kyle Leathers1, Patrick Crumrine2
Pharmaceuticals, pesticides, and other chemicals are entering the world’s waters at increasing rates. While a considerable number of studies have been published documenting the effects of pesticides, there has been little research conducted on the effects of pharmaceuticals. One class of pharmaceutical that is widely used and has been shown to affect aquatic insect behavior is antihistamines. Most studies that include these drugs have focused on lethal concentrations for organisms and few examine sublethal effects that could influence behavior and foraging patterns. Furthermore, these studies have focused on single species and not community interactions. Finally, studies investigating how antihistamines, which may alter insect nervous system function, affect community interactions in the presence of other chemicals such as insecticides that also alter nervous system function have not been conducted. Using mesocosms, I tested how 2 ppb of the antihistamine diphenhydramine and 10 ppb of the insecticide carbaryl separately and in combination affected intraguild predation (IGP) between common aquatic insect predators (Anax junius, Cybister fimbriolatus, and Sympetrum semicinctum. IGP within this system has been studied extensively, but few studies have considered the role of anthropogenic stress. S. semicinctum and A. junius survival decreased significantly over the course of the 3-day experiment, supporting previous intraguild predation experiments. However, there were no significant effects of the chemical treatments on any of the response variables including S. semicinctum survival, A. junius survival and the proportion of prey consumed by C. fimbriolatus and A. junius predators. The levels of the chemicals used in this experiment are commonly found in nature and solely based on these results, it does not appear that diphenhydramine and carbaryl have significant effects on IGP between study organisms. Further testing of carbaryl and diphenhydramine at a range of concentrations is a potential area for future work.
Author affiliations: 1Department of Environmental Sciences, University of Virginia; 2Department of Biological Sciences, Rowan University

9:42- 9:55 am Oxygen metabolism of intertidal oyster reefs measured by aquatic eddy covariance. Martin P. Volaric, Peter Berg, and Matthew A. Reidenbach
Oyster reef restoration is pursued at numerous places worldwide, yet little is known about how ecosystem function changes as restoration reefs develop. In this study we used the aquatic eddy covariance technique to measure the oxygen metabolism of four intertidal sites on the Virginia, USA coast: a mature oyster reef, two restoration reefs, and a mudflat. Oyster densities of the three reefs (± SE) were 350 ± 62, 295 ± 35, and 186 ± 66 oysters m-2 (n = 4, 4, 7). Mean summer values of nighttime oxygen uptake (± SE) were -488 ± 23, -428 ± 16, -300 ± 10, and -56 ± 10 mmol m-2 d-1 over the mature reef, two restoration reefs, and mudflat respectively (n = 265, 129, 101, 93). At all sites the presence of primary producers resulted in smaller daytime vs. nighttime fluxes, as rates of summer Gross Primary Production on the reefs ranged from 233 to 424 mmol m-2 d-1. Nighttime uptake was similar across all three oyster reefs when normalized by density, with values between -1.8 and -2.3 mmol m-2 d-1 oyster-1. Our study shows that oxygen demand scales with oyster density as restoration reefs grow and accrete, that primary producers can strongly impact reef oxygen dynamics, and that eddy covariance measurements can be used to quantify reef restoration success.
Author affiliations: Department of Environmental Sciences, University of Virginia
Break: 9:55 am- 10:00 am

