Susquehanna River Research Articles

Factors Influencing the Prevalence of Hyperpigmented Melanistic Lesions in Smallmouth Bass Micropterus dolomieu in the Susquehanna River Basin, Pennsylvania.

Hyperpigmented melanistic lesions (HPMLs) are a visual anomaly documented on the skin of smallmouth bass Micropterus dolomieu in the Susquehanna River Basin, Pennsylvania and in numerous other geographical locations. Currently, there is a lack of information on environmental and fish characteristics that may influence the prevalence of HPMLs associated with a recently described Adomavirus. The goal of this study was to understand potential drivers associated with HPMLs in socioeconomically and ecologically important riverine smallmouth bass populations. A total of 16,220 smallmouth bass were collected and examined for HPMLs between 2012 and 2022 in the Susquehanna River Basin. Overall, HPMLs were documented on 2.9% of fish collected. The interaction between temperature and fish size suggested differing relationships between shorter and longer fish with respect to temperature. Predicted probability of HPML prevalence ranged from 1.1% (95% CI = 0.3, 3.2) at 4°C to 0.01% (CI = 0.00, 0.04) at 26°C for an age-0 (125 mm) fish. In contrast, predicted probability of HPML prevalence ranged from 10.5% (95% CI = 5.8, 18.9) at 4°C to 0.8% (CI = 0.4, 1.5) at 26°C for an adult (322 mm) fish. Overall, HPMLs were more common in longer fish during cooler temperature periods which also corresponds to key life history periods for smallmouth bass (e.g., pre-spawn and overwintering) and could represent different exposure histories for juvenile and adult fish.

Diet and Habitat Comparison of Two Closely Related Darters (Percina bimaculata and Percina caprodes)

The Chesapeake Logperch (Percina bimaculata) is a medium-sized darter that has had a limited distribution in Pennsylvania and Maryland. It is a threatened species native to the Susquehanna River and historically occurred in the Potomac River. It is currently being reviewed to determine if it should be listed as federally endangered. There are major efforts to reintroduce the Chesapeake Logperch to where it was historically native. Toward this end, we documented the selected habitats and diets, to aid in the selection of new habitats for reintroduction. Because historical data on habitat selection and diet of the Chesapeake Logperch were not available, we compared these habitats selected to those of the closely related Northern Logperch (P. caprodes semifasciata), and diet to the Ohio Logperch (P. caprodes caprodes). The habitat occupied by the Chesapeake Logperch was only a portion of that occupied by the Northern Logperch. Selection of streams for reintroduction can use data presented herein for the Chesapeake Logperch and historical data for the Northern Logperch. The diet of both the Chesapeake Logperch and the Ohio Logperch indicated that their diets differ, thus the prey items reported herein must be present when selecting putative reintroduction sites. These results will help to create more informed choices for streams considered for the reintroduction of the Chesapeake Logperch.

Integrating Values to Improve the Relevance of Climate‐Risk Research

AbstractClimate risks are growing. Research is increasingly important to inform the design of risk‐management strategies. Assessing such strategies necessarily brings values into research. But the values assumed within research (often only implicitly) may not align with those of stakeholders and decision makers. These misalignments are often invisible to researchers and can severely limit research relevance or lead to inappropriate policy advice. Aligning strategy assessments with stakeholders' values requires a holistic approach to research design that is oriented around those values from the start. Integrating values into research in this way requires collaboration with stakeholders, integration across disciplines, and attention to all aspects of research design. Here we describe and demonstrate a qualitative conceptual tool called a values‐informed mental model (ViMM) to support such values‐centered research design. ViMMs map stakeholders' values onto a conceptual model of a study system to visualize the intersection of those values with coupled natural‐human system dynamics. Through this mapping, ViMMs integrate inputs from diverse collaborators to support the design of research that assesses risk‐management strategies in light of stakeholders' values. We define a visual language for ViMMs, describe accompanying practices and workflows, and present an illustrative application to the case of flood‐risk management in a small community along the Susquehanna river in the Northeast United States.

