Geology topics

Daniel D. Magoulick

Publications and source records attributed to Daniel D. Magoulick.

At least 19 recordsLinked to original sources

USGS2026

Seasonal and hydrologic variation influences habitat and functional structure of stream fish assemblages

Introduction: Hydrologic variability is a key driver of ecological structure in lotic systems, shaping habitat conditions, taxonomic diversity, and the functional traits that mediate species’ persistence and performance (e.g., reproductive success). While many studies examine taxonomic responses to variation in flows, few evaluate how spatiotemporal hydrologic variation influences the functional organization within stream fish communities. Methods: We quantified seasonal habitat structure and functional trait diversity of fish assemblages across six Ozark Plateau headwater streams representing two contrasting flow regimes: Groundwater Flashy and Runoff/Intermittent Flashy. Fish and habitat data were collected seasonally during a dry year (2002) and a wet year (2003). Functional space was constructed using PCoA of morphological, ecological, and life-history traits, and functional diversity was measured using community weighted means (CWMs), functional richness (FRic), functional evenness (FEve), and functional divergence (FDiv). Results: We found that habitat structure differed strongly by flow regime and season, with Runoff/Intermittent streams exhibiting pronounced reductions in depth, area, and velocity, while groundwater streams remained structurally stable. Functional identity of assemblages was similar across flow regimes, dominated by benthic, hydrodynamic taxa with opportunistic and periodic life-history strategies. However, functional structure differed significantly: FEve and FDiv were consistently lower in Runoff/Intermittent Flashy streams in both years, indicating assemblage dominance of species with similar trait combinations and reduced trait partitioning under variable flow. FRic and taxonomic richness remained stable across seasons and flow regimes, suggesting high functional redundancy despite species turnover. Discussion: Together, results show that flow regime mediates both habitat structural stability and functional organization. As climatic warming and extreme drought increase hydrologic instability in headwaters, functional trait approaches provide a sensitive tool for detecting losses of functional roles that may not be evident by using taxonomic metrics alone.

Arkansas, Kansas, Missouri, Oklahoma↗

USGS2026

Assimilation efficiency of rainbow trout fed natural diets

Assimilation efficiency is a critical assumption of stable isotope mixing models and bioenergetics models, yet few studies examine how assimilation efficiency influences modeling inferences. We conducted laboratory experiments to determine rainbow trout ( Oncorhynchus mykiss ) assimilation efficiencies. Assimilation efficiency averaged 55.8% (SE ± 0.90) and 64.5% (SE ± 1.98) at the 10% and 25% ration levels, respectively, and did not differ significantly. Caloric energy egested in feces was not significantly different between ration levels. Caloric energy excreted in ammonia and urea was significantly different between the ration levels, with a higher amount at the 25% ration level. Absorption efficiency was significantly greater at a higher ration level. Percent energy egested in feces was significantly greater at lower ration levels. Percent energy excreted as ammonia and urea was high compared to previous studies and did not differ significantly by ration level. Our estimates of assimilation efficiency of rainbow trout (56% and 65%) were lower than some previously reported estimates, and our estimates of energy losses (feces and ammonia) were higher than some previous estimates. As knowledge of species-specific assimilation efficiencies increases, our ability to draw strong inferences and improve the accuracy of model predictions will improve.

Environmental Biology of Fishes↗

USGS2026

Effects of prey and tissue type on δ13C and δ15N discrimination and turnover rates of rainbow trout

