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Recent Submissions
Stabilized vs. Unstabilized Barrier Islands: How Shoreline Engineering Shapes the Habitat, Prey, and Distribution of Red Knots, Black‑bellied Plovers, and Piping Plovers after Five Years
Alvino, Camille Rose (Virginia Tech, 2026-10-23)
Climate change-driven storms and sea-level rise are altering Mid-Atlantic coastlines at accelerating rates, particularly in barrier-island landscapes. Migrating shorelines threaten coastal infrastructure and create pressure on imperiled shorebirds that depend on high-quality foraging grounds year-round. Shoreline-stabilizing techniques, including beach nourishment, breakwaters, and revetments, are used to mitigate coastal erosion and protect local infrastructure, but their direct and indirect impacts on shorebird populations and their prey are poorly understood. The Virginia barrier island system, recognized for its ecological importance to shorebirds, is currently undeveloped except for one island, Wallops Island, which has undergone various stabilization measures to protect critical infrastructure. This system provides a unique opportunity to expand existing knowledge of how ecological and geomorphic factors influence shorebird foraging habitat use in the context of anthropogenically altered shorelines. The goals of my thesis were to quantify the ecological and geomorphological drivers of the federally threatened piping plover (Charadrius melodus), the federally threatened rufa red knot (Calidris canutus rufa) and the black-bellied plover (Pluvialis squatarola) and their prey in the context of stabilized and unstabilized shorelines in coastal Virginia. We evaluated 4 important foraging habitats (sandy ocean beach, peat banks, bay shoreline, and interior pools) on the 5 northernmost barrier islands in Virginia: partially stabilized Wallops Island and unstabilized Assawoman, Metompkin, Assateague Islands, and Gargatha Beach. In 2024 and 2025, we conducted monthly point count surveys from May 1st to August 31st for breeding season adult piping plovers and from April 15th to June 30th and August 1st to October 15th for migratory red knots, black-bellied plovers, and co-occurring shorebirds, and collected core samples to evaluate benthic prey availability. We also sampled terrestrial insects monthly from May to August due to their importance to piping plover foraging ecology during the breeding season. We implemented Bayesian mixed-effects modeling on a series of a priori candidate models to estimate the effect of distance to the nearest and each individual type of stabilization, along with important environmental and geomorphological covariates, on the presence of all three focal species and their benthic and terrestrial prey densities. We also compared our terrestrial prey densities and habitat distributions with historical data in Virginia and with 2 recent studies in New York and North Carolina to examine geographic or longitudinal differences in terrestrial prey availability for piping plovers in our study. We found that piping plovers were more likely to be present, and total benthic, worm and crustacean prey abundances were higher at greater distances from the stabilization actions during the piping plover breeding season at 4-5 years since the most recent activities. However, other factors such as habitat type and beach width were stronger predictors of piping plovers and their prey than distance to the nearest stabilization, with foraging piping plovers most likely to be present on peat bank habitats and on wider beaches. We found the opposite relationship with benthic insect larvae and terrestrial prey, which were more abundant closer to the stabilization actions during the piping plover breeding season; likely driven by their high abundances in the human-created borrow pool adjacent to the stabilization footprint. We found that red knot presence was more likely farther from the nearest stabilization features in all habitat types, but that stabilization was a weaker predictor of red knot presence than other ecological and geomorphic factors. Black-bellied plovers were strongly influenced by distance to stabilization, with contrasting relationships with stabilization depending on habitat type. Black-bellied plovers were more likely to be present farther from stabilized features when using peat, bay and pool habitats, all of which occurred outside of the footprint of stabilization. However, black-bellied plovers were more likely to be present closer to stabilization when foraging in sandy ocean intertidal habitat. Both red knots and black-bellied plovers were more likely to be present with higher abundances of other shorebirds and increased prey species richness, and black-bellied plovers were more present in areas where the shoreline change rate was negative (e.g., eroding or retreating). Our results showed that 4-5 years after shoreline stabilization actions on Wallops Island, benthic invertebrates in the sandy ocean intertidal zone had recovered to similar densities as the surrounding islands, but the highest densities occurred on peat banks outside stabilized areas. We suggest that future stabilization efforts both create high-quality foraging habitats, such as the borrow pool, within or adjacent to the stabilization footprint and conserve the potential for adjacent areas to respond to natural coastal processes that create bayside, pool, and peat habitats for foraging shorebirds. Future studies should deploy a before-after-control-impact design for at least 4 years pre- and post-action to better understand recovery times of avian and prey metrics, and to better tease out the impacts of individual stabilization actions.
Protecting Apple Blossoms from Spring Frost: The Potential and Limitations of Cryoprotectants
Jahed, Khalil R.; Sherif, Sherif M. (Virginia Cooperative Extension, 2026-10-21)
Spring frost presents a major abiotic constraint on apple production, with shifting climates increasing the risk of early bloom exposure to sub-zero temperatures. To evaluate alternative mitigation strategies, we tested the efficacy of four commercial foliar cryoprotectants (KDL, ThermoMax, Glacier, and diKap) on 'Pink Lady' apple blossoms across three growing seasons. Biochemical analyses revealed that these applications enhance frost resilience by triggering the accumulation of protective metabolites, specifically proline and non-structural carbohydrates, which minimize cellular dehydration and membrane rupture. Field evaluations demonstrated that cumulative sub-zero exposure time is the primary driver of floral mortality, with a critical lethal threshold of approximately 30 minutes. Although freezes exceeding two hours overwhelmed all treatments, specific applications such as ThermoMax and diKap successfully preserved 5?6% of king flowers under severe stress, a margin physiologically sufficient to maintain a commercial crop load. Furthermore, these pre-bloom treatments proved safe for commercial implementation, presenting no negative effects on fruit quality and occasionally improving harvest size, sweetness, and firmness.