Geomorphic History Determined by a New Glacial History Paradigm and Topographic Map Interpretation, Towanda Creek Drainage Basin, PA (USA)

Pennsylvania’s Towanda Creek drainage basin geomorphic history is determined by using a recently proposed geology and glacial history paradigm (which predicts massive and prolonged southwest oriented continental ice sheet meltwater floods flowed across Pennsylvania) when interpreting previously unexplained topographic map drainage system and erosional landform evidence. The new paradigm explains most of the region’s erosional landforms including barbed tributaries, drainage divides, through valleys (valleys crossing drainage divides), water and wind gaps, valley orientations, entrenched meanders, through valley and gap floor elevations, regional ridge crest elevations, upland area elevations, and intervening lowland elevations. The new paradigm suggests the present-day northeast-oriented Towanda Creek drainage basin formed as immense and prolonged southwest-oriented floods first lowered a low relief surface (now preserved if preserved at all by the region’s highest elevations) in the area between the present-day northeast-trending Blossburg and Barclay synclinal uplands and also to the south of the Barclay synclinal upland. Those floodwaters after flowing across the present-day northeast-oriented Towanda Creek drainage basin flowed in a southwest direction through the now southwest-oriented Lycoming and Loyalsock Creek drainage basins and then to and along a now northeast oriented West Branch Susquehanna River valley segment before continuing in a southwest direction along what is now the Allegheny Front. Headward erosion of today’s southeast-oriented North Branch Susquehanna River valley segment between Pittston and Athens, Pennsylvania captured and reversed the beheaded southwest-oriented floodwaters to create the northeast-oriented Towanda Creek drainage system seen today.

Algorithmically detected rain-on-snow flood events in different climate datasets: a case study of the Susquehanna River basin

Abstract. Rain-on-snow (RoS) events in regions of ephemeral snowpack – such as the northeastern United States – can be key drivers of cool-season flooding. We describe an automated algorithm for detecting basin-scale RoS events in gridded climate data by generating an area-averaged time series and then searching for periods of concurrent precipitation, surface runoff, and snowmelt exceeding predefined thresholds. When evaluated using historical data over the Susquehanna River basin (SRB), the technique credibly finds RoS events in published literature and flags events that are followed by anomalously high streamflow as measured by gauge data along the river. When comparing four different datasets representing the same 21-year period, we find large differences in RoS event magnitude and frequency, primarily driven by differences in estimated surface runoff and snowmelt. Using dataset-specific thresholds improves agreement between datasets but does not account for all discrepancies. We show that factors such as meteorological forcing and coupling frequency, as well as choice of land surface model, play roles in how data products capture these compound extremes and suggest care is to be taken when climate datasets are used by stakeholders for operational decision-making.

Temporal analysis of water chemistry and smallmouth bass (Micropterus dolomieu) health at two sites with divergent land use in the Susquehanna River watershed, Pennsylvania, USA

Monitoring wild fish health and exposure effects in impacted rivers and streams with differing land use has become a valuable research tool. Smallmouth bass (Micropterus dolomieu) are a sensitive, indicator species that exhibit signs of immunosuppression and endocrine disruption in response to water quality changes and contaminant exposure. To determine the impact of agriculture and development on smallmouth bass health, two sites (a developed/agriculture site and a forested site) in the Susquehanna River watershed, Pennsylvania were selected where bass and water chemistry were sampled from 2015 to 2019. Smallmouth bass were sampled for histopathology to assess parasite and macrophage aggregate density in the liver and spleen, condition factor (Ktl), hepatic gene transcript abundance, hepatosomatic index (HSI), and a health assessment index (HAI). Land use at the developed/agriculture site included greater pesticide application rates and phytoestrogen crop cover and more detections and higher concentrations of pesticides, wastewater-associated contaminants, hormones, phytoestrogens, and mycotoxins than at the forested site. Additionally, at the developed/agriculture site, indicators of molecular changes, including oxidative stress, immune/inflammation, and lipid metabolism-related hepatic gene transcripts, were associated with more contaminants and land use variables. At both sites, there were multiple associations of contaminants with liver and/or spleen macrophage aggregate density, indicating that changes at the molecular level seemed to be a better indicator of exposures unique to each site. The findings illustrate the importance of timing for land management practices, the complex mixtures aquatic animals are exposed to, and the temporal changes in contaminant concentration. Agricultural practices that affect hepatic gene transcripts associated with immune function and disease resistance were demonstrated which could negatively affect smallmouth bass populations.