Stable isotope analysis is used often in ecological studies to examine dietary patterns of consumers and food web structure, yet we still know little regarding some underlying assumptions, including for well-studied species like rainbow trout Oncorhynchus mykiss . We assessed δ 13 C and δ 15 N discrimination (∆) and turnover rates in blood, liver and white muscle of rainbow trout fed natural prey items (sculpin and chironomids). Liver had the fastest turnover rates for both δ 15 N and δ 13 C (4–6 months), followed by blood (4–7 months) and white muscle (7–9 months). Metabolism accounted for more isotopic turnover (82–93%) than growth, with the exception of δ13C in the blood of rainbow trout fed chironomids (33% of isotopic turnover was metabolic). Discrimination factors differed by tissue and diet, with ∆δ 15 N showing highest enrichment in white muscle (3.8‰; 95% CI 3.3–4.3), followed by blood (2.9‰; 95% CI 2.4–3.4) and liver (2.5‰; 95% CI 1.9–3.1) compared to the hatchery diet. The ∆δ 13 C of liver showed higher enrichment (1.9‰; 95% CI 1.7–2.1) than white muscle (1.7‰; 95% CI 1.4–2.0) and blood (1.5‰; 95% CI 1.3–1.7). It is crucial that future models incorporate species-specific tissue turnover and discrimination factors to enable drawing strong inferences and improve accuracy of model predictions.

Hydrobiologia↗

USGS2026

Hydrologic variability drives environmental and geospatial relationships in Smallmouth Bass (Micropterus dolomieu) distribution

Hydrologic variation is a primary driver of stream ecosystems. Changing hydrology can lead to assemblage shifts and alterations in suitable habitat for freshwater species. As climate change is predicted to alter flow patterns in addition to increasing water temperatures, insight into relationships between species occupancy, hydrology, and temperature is critical for understanding current and future distributions. We examined how hydrologic variability, temperature, and other environmental variables interact to influence Micropterus dolomieu (Smallmouth Bass) occurrence. We used Spatial Stream Network models, allowing for the incorporation of spatial autocorrelation along streams' unique dendritic network, to examine Smallmouth Bass occupancy across a range of hydrologic variation in the Ozark-Ouachita Interior Highlands, USA. Hydrologic variation was the main driver of Smallmouth Bass occurrence, with occurrence more likely in groundwater streams with low hydrologic variation and high flow permanence. For groundwater streams, occurrence was positively associated with summer stream temperature and negatively associated with annual stream temperature. As variation increased, more variables showed significant relationships with occurrence. Distance metrics were important for all models, however as hydrologic disturbance increased, flow connected distance played a lesser role and stream distance played a greater role. Hydrologic variability was the overarching determinant of Smallmouth Bass occurrence and strongly influenced the predictive importance of environmental variables and geospatial relationships. Greater hydrologic variability resulted in stronger statistical relationships between occurrence and environmental variables and an increased importance of system connectivity. As climate change alters hydrologic processes and streams become more variable, understanding and accounting for these shifting relationships is essential.

Arkansas, Kansas, Missouri, Oklahoma↗

USGS2025

Native crayfish shows high desiccation tolerance and potential to outcompete invader

Biological invasions threaten global biodiversity, with aquatic systems being particularly susceptible. Invasive crayfish drive native crayfish imperilment in North America and worldwide. Despite the probable increase in extreme hydrological events, the synergistic effects from invasive species and drought on crayfish are understudied. The invasion of Faxonius neglectus chaenodactylus in the Spring River drainage (AR, MO) has likely contributed to native crayfish displacement through mechanisms related to stream drying. F. n. chaenodactylus may further expand its range, posing a threat to other native species like Faxonius marchandi , the Mammoth Spring crayfish, a narrow-ranged endemic. We used stream mesocosms to examine (1) effects of invasive species on F. marchandi growth and survival, (2) responses of both species to simulated stream drying, and (3) additive effects of invasion and drought on F. marchandi . Additionally, we assessed differential desiccation tolerance using environmental chambers. We found no significant interaction between drought and competition nor any significant main effects on crayfish mass change or survival; however, interspecific competition significantly reduced length change in F. n. chaenodactylus . All populations showed differential desiccation tolerance, with survival rates varying significantly ( p < 0.05) and carapace length (CL) positively influencing survival ( p < 0.01). Understanding the effects of drought, invasion, and their interactions on native crayfish is essential, particularly given the potential expansion of an invader and increasing drought intensity from future climate change.

