Eastern Shore Of Virginia Research Articles

Enhancing human resilience against climate change: Assessment of hydroclimatic extremes and sea level rise impacts on the Eastern Shore of Virginia, United States

Coastal regions face climate-induced threats that have likely increased over the past four decades. In this work, we quantify the future climate impacts on hydroclimatic extremes in the risk-prone, 15-m-above-sea-level Eastern Shore of Virginia (ESVA) region, utilizing the Sixth International Coupled Model Intercomparison Project (CMIP6) Assessment Report 6 (AR6) and General Circulation Models (GCMs). We incorporate historical data on demographics and disasters, land use land cover (LULC), Landsat imagery, and sea level rise (SLR) to better understand and highlight the correlation between hydroclimatic extremes and societal components in this region. The hydrological model Soil and Water Assessment Tool (SWAT), Standardized Precipitation Index (SPI), Normalized Difference Water Index (NDWI), and Interquartile Range (IQR) method have been used to evaluate the intensity and frequency of projected climate extremes, in which SLR projections under different greenhouse gas emission pathways are temporally and spatially quantified. Our findings include (1) a trend towards wetter conditions is found with an increase in the number of flood events and up to an 8.9 % rise in the severity of flood peaks compared to the 2003–2020 period; (2) current coastal high-risk regions, identified using historical data of natural disasters, demographics, and LULC, are projected to be more susceptible to future climate impacts; and (3) low-lying coastal towns and regions are identified as currently vulnerable to coastal and SLR-induced flooding and are projected to become even more susceptible by 2100. This is the first effort that provides a valuable scientific basis for anticipated shifts in future climate patterns, essential for natural hazard prevention in ESVA. It highlights the need for authorities and decision-makers to plan and implement adaptive strategies and sustainable policies for the ESVA region and other coastal areas across the United States.

At the Intersection of Science and Education: The Process of Scientists and Educators Co‐developing Authentic Learning Experiences for K‐16 Students

AbstractStudents lose interest in science as they progress from elementary to high school. There is a need for authentic, place‐based science learning experiences that can increase students' interest in science. Scientists have unique skillsets that can complement the work of educators to create exciting experiences that are grounded in pedagogy and science practices. As scientists and educators, we co‐developed a lesson plan for high school students on the Eastern Shore of Virginia, a historically underserved coastal area, that demonstrated realistic scientific practices in students' local estuaries. After implementation of the lesson plan, we observed that students had a deeper understanding of ecosystem processes compared to their peers who had not been involved, were enthusiastic about sharing their experiences, and had a more well‐rounded ability to think like a scientist than before the lesson plan. We share our experiences and five best practices that can serve as a framework for scientists and educators who are motivated to do similar work. Through collaboration, scientists and educators have the potential to bolster student science identities and increase student participation in future scientific endeavors.

Quantifying seasonal to multi-decadal signals in coastal water quality using high- and low-frequency time series data

Abstract To inform water quality monitoring techniques and modeling at coastal research sites, this study investigated seasonality and trends in coastal lagoons on the eastern shore of Virginia, USA. Seasonality was quantified with harmonic analysis of low-frequency time-series, approximately 30 years of quarterly sampled data at thirteen mainland, lagoon, and ocean inlet sites, along with 4–6 years of high-frequency, 15-min resolution sonde data at two mainland sites. Temperature, dissolved oxygen, and apparent oxygen utilization (AOU) seasonality were dominated by annual harmonics, while salinity and chlorophyll-a exhibited mixed annual and semi-annual harmonics. Mainland sites had larger seasonal amplitudes and higher peak summer values for temperature, chlorophyll-a and AOU, likely from longer water residence times, shallower waters, and proximity to marshes and uplands. Based on the statistical subsampling of high-frequency data, one to several decades of low-frequency data (at quarterly sampling) were needed to quantify the climatological seasonal cycle within specified confidence intervals. Statistically significant decadal warming and increasing chlorophyll-a concentrations were found at a sub-set of mainland sites, with no distinct geographic patterns for other water quality trends. The analysis highlighted challenges in detecting long-term trends in coastal water quality at sites sampled at low frequency with large seasonal and interannual variability.