10:00- 10:14 am Measurement of Vertical and Horizontal Change in Salt Marshes Experiencing Rapid Sea Level Rise. Jessica Flester, Linda K. Blum, Art Schwarzschild, John H. Porter
Wetlands are threatened by sea-level rise (SLR), especially on the Mid-Atlantic coast which has been recognized as a hot spot for SLR. Marsh survival is governed by two main responses to this threat: vertical growth, and horizontal movement and conversion of uplands to salt marsh (transgression). In two mainland salt marshes at the Virginia Coast Reserve (VCR), changes in marsh surface elevation were determined for a 15-year period (2001–2016). Marsh transgression was measured through a GIS analysis of satellite imagery of the marsh-upland boundary pre- and post-Hurricane Sandy, between 2002 and 2013. Transgression was the dominant process occurring along the marsh upland boundary in both of the salt marshes studied. In the Cushman’s Landing marsh, transgression occurred along 100% of the upland boundary. In the Indiantown marsh transgression occurred along 82% of the marsh upland boundary, while progression occurred along 18% of the boundary. Additionally, at both of the study sites marsh surface elevation decreased over time. In Cushman’s the average rate of change was -7.88 mm yr-1, and in Indiantown the average rate of elevation change was -2.81 mm yr-1. Therefore, there is a positive correlation between marsh transgression and a decrease in marsh surface elevation. These findings suggest a relationship between vertical marsh change and horizontal marsh change; however, further work must be done for more marshes at the VCR LTER to determine the generalizability of these results to other geomorphic settings. This research will serve as a foundation for investigating the relationships between vertical and horizontal change in marshes with SLR.
Author affiliations: Department of Environmental Sciences, University of Virginia
10:14- 10:28 am Salt marsh decline and mangrove expansion in the face of anthropogenic forcing. Allisa Vincent
Due to anthropogenic forcing, plant species abundance and distribution is shifting at a variety of ecological scales. At the landscape level shifts, can cause fundamental changes to the ecology of ecosystems. In the subtropical region shifts in vegetation patterns are occurring at the ecotone where salt marsh and mangrove species coexist. The ecotone occurs as a dynamic stable state between salt marsh grass and forbs and mangrove woody vegetation. The vegetation composition is controlled by climate and disturbance events which cause mangrove die-off and expansion. Recently this ecotone has been receiving more attention as mangrove species have expanded their range poleward and replaced salt marsh species in some areas at a rapid rate, as well as salt marshes experiencing large die-off events and landscape level habitat loss. This shift poleward of mangrove vegetation and loss of salt marsh habitat could have lasting effects on ecosystem services provided by coastal habitats such as coastal protection, erosion prevention, nutrient cycling, fisheries maintenance, and rates of carbon sequestration influencing local and regional economies. In this review I have four main objectives (i) discuss the evidential support for mangrove latitude extension (ii) highlight the evidence and effects of fragmentation on salt marshes (iii) discuss the dispersal limitation of salt marshes versus mangrove species and (iv) identify how these factors may contribute to the shifting dynamics in the salt marsh mangrove ecotone. This review allows me to discuss the role dispersal limitation and fragmentation play in contributing to the salt marsh to mangrove ecotone shift and identify questions that need to be resolved in order to better understand the future role of anthropogenic forcing on the salt marsh mangrove ecotone.
Author affiliations: Department of Environmental Sciences, University of Virginia
10:28- 10:42 am Establishment of Kosteletzkya pentacarpos in abandoned agricultural fields facilitate upland transition to salt marsh. Long E.V., K. Spady, and L.K. Blum
Due to anthropogenic forcing, plant species abundance and distribution is shifting at a variety of ecological scales. At the landscape level shifts, can cause fundamental changes to the ecology of ecosystems. In the subtropical region shifts in vegetation patterns are occurring at the ecotone where salt marsh and mangrove species coexist. The ecotone occurs as a dynamic stable state between salt marsh grass and forbs and mangrove woody vegetation. The vegetation composition is controlled by climate and disturbance events which cause mangrove die-off and expansion. Recently this ecotone has been receiving more attention as mangrove species have expanded their range poleward and replaced salt marsh species in some areas at a rapid rate, as well as salt marshes experiencing large die-off events and landscape level habitat loss. This shift poleward of mangrove vegetation and loss of salt marsh habitat could have lasting effects on ecosystem services provided by coastal habitats such as coastal protection, erosion prevention, nutrient cycling, fisheries maintenance, and rates of carbon sequestration influencing local and regional economies. In this review I have four main objectives (i) discuss the evidential support for mangrove latitude extension (ii) highlight the evidence and effects of fragmentation on salt marshes (iii) discuss the dispersal limitation of salt marshes versus mangrove species and (iv) identify how these factors may contribute to the shifting dynamics in the salt marsh mangrove ecotone. This review allows me to discuss the role dispersal limitation and fragmentation play in contributing to the salt marsh to mangrove ecotone shift and identify questions that need to be resolved in order to better understand the future role of anthropogenic forcing on the salt marsh mangrove ecotone.
Author affiliations: Department of Environmental Sciences, University of Virginia
10:42- 10:55 am Seagrass restoration stimulates nitrogen cycling. Lillian R. Aoki, Karen J. McGlathery
Following the wholesale loss of seagrass in Virginia’s coastal bays in the 1930s, large-scale restoration has lead to the establishment of over 25 km2 of seagrass meadow by 2016. We measured a suite of nitrogen processes in the restored meadow and in adjacent bare sediment in order to understand the effects of this state change on nitrogen (N) cycling. We used in situ push-pull incubations to measure denitrification and DNRA and laboratory incubations to measure N fixation. We measured dissolved N fluxes across the sediment-water interface using benthic chambers and calculated burial rates from the N content and accretion rates of the sediment. In addition to processes, we measured standing stocks of N in the sediment and in seagrass biomass, using the leaf marking technique to measure changes to the biomass stock over time. Our results showed that N processes were enhanced in the meadow compared to adjacent bare sediment, likely due to increased sedimentation and release of oxygen and labile carbon from seagrass roots. In particular, N storage and removal were enhanced in the meadow. Standing stocks were orders of magnitude greater than fluxes. The stimulation of N removal and storage in the restored meadow may buffer increased N loading to the coastal bays as Virginia’s Eastern Shore experiences increased development and agricultural intensification.
Author affiliations: Department of Environmental Sciences, University of Virginia

Panel Discussion: 11:00 am- 11:45 am

Odum Room, Clark Hall. Panelists will discuss the theme of Global Change and Public Health and their research in that context.

Lunch: 11:45 am- 12:30 pm

Odum Room, Clark Hall.

Poster Session: 12:30 pm- 2:00 pm

Mural Room, Clark Hall.