Feeding habits and ecological implications of the invasive Flathead Catfish in the Susquehanna River basin, Pennsylvania

AbstractObjectiveFlathead Catfish Pylodictis olivaris are a widespread aquatic invasive species within the United States and a recent invader in the Susquehanna River basin, Pennsylvania. Flathead Catfish are piscivores known to consume native and recreationally important fish species. In the mid‐Atlantic United States, it is unknown how this invader is impacting food webs and which species may be at greatest predation risk. To address this knowledge gap, we DNA barcoded stomach contents collected from Flathead Catfish to identify prey species and elucidate potential predatory impacts of Flathead Catfish in the Susquehanna River.MethodsWe used a Bayesian hierarchical multivariate probit model to investigate if the probability of prey species occurrence in the diets of Flathead Catfish varied seasonally or was a function of Flathead Catfish length.ResultA total of 576 Flathead Catfish were collected during 2020–2021, with 241 individuals having recoverable stomach contents. In all, we identified 47 different prey species. The most common prey species were rusty crayfish Faxonius rusticus, Margined Madtom Noturus insignis, and shiners Notropis spp. While frequency of occurrence of prey species differed across Flathead Catfish length classes (<300 mm, 301–600 mm, 601–900 mm TL), rusty crayfish were commonly found (33.7–44.0% of diets) in stomachs of all size‐classes.ConclusionWe found that Flathead Catfish length and seasonality did influence occurrence probability differentially for several prey species. For example, Channel Catfish Ictalurus punctatus were more likely to appear in shorter Flathead Catfish while Smallmouth Bass Micropterus dolomieu appeared in larger Flathead Catfish. We demonstrate significant variation in Flathead Catfish predation, increasing our understanding of predator–prey dynamics, which is necessary to better manage and identify future impacts to aquatic communities in the Susquehanna River basin.

Population genetic structure and demographic history reconstruction of introduced flathead catfish (Pylodictis olivaris) in two US Mid-Atlantic rivers.

Population genetic analysis of invasive populations can provide valuable insights into the source of introductions, pathways for expansion, and their demographic histories. Flathead catfish (Pylodictis olivaris) are a prolific invasive species with high fecundity, long-distance dispersal, and piscivorous feeding habits that can lead to declines in native fish populations. In this study, we analyse the genetics of invasive P. olivaris in the Mid-Atlantic region to assess their connectivity and attempt to reconstruct the history of introduced populations. Based on an assessment across 13 microsatellite loci, P. olivaris from the Susquehanna River system (N = 537), Schuylkill River (N = 33), and Delaware River (N = 1) have low genetic diversity (global Hobs = 0.504), although we detected no evidence of substantial inbreeding (FIS = -0.083 to 0.022). P. olivaris from these different river systems were genetically distinct, suggesting separate introductions. However, population structure was much weaker within each river system and exhibited a pattern of high connectivity, with some evidence of isolation by distance. P. olivaris from the Susquehanna and Schuylkill rivers showed evidence for recent genetic bottlenecks, and demographic models were consistent with historical records, which suggest that populations were established by recent founder events consisting of a small number of individuals. Our results show the risk posed by small introductions of P. olivaris, which can spread widely once a population is established, and highlight the importance of prevention and sensitive early detection methods to prevent the spread of P. olivaris in the future.