Plant Density Recommendations and Plant Nutrient Status for High Tunnel Tomatoes in Virginia

Open-field tomatoes in Virginia are traditionally planted in a single row with 2 ft (0.60 m) of in-row spacing, resulting in a plant density of 4356 plants per acre (10,890 plants/ha). However, there has been increasing interest among small and medium-sized farmers in high tunnel production. In order to be profitable, farmers must maximize their yield per unit area and take advantage of the potential benefits of producing under high tunnels. A common approach under greenhouse conditions is to increase the planting density to enhance yield per area. However, high tunnel farmers often extrapolate open-field practices to their high tunnels as they believe both systems are closer related together than to greenhouse production. In those cases, high tunnel farmers could potentially be neglecting yield increases due to their planting density selection. Additionally, irrigation and fertilization management (fertigation) under high tunnels tend to be more efficient than open-field systems, as the frequency of application is increased with a lower volume per application. A higher efficiency of fertigation could alter plant yield responses, especially under traditional planting-density systems. Hence, this study aimed to identify the effect of high planting density on high tunnel tomatoes and their nutrient status on the Eastern Shore of Virginia. The experiment was established on a completely randomized block design with four replications, with 20 ft (6.09 m) experimental plots. We evaluated the combination of two in-row distances and single and double planting rows, with treatments consisting of 2 ft of in-row distance in a single row (4356 plants/acre—current open-field recommendation), 1.5 ft (0.45 m) of in-row distance in a single row (5808 plants/acre [14,520 plants/ha]), 2 ft of in-row distance in a double row (8712 plants/acre [21,780 plants/ha]), and 1.5 ft of in-row distance in a double row (11,616 plants/acre [29,040 plants/ha]). Summer-grown tomatoes produced on the Eastern Shore of Virginia under high tunnel conditions should be planted with 2 ft of in-row spacing and with a single row of plants per planting bed. Increasing the plant density or modifying the current recommended plant distribution could result in yield losses per plant between 32% and 46% and substantial increases in production costs compared with the traditional planting density. Throughout all treatments, tomato plants did not show deficient nutrient status. We hypothesized that irrigation water and pollination were the limiting factors that promoted a decrease in yield per plant for the high-density treatments.

Hydrodynamics and Sediment-Transport Pathways along a Mixed-Energy Spit-Inlet System: A Modeling Study at Chincoteague Inlet (Virginia, USA)

Tidal-inlet systems are dynamic features that respond to short-term (e.g., storms) and longer-term processes (e.g., sea-level rise, changes in tidal prism). The Chincoteague Inlet system, located along the northern Eastern Shore of Virginia (USA), is a dynamic coastal complex that experiences rapid change associated with sediment redistribution and a shifting inlet throat due to the southern elongation of adjacent Assateague Island. In this study, a numerical model based on Delft3D with coupled flow–waves, multiclass sediment transport, and morphologic feedback was developed to quantify the hydrodynamic and geomorphic controls within this rapidly evolving inlet–spit system and to develop a more comprehensive understanding of regional to local controls on sediment-transport pathways. Model results show that most of the sand transport along southern Assateague Island is sequestered nearshore and proximally in deeper sinks within Fishing Point, and, of that, only finer sand sizes are transported around the spit, confirming previous analysis and hypothesis. The model also showed that sand transport toward the south increases along Wallops Island and quantified spatially explicit transport trends for selected sediment classes, revealing that coarser sediment bypassing is a punctuated process that is proportional to storms.

Salmonella Prevalence Is Strongly Associated with Spatial Factors while Listeria monocytogenes Prevalence Is Strongly Associated with Temporal Factors on Virginia Produce Farms.