Arkansas, Missouri↗

USGS2025

Relationships between larval fish drift, time of day and discharge in an Ozark stream

We examined the relationship between larval fish numbers and discharge during a high flow event in Bear Creek, Arkansas, a small Ozark stream. Additionally, we examined the relationship between fish numbers and time of day, and the spatial distribution of families and size classes. A total of 3,083 fish from five families were collected. Leuciscidae was the dominant family collected, followed by Percidae, and Catostomidae. Larval fish in Bear Creek were not susceptible to increased discharge from the flood event, as all three families exhibited strong significant negative relationships to discharge at night when discharge began to decline. Larval fish in Bear Creek drifted significantly more at night than during the day, with the exception of large percids, which exhibited no diel pattern. Leuciscidae and small Percidae showed a spatial pattern of distribution across the stream at night, with higher drift densities in near shore nets. The results from our study indicate that fish drift in Bear Creek was an active process, with most larval fish drifting in response to decreased light intensity. We suggest future studies consider the effects of flood intensity on larval fish drift relative to diel periodicity.

Arkansas↗

USGS2025

Disturbance is the primary determinant of food chain length when the top predator is constant

Food chain length (FCL) is a primary determinant of food web structure and is hypothesized to be influenced by habitat size, productivity, and disturbance. Understanding the environmental characteristics that determine food chain length can assist in understanding how food webs may be impacted due to changes in habitats and environmental characteristics. This study examines the impact of hydrologic disturbance on stream food webs when the top predator is constant. We analyzed FCL in less disturbed groundwater flashy streams and more disturbed runoff flashy streams using stable isotopes. Despite no difference in species richness or fish density, food chains in more disturbed streams had a lower FCL compared to food chains in more stable streams. Assemblage analysis showed that flow regime and drainage area significantly impacted individual species abundances. The more disturbed runoff flashy streams had higher proportions of primary consumer fish, such as the algivorous Campostoma sp. (Stonerollers), which likely drives the reduced FCL. Drainage area and land cover had non-significant relationships with FCL. Shifting community structure due to hydrologic variability likely leads to differences in diet of Micropterus dolomieu (Smallmouth Bass), and thus a difference in FCL.

Arkansas, Missouri, Oklahoma↗

USGS2023

Flight capacity and response to habitat drying of endemic diving beetles (Coleoptera: Dytiscidae) in Arkansas (USA)

The ability to colonize new habitat is essential for wild populations affected by disturbance or other forms of habitat change. For aquatic insects in small streams, overland flight is an important strategy for dispersal when barriers to in-stream migration exist and when populations are isolated in upland habitats. Two Ozark-endemic water beetles ( Heterosternuta sulphuria and Heterosternuta phoebeae ) have shown little overlap in distributions, with the former frequently occurring in small upland watersheds and the latter occurring in aquatic habitats farther downstream in larger watersheds. Because H. sulphuria has been associated with perennial aquatic habitats, we hypothesized that H. sulphuria individuals could exhibit low capacity for flight, thereby affecting population distributions over time. Laboratory flight observations showed that zero individuals of H. sulphuria flew ( n = 67), whereas 17 of 76 individuals of H. phoebeae were observed to fly. Stream habitat drying experiments provided further evidence of the weak capacity for flight and overland migration of H. sulphuria , with low probabilities of survivorship in microhabitats exposed to drying. Weak flight capacity and apparent intolerance to habitat drying have important implications for the evolutionary history and conservation of H. sulphuria in small Ozark streams exposed to variable flow regimes and stream margins vulnerable to disturbances.