Differences in life history patterns of American shad (Alosa sapi dissima) populations between ancestral, Atlantic coast, and non-native Pacific coast rivers of North America

Organisms naturalized outside their native range can reveal new life history patterns in new environments. Here, we compare life history patterns of American shad, Alosa sapidissima, from five rivers along the U.S. Pacific coast (introduced range) with contemporary data from the Atlantic coast source populations. The Pacific coast fish grew slower, matured at a younger age, and were less often iteroparous than conspecifics from the Hudson River and Susquehanna River sources. Differences among the Pacific coast populations indicated that some combination of phenotypic plasticity and genetic adaptation has occurred since the transplants in the 1870s. Microchemical analysis of otoliths from returning adults demonstrated an immature, extended freshwater life history form, locally known as “mini-shad”. These fish remain in the river for at least 1 year or enter salt water briefly and then return to fresh water for several months prior to subsequent seaward migration and return as adults. This and other forms of variation (extent of estuary use and size at sea water entry) expand the understanding of Alosine migration and life history diversity.

Sediment–vegetation interactions determine the fate of fluvial sediment in the upper reaches of a large estuary

AbstractFeedbacks between sediment and plants in the submersed aquatic vegetation (SAV) beds of the Susquehanna Flats help modulate sediment delivery into the upper Chesapeake Bay from its major tributary (Susquehanna River). Recent modeling work has shown that SAV can steer the river plume, directly controlling sediment transport and fate. However, transport mechanisms likely differ between flood and non‐flood conditions and depend on event timing. An opportunity to evaluate these insights in the field occurred with several flood events in summer 2018. Sediment and biomass samples were collected after the flood in the large, continuous main SAV bed of the Flats and in smaller patches to the west of the main bed to evaluate the effect of SAV bed size (width). Sediment characteristics (grain size, organic content) and deposition rates were compared to previous observations during non‐flood conditions in the main bed in 2014–2015 and in the smaller patches in 2019. Overall, sediment deposition rates could be predicted by an empirical model including sediment load, vegetation biomass, and SAV bed width, reflecting the role of vegetation in steering the Susquehanna River plume and modulating sediment input to the upper Chesapeake Bay. Understanding spatiotemporal patterns of sedimentation is essential for realistic estimates of sediment and nutrient (especially nitrogen and carbon) storage in freshwater SAV systems, which have not received as much attention as their saltwater counterparts.

Isolation and Characterization of the Chromatic-Acclimating, Filamentous Cyanobacterium Pseudanabaena sp. Strain SR411.

We isolated Pseudanabaena sp. Strain SR411, a novel filamentous, nonheterocystous, freshwater cyanobacterium from the West Branch of the Susquehanna River in Pennsylvania. Analysis of phycobilisome protein accumulation indicates Pseudanabaena SR411 acclimates to changing light wavelengths and we classified it as a chromatic acclimating cyanobacterium type CA3. The 5,780,083 bp genome has a GC content of 42.2% in which we identified 5,218 coding sequences and 58 RNA sequences. The genome includes putative homologs to the CA3 regulatory proteins RcaE, RcaF and RcaC.

Legacy sediment as a potential source of orthophosphate: Preliminary conceptual and geochemical models for the Susquehanna River, Chesapeake Bay watershed, USA

