The Dark Side of Empowering Leadership: A Multilevel Study of Differentiated Leadership on Team and Individual Dynamic Performance

In this study I integrate self-determination theory and social comparison theory to create a new theoretical lens that highlights the multilevel dark side of empowering leadership. Examining how team leaders differentially empower team members stands in contrast to prior research, which has limited its analyses to the effects of individual-focused or team-focused empowering leadership. I examine the social underpinnings of empowering leadership by analyzing differentiated empowering leadership (DEL) within teams and its effects on team dynamics. In so doing, I propose that DEL triggers team members to engage in social comparisons among one another regarding the empowering leadership they receive. These social comparisons generate negative relationships among team members, restricting the team’s collective ability to initiate and adapt to change, particularly among teams with higher levels of task interdependence. I also theoretically argue the existence of two unique cross-level processes through which DEL impacts team member psychological empowerment, and in turn individual proactive and adaptive performance. First, I theorize that DEL stimulates team member psychological empowerment through empowering leadership-social comparisons (ELSC). Second, I propose that DEL undermines team member psychological empowerment by producing relationship conflicts among team members. In summary, I highlight the multi-level processes and boundary condition through which DEL negatively impact team dynamic performance and individual team member motivation and subsequent dynamic performance. To test the proposed relationships I gathered data from 72 teams across four industries. Although the data revealed that ELSC is positively linked to psychological empowerment, revealing the impact of ELSC above and beyond the direct effects of individual empowering leadership and leader-member exchange (LMX), the data did not fully support any of the other hypotheses. Nonetheless, the data reveal that DEL does impact team learning and individual adaptability through team and individual engagement. Thus, team leaders should consider how they go about empowering their team members, because the more differentially they empower them, the less engaged they will be in their collective and individual work. These subsequent findings also display that DEL is unique from LMX differentiation and that future research should explore other effects DEL has on team and individual outcomes

The Dark Side of Empowering Leadership: A Multilevel Study of Differentiated Leadership on Team and Individual Dynamic Performance

In this study I integrate self-determination theory and social comparison theory to create a new theoretical lens that highlights the multilevel dark side of empowering leadership. Examining how team leaders differentially empower team members stands in contrast to prior research, which has limited its analyses to the effects of individual-focused or team-focused empowering leadership. I examine the social underpinnings of empowering leadership by analyzing differentiated empowering leadership (DEL) within teams and its effects on team dynamics. In so doing, I propose that DEL triggers team members to engage in social comparisons among one another regarding the empowering leadership they receive. These social comparisons generate negative relationships among team members, restricting the team’s collective ability to initiate and adapt to change, particularly among teams with higher levels of task interdependence. I also theoretically argue the existence of two unique cross-level processes through which DEL impacts team member psychological empowerment, and in turn individual proactive and adaptive performance. First, I theorize that DEL stimulates team member psychological empowerment through empowering leadership-social comparisons (ELSC). Second, I propose that DEL undermines team member psychological empowerment by producing relationship conflicts among team members. In summary, I highlight the multi-level processes and boundary condition through which DEL negatively impact team dynamic performance and individual team member motivation and subsequent dynamic performance. To test the proposed relationships I gathered data from 72 teams across four industries. Although the data revealed that ELSC is positively linked to psychological empowerment, revealing the impact of ELSC above and beyond the direct effects of individual empowering leadership and leader-member exchange (LMX), the data did not fully support any of the other hypotheses. Nonetheless, the data reveal that DEL does impact team learning and individual adaptability through team and individual engagement. Thus, team leaders should consider how they go about empowering their team members, because the more differentially they empower them, the less engaged they will be in their collective and individual work. These subsequent findings also display that DEL is unique from LMX differentiation and that future research should explore other effects DEL has on team and individual outcomes

Geostatistical features of streambed vertical hydraulic conductivities in Frenchman Creek Watershed in Western Nebraska

This study evaluated the spatial variability of streambed vertical hydraulic conductivity (Kv) in different stream morphologies in the Frenchman Creek Watershed, Western Nebraska, using different variogram models. Streambed Kv values were determined in situ using permeameter tests at 10 sites in Frenchman, Stinking Water and Spring Creeks during the dry season at baseflow conditions. Measurements were taken both in straight and meandering stream channels during a 5 day period at similar flow conditions. Each test site comprised of at least three transects and each transect comprised of at least three Kv measurements. Linear, Gaussian, exponential and spherical variogram models were used with Kriging gridding method for the 10 sites. As a goodness-of-fit statistic for the variogram models, cross-validation results showed differences in the median absolute deviation and the standard deviation of the cross-validation residuals. Results show that using the geometric means of the 10 sites for gridding performs better than using either all the Kv values from the 93 permeameter tests or 10 Kv values from the middle transects and centre permeameters. Incorporating both the spatial variability and the uncertainty involved in the measurement at a reach segment can yield more accurate grid results that can be useful in calibrating Kv at watershed or sub-watershed scales in distributed hydrological models