Arkansas↗

USGS2023

Predicting habitat and distribution of an interior highlands regional endemic winter stonefly (Allocapnia mohri) in Arkansas using random forest models

Stoneflies are a globally threatened aquatic insect order. In Arkansas, a diverse group of winter stonefly (Capniidae: Allocapnia ) have not been surveyed since the 1980s, likely because species-level identification requires the rarely-collected adult form. Allocapnia mohri , a regional endemic, was previously commonly found in mountainous, intermittent streams from the Ouachita Mountains ecoregion north to the Ozark Highlands, but no species distributional models including land use or climate variables exist to our knowledge. We collected adults from 71 stream reaches from the historic Arkansas range from November to April 2020 and 2021. We modeled distributions using random forest (RF) models populated with landscape, climate, and both data to determine which were most predictive of species presence. Correlations between landscape or climate variables and presence were examined using multiple logistic regression. The landscape RF models performed better than the climate or landscape + climate RF models. A. mohri presence sites tended to have a greater elevation, a lower mean July temperature, and a greater percentage of very slow infiltration soils in the watershed, compared to absence sites. A. mohri was absent at the Ouachita Mountains sites and may be experiencing a range contraction or migration northward.

Arkansas↗

USGS2022

Drought and nutrient pollution produce multiple interactive effects in stream ecosystems

Drought and nutrient pollution can affect the dynamics of stream ecosystems in diverse ways. While the individual effects of both stressors are broadly examined in the literature, we still know relatively little about if and how these stressors interact. Here, we performed a mesocosm experiment that explores the compounded effects of seasonal drought via water withdrawals and nutrient pollution (1.0 mg/L of N and 0.1 mg/L of P) on a subset of Ozark stream community fauna and ecosystem processes. We observed biological responses to individual stressors as well as both synergistic and antagonistic stressor interactions. We found that drying negatively affected periphyton assemblages, macroinvertebrate colonization, and leaf litter decomposition in shallow habitats. However, in deep habitats, drought-based increases in fish density caused trophic cascades that released algal communities from grazing pressures; while nutrient enrichment caused bottom-up cascades that influenced periphyton variables and crayfish growth rates. Finally, the combined effects of drought and nutrient enrichment interacted antagonistically to increase survival in longear sunfish; and stressors acted synergistically on grazers causing a trophic cascade that increased periphyton variables. Because stressors can directly and indirectly impact biota—and that the same stressor pairing can act differentially on various portions of the community simultaneously—our broad understanding of individual stressors might not adequately inform our knowledge of multi-stressor systems.

PLoS ONE↗

USGS2022

Morphological traits related to potential invasiveness of two subspecies of the crayfish Faxonius neglectus

Biological invasions have major environmental and economic impacts, and pose a serious threat to global biodiversity. Invasive crayfish species are one of the greatest threats to native crayfish biodiversity. Additionally, almost 50% of US and Canadian species are considered at risk, making crayfish one of the most imperiled taxonomic groups in the world. Small-scale (extralimital) invasions are often overlooked and may be more common than large-scale (extraregional) invasions. One example of an extraregional and extralimital invader is the Ringed Crayfish ( Faxonius neglectus ), which has been independently introduced multiple times to drainages throughout the United States, including those adjacent to its native range. Traits related to invasiveness, such as chelae size, are suggested to differ between invasive crayfish from extralimital and extraregional source populations with larger size related to increased invasiveness. We examined morphological traits related to invasion potential for both subspecies of F . neglectus , F . neglectus neglectus and F . neglectus chaenodactylus . We sampled 28 stream sites within the known native range of F . neglectus , including the Neosho and Upper White River drainages in Oklahoma, Arkansas and Missouri. Total carapace length, chelae length and chelae width of 30 adult male F . neglectus were measured from each site. We found significant differences in crayfish morphological characteristics among stream sites. We found significantly greater chelae length:carapace length (ChL:CarL) and chelae width:chelae length (ChW:ChL) in F . neglectus chaenodactylus than F . neglectus neglectus . Even among F . neglectus neglectus populations, there were significant differences in ChL:CarL and ChW:ChL. Morphological characteristics suggest that F . neglectus chaenodactylus and some populations of F . neglectus neglectus may be pre-adapted to the role of invader.