Nutrient pollution from agriculture and urban areas plus acid mine drainage (AMD) from legacy coal mines are primary causes of water-quality impairment in the Susquehanna River, which is the predominant source of freshwater and nutrients entering the Chesapeake Bay. Recent increases in the delivery of dissolved orthophosphate (PO4) from the river to the bay may be linked to long-term increases in pH, decreased acidity of precipitation, and decreased acidity, iron, and aluminum loading from widespread AMD. Since the 1950s, baseline pH increased from ~6.5 to ~8 in the West Branch and “North Branch” of the Susquehanna River, which drain bituminous and anthracite coalfields of Pennsylvania. A current baseline pH of ~8 and daily maxima exceeding 9 have been documented along the lower Susquehanna River. In response to improved river quality, bioavailable PO4 now may be released into solution from legacy sediment that has filled major impoundments in lower reaches of the river. At typical pH (5–8) of natural water, aqueous PO4 species tend to be adsorbed by hydrous iron, aluminum, and manganese oxides that coat soil and sediment particles; however, PO4 may be substantially desorbed at pH >8. We created a geochemical model that simulates equilibrium aqueous/solid distributions of PO4 as pH and other solution characteristics change. Considering current conditions in the lower Susquehanna River, the model demonstrates potential for extensive release of adsorbed PO4 at pH >8. Empirical data from laboratory experiments corroborate model results. The transfer of PO4 into the water column may increase algae growth, which removes CO2 and drives pH to higher values, facilitating additional PO4 release and exacerbating the potential for harmful algal blooms. Thus, legacy sediment is a currently unquantified source of PO4 that warrants consideration by resource managers and programs collaborating to reduce phosphorus loads to the bay and similar settings worldwide.

The 1996 Mid-Atlantic Winter Flood: Exploring Climate Risk through a Storyline Approach

Abstract This article explores the application of thermodynamic perturbations to a historical midlatitude, wintertime, rain-on-snow flood event to evaluate how similar events may evolve under different climate forcings. In particular, we generate a hindcast of the 1996 Mid-Atlantic flood using an ensemble of 14-km variable-resolution simulations completed with the U.S. Department of Energy’s global Energy Exascale Earth System Model (E3SM). We show that the event is skillfully reproduced over the Susquehanna River Basin (SRB) by E3SM when benchmarked against in situ observational data and high-resolution reanalyses. In addition, we perform five counterfactual experiments to simulate the flood under preindustrial conditions and four different levels of warming as projected by the Community Earth System Model Large Ensemble. We find a nonlinear response in simulated surface runoff and streamflow as a function of atmospheric warming. This is attributed to changing contributions of liquid water input from a shallower initial snowpack (decreased snowmelt), increased surface temperatures and rainfall rates, and increased soil water storage. Flooding associated with this event peaks from around +1 to +2 K of global average surface warming and decreases with additional warming beyond this. There are noticeable timing shifts in peak runoff and streamflow associated with changes in the flashiness of the event. This work highlights the utility of using storyline approaches for communicating climate risk and demonstrates the potential nonlinearities associated with hydrologic extremes in areas that experience ephemeral snowpack, such as the SRB.

Atmospheric Drivers Associated with Extreme Snow Ablation and Discharge Events in the Susquehanna River Basin: A Climatology

Abstract Extreme snow ablation can greatly impact regional hydrology, affecting streamflow, soil moisture, and groundwater supplies. Relatively little is known about the climatology of extreme ablation events in the eastern United States, and the causal atmospheric forcing mechanisms behind such events. Studying the Susquehanna River basin over a 50-yr period, here we evaluate the variability of extreme ablation and river discharge events in conjunction with a synoptic classification and global-scale teleconnection pattern analysis. Results indicate that an average of 4.2 extreme ablation events occurred within the basin per year, where some 88% of those events resulted in an increase in river discharge when evaluated at a 3-day lag. Both extreme ablation and extreme discharge events occurred most frequently during instances of southerly synoptic-scale flow, accounting for 35.7% and 35.8% of events, respectively. However, extreme ablation was also regularly observed during high pressure overhead and rain-on-snow synoptic weather types. The largest magnitude of snow ablation per extreme event occurred during occasions of rain-on-snow, where a basinwide, areal-weighted 5.7 cm of snow depth was lost, approximately 23% larger than the average extreme event. Interannually, southerly flow synoptic weather types were more frequent during winter seasons when the Arctic and North Atlantic Oscillations were positively phased. Approximately 30% of the variance in rain-on-snow weather type frequency was explained by the Pacific–North American pattern. Evaluating the pathway of physical forcing mechanisms from regional events up through global patterns allows for improved understanding of the processes resulting in extreme ablation and discharge across the Susquehanna basin. Significance Statement The purpose of this study is to better understand how certain weather patterns are related to extreme snowmelt and streamflow events and what causes those weather patterns to vary with time. This is valuable information for informing hazard preparation and resource management within the basin. We found that weather patterns with southerly winds were the most frequent patterns responsible for extreme melt and streamflow, and those patterns occurred more often when the Arctic and North Atlantic Oscillations were in their “positive” configuration. Future work should consider the potential for these patterns, and related impacts, to change over time.