Decreasing UVA’s Nitrogen Footprint through Organic Food. Gabriella Freckmann, James Galloway, Elizabeth Castner
Reactive nitrogen is necessary for food production. However, too much reactive nitrogen leads to negative environmental impacts. There are two sources of reactive N, recycled (e.g., compost, non-legume green manure) and new (e.g., biological nitrogen fixation through legumes and the Haber-Bosch process). Because recycled N uses existing N, it does not increase the amount of reactive N like new N does. And therefore it does not contribute to more pollution when N in food production is lost to the environment. The objective of this study was to determine to what degree new N used to produce food would be decreased with an increase in purchasing organically-produced food.
Food production is the largest part of UVA’s N footprint so determining the source of N that comes from that is important in decreasing N pollution. Three scenarios were created using the food production section of the nitrogen footprint calculator. The first scenario adjusted the amount of organic purchasing in each food category for 1, 30 and 100%. The second changed the organic purchasing to 30, 50, 75 and 100% in the bovine, poultry and vegetables categories. And the third scenario accounted for 30, 50, 75 and 100% organic purchasing in the cheese, eggs, milk, beverages, fruit and vegetable categories. We found that increasing the amount of organic purchasing decreased the amount of new N. Specifically, when increasing organic purchasing from 1 to 100% in the first scenario there was a 66% decrease in new N, in the second scenario, a 36% decrease and in the third scenario, a 23% decrease. We suggest that the best way to decide in which categories and by how much to increase organic purchasing is to engage students and see what the demand is and work with Dining to determine what is feasible.
Author affiliations: Department of Environmental Sciences, University of Virginia

Characterizing marsh vulnerability to erosion along the Virginia Eastern Shore. A. Ferguson, P. Wiberg
Sea level rise, increased storminess, and human population growth amplify coastal erosion problems, pressuring landowners to implement shoreline protection measures for valuable infrastructure. Growing concern over physical and biological tradeoffs associated with hard stabilization techniques has increased interest in nature-based solutions. Living shorelines provide erosion control while maintaining ecosystem functions. The successful implementation of living shoreline treatments involves the identification of vulnerable salt marsh areas using information on site-specific erosion and inundation variables. The main goal of this study is to develop a better understanding of the characteristics that contribute to the vulnerability of fringing salt marshes and to suggest appropriate shoreline stabilization techniques. The objective assessment of salt marsh vulnerability to erosion is possible through the development of a marsh vulnerability index (MVI) that allows physical and climatological variables to be related in a quantifiable manner. The MVI considers variables unique to fringing salt marshes in shallow coastal bays and provides insight into which variables are most influential and where physical changes are most likely to occur. Ultimately, the MVI will help planners and managers balance conservation with cost by prioritizing vulnerable shorelines.
Author affiliations: Department of Environmental Sciences, University of Virginia

Hadley Cell Expansion and Subtropical Drying Over Land. D. Schmidt, K. Grise
Since at least 1979, the Hadley cells have expanded poleward in each hemisphere. Since the subtropical dry zones owe their existence to the descending branch of the Hadley cells, it is natural to expect that the dry zones themselves should shift poleward as well. This in turn could cause decreases in precipitation on the poleward margins of the dry zones, but it is not immediately clear whether this drying would occur primarily over land regions or over oceans. Thus, in this project, we test the degree to which tropical expansion is associated with subtropical drying over land. Preliminary results suggest that tropical expansion is in fact associated with decreases in precipitation in the mid-latitudes, but that this drying occurs primarily over the ocean basins. In the northern hemisphere, this is because the drying is zonally asymmetric, and mostly avoids land–with some significant exceptions. In the southern hemisphere, this is because, while the drying region forms a more zonally symmetric band, this band lies too far south to affect most land masses. In a future expansion of this work, we plan to compare the observations with a number of model runs, which will allow us to distinguish more easily between tropical width changes associated with the ENSO cycle and those associated with greenhouse gas emissions.
Author affiliations: Department of Environmental Sciences, University of Virginia

Nitrous Oxide emission estimates using atmospheric observations of vertical profiles in a polluted agricultural region. Solianna Herrera1, Glenn S Diskin2, Sally Pusede1
Nitrous oxide (N2O) is a long-lived and highly potent greenhouse gas that also destroys stratospheric ozone. Largely attributed to changes in agricultural sources, N2O concentrations are increasing at a steady rate of 0.8 ppb y–1 globally. Emission rates of N2O remain poorly constrained, with N2O sources arguably among the most uncertain of the long-lived greenhouse gases. This study quantifies N2O emissions at the kilometer-spatial scale in the wintertime in a region with both agricultural and urban sources, the San Joaquin Valley of California. To do this, we use the large number vertical profiles of N2O and other relevant trace gases measured by the P3 aircraft during the NASA DISCOVER-AQ campaign that took place throughout the San Joaquin Valley in January–February 2013. We exploit the observed variability in profile shape by time of day, day to day, and location (over urban versus agricultural sources), along with chemical and physical constraints on mixing and the timing of decoupling between the surface boundary layer and residual layers aloft.
Author affiliations: 1Department of Environmental Sciences, University of Virginia, 2NASA Langley Research Center