Arkansas, Kansas, Missouri, Oklahoma↗

USGS2022

Hydrologic and environmental thresholds in stream fish assemblage structure across flow regimes

The characteristic pattern of variation in flow magnitude, frequency, duration, timing, and rate of change defines the flow regime of rivers and streams and is a key driver of ecosystem processes in fluvial ecosystems. Understanding how freshwater biotic assemblages change across gradients of hydrology and anthropogenic-source disturbance in different streamflow regimes is crucial to managing for sustainable environmental flows and watershed conservation. We compiled long-term (1916–2016) occurrence records for fishes collected in the Ouachita-Ozark Interior Highlands and West Gulf Coastal Plain streams, together with hydrologic metrics calculated from daily streamflow data measured at USGS stream gauging stations (n = 111), to examine important drivers and thresholds for fish assemblage turnover in groundwater (GW), runoff (RO), and intermittent (INT) flow regimes. We also examined the importance of spatial gradients (latitude, longitude, elevation, drainage area) and anthropogenic-source stressors (Hydrologic Disturbance Index; HDI) for fish assemblage turnover using a gradient forest modeling approach. Watershed fragmentation was of high importance for fish assemblage turnover in RO and INT streams, while changes in dam storage were more important for fishes in GW streams. Hydrologic metrics describing seasonal and stochastic properties of daily streamflow (Mag6) were most important for fish assemblage turnover in INT streams. Timing of high flow events had significantly higher importance compared to flow magnitude, duration, and frequency metrics, especially for fish assemblages in GW and INT streams. The frequency and timing of low flow events had high importance for fish assemblage turnover across all stream flow classes, while the magnitude of low flows and the magnitude and rate of change of average flows was most important for INT stream fish assemblages. In addition to benefiting multi-species conservation and management actions through identification of local and regional flow-ecology relationships generalized across different flow regimes, the results of this study provide a better understanding of complex nonlinear threshold effects, which is critical to anticipating changes in aquatic ecosystems and communities.

Arkansas, Missouri, Oklahoma↗

USGS2021

Hydrologic variation influences stream fish assemblage dynamics through flow regime and drought

Hydrologic variation can play a major role in structuring stream fish assemblages and relationships between hydrology and biology are likely to be influenced by flow regime. We hypothesized that more variable flow regimes would have lower and more variable species richness, higher species turnover and lower assemblage stability, and greater abiotic environment-fish relationships than more stable flow regimes. We sampled habitats (pool, run, and riffle) in three Runoff/Intermittent Flashy streams (highly variable flow regime) and three Groundwater Flashy streams (less variable flow regime) seasonally (spring, early summer, summer and autumn) in 2002 (drought year) and 2003 (wet year). We used backpack electrofishing and three-pass removal techniques to estimate fish species richness, abundance and density. Fish species richness and abundance remained relatively stable within streams and across seasons, but densities changed substantially as a result of decreased habitat volume. Mixed model analysis showed weak response variable-habitat relationships with strong season effects in 2002, and stronger habitat relationships and no season effect in 2003, and flow regime was not important in structuring these relationships. Seasonal fish species turnover was significantly greater in 2002 than 2003, but did not differ between flow regimes. Fish assemblage stability was significantly lower in Runoff/Intermittent Flashy than Groundwater Flashy streams in 2002, but did not differ between flow regimes in 2003. Redundancy analysis showed fish species densities were well separated by flow regime in both years. Periodic and opportunistic species were characteristic of Runoff/Intermittent Flashy streams, whereas mainly equilibrium species were characteristic of Groundwater Flashy streams. We found that spatial and temporal variation in hydrology had a strong influence on fish assemblage dynamics in Ozark streams with lower assemblage stability and greater fluctuations in density in more hydrologically variable streams and years. Understanding relationships between fish assemblage structure and hydrologic variation is vital for conservation of fish biodiversity. Future work should consider addressing how alteration of hydrologic variation will affect biotic assemblages.