Topological Relationship‐Based Flow Direction Modeling: Stream Burning and Depression Filling

AbstractFlow direction modeling consists of (a) an accurate representation of the river network and (b) digital elevation model (DEM) processing to preserve characteristics with hydrological significance. In part 1 of our study, we presented a mesh‐independent approach to representing river networks on different types of meshes. This follow‐up part 2 study presents a novel DEM processing approach for flow direction modeling. This approach consists of (a) a topological relationship‐based hybrid breaching‐filling method to conduct stream burning for the river network and (b) a modified depression removal method for rivers and hillslopes. Our methods reduce modifications to surface elevations and provide a robust two‐step procedure to remove local depressions in DEM. They are mesh‐independent and can be applied to both structured and unstructured meshes. We applied our new methods with different model configurations to the Susquehanna River Basin. The results show that topological relationship‐based stream burning and depression‐filling methods can reproduce the correct river networks, providing high‐quality flow direction and other characteristics for hydrologic and Earth system models.

Pay-for-practice or Pay-for-performance? A coupled agent-based evaluation tool for assessing sediment management incentive policies

Cost-shared programs have been applied to incentivize the adoption of agricultural best management practices (BMPs) to address the long-standing water quality issue in the Chesapeake Bay watershed, US. However, the business-as-usual (BAU) incentive program (i.e., pay-for-practice, paying cost share for implementing BMPs) is likely to miss the Total Maximum Daily Load target to reduce 20% of the total suspended sediment (TSS) in 2010 by 2025. Some field experiments indicate that pay-by-performance (PFP; paying lower cost share but with additional bonus payment per unit sediment reduction) can better motivate community involvement leading to greater water quality control outcomes. However, the effectiveness of different incentive policies is still unclear at a basin scale. We propose a coupled agent-based modeling tool to quantify the performance of different incentive policies. The tool considers farmers’ (i.e., agents’) BMP adoption dynamics affected by the social norm and the potential bonus payment. Specifically, we compare individual-based PFP (PFPi) and group-based PFP (PFPg) with BAU. Results of our proposed model applied to the selected study area, the Susquehanna River Basin, Chesapeake Bay’s largest tributary watershed, suggest that PFP can achieve higher TSS reduction with less cost. PFPg shows the best basin-wide TSS reduction associated with the least uncertainty among all tested policies. Also, the performance of PFPg is less impacted by the change in the bonus payment compared to PFPi attributed to farmers’ collaboration efforts. Potentially, the proposed policy evaluation tool can better inform an achievable target with policy suggestions in assistance with social studies (e.g., surveys and behavioral experiments).

Chickies Rock, a striking promontory on the Susquehanna River: the early Cambrian type locality of the trace fossil Skolithos and a model site for structural analysis