Temperature effects on seagrass recovery in a Virginia Coastal Bay. A. Berger, P. Berg, K. McGlathery.
Seagrass meadows are valued for the ecosystem services they provide, including blue carbonsequestration due to high rates of net primary production and carbon burial in the sediment. In response to recent worldwide seagrass declines, conservation efforts have emerged to protect, monitor, and restore seagrass habitats. Understanding the resilience of seagrass meadows is key to the successful restoration of ecosystem services. A recent die-off event in one of the coastal bays of the Virginia Coastal Reserve (VCR) Long Term Ecological Research (LTER) site provides an unprecedented opportunity to study the recovery and resilience of seagrass habitats. This seagrass (Zostera marina) meadow is part of a landscape-scale restoration project at the VCR LTER that started in 2001. The meadow was thriving until summer 2015, when field observations indicated a dramatic decline in shoot density likely related to high summertime water temperatures. There is little consensus on a specific threshold, but high temperatures are known to affect seagrass metabolism.This study uses HOBO temperature data, seagrass density measurements, and eddy covariance oxygen flux measurements to investigate the effect of temperature on seagrass recovery at the VCR LTER. Preliminary data suggest spatial differences in daytime water temperatures may be related to the spatial heterogeneity of seagrass recovery observed in 2016. As more data become available, it will be possible to quantify the effect of temperature on seagrass metabolism, thereby providing critical information on the high-temperature threshold for Z. marina and how the frequency and duration of high-temperature events affects seagrass metabolism and biomass. The VCR LTER site is a model for temperate systems globally, and is an ideal natural laboratory to study the potential impact of warming oceans on seagrass resilience.
Author affiliations: Department of Environmental Sciences, University of Virginia

Meteorological observations in a valley during the 21 August 2017 solar eclipse Ross Palomaki, Stephan De Wekker
On 21 August 2017, a solar eclipse will occur over the United States for the first time since 1979. This presents a rare opportunity for atmospheric scientists to collect atmospheric measurements in a quasi-laboratory setting, as the timing of the eclipse is known with accuracy to fractions of a second. Meteorological data have been collected over flat terrain during past eclipse events, but a comprehensive dataset from a mountainous site does not exist.

This project will focus on the evolution of the atmosphere in and above a valley in the Great Smoky Mountains, which fall within the path of totality for the 2017 eclipse. Thermally-driven wind patterns are present in valleys of all sizes, and are driven by pressure gradients generated by incoming solar radiation. Thermally-driven winds typically blow upslope and upvalley during the day and reverse direction at night. I will focus on the following questions: [Q1] Is there an observable change in winds over the valley floor as a result of changes in thermal forcing during the eclipse? [Q2] How does temperature change with time at the surface, and to what altitude do these changes in temperature vertically propagate? [Q3] How do cloud cover and atmospheric boundary layer (ABL) height over the valley respond to changes in thermal forcing?

In this poster, I will describe the experimental design and instrumentation setup for the August field campaign. Some background information about atmospheric responses to changes in radiation will also be presented, with emphasis on responses in complex terrain.
Author affiliations: Department of Environmental Sciences, University of Virginia