The Extent of Seasonally Suitable Habitats May Limit Forage Fish Production in a Temperate Estuary

The sustained production of sufficient forage is critical to advancing ecosystem-based management, yet factors that affect local abundances and habitat conditions necessary to support aggregate forage production remain largely unexplored. We quantified suitable habitat in the Chesapeake Bay and its tidal tributaries for four key forage fishes: juvenile spotted hake Urophycis regia, juvenile spot Leiostomus xanthurus, juvenile weakfish Cynoscion regalis, and bay anchovy Anchoa mitchilli. We used information from monthly fisheries surveys from 2000 to 2016 coupled with hindcasts from a spatially interpolated model of dissolved oxygen and a 3-D hydrodynamic model of the Chesapeake Bay to identify influential covariates and construct habitat suitability models for each species. Suitable habitat conditions resulted from a complex interplay between water quality and geophysical properties of the environment and varied among species. Habitat suitability indices ranging between 0 (poor) and 1 (superior) were used to estimate seasonal and annual extents of suitable habitats. Seasonal variations in suitable habitat extents in Chesapeake Bay, which were more pronounced than annual variations during 2000–2016, reflected the phenology of estuarine use by these species. Areas near shorelines served as suitable habitats in spring for juvenile spot and in summer for juvenile weakfish, indicating the importance of these shallow areas for production. Tributaries were more suitable for bay anchovy in spring than during other seasons. The relative baywide abundances of juvenile spot and bay anchovy were significantly related to the extent of suitable habitats in summer and winter, respectively, indicating that Chesapeake Bay habitats may be limiting for these species. In contrast, the relative baywide abundances of juvenile weakfish and juvenile spotted hake varied independently of the spatial extent of suitable habitats. In an ecosystem-based approach, areas that persistently provide suitable conditions for forage species such as shoreline and tributary habitats may be targeted for protection or restoration, thereby promoting sufficient production of forage for predators. Further, quantitative habitat targets or spatial thresholds may be developed for habitat-limited species using estimates of the minimum habitat area required to produce a desired abundance or biomass; such targets or thresholds may serve as spatial reference points for management

Evaluation of selected watershed characteristics to identify best management practices to reduce Nebraskan nitrate loads from Nebraska to the Mississippi/Atchafalaya River basin

Nebraskan streams contribute excess nitrogen to the Mississippi/Atchafalaya River Basin and Gulf of Mexico, which results in major water-quality impairments. Reducing the amount of nitrogen (N) exported in these streams requires the use of best management practices (BMPs) within the landscape. However, proper BMP utilization has rarely been statistically connected to potential controls of N export within watersheds, particularly precipitation and soil characteristics. In this study, 19 watershed variables were evaluated in five categories (hydrological, physiographic, point sources, land use, and soil properties) to determine the characteristics that influenced variable nitrate nitrogen (NO3-N) concentrations in 17 Nebraska watersheds with known high NO3-N export rates. Each characteristic was derived from publicly-available datasets in an effort to develop a multiregional method. Of the 19 variables evaluated, 10 variables (developed, cropland, herbaceous, forest, excessively- drained soils, precipitation, base-flow index, slope, organic matter and point sources) were identified to statistically influence stream NO3-N concentrations. The 17 watersheds were divided into five subset groups using principal component analysis. Distributions of the 10 watershed variables were then used to determine the most applicable BMPs for NO3-N reductions for each stream subset: excessively drained with high baseflow index (Groups 1 and 2), dominantly row crop land usage with well-drained soils, higher precipitation, and an increased tendency for surface runoff concerns (Group 3), highly developed watersheds (Group 4), and single river dominated by wastewater treatment plant discharge (Group 5). Based on the most influential variables a variety of BMPs were recommended, including N fertilizer application management and accounting for N credit from mineralization and NO3-N in irrigation water (Groups 1 and 2), installation of riparian buffers and wetlands (Group 3), urban BMPs such as bioretention cells and permeable pavement (Group 4), and upgrades to the wastewater treatment plant (Group 5). This study provides an improved technique for facilitating watershed management by linking BMPs directly to the characteristics of each watershed to reduce current nitrate export

