George T. Merovich

We sampled headwater streams to characterize impacts of unconventional shale gas development (SGD) on aquatic ecosystems. The study area was relatively un-impacted by confounding activities. Intensity of SGD over the study decreased then increased again but not to levels seen the first year. Shale gas development was associated with increased, but non-impaired, water pH and specific conductance during the latter part of the study. Metrics summarizing macroinvertebrate assemblages were better on average in un-impacted reaches. A genus-level multimetric index of biotic integrity was statistically lower downstream of impacts compared to upstream, but only in the year when SGD activity was most intense. Multivariate analyses indicated that assemblages diverged in similarity downstream compared to upstream of impacts in the first and last years of the study when SGD activity was elevated. Assemblage divergence was related to variation in water quality. Indicator species analysis linked a few key taxa to un-impacted conditions in the first year of the study; tolerant taxa were indicators for impacted conditions later in the study. Our study links SGD to weak negative changes in water quality and benthic macroinvertebrates, which may have negative consequences to food quality for wildlife that rely on aquatic prey within forested systems.

Hybridization of non-native crayfishes with native crayfishes can facilitate invasion success of the non-native. We report novel genetic evidence of hybridization between rusty crayfish, Faxonius rusticus (Girard, 1852), and Allegheny crayfish, F. obscurus (Hagen, 1870), two non-native species in the upper Juniata River basin of central Pennsylvania. We used double-digest restriction-associated DNA sequencing, which yielded 28,031 single nucleotide polymorphisms, to characterize the extent of hybridization. Two of eight individuals with mixed character traits were identified as the progeny of hybrids backcrossed into rusty crayfish. One individual, presumed to be a rusty crayfish in the field, was genetically identified as a hybrid backcross to rusty crayfish. The three crayfish taxa (rusty, Allegheny, and intermediates) are virtually indistinguishable based on typical morphological characters. Key character traits that distinguish rusty and Allegheny crayfishes can be mixed atypically in certain individuals (i.e., intermediates). Our results indicate that introgressive hybridization has occurred between rusty and Allegheny crayfishes, and that at least some of the character-trait intermediate individuals have hybrid ancestry. Hybridization may be an additional means by which invasive rusty crayfish increase their fitness and dominance at the expense of existing species and their habitat.

Acid mine drainage (AMD) and acid rain are important sources of impairment to streams in the Tygart Valley and Cheat River basins in north central West Virginia, USA. Due to a network of abandoned mined lands and bond forfeiture sites in this coal-mining region, AMD represents severe, but rather localized impacts to water quality. AMD is a consequence of the chemical oxidation of reduced geological minerals (sulfides) usually associated with coal during mining operations. The reactions produce aqueous solutions high in sulfates and dissolved metals when the minerals are exposed to the oxic environment through land disturbance. In addition, the weakly buffered and mostly acid producing to circum-neutral mineral geology of this region makes surface waters susceptible to the chemical consequences of acid rain. Acid rain forms when gaseous compounds of nitrogen and sulfur from fossil fuel combustion react with atmospheric moisture.;I tested a classification system based on water chemistry in streams of these two basins. Streams of the region ranged from very good water quality (reference type) to increasingly impaired by AMD (moderate to severe AMD types). Streams with soft water had characteristics associated with the impacts from acid rain, and streams with hard water were either natural occurrences or were influenced by alkaline materials injected into water to treat acid sources. A transitional water quality type was recognized, which was very difficult to characterize because of its gradation in chemistry across the spectrum from reference and hard water types to waters increasingly influenced by AMD.;It is commonly observed that benthic macroinvertebrates in streams from unpolluted waters are distributed continuously without being organized into discrete communities. The discreteness of water quality observed in this research, however, suggests that benthic macroinvertebrates ought not to be distributed continuously, but rather should correspond discretely to water quality types as distinct communities. Therefore, I tested the expectation that macroinvertebrate communities should be distributed in concordance with water quality types in the Cheat River basin. Multivariate models suggested that water quality types significantly structured macroinvertebrates. Measures of classification strength by water quality on community composition were weak, but significant. Indicator species analysis found several important macroinvertebrate genera that were linked especially to reference and soft water quality types.;In the Cheat River mainstem, benthic macroinvertebrate communities and a measure of stream ecosystem health were highly correlated to spatial and temporal inputs of AMD and thermal effluent. However, when these stressors occurred simultaneously, stream health and