The heterogeneity of produce production environments complicates the development of universal strategies for managing preharvest produce safety risks. Understanding pathogen ecology in different produce-growing regions is important for developing targeted mitigation strategies. This study aimed to identify environmental and spatiotemporal factors associated with isolating Salmonella and Listeria from environmental samples collected from 10 Virginia produce farms. Soil (n = 400), drag swab (n = 400), and irrigation water (n = 120) samples were tested for Salmonella and Listeria, and results were confirmed by PCR. Salmonella serovar and Listeria species were identified by the Kauffmann-White-Le Minor scheme and partial sigB sequencing, respectively. Conditional forest analysis and Bayesian mixed models were used to characterize associations between environmental factors and the likelihood of isolating Salmonella, Listeria monocytogenes (LM), and other targets (e.g., Listeria spp. and Salmonella enterica serovar Newport). Surrogate trees were used to visualize hierarchical associations identified by the forest analyses. Salmonella and LM prevalence was 5.3% (49/920) and 2.3% (21/920), respectively. The likelihood of isolating Salmonella was highest in water samples collected from the Eastern Shore of Virginia with a dew point of >9.4°C. The likelihood of isolating LM was highest in water samples collected in winter from sites where <36% of the land use within 122 m was forest wetland cover. Conditional forest results were consistent with the mixed models, which also found that the likelihood of detecting Salmonella and LM differed between sample type, region, and season. These findings identified factors that increased the likelihood of isolating Salmonella- and LM-positive samples in produce production environments and support preharvest mitigation strategies on a regional scale. IMPORTANCE This study sought to examine different growing regions across the state of Virginia and to determine how factors associated with pathogen prevalence may differ between regions. Spatial and temporal data were modeled to identify factors associated with an increased pathogen likelihood in various on-farm sources. The findings of the study show that prevalence of Salmonella and L. monocytogenes is low overall in the produce preharvest environment but does vary by space (e.g., region in Virginia) and time (e.g., season), and the likelihood of pathogen-positive samples is influenced by different spatial and temporal factors. Therefore, the results support regional or scale-dependent food safety standards and guidance documents for controlling hazards to minimize risk. This study also suggests that water source assessments are important tools for developing monitoring programs and mitigation measures, as spatiotemporal factors differ on a regional scale.

Use of mammalian museum specimens to test hypotheses about the geographic expansion of Lyme disease in the southeastern United States

Lyme disease, caused primarily in North America by the bacterium Borrelia burgdorferi sensu stricto, is the most frequently reported vector-borne disease in North America and its geographic extent is increasing in all directions from foci in the northeastern and north central United States. Several southeastern states, including Virginia and North Carolina, have experienced large increases in Lyme disease incidence in the past two decades, with the biggest changes in incidence occurring in the western portion of each state. We tested the hypothesis that B. burgdorferi s.s. was present in western Virginia and North Carolina Peromyscus leucopus populations prior to the recent emergence of Lyme disease. Specifically, we examined archived P. leucopus museum specimens, sampled between 1900 and 2000, for B. burgdorferi s.s. DNA. After confirming viability of DNA extracted from ear punch biopsies from P. leucopus study skins collected between 1945 and 2000 in 19 Virginia counties and 17 North Carolina counties, we used qPCR of two species-specific loci to test for the presence of B. burgdorferi s.s. DNA. Ten mice, all collected from the Eastern Shore of Virginia in 1989, tested positive for presence of B. burgdorferi; all of the remaining 344 specimens were B. burgdorferi-negative. Our results suggest that B. burgdorferi s.s was not common in western Virginia or North Carolina prior to the emergence of Lyme disease cases in the past two decades. Rather, the emergence of Lyme disease in this region has likely been driven by the relatively recent expansion of B. burgdorferi s.s. in southward-moving ticks and reservoir hosts in the mountainous counties of these two states.

The Effect of Salt Marsh on Residential Property Values

Salt marshes provide a myriad of critical ecosystem services yet have been threatened by urban expansion, sea level rise, and the armoring of coastal property. This study uses a hedonic property price method to evaluate the effects of salt marshes on residential property values in the Eastern Shore of Virginia. Contrary to findings from the wetland literature, results show an insignificant relationship between proximity to salt marsh and residential property values. In contrast, results show a statistically significant increase in property values with increasing proportions of salt marsh within 250 to 500 meters of the parcel. Furthermore, the increase in value is found to be larger for proportions of preserved relative to non-preserved salt marsh in this proximity of the home. The findings of this study can contribute to understanding the spatial patterns for housing premiums stemming from salt marshes. The information can be used to guide coastal management agencies on how to conserve salt marshes in a way that promotes residential property values.