Arkansas, Missouri, Oklahoma↗

USGS2021

Modeling effects of disturbance across life history strategies of stream fishes

A central goal of population ecology is to establish linkages between life history strategy, disturbance, and population dynamics. Globally, disturbance events such as drought and invasive species have dramatically impacted stream fish populations and contributed to sharp declines in freshwater biodiversity. Here, we used RAMAS-Metapop to construct stage-based demographic metapopulation models for stream fishes with periodic, opportunistic, and equilibrium life history strategies and assessed their responses to disturbance scenarios that approximated the effects of invasion, drought, and the additive effects of both disturbances. Our models indicated that populations respond differentially to disturbance based on life history strategy. Equilibrium strategists were best able to deal with simulated invasion. Periodic strategists did well under lower levels of drought, whereas opportunistic strategists outperformed other life histories under extreme seasonal drought. When we modeled additive effects scenarios, these disturbances interacted synergistically, dramatically increasing terminal extinction risk for all three life history strategies. Modeling exercises that examine broad life history categories can help to answer fundamental ecological questions about the relationship between disturbance resilience and life history, as well as help managers to develop generalized conservation strategies when species-specific data are lacking. Our results indicate that life history strategy is a fundamental determinant of population trajectories, and that disturbances can interact synergistically to dramatically impact extinction outcomes.

Oecologia↗

USGS2020

Effect of stream permanence on predation risk of lotic crayfish by riparian predators

Given the importance of crayfish in stream ecosystems, gaining insight into the role of stream permanence in maintaining predator–prey interactions is critical. Our objectives were to determine the influence of stream permanence and season on crayfish predation and assess the role of stream permanence and crayfish density on the presence of predators, while accounting for imperfect detection. We conducted surveys of crayfish density, mammalian scat, and environmental variables within 10 intermittent and 10 permanent streams in the Ozark Highlands. We used occupancy modeling to assess the relationship between predator presence, crayfish density, and environmental variables. Stream permanence did not play a role in determining relative frequency of occurrence or percent volume of crayfish prey in mammalian diets. However, percent volume and relative frequency of crayfish prey found in scats differed by season, with both highest in spring and summer. The relative frequency and percent volume of fish prey showed a significant interaction of season by stream permanence, which may be the first instance of this observation. Procyon lotor (Raccoon) had the highest detection probability ( p = 0.39), whereas Neovison vison (American Mink; p = 0.15) and Lontra canadensis (River Otter; p = 0.03) had low detection probabilities. Further study into predator–prey interactions in the context of hydrology, particularly when related to imperiled groups like freshwater crayfishes, is needed since climate change is expected to alter hydrologic patterns.

Arkansas, Missouri↗

USGS2019

Flow alteration-ecology relationships in Ozark Highland streams: Consequences for fish, crayfish and macroinvertebrate assemblages