Abstract Chickies Rock rises abruptly from the east bank of the Susquehanna River at Columbia, Pennsylvania, where it breaks through a ridge held up by massively bedded quartzite. Here in the 1830s, Samuel Haldeman recognized long straight tubes that he later described as Skolithos linearis , penetrating the quartzite. Uncertain about the nature of these cylindrical ‘vermiform or linear’, unbranched ‘stems’, Haldeman first treated them as a subgenus of Fucoides , to which root-like traces were then often assigned. By the time James Hall first illustrated the species in 1847, Haldeman was sure they were burrows of a worm-like animal, as the name he had chosen implied. Since 1960, Donald Wise has developed a detailed analysis of structural deformation of the Chickies Anticline, using the Skolithos burrows as ‘plumb-bobs’ against which Taconic rotation of the rock fabric can be measured. Wise showed that later Alleghanian deformation produced prominent folds with external rotation up to twice as great as that of the rock fabric itself. Now conserved as a county park, Chickies Rock attracts many visitors. Its cliff-top is a superb viewpoint from which to contemplate progressive westward migration of the Appalachian drainage divide, ongoing since the late Jurassic opening of the Atlantic Ocean.

Morphological Comparison of the Chesapeake Logperch Percina bimaculata with the Logperch Percina c. caprodes and Percina c. semifasciata in Pennsylvania

The Chesapeake logperch, Percina bimaculata (Halderman) has a disjunct distribution when compared to other species in the subgenus Percina. Members of this subgenus in Pennsylvania include Percina caprodes caprodes (Rafinesque), Percina caprodes semifasciata (DeKay), and P. bimaculata. Historically the Chesapeake logperch was known only from the Susquehanna River and Potomac River basins. Its range is now restricted to the Susquehanna River below Holtwood Dam and upper Chesapeake Bay. It has been extirpated from the Potomac River and the type locality near Columbia, PA. Attempts are being made to reintroduce it into tributaries of the Susquehanna River near Columbia, PA. We postulate that P. bimaculata diverged from a population of Percina caprodes semifasciata. A naked nape and the fact that both of these species do not occur above the fall line in Pennsylvania support such a relationship.

Assembling the Right Pieces: Developing an Interdisciplinary Team to Study Disease, Decline, and Recovery of a World‐Class Smallmouth Bass Fishery

Managing and understanding fisheries dynamics are becoming more complex as new and seemingly more complicated environmental factors are identified. Often management requires resources beyond that of any one entity and calls for collaboration among partners with differing priorities and backgrounds to account for the complexity of factors influencing fisheries. We present a collaborative case study from the Susquehanna River basin, Pennsylvania, where Smallmouth Bass Micropterus dolomieu have faced population declines, mortality events, and notable signs of disease in recent years. Collaboration was required to study many facets of the fishery and the environment simultaneously to better understand risk factors and underlying relationships influencing Smallmouth Bass health. The outcomes from this interdisciplinary collaboration allowed for identification of contributing risk factors, led to the development of products and analytical techniques that were mutually beneficial to all partners involved, and provided knowledge that was integrated into fish health and fisheries management.

Linking Stream Chemistry to Subsurface Redox Architecture

AbstractAs drinking‐water scarcity grows worldwide, we need to improve predictions of the quantity and quality of our water resources. An overarching problem for model improvement is that we do not know the geological structure of aquifers in sufficient detail. In this work, we demonstrate that mineral‐water reactions imprint structure in the subsurface that impacts the flow and transport of some chemical species. Specifically, pyrite, a ubiquitous mineral, commonly oxidizes and depletes in the upper layers of the weathering profile in most humid watersheds, only remaining at depths of meters. We hypothesize that variations in concentrations (C) of pyrite‐derived sulfate released into rivers as a function of discharge (q) reflect the rate‐limiting step and depth of pyrite‐oxidizing layers. We found that log C − log q behaviors thus differ in small and large watersheds in the Susquehanna River Basin as well as in selected watersheds in the Western United States. Although coal mining changes pyrite oxidation from closed to open system with respect to O2, patterns in stream chemistry as a function of discharge are consistent with deep and shallow pyrite oxidation zones in small and large watersheds respectively. Therefore, understanding the subsurface patterns of mineral reactions and how they affect the architecture of aquifers will elucidate patterns of changing river chemistry and our ability to manage water resources in the future under accelerated land use and climate change.