Oil Spill Preparedness and Response: Building the Capacity to Protect Public Welfare and Support Community Resilience

Abstract Some oil spills become disastrous for communities who live and work in proximity of the spill, even when a disaster is not formally declared. For decades, social science researchers have reported the negative impacts of such oil spills on communities, but their findings remain in the literature and have not resulted in improvements to oil spill preparedness and response practice. Effective response to an oil spill which has the potential to become a social disaster requires leaders in emergency management to proactively address spill threats to public welfare in addition to stopping the release of oil and cleaning up the spill. To accomplish this, the oil spill community could proactively engage stakeholders at the grass-roots level to share information, address questions and concerns through risk communication, and include inputs for pre-spill planning. The capacity to engage with vulnerable communities and stakeholders before, during, and after an oil spill is one measure of a successful response. This paper is a collaborative effort among oil spill specialists, social science researchers, and community members on the Eastern Shore of Virginia to prepare for a serious oil spill and mitigate its potential threats. This remote area of global ecological significance is highly vulnerable to an offshore persistent oil spill that could negatively impact the way of life of many community members who depend upon the environment. Prior to this effort, community members were not engaged in oil spill preparedness. A subcommittee of the Virginia Area Committee sought community input in developing a new annex of the Area Contingency Plan. This effort engaged non-governmental organizations (NGOs), academia, watermen, local governmental agencies, and others on the Eastern Shore, recognizing the importance of two-way communications with stakeholders, rather than one-way outreach. In addition, social scientists who have studied major spills identify opportunities to adapt oil spill practices and help communities recover from potential psychosocial and incident-specific impacts. The community aspects of the new annex were exercised during a 4-day, full-scale Area Exercise under Preparedness for Response Exercise Program (PREP), along with other pre-exercise activities, to support public welfare and community resiliency. Through this work, the authors demonstrate adaptations to strengthen incident management by leveraging networks of trusted relationships developed during planning with local government, elected officials, and communities.

Review: The Great Migration and the Democratic Party: Black Voters and the Realignment of American Politics in the 20th Century, by Keneshia N. Grant

Review: <i>The Great Migration and the Democratic Party: Black Voters and the Realignment of American Politics in the 20th Century</i>, by Keneshia N. Grant

Implications of Sea Level Rise for Bee Communities in Rural Eastern Virginia Coastal Habitats

In the coastal mid-Atlantic region of the USA, landscapes are a mosaic of upland habitats (woodland, grassland, old fields and farmland) and low-lying coastal salt marsh. Flooding and salinization of coastal areas due to sea-level rise result in the conversion of upland habitats to salt marsh, and change the relative proportion of habitat types surrounding coastal farmland. This has the potential to influence population sizes of organisms living in this area and could alter the ecosystem services, such as pollination, that these habitats provide. To examine the potential outcome of these habitat conversions, we used blue vane traps at 14 sites along the Eastern Shore of Virginia (USA) to compare the bee communities of salt marsh, old fields and agricultural fields. Although there was no difference among habitat types for total bee abundance per site, we found that the coastal marsh is depauperate in bee species relative to old fields and agricultural fields, and that the bee species using the marsh habitat tend to be specialists of plant families that are common in the marsh (Asteraceae and Malvaceae) but are relatively uncommon in local agriculture. Thus, the transition of upland areas to marsh not only has the potential to impact agricultural productivity directly through salt water intrusion, ultimately it may also reduce the species richness of native bees available to provide pollination services to coastal agriculture.

What does it cost to ensure salt marsh migration? Using hedonic modeling to inform cost-effective conservation

The preservation of salt marshes under rapid sea-level rise (SLR) typically requires the conservation of marsh transgression zones—undeveloped uplands onto which marshes can migrate. Optimal planning for conservation of this type requires information on the expected benefit of marsh conservation and the cost of land suitable for marsh migration in particular areas. While information is available on marsh benefits within the literature, prior research provides little insight on associated land conservation costs. The coastal hedonic pricing literature focuses primarily on developed land, and there are no models designed to predict the cost of conserving land suitable for marsh migration. This paper develops a hedonic property value model to predict cost and explore price patterns associated with purchases of undeveloped land suitable for salt marsh migration under SLR. The model is illustrated using a case study from the Eastern Shore of Virginia, with a dataset consisting of open-market sales of undeveloped land from 2014 to 2017. Particular attention is paid to characteristics that determine marsh migration potential such as coastal distance, elevation and connectivity. Results demonstrate the insight for conservation planning that can be provided by models of this type and the errors associated with the use of simplified proxies to predict conservation costs of land suitable for marsh migration.