We related Louisiana Waterthrush (Parkesia motacilla) demographic response and nest survival to benthic macroinvertebrate aquatic prey and to shale gas development parameters using models that accounted for both spatial and non-spatial sources of variability in a Central Appalachian USA watershed. In 2013, aquatic prey density and pollution intolerant genera (i.e., pollution tolerance value <4) decreased statistically with increased waterthrush territory length but not in 2014 when territory densities were lower. In general, most demographic responses to aquatic prey were variable and negatively related to aquatic prey in 2013 but positively related in 2014. Competing aquatic prey covariate models to explain nest survival were not statistically significant but differed annually and in general reversed from negative to positive influence on daily survival rate. Potential hydraulic fracturing runoff decreased nest survival both years and was statistically significant in 2014. The EPA Rapid Bioassessment protocol (EPA) and Habitat Suitability Index (HSI) designed for assessing suitability requirements for waterthrush were positively linked to aquatic prey where higher scores increased aquatic prey metrics, but EPA was more strongly linked than HSI and varied annually. While potential hydraulic fracturing runoff in 2013 may have increased Ephemeroptera, Plecoptera, and Trichoptera (EPT) richness, in 2014 shale gas territory disturbance decreased EPT richness. In 2014, intolerant genera decreased at the territory and nest level with increased shale gas disturbance suggesting the potential for localized negative effects on waterthrush. Loss of food resources does not seem directly or solely responsible for demographic declines where waterthrush likely were able to meet their foraging needs. However collective evidence suggests there may be a shale gas disturbance threshold at which waterthrush respond negatively to aquatic prey community changes. Density-dependent regulation of their ability to adapt to environmental change through acquisition of additional resources may also alter demographic response.

Lake sturgeon Acipenser fulvescens populations show a variety of movement patterns that are poorly understood. To compare two migratory phenotypes of A. fulvescens in the St. Clair River, MI, USA, multiple data types were analysed. Individual fish were classified into migratory phenotypes based on acoustic telemetry data collected 2012–2015. Acipenser fulvescens consistently showed movement from the St. Clair River upriver into Lake Huron or downriver into Lake St. Clair. The two migratory phenotypes were then compared for differences in morphometrics, genetics and epigenetics. Morphological differences based on linear measurements were not detected between phenotypes. Microsatellite data from 11 loci suggested one population with no genetic differentiation between migratory phenotypes. Our epigenetic results indicated that the migratory phenotypes are differentially methylated (P < 0.05), thus epigenetics may be associated with migratory differences in A. fulvescens. Only one restriction site was identified to be driving the differential methylation (P < 0.05). While little evidence at neutral loci occurred for genetic differentiation of A. fulvescens, DNA methylation may play a role in the observed movement pattern variation. When combined with microsatellite and morphometric analyses, our results suggested that different migratory patterns may reflect phenotypic plasticity, allowing A. fulvescens to acclimate to short‐term environmental variability. Without an integrated approach, the role of epigenetics in the migratory phenotype of A. fulvescens may have been overlooked. Further characterization of migratory phenotypes could be important for management to conserve behavioural variation across the distribution of A. fulvescens and for design of stocking guidelines.

Assessments of watershed-based restoration efforts are rare but are essential for the science of stream restoration to advance. We conducted a watershed scale assessment of Abram Creek before and after implementation of a watershed-based plan designed to maximize ecological recovery from acid mine drainage (AMD) impairment. We surveyed water chemistry, physical habitat, benthic macroinvertebrates, and fish community structure in three stream types: AMD-impacted (14 streams), AMD-treated (13 streams), and unimpaired reference (4 streams). We used in-stream measurements to quantify ecological loss from AMD, the amount of ecological recovery expected through remediation, and the observed degree of post-treatment recovery. Sites impaired by AMD improved in water quality with AMD treatment. Dissolved metals and acidity declined significantly in treated streams, but sulfate and specific conductance did not. Likewise, sites impaired by AMD improved in bio-condition scores with AMD treatment. EPT genera increased significantly but were lower compared to unimpaired streams. We found fish at nine treated sites that had none before treatment. Community-level analyses indicated improved but altered assemblages with AMD treatment. Analysis of pre-treatment conditions indicated that only 30% of the historic fishery remained. Remediation was expected to recover 66% of the historic fishery value, and assessment of post-treatment conditions indicates that 52% of the historic fishery has been recovered after 3 years. Developing expected endpoints for restoration outcomes provides a tool to objectively evaluate successes and can guide adaptive management strategies.

Plant litter decomposition varies by species and environmental conditions. To study environmental controls of decomposition, we measured plant litter decomposition rates in six wetlands located in West Virginia, USA. Four common wetland litter species were used: broadleaf cattail (Typha latifolia L.), common rush (Juncus effusus L.), brookside alder (Alnus serrulata (Ait.) Willd.), and reed canary grass (Phalaris arundinacea L.). A fifth litter type was created from a mix of common rush, brookside alder, and reed canary grass. Litter bags were collected over two years, from December 2007 to December 2009, and environmental variables near litter bags were measured every two weeks. Nine environmental parameters and one study parameter were then used to construct and test the ability of 22 a-priori models to predict the decomposition rate of each litter type. The environmental variables that most influenced and, therefore, best predicted decomposition rate varied among litter types. Brookside alder decomposition rate was best predicted by soil temperature (ST), water pH (WPH), and the number of transitions between flooded and exposed conditions (FET); reed canary grass decomposition rate was best predicted by air temperature (AT), WPH, and ST; common rush decomposition rates were best predicted by AT; broadleaf cattail decomposition rate was best predicted by hydroperiod (HP) and FET; and the mixed litter decomposition rate was best predicted by AT and WPH. Overall, AT, ST, and WPH were directly related to decomposition rate, while HP was inversely related. The FET was directly related to decomposition rates of common rush and broadleaf cattail and inversely related to the decomposition rate of brookside alder. The study of litter decomposition helps reveal the link between environmental conditions and wetland function.