Emissions from rice cultivation across the South Korean Peninsula: changes in atmospheric composition due to biochemical processes during rice field flooding Claire So1, Michelle Kim2, Paul Wennberg2, Alex Teng2, John Crounse2, Glenn Diskin3, Thomas Slate3, Mario Rana3, Joshua DiGangi3, Yonghoon Choi3, Stacey Hughes4, Donald Blake4, Lisa Kaser5, Armin Wisthaler6, Sally Pusede1
Nitrous oxide (N2O) and methane (CH4) are important long-lived greenhouse gases. Known anthropogenic sources of these gases include rice cultivation, which represents anywhere between 5% and 20% of methane emissions globally. Gas fluxes are dependent on a variety of factors, including, but not limited to, the timing of fertilizer application and field flooding. Here, we use measurements collected on-board the NASA DC-8 to quantify controls over emissions from South Korean rice cultivation. We combine observations of N2O and CH4 with measurements of other volatile molecules also produced at certain stages of anaerobic respiration in flooded rice fields, including volatile alcohols and organic acids and molecular hydrogen. Due to the highly integrated distribution of South Korean rice cultivation within urban and agricultural areas, remote sensing imagery from LANDSAT and MODIS, and GIS mapping data are also used to isolate rice paddy signals from urban and industrial plumes.
Author affiliations: 1Department of Environmental Sciences, University of Virginia, 2 Caltech, 3 NASA Langley Research Center, 4 University of California Irvine, 5 National Center for Atmospheric Research, 6 University of Oslo
Isoprene variability as a probe of long-term changes in atmospheric oxidation. Jaime F. Anderson1, Sally E. Pusede2
Isoprene is a reactive hydrocarbon emitted by the biosphere. The lifetime of isoprene against oxidation is less than an hour on a typical summer day, with the most important oxidant being the hydroxyl radical (OH). The concentration of OH and the production of ozone, a harmful pollutant, are linked through complex photochemistry that varies nonlinearly with nitrogen oxides (NOx), hydrocarbons including isoprene, and temperature. Emission controls to reduce stratospheric ozone are expected to have also altered OH concentrations. However, there are no inter-annual records of OH. By exploiting the weekday weekend dependence of NOx, we use 20 years of isoprene observations across the U.S. to test trends in OH with NOx and temperature. Trends in isoprene NOx dependence are a more direct probe of changes in oxidation mechanism than ozone. We will use the isoprene NOx probe to directly test the effects of drought on oxidation mechanism.
Author affiliations: 1Department of Chemistry, University of Virginia, 2 Department of Environmental Sciences, University of Virginia
Variation in Response of a Native Plant Meadow to Artificial Nighttime Lighting. Melissa Hey, Kyle Haynes, Ariel Firebaugh
Artificial nighttime lighting is widespread across terrestrial systems and is predicted to have deleterious effects on local flora and fauna. We explored the effects of artificial nighttime lighting on grasses and forbs in a native plant meadow at Blandy Experimental Farm in Boyce, VA between 2015 and 2016. The presence of light at night had a significant effect on aboveground biomass: lit plots had greater aboveground plant biomass than unlit plots (p=0.004). This trend was driven by the response of warm season C4 grasses to light (> 80% of total biomass). The marked increase in aboveground biomass prompted further investigation to grass tissue nutrient levels. We found no effect of light treatment on tissue C:N ratios of grasses in either year (p>0.1). These results demonstrate the complex nature of organisms’ responses to artificial nighttime lighting, and highlight the need for future research in this field of study.
Author affiliations: Department of Environmental Sciences, University of Virginia
Comparing modern carbon burial in aquatic ecosystems.
Alice Besterman, Grace Wilkinson, Cal Buelo, Jessica Gephart, Michael Pace
Carbon burial in the sediments of aquatic ecosystems is an important component of long-term C-storage and relevant to the global carbon budget. Sediment carbon accumulation rates have been measured and synthesized for many aquatic ecosystem types. Cross-system analyses further reveal generalities about carbon dynamics. However, sediment carbon accumulation has not been systematically compared across aquatic ecosystems including wetlands. We synthesized estimates of sediment carbon accumulation rates from 186 studies categorized into 21 system types across the inland water to marine continuum. We limited our analysis to studies that measured modern accumulation rates directly (excluding methods such as sediment traps, particle fluxes, and radiocarbon dating). Mean accumulation rates were calculated for individual system types (e.g. lakes, mangroves, marshes) and compared. Across all systems carbon accumulation rates spanned 4 orders of magnitude (0.2 to 7,000 g C m-2 yr-1). Reservoirs and deltas accumulate carbon at the highest rates among examined systems, while seagrass beds and fjords had among the lowest rates. While there is significant variability in modern carbon accumulation rates among and within systems, based on our synthesis it is evident there is substantial carbon burial in aquatic ecosystems at a global scale.