Diversity and Dynamics of Salmonella enterica in Water Sources, Poultry Litters, and Field Soils Amended With Poultry Litter in a Major Agricultural Area of Virginia

The Eastern Shore of Virginia (ESV) is a major agricultural region in Virginia and in the past has been linked to some tomato-associated outbreaks of salmonellosis. In this study, water samples were collected weekly from irrigation ponds and wells in four representative vegetable farms (Farms A–D, each farm paired with one pond and one well) and a creek as well. In addition, water samples from two sites in the Chesapeake Bay on the ESV were collected monthly. Poultry litter was sampled monthly from three commercial broiler farms. Soil samples were collected monthly after fertilization with poultry litter from 10 farms in 2014 and another 14 farms in 2015. A most probable number method was used to detect Salmonella enterica presence and concentration in collected samples. Presumptive Salmonella colonies were confirmed by the cross-streaking method. Molecular serotyping was carried out to determine the Salmonella serovars. The average prevalence of Salmonella in pond, well, creek, and bay water samples was 19.3, 3.3, 24.2, and 29.2%, respectively. There were significant spatial and temporal differences for Salmonella incidence in various water sources. The prevalence of S. enterica in four tested ponds from farms A, B, C, and D were 16, 12, 22, and 27%, respectively. While the prevalence of S. enterica in irrigation wells was significantly lower, some well water samples tested positive during the study. Salmonella Newport was found to be the predominant serovar isolated from water samples. All poultry houses of the three tested broiler farms were Salmonella-positive at certain sampling points during the study with prevalence ranging from 14.3 to 35.4%. Salmonella was found to be able to survive up to 4 months in poultry litter amended soils from the tested farms in 2014, and up to 6 months in 2015. This research examined the dynamics of S. enterica in relationship to water source, poultry litter, and amended soil in a major agricultural area, and provides useful information for food safety risk assessments.

Food Resources for Wintering and Spring Staging American Black Ducks

Abstract Habitat restoration and enhancement objectives for wintering waterfowl are typically derived by a bioenergetics modeling approach. This approach has been developed as a planning tool to identify the amount of foraging habitat required to meet North American Waterfowl Management Plan population objectives. Our objective was to provide the energetic supply component of the bioenergetics model at an important wintering area for American black ducks Anas rubripes in the Atlantic Flyway, the Eastern Shore of Virginia. We estimated food availability among four main wetland cover types used by overwintering American black ducks: brackish water, freshwater, mudflat, and salt marsh. Mudflat (221 ± 50 kg/ha) and salt marsh (728 ± 175 kg/ha) had the highest amounts of available invertebrate food density, and freshwater (42 ± 9 kg/ha) had the highest amounts of available seed biomass. Our results suggest that seed density found in freshwater wetlands on the Eastern Shore of Virginia is considerably lower than densities found in inland freshwater cover types used by dabbling ducks. We also found that levels of invertebrate density found in Virginia mudflat and salt marsh are considerably lower than levels on Long Island, New York, and in southern New Jersey. Lower levels of food density compared with both more inland and northern wintering areas suggest that American black ducks wintering in Virginia are more likely to be limited by forage availability than American black ducks and other dabbling ducks wintering both inland and in the northern portion of the wintering range.

The impacts of warming and hypoxia on the performance of an obligate ram ventilator.

Climate change is causing the warming and deoxygenation of coastal habitats like Chesapeake Bay that serve as important nursery habitats for many marine fish species. As conditions continue to change, it is important to understand how these changes impact individual species’ behavioral and metabolic performance. The sandbar shark (Carcharhinus plumbeus) is an obligate ram-ventilating apex predator whose juveniles use Chesapeake Bay as a nursery ground up to 10 years of age. The objective of this study was to measure juvenile sandbar shark metabolic and behavioral performance as a proxy for overall performance (i.e. fitness or success) when exposed to warm and hypoxic water. Juvenile sandbar sharks (79.5–113.5 cm total length) were collected from an estuary along the eastern shore of Virginia and returned to lab where they were fitted with an accelerometer, placed in a respirometer and exposed to varying temperatures and oxygen levels. Juvenile sandbar shark overall performance declined substantially at 32°C or when dissolved oxygen concentration was reduced below 3.5 mg l−1 (51% oxygen saturation between 24–32°C). As the extent of warm hypoxic water increases in Chesapeake Bay, we expect that the available sandbar shark nursery habitat will be reduced, which may negatively impact the population of sandbar sharks in the western Atlantic as well as the overall health of the ecosystem within Chesapeake Bay.