Seasonal and Annual Variation in the Extent of Suitable Habitats for Forage Fishes in Chesapeake Bay, 2000-2016

The sustained production of sufficient forage is critical to advancing ecosystem-based management in Chesapeake Bay. Yet factors that affect local abundances and habitat conditions necessary to support forage production remain largely unexplored. Here, we quantified suitable habitat in the Chesapeake Bay region for four key forage fishes: bay anchovy Anchoa mitchilli, juvenile spot Leiostomus xanthurus, juvenile weakfish Cynoscion regalis, and juvenile spotted hake Urophycis regia. We coupled information from 17 years of monthly fisheries surveys with hindcasts from a numerical model of dissolved oxygen (DO) conditions and a 3-D hydrodynamic model of the Bay that provided estimates of habitat conditions across 18 covariates of salinity, temperature, DO, depth, and current speed for the period 2000 to 2016. Sediment composition and distance to shore metrics were also considered. The hindcast covariates were subsampled at the times and locations of the fisheries surveys to provide dynamic habitat metrics that are not generally observed at the time of fish sampling (e.g., current velocity, salinity stratification). Hindcast covariates were also used to describe habitat conditions in areas of Chesapeake Bay that are not sampled routinely by fisheries-independent surveys such as the Potomac River and Mobjack Bay. Boosted regression trees were used to identify influential habitat covariates for each species, and these influential covariates were then used to construct habitat suitability models. Habitat suitability indices, which ranged between 0 (poor habitat) and 1 (superior habitat), were assigned to each location in the 3-D model grid for each season in 2000-2016. Based on the estimated habitat suitability index and using a GIS approach, we quantified suitable habitat (defined as habitats with a habitat suitability index \u3e 0.5) throughout the Chesapeake Bay and its tidal tributaries. Furthermore, we validated the modeling approach using out-of-sample observations from Mobjack Bay in 2010-2012. Suitable seasonal habitat extents for forage species exhibited strong seasonal and annual signals reflecting temporal heterogeneity in habitat conditions in Chesapeake Bay. Current speed, water depth, and either temperature or dissolved oxygen were identified as important covariates for the four forage species we examined, and distance to shore was important for three of the four species; thus, suitable habitat conditions resulted from a complex interplay between water quality and the physical properties of the habitat. In our study, two species exhibited a relationship between relative abundance and extent of suitable habitats – juvenile spot in summer and bay anchovy in winter; as such, estimates of the minimum habitat area required to produce a desired abundance (or biomass) of forage fish can be used to establish quantitative habitat targets or spatial thresholds that may serve as spatial reference points for management. In an ecosystem-based approach, important habitats may be targeted for protection (e.g., by limiting fishing activities that may incidentally capture or injure forage fishes) or restoration (e.g., by improving water quality conditions), thereby ensuring production of sufficient forage for predators. In addition, the consequences of aquatic habitat alterations, whether due to climate change or physical disturbances can be investigated using projections of environmental conditions and habitat suitability in the region, though these projections will introduce additional uncertainty

Groundwater level assessment and prediction in the Nebraska Sand Hills using LIDAR-derived lake water level

The spatial variability of groundwater levels is often inferred from sparsely located hydraulic head observations in wells. The spatial correlation structure derived from sparse observations is associated with uncertainties that spread to estimates at unsampled locations. In areas where surface water represents the nearby groundwater level, remote sensing techniques can estimate and increase the number of hydraulic head measurements. This research uses light detection and ranging (LIDAR) to estimate lake surface water level to characterize the groundwater level in the Nebraska Sand Hills (NSH), an area with few observation wells. The LIDAR derived lake groundwater level accuracy was within 40 cm mean square error (MSE) of the nearest observation wells. The lake groundwater level estimates were used to predict the groundwater level at unsampled locations using universal kriging (UK) and kriging with an external drift (KED). The results indicate unbiased estimates of groundwater level in the NSH. UK showed the influence of regional trends in groundwater level while KED revealed the local variation present in the groundwater level. A 10-fold cross-validation demonstrated KED with better mean squared error (ME) [–0.003, 0.007], root mean square error (RMSE) [2.39, 4.46], residual prediction deviation (RPD) [1.32, 0.71] and mean squared deviation ratio (MSDR) [1.01, 1.49] than UK. The research highlights that the lake groundwater level provides an accurate and cost-effective approach to measure and monitor the subtle changes in groundwater level in the NSH. This methodology can be applied to other locations where surface water bodies represent the water level of the unconfined aquifer and the results can aid in groundwater management and modeling