Author affiliations: Department of Environmental Sciences, University of Virginia
Decreasing Individual’s Environmental Footprints Through Environmental Impact Labeling. Christine DeRieux, Hannah Piester, Elizabeth Castner, James N. Galloway
The Spring 2017 iteration of the Nitrogen Working Group’s experiment on the effect of environmental impact labels on consumer choice will be located at the Fine Arts Café where customers will be randomly assigned to one of three conditions. Materials used in this study include menus with sustainability rankings for each item which convey environmental costs using a 1-5 star ranking system within menu categories/food groups as well as surveys with questions about sustainability meant to prompt customers to think about their attitudes about the cause (priming/information framing).
In the first condition, there will be a control survey, which will provide no priming and no environmental cost information. This condition will be used as a baseline for comparison. Customers in the second condition will be handed a survey with both filler questions and questions meant to prime thoughts about sustainability and the environment. This condition will test only the effect of priming/information framing on consumer choices. In the last condition, customers will receive the labeled menu, the sustainability survey, and filler questions. This condition is meant to test the efficacy of both priming/information framing and environmental cost information together in promoting more sustainable food choices amongst customers. Data collection will be streamlined by the use of a receipt collection system to determine the condition the customer was a part of. As the customer orders, they will hand in all of the materials they were exposed to during the study, and those materials will be attached to their respective receipts by the Dining employees. Customers will also be offered a 1-2 dollar coupon for participating in the experiment.
Author affiliations: Department of Environmental Sciences, University of Virginia
Influence of grid spacing in mountainous terrain on simulated planetary boundary layer depths in large-scale transport models.
Gert-Jan Duine and Stephan F.J. De Wekker
The difficulty of modeling atmospheric transport and mixing processes introduces significant uncertainties in the atmospheric fluxes estimated with carbon transport models. An important diagnostic for vertical transport and mixing is the planetary boundary layer (PBL) depth, the height above the surface up to which surface fluxes of heat, moisture, momentum, and trace gases such as CO2 are transported and mixed on a diurnal time scale. CO2-concentrations at the surface are inversely related to the PBL depth. PBL depths are known to vary considerably in mountainous areas. Atmospheric transport models used for CO2-flux estimations are typically run on coarse grid spacing (i.e. around 100 km horizontal resolution)and therefore miss terrain information needed for an accurate PBL depth calculation and so a correctCO2-budget estimation. In this poster, we relate subgrid terrain parameters to differences in PBL depths between a ‘coarse’ (10 km horizontal grid spacing) and a ‘fine’ (3.3 km) grid domain. We focus on an area which consists of a mixture of flat and mountainous terrain, and investigate for a period of two consecutive years. We find that PBL depths are larger in the coarse than in the fine grid domain. Most significant differences are found for areas with unresolved ridges and attain more than 200 min summer, or a relative difference of about 10%.The PBL depth differences can only be partly removed after correcting for the fine grid terrain elevation in the coarse domain, or the use of PBL height. The choice of the parameter for evaluation of a coarse model depends greatly on whether the PBL follows the terrain elevation or not. On a longer term, the understanding of these differences would lead to an improved simulation and understanding of the location and quantification of North American and global carbon sources and sinks.
Author affiliations: Department of Environmental Sciences, University of Virginia

Opening Remarks, 2 pm

Clark Hall 108.