Protecting Peaches from Spring Frost: Delaying Bloom with JA Inhibition
Jahed, Khalil R.; Sherif, Sherif M. (Virginia Cooperative Extension, 2026-08-26)
Spring frost threatens temperate fruit production by damaging early-blooming floral tissues. Modulating bloom phenology offers a viable mitigation strategy. Because jasmonic acid (JA) promotes budbreak, we hypothesized that JA inhibitors could delay peach flowering. Over three seasons (2023-2025), two JA inhibitors, propyl gallate and antipyrine, were applied as foliar sprays to "Redhaven" and "Sunhigh" peach cultivars. Antipyrine consistently delayed full bloom by 2 to 5 days across years and cultivars. Propyl gallate induced delays of 1 to 3 days, exhibiting higher inter-annual variability dependent on early spring temperatures. Crucially, neither compound negatively impacted final fruit set at harvest. Furthermore, treatments maintained essential fruit quality attributes, including firmness and total soluble solids, while, in some cases, enhancing fruit size. These findings demonstrate that bloom delay offers a novel, resource-efficient strategy to protect deciduous orchards from late spring frost damage without compromising yield or quality.
Naphthaleneacetic Acid: A Key Tool for Reducing Preharvest Fruit Drop and Sustaining Apple Red Coloration
Tipu, Mohammad; Jahed, Khalil R.; Sherif, Sherif M. (Virginia Cooperative Extension, 2025-09-17)
Preharvest fruit drop (PFD) causes significant yield losses in ‘Honeycrisp’ apples. This study evaluated naphthaleneacetic acid (NAA), aminoethoxyvinylglycine (AVG), and their combined application for PFD management, assessing fruit retention and quality for two growing seasons. All treatments generally reduced PFD compared to controls, with AVG, commercially known as “ReTain” (Valent BioSciences LLC), often showing the greatest reduction. However, ReTain consistently impaired red fruit color development. In contrast, NAA, commercially available as “Refine” (Fine Americas, Inc.), effectively controlled PFD without negatively impacting color or firmness, and it improved fruit sweetness. These findings highlight that while both can reduce drop, Refine provides a better balance for ‘Honeycrisp’ growers by mitigating PFD while preserving or enhancing key quality attributes like color and sweetness compared to ReTain.
Multi-Scale Characterization of Mining-Induced Deformation Using Radar
Tascione, Matthew Alex (Virginia Tech, 2026-10-22)
The theme of this dissertation is the quantitative characterization of mining-induced deformation using radar methods. Underground excavation can produce fractures that reduce roof stability and surface deformation that may affect mine-related or public infrastructure. However, these responses are difficult to characterize because fractures are concealed within the rock mass and surface deformation may extend across large areas. The principal contribution of this dissertation is the development of quantitative radar-based approaches that extend beyond detecting deformation to measuring its geometry, magnitude, spatial distribution, and evolution across multiple scales.
Ground-penetrating radar (GPR) data were acquired on the roof of an underground salt mine to detect fractures concealed within the rock mass. Radar observations were calibrated and validated using fractures logged in drillholes, enabling quantitative estimates of fracture location and aperture. GPR detected fractures with apertures as small as approximately 1 mm and mapped substantial variations in aperture along individual fractures. The results demonstrate that GPR can noninvasively quantify mining-induced fractures beyond the discrete locations sampled by drilling.
A dense grid of GPR profiles was subsequently used to reconstruct 15 laterally continuous fractures as three-dimensional surfaces with measured aperture. The fractures are shallowly dipping, approximately planar extensional features, with fracture intensity greatest near the mine roof and decreasing upward into the rock mass. Fracture size and aperture exhibit substantial variability and do not scale according to a simple linear elastic fracture mechanics model. Although the number of fractures limits population-scale statistical inference, the measurements provide rare field-based three-dimensional constraints on fracture geometries and network statistics commonly inferred from lower-dimensional observations or numerical models.
Interferometric synthetic aperture radar (InSAR) was used to characterize surface deformation across the southwest Wyoming trona mining district. Ascending and descending Sentinel-1 observations spanning approximately 19 months were combined to estimate vertical displacement. Six subsidence features and one apparent-uplift feature were identified, with peak cumulative subsidence ranging from 62 to 198 mm. The features differed substantially in spatial extent, geometry, cumulative displacement volume, temporal evolution, tilt, and curvature. Longwall-associated features were generally compact, whereas room-and-pillar-associated features were more elongated. However, variability among features associated with the same mining method shows that mining method alone did not determine the surface response. These results show that displacement magnitude alone does not adequately characterize mining-related surface deformation.
Together, these studies demonstrate the ability of radar methods to quantitatively characterize mining-induced deformation from millimeter-scale fracture opening to kilometer-scale surface displacement. These complementary approaches provide field-based constraints on the geomechanical response to underground excavation and measurements relevant to mine safety and surface infrastructure.