Controls on Sediment Suspension, Flux, and Marsh Deposition near a Bay-Marsh Boundary

The sustainability of marshes adjacent to coastal bays is driven by the exchange of sediment across the marsh-bay boundary, where edge erosion commonly leads to lateral marsh loss and enhanced vertical accretion. The timing and patterns of sediment deposition on salt marshes adjacent to larger bodies of water such as coastal bays, however, differ from those on better-studied tidal creek marshes primarily owing to the importance of wind-waves. We combined field measurements and modeling to examine controls on suspended sediment concentrations and fluxes on a tidal flat (tidal range of 1.2 m) and rates of sediment deposition on the adjacent marsh at a site on the Eastern Shore of Virginia. Suspended sediment concentrations over tidal flats were strongly controlled by waves. Yet, storm winds sufficient to drive large resuspension events often coincided with peak tidal elevations that were too low to flood the marsh, which was oriented away from the wind directions most favorable for storm surge, thereby restricting storm-driven, episodic sediment delivery to the marsh. Winds also drove wide variability in the direction of surface currents near the marsh edge when water depths were high enough to flood the marsh. Nevertheless, our results show that sediment in the upper water column over the tidal flat was effectively transported across the marsh edge during flooding tides. A sediment deposition model developed to investigate the combined effects of vegetation and wave action on depositional patterns predicted that waves displace maximum deposition inland from the marsh edge, consistent with measured deposition at the study site. Marsh deposition was sensitive to inundation frequency as well as the concentration of sediment in water flooding the marsh, underscoring the importance of nontidal controls on water surface elevation, such as meteorological effects (e.g., storm surge) and sea level rise. Whereas short-term increases in marsh inundation enhance deposition, sea level rise that results in deeper average water depths over the tidal flats decreases deposition if marsh elevation is rising in step with sea level.

Agricultural Practices Influence Salmonella Contamination and Survival in Pre-harvest Tomato Production.

Between 2000 and 2010 the Eastern Shore of Virginia was implicated in four Salmonella outbreaks associated with tomato. Therefore, a multi-year study (2012–2015) was performed to investigate presumptive factors associated with the contamination of Salmonella within tomato fields at Virginia Tech’s Eastern Shore Agricultural Research and Extension Center. Factors including irrigation water sources (pond and well), type of soil amendment: fresh poultry litter (PL), PL ash, and a conventional fertilizer (triple superphosphate – TSP), and production practices: staked with plastic mulch (SP), staked without plastic mulch (SW), and non-staked without plastic mulch (NW), were evaluated by split-plot or complete-block design. All field experiments relied on naturally occurring Salmonella contamination, except one follow up experiment (worst-case scenario) which examined the potential for contamination in tomato fruits when Salmonella was applied through drip irrigation. Samples were collected from pond and well water; PL, PL ash, and TSP; and the rhizosphere, leaves, and fruits of tomato plants. Salmonella was quantified using a most probable number method and contamination ratios were calculated for each treatment. Salmonella serovar was determined by molecular serotyping. Salmonella populations varied significantly by year; however, similar trends were evident each year. Findings showed use of untreated pond water and raw PL amendment increased the likelihood of Salmonella detection in tomato plots. Salmonella Newport and Typhimurium were the most frequently detected serovars in pond water and PL amendment samples, respectively. Interestingly, while these factors increased the likelihood of Salmonella detection in tomato plots (rhizosphere and leaves), all tomato fruits sampled (n = 4800) from these plots were Salmonella negative. Contamination of tomato fruits was extremely low (< 1%) even when tomato plots were artificially inoculated with an attenuated Salmonella Newport strain (104 CFU/mL). Furthermore, Salmonella was not detected in tomato plots irrigated using well water and amended with PL ash or TSP. Production practices also influenced the likelihood of Salmonella detection in tomato plots. Salmonella detection was higher in tomato leaf samples for NW plots, compared to SP and SW plots. This study provides evidence that attention to agricultural inputs and production practices may help reduce the likelihood of Salmonella contamination in tomato fields.