General Session: 2:00 pm- 3:00 pm

Clark Hall 108.

2:02- 2:16 pm Setting and Reaching Institutional N Footprint Reduction Goals: A Case Study at the University of Virginia. Elizabeth Milo1, Elizabeth Castner1, Lia Cattaneo1, James N. Galloway1, Allison M. Leach2
Reactive nitrogen is both essential and detrimental to life on Earth. While nitrogen is a key component of protein, it is also a pollutant that can cause climate change, eutrophication, and more. The University of Virginia (UVA) is the only university that has approved a nitrogen footprint reduction goal. This goal was approved by UVA’s governing board in 2013 and aims to reduce the University’s nitrogen footprint by 25% below 2010 levels by 2025. Note that for this study, the boundaries of the N footprint calculation at UVA includes on-campus university operations but excludes the food component of the universities health system. UVA has calculated its footprint for 2010 and 2014 and will continue to complete a benchmark calculation every four years. The UVA N footprint group and the Office for Sustainability have determined a number of scenarios to reduce the University’s N footprint. Examples of these include implementing a Meatless Mondays program, composting all food waste at the University and switching from coal to natural gas at the heating plant. Since the 2010 baseline year, UVA’s N footprint has changed from a total of 403 to 393 MT N; the total reduction needs to be to 303 MT N. The decrease in the universities N footprint can be partially attributed to the decrease in coal use in the universities heating plant. . This paper examines the potential of additional scenarios that could be implemented to reach this goal. UVA hopes to serve as a model for other universities and institutions that want to reduce their environmental impact by setting and achieving N reduction goals.
Author affiliations: 1Department of Environmental Sciences, University of Virginia, 2 University of New Hampshire.
2:16- 2:30 pm The effect of wildfire on stream mercury and organic carbon in a Southern Appalachian forested watershed Allison Jensen, Ami Riscassi, Todd Scanlon
Wildfires alter forested ecosystems by mobilizing mercury and carbon, two compounds that are closely linked in terrestrial soils and vegetation. Studies have shown that wildfires release mercury to the atmosphere as gaseous elemental or particulate-bound Hg, which can be locally redeposited, and that wildfires leave charred organic material on the soil surface, which can be mobilized into steams during precipitation events. However, no studies have conducted a detailed evaluation of the impact of wildfire on mercury and carbon dynamics in streams.
This study investigates the coupled transport of mercury and carbon at Twomile Run, a forested headwater stream, following a wildfire that occurred last April in Shenandoah National Park. Since June, we have been collecting baseflow samples and high-flow samples during precipitation events. Samples are analyzed for dissolved and particulate mercury (HgD and HgP, respectively), UV absorbance at 254 nm (UV254, surrogate for DOC character), total suspended solids (TSS), and volatile solids (VS). These parameters will be compared to those in control streams, nearby streams that were not burned in the fire. Initial sample evaluation indicates that, under baseflow and high-flow conditions, HgD concentrations and the HgD:UV254 ratio are similar to those in unburned streams. Under baseflow conditions, HgP concentrations and the HgP:TSS ratio are also similar to those in unburned streams. However, under high-flow conditions, HgP is an order of magnitude higher per unit of TSS and VS than it is in unburned streams. We will continue to evaluate stream samples through the winter and spring to quantify mercury and carbon dynamics over a range of discharge conditions. These findings will give us a better understanding of the impact of wildfire on downstream Hg and carbon transport and will provide insight into how Hg cycling might change in the future, as wildfires are expected to increase with climate change.
Author affiliations: Department of Environmental Sciences, University of Virginia.
2:30 - 2:44 pm Effects of algal biofilm patchiness on boundary layer hydrodynamics. E. A. K. Murphy1, J. M. Barros2, M. P. Schultz3, K. A. Flack2, C. N. Steppe4, M. A. Reidenbach1
Algal biofilms commonly foul natural and man-made aquatic surfaces such as ship hulls, where they impose severe drag and therefore economic penalties. Biofilms are often found in high-speed, unidirectional flow environments, such as on ship hulls and riverbeds. Biofilms are algal or bacterial cells embedded in extracellular polymeric substance (EPS), and behave as a viscoelastic solid. When biofilms grow under hydrodynamic stress, they form flexible streamers. This compliant surface with protruding streamers results in complex interactions between biofilms and hydrodynamics. Hydrodynamic forces can result in spatially heterogeneousformation of biofilms and sloughing off of biofilms, leading to patchy coverage. We investigated the effects of biofilm patchiness on high Reynolds number boundary layer hydrodynamics by using high resolution Particle Image Velocimetry (PIV) to visualize flow over biofilms grown under shear on acrylic plates. Biofilm, even with sparse, thin coverage is shown to increase turbulence and Reynolds shear stresses in turbulent boundary layers. Over patchy biofilms, the structure of the boundary layer, including both the velocity and Reynolds shear stress profiles were spatially heterogeneous, as is turbulent kinetic energy and the generation and intensity of turbulent bursts and sweeps, which we investigated using quadrant analysis. The friction coefficient (Cf), which is indicative of drag, increased from 0.007 on a smooth wall to 0.01 over biofilm. The Cf also exhibited spatial differences over the patchy biofilms, indicating that as biofilm communities develop they are subject to changing hydrodynamic forces.
Author affiliations: 1 Department of Environmental Sciences, University of Virginia, 2United States Naval Academy, Department of Mechanical Engineering, 3United States Naval Academy, Department of Naval Architecture and Ocean Engineering, 4United States Naval Academy, Department of Oceanography.
2:44- 2:58 pm How to separate mesoscale from microscale motions within a valley atmosphere? Nevio Babic1,Zeljko Vecenaj2, Stephan F. J. De Wekker1
The notion of decomposing time series of winds and scalars into a mean and a fluctuating component, represents the very cornerstone of the eddy covariance technique. Assuming that the turbulent, microscale motions of interest are separated from macroscale motions by a spectral gap, one can readily apply such a decomposition. Historically known as Reynolds decomposition, it is essential for the determination of the turbulent fluxes in the atmospheric boundary layer. Proper estimates of these fluxes are crucial for a number of applications, including calculating the annual budget of the net ecosystem exchange or the development of new turbulence closure parameterizations for numerical weather prediction. A number of studies have reported a range of gap scales that fall into such a spectral gap, especially for flat terrain. However , a spatially richer information on these gap scales is still lacking, especially over complex terrain, such as a mountain valley. In addition, valley flows are more sensitive to flow conditions aloft, making them more susceptible to mesoscale phenomena which may completely degrade the presence of the spectral gap itself. Thus, more information is needed about the variability of gap scales over complex terrain. The main dataset we analyze is comprised of measurements obtained during the Terrain-Induced Rotor Experiment, conducted in the spring 2006 in Owens Valley, CA. Specifically, we analyze time series of winds obtained on 16 weather stations spread out across the valley, as well as sonic anemometer measurements of winds and temperature at three locations. To these we apply three methods to determine the climatology of gap scales, including the fast Fourier transform, ogive analysis, and multiresolution flux decomposition. We also focus on several phenomena typical for complex terrain, such as rotors and hydraulic jumps, with the goal of determining if and how gap scales react to their occurence.
Author affiliations: 1Department of Environmental Sciences, University of Virginia, 2 Department of Geophysics, University of Zagreb