ISOTOPIC COMPOSITION OF GROUNDWATER AND PRECIPITATION IN NEBRASKA, USA

Groundwater is vital worldwide for water supply, agriculture and industry. Nearly 60% of all water use in Nebraska is from groundwater. Over 90% of groundwater is used for irrigation in Nebraska, which has the largest area of irrigated land in the United States. Many Nebraskans depend on groundwater for drinking water, both from private wells and municipal wells. The sustainability of groundwater resources is dependent on groundwater recharge. The recharge processes, as well as climatic patterns, influence the stable isotope signatures. Based on weekly samples collected at two monitoring stations managed by the National Atmospheric Deposition Program (NADP), Harvey (2001) and Harvey and Welker (2000) presented an overview of isotopic composition of precipitation in Nebraska. Two stations, located in Mead and North Platte (Figure 1), were monitored from 1992-1994 and 1989-1994, respectively. This data illustrated patterns in the isotopic composition of precipitation, both spatially and seasonally. To better understand the recharge processes, over 789 groundwater samples were collected across Nebraska in 2011 and their isotopic signatures analyzed. While other studies have evaluated isotope ratios (seasonal ratios) (Jasechko et al., 2017; Sanchéz-Murillo and Birkel., 2016), in this study we compared the precipitation signals. The objective of this study was to investigate recharge characteristics based on stable isotope signatures of groundwater and comparisons of the isotopic composition of groundwater and precipitation across Nebraska

Extent of Suitable Habitats for Juvenile Striped Bass: Dynamics and Implications for Recruitment in Chesapeake Bay

The production of striped bass Morone saxatilis in Chesapeake Bay supports recreational and commercial fisheries along the Atlantic coast of the United States, but factors that contribute to high abundances of juvenile life stages are not fully understood. In this study, we characterized and quantified suitable and optimal habitat conditions in the Chesapeake Bay for two age groups of juvenile striped bass in discrete portions of the Bay: young-of-the-year (age-0) fish in shoreline and nearshore habitats, and resident sub-adults (age-1 to -4) in the mainstem and Bay-wide. We coupled information from 24 years of monthly fisheries surveys with hindcasts from a 3-D hydrodynamic model of the Bay and a numerical model of dissolved oxygen (DO) conditions. These models provided estimates of habitat conditions for 1996 to 2019 for 33 metrics of temperature, salinity, current speed, depth, DO, and physical features of habitats. Boosted regression trees were used to identify influential habitat covariates for each group, and those covariates were used to develop nonparametric habitat suitability models based on environmental conditions at the time and location of sampling. Habitat suitability indices (HSI), ranging from 0 (poor habitat) to 1 (high-quality habitat), were assigned to each grid in the 3-D model for each season in 1996 to 2019. We quantified suitable (HSI \u3e 0.5) and optimal (HSI \u3e 0.7) on a seasonal and annual basis, and across a range of environmental conditions (wet vs. dry years; warm vs. cool years). We also estimated the persistence of suitable habitats through time as the percent of years during which conditions were suitable at a given site; persistence allowed us to identify areas of the Bay and tidal tributaries that consistently supported suitable conditions for juvenile striped bass. Specific habitat conditions that defined suitable and optimal habitats for age-0 and age 1-4 striped bass varied across seasons and among years, reflecting changes in water quality conditions in Chesapeake Bay and changes in habitat use by striped bass during their first few years of life. Metrics of water quality, especially dissolved oxygen, were consistently identified as important covariates for juvenile striped bass; these conditions are of greater importance in determining habitat suitability than specific physical features especially for a highly mobile species and may be used to inform existing decision-support tools. In our study, we found no evidence that habitat use by striped bass in Chesapeake Bay was moderated by a strict threshold for any given covariate, and average to above-average abundances of striped bass were encountered in sub-suitable conditions; thus, habitat use resulted from a combination of abiotic, and likely biotic, conditions. Neither age group exhibited a statistically significant relationship between relative abundance and the extent of suitable habitats, however, for nearly all ages and seasons, relative abundance increased with greater extent of suitable habitats suggesting that detection of this relationship requires additional annual observations. A significant decrease in the extent of suitable habitat through time (1996 to present) was observed in spring and early summer, reflecting a change in suitable environmental conditions; with additional study years, declines in the relative abundance of age-0 and age 1-4 fish may be observed as suitability of habitats continues to decline. Given the high degree of interannual variability in abundance that is characteristic of estuarine-dependent species like striped bass, the availability and quantity of suitable and high-quality habitats at the scale of individual tributaries and Bay-wide may play an important role in production of this species