Microbial Quality of Agricultural Water Used in Produce Preharvest Production on the Eastern Shore of Virginia

Several produce-borne outbreaks have been associated with the use of contaminated water during preharvest applications. Salmonella has been implicated in a number of these outbreaks. The purpose of this study was to evaluate the microbial quality of agricultural surface water used in preharvest production on the Eastern Shore of Virginia in accordance with the Food Safety Modernization Act's Produce Safety Rule water standards. The study also examined the prevalence, concentration, and diversity of Salmonella in those water sources. Water samples (1 L) from 20 agricultural ponds were collected during the 2015 and 2016 growing seasons ( n = 400). Total aerobic bacteria, total coliforms, and Escherichia coli were enumerated for each sample. Population levels of each microorganism were calculated per 100-mL sample and log transformed, when necessary. Samples (250 mL) were also enriched for Salmonella. Presumptive Salmonella isolates were confirmed by PCR ( invA gene) and were serotyped. In 2016, the concentration of Salmonella in each sample was also estimated by most probable number (MPN). Indicator bacteria and environmental and meteorological factors were analyzed for their association with the detection of a Salmonella-positive water sample by using logistic regression analysis. Seventeen of the 20 ponds met the Food Safety Modernization Act's Produce Safety Rule standards for production agricultural water. Three ponds did not meet the standards because the statistical threshold value exceeded the limit. Salmonella was detected in 19% of water samples in each year (38 of 200 in 2015 and 38 of 200 in 2016). Of the 118 Salmonella isolates serotyped, 14 serotypes were identified with the most prevalent being Salmonella Newport. E. coli concentration, farm, and total aerobic bacteria concentration were significantly associated with the likelihood of detecting a Salmonella-positive sample The average concentration of Salmonella in all samples was 4.44 MPN/100 mL, with the limit of detection being 3.00 MPN/100 mL. The highest concentration of Salmonella was 93.0 MPN/100 mL. These data will assist in a better understanding of the risks that production water poses to produce contamination events.

Do Macroalgal Mats Impact Microphytobenthos on Mudflats? Evidence from a Meta-Analysis, Comparative Survey, and Large-Scale Manipulation

Eutrophication and species introductions have resulted in increased macroalgal biomass in coastal ecosystems around the globe. Macroalgal mats may compete with microphytobenthos (MPB) for light and nutrients and, due to their position in the canopy, have a negative impact on MPB biomass. We tested this effect by conducting a meta-analysis of prior experiments, as well as a comparative survey, and a macroalgal-removal manipulation in the coastal lagoons of the Virginia Coastal Reserve (VCR) on the eastern shore of Virginia (USA). In all cases, MPB biomass was estimated using benthic chlorophyll as a proxy. While prior individual studies documented impacts of macroalgae, when effect sizes were averaged across studies, there was no consistent effect of macroalgal biomass on MPB biomass. In the VCR, a non-native red macroalga, Gracilaria vermiculophylla, dominates intertidal mats and attains high biomasses at some sites. Nevertheless, MPB biomass was unrelated to macroalgal mass based on a survey of mudflats. Further, when macroalgae were experimentally manipulated on a mudflat using a before and after impact design, there was no change in MPB. Based on the meta-analysis, survey, and manipulation we conducted, macroalgal mats do not have a generalizable effect on MPB, interactions seem context-dependent, and in the VCR, the effects on MPB appear neutral. This finding is important given the significance of MPB in supporting food webs and other estuarine ecosystem functions, as well as the increasing frequency and intensity of macroalgal blooms.

Draft Genome Sequences of Two Salmonella Strains Isolated from Wild Animals on the Eastern Shore of Virginia.

ABSTRACTAntimicrobial-resistant (AMR) Salmonella infections pose a significant public health threat. Here, we announce two draft genomes of Salmonella strains isolated from wildlife harboring an alarming array of antibiotic resistance genes. Continued investigations of these genomes will provide insight into the possible attribution of AMR Salmonella infection of wild animals.