Special Session (Global Change and Public Health) 3:00 pm- 4:00 pm

Clark Hall 108

3:02 – 3:16 pm Evaluating spatial indicators of algal blooms. Cal Buelo, Michael Pace
Phytoplankton exhibit a range of dynamics from relative stability to bloom cycles. These dynamics are driven by a variety of factors (e.g. nutrient loading rates, grazing, physical characteristics of the environment). Theory suggests that changes in drivers approaching critical transitions, for example from clear-water to algae-dominated states, manifest in statistical properties of systems in both time and space. Temporal indicators of proximity to thresholds have been well studied in models, lab experiments, and even a few whole ecosystem manipulations. While spatial indicators are also supported by theory, their evaluation has lagged behind that of temporal indicators. A few studies utilizing spatial models of terrestrial vegetation in arid landscapes have demonstrated the promise of these indicators, however it is unclear if aquatic systems will show similar patterns due to differences in the physical environment. We use a spatial phytoplankton model that incorporates the physical forces in aquatic systems and captures observed patterns in algae blooms to test for spatial indicators of thresholds in algae bloom drivers. Spatial indicators successfully signaled approaching transitions in phytoplankton dynamics across varying levels of physical forcing. These results are promising for potential application of these indicators to real aquatic ecosystems, especially considering the increased availability of spatial data from technologies such as remote sensing.
Author affiliations: Department of Environmental Sciences, University of Virginia
3:16 – 3:30 pm Environmental and Health Damage Costs of Nitrogen Emissions from UVA’s Main Heating Plant. Anna Perry, James Galloway, Elizabeth Castner, William Shobe
This past Fall 2016 semester, research was conducted within the Nitrogen Working Group with the objective to capture the historical levels of nitrogen emissions from UVA’s Main Heating Plant and associated social costs. Additionally, projections of nitrogen emissions from the MHP were estimated using the assumption that anatural gas pipeline will be completed in 2020 that will carry 100% natural gas to the MHP, eliminating coal as a fuel source entirely. Levels of NOx emissions were determined using UVA’s emission factors for coal and natural gas and the historical fuel mix, which has trended downward from 83% coal in 1988 to around 42% coal in 2014, the remainder being natural gas. Because the NOx emission factor for coal is a magnitude greater than that of natural gas, the increase in natural gas supply in the past fifteen years has significantly reduced UVA’s on-grounds nitrogen emissions and social costs. Upon completion of a natural gas pipeline in 2020, levels of nitrogen emissions would drop to unprecedented lows. Damages, which ranged from biodiversity loss to respiratory illness, were measured from given dollar amounts per kg of N. Social costs were divided into environmental and health damages, with the highest costs stemming from health damages due to NOx emissions. Just as the levels of nitrogen emissions decreased in recent years, the associated social costs fell as well, from a peak of ~ $2 million in 2000 to a recent low of ~$500,000 in 2013. Social costs associated with nitrogen emissions by 2025 are projected to be less than $150,000 annually. Under the framework of the 25% reduction goal for nitrogen emissions by 2025, the conversion to 100% natural gas in the MHP could account for up to a quarter of the desired reduction.
Author affiliations: Department of Environmental Sciences, University of Virginia
3:30 – 3:44 pm Arctic Design Group: Framing Logics Ben DiNapoli, Ziqi Chen, Austin Edwards, Tyler Mauri, Leena Cho, Matthew Jull
The acceptance of a new Arctic typology is a gradual process in the Alaskan Native context. A vernacular architecture is established only when the occupants of the built environment are as integrated into the process of building as the building is to their needs. In the context of Shishmaref, Alaska, an indigenous community located on an eroding barrier island, the need for a new Arctic housing typology is derived from the lack of an existing dialogue with the changing context and needs of Shishmaref. Addressing a failure to resolve critical issues related to changing climatic conditions, a flexible housing framework is necessary to adapt to an array of environmental, social and economic conditions. An architecture that is centered around the occupant is imperative.
While the western-implemented solution to housing in the Arctic introduced rigid mechanical systems that waste energy, ignore their environmental impacts and neglect cultural values, the imagined mode in which housing is operating in the relocation of Shishmaref creates internal microclimates – new typologies of habitation from sensory and physiological treatments of building technique. Can the house itself operate in a way that embraces and embodies the extreme climate of the western Arctic region, replacing the need for expensive technical solutions? The prototype house regulates program sequence from cool to warm; air filters from fresh to stale; humidity is channeled from dry to wet; light becomes accessible even in winter months; insulation is a result of form, not system. The primary activity across all spaces is a direct result of the confluence of seen and unseen phenomenological forces. Designed considering pressure, heat, humidity and human occupation, the proposed Arctic housing typology produces a new vernacular form that restores authority and ownership to the native Shishmaref population, while addressing multiple environmental, socioeconomic and cultural challenges.
Author affiliations: Department of Landscape Architecture, University of Virginia
3:44 – 3:58 pm Krista Rand
The magnitude and frequency of extreme weather is increasing worldwide, as is awareness of the role that post-disaster recovery plays in public health, a key metric of resilience. It is known that vulnerable populations, particularly those with intersecting individual or household identities including the poor, disabled, incarcerated, elderly, as well as those with small children, are at higher risk of poor post-disaster health outcomes. Prior to disasters, the civil infrastructure systems on which these residents depend may be less well-maintained than in areas where residents have better access to decision-makers. In addition, these populations fail to evacuate at higher rates than other community members. Compounding disaster-related traumas, these populations may be either stranded in place post-event or evacuated en masse, with less choice of destination and greater difficulty returning than those with more resources. In both cases, these disadvantaged populations may experience post-disaster interruptions in their ability to secure appropriate food, shelter, water, maintenance drugs, and medications for acute conditions. Using the critical needs of vulnerable populations to prioritize infrastructure recovery activities may reduce the likelihood of stranding and diasporic conditions as well as the attendant health impacts. Conversely, because of the potential for long-term mass displacement, delayed or inadequate recovery efforts that do not center the experiences of disadvantaged residents have the potential to reverberate at the regional, national and even global level.
Author affiliations: Department of Systems and Information Engineering, University of Virginia

Keynote Seminar: 4:05 – 5:05 pm. “Of Mice and Men: Emerging Infectious Disease in a Warmer, More Fragmented World”

Clark Hall 108
Dr. Richard Ostfeld, Cary Institute of Ecosystem Science

Infectious diseases of humans are emerging at an accelerating pace. To what extent is this acceleration facilitated by anthropogenic environmental changes? In this presentation, Ostfeld will explore a set of principles that might pertain broadly to emerging infectious diseases and will apply these principles to three tick-borne zoonoses (diseases transmitted from non-human vertebrates to people) that are highly prevalent in the temperate zone worldwide. He will demonstrate that the small mammals responsible for disease transmission (the “reservoirs”) are species that thrive when natural habitats are fragmented and biodiversity is lost. In contrast, the species that inhibit transmission are vulnerable to anthropogenic disturbances. As a result, risk and incidence of tick-borne diseases increase when vertebrate diversity declines. Recent meta-analyses demonstrate that increased disease risk is a general, widespread consequence of decreases in biodiversity. In addition to fragmentation and biodiversity loss, climate change is influencing the seasonal timing of tick-borne diseases and the probability of new outbreaks of mosquito-borne disease, such as Zika virus disease, in the United States. This body of research suggests that environmental policies that diminish or reverse biodiversity loss and climate warming are likely to reduce the burden of disease in humans and other hosts.

Reception: 5:05 – 7:00 pm.

Odum Room, Clark Hall

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