We examined flow alteration-ecology relationships in benthic macroinvertebrate , fish, and crayfish assemblages in Ozark Highland streams, USA, over two years with contrasting environmental conditions, a drought year (2012) and a flood year (2013). We hypothesized that: 1) there would be temporal variation in flow alteration-ecology relationships between the two years, 2) flow alteration-ecology relationships would be stronger during the drought year vs the flood year, and 3) fish assemblages would show the strongest relationships with flow alteration. We used a quantitative richest-targeted habitat (RTH) method and a qualitative multi-habitat (QMH) method to collect macroinvertebrates at 16 USGS gaged sites during both years. We used backpack electrofishing to sample fish and crayfish at 17 sites in 2012 and 11 sites in 2013. We used redundancy analysis to relate biological response metrics, including richness, diversity, density, and community-based metrics, to flow alteration. We found temporal variation in flow alteration-ecology relationships for all taxa, and that relationships differed greatly between assemblages. We found relationships were stronger for macroinvertebrates during the drought year but not for other assemblages, and that fish assemblage relationships were not stronger than the invertebrate taxa. Magnitude of average flow, frequency of high flow, magnitude of high flow, and duration of high flow were the most important categories of flow alteration metrics across taxa. Alteration of high and average flows was more important than alteration of low flows. Of 32 important flow alteration metrics across years and assemblages, 19 were significantly altered relative to expected values. Ecological responses differed substantially between drought and flood years, and this is likely to be exacerbated with predicted climate change scenarios. Differences in flow alteration-ecology relationships among taxonomic groups and temporal variation in relationships illustrate that a complex suite of variables should be considered for effective conservation of stream communities related to flow alteration.

Arkansas, Missouri, Oklahoma↗

USGS2019

Predicting hydrologic disturbance of streams using species occurrence data

Aquatic organisms have adapted over evolutionary time-scales to hydrologic variability represented by the natural flow regime of rivers and streams in their unimpaired state. Rapid landscape change coupled with growing human demand for water have altered natural flow regimes of many rivers and streams on a global scale. Climate non-stationarity is expected to further intensify hydrologic variability, placing increased pressure on aquatic communities. Using a machine learning approach and georeferenced species occurrence data, we modeled and mapped spatial patterns of hydrologic disturbance for streams in Arkansas, Missouri, and eastern Oklahoma. Random forest (RF) models trained on fish community data, hydrologic, and landscape metrics for gaged streams in the National Hydrography (NHDPlusV2) database were used to predict a hydrologic disturbance index (HDI) for ungaged streams. The HDI is part of the USGS Geospatial Attributes of Gages for Evaluating Streamflow (GAGESII) database and is a composite index of watershed-scale disturbance from anthropogenic stressors. Fish presence/absence data had similar overall model prediction accuracy (77%; 95% CI: 0.74, 0.80) as flow variables (76%; CI: 0.73, 0.80). Including topographic variables increased the RF prediction accuracy of both the fish (90%; CI: 0.88, 0.92) and flow models (86%; CI: 0.84, 0.89). Spatial patterns of hydrologic disturbance suggest distinct ecohydrological regions exist where conservation actions may be focused. Streams with low HDI were predominately located in the Ozark Highlands, Boston Mountains, and Ouachita Mountains. Correlation analysis of HDI by flow regime showed groundwater stable streams had the lowest disturbance frequency, with over 50% of stream reaches with low HDI located in forested land cover. HDI was highest for big rivers, intermittent runoff streams and streams in areas of agricultural land use. Our results show long-term georeferenced biological data can provide a valuable resource for predictive modeling of hydrologic disturbance for ungaged rivers and streams.

Arkansas, Missouri, Oklahoma↗

USGS2019

Population characteristics of Ozark Bass (Ambloplites constellatus) in the upper White River basin of northern Arkansas

Ozark Bass ( Ambloplites constellatus ) is an understudied, endemic fish species in the Upper White River Basin of northern Arkansas. This study was part of an effort by fisheries managers to gather baseline data about the Ozark Bass to aid in understanding population dynamics and contribute to the limited data available for use in determining the efficacy of harvest regulations. Select population characteristics of Ozark Bass in two northern Arkansas streams were determined, population characteristics of Ozark Bass were compared to Shadow Bass ( Ambloplites ariommus ) and Rock Bass ( Ambloplites rupestris ) data collected from previous studies in southern Missouri, and relative condition, length-at-age, and annual survival of Ozark Bass were compared between sample streams. Sampling occurred in Crooked Creek and the Buffalo River during summer 2013 via boat electroshocking. Length and weight data were recorded for all Ozark Bass collected, and fish ages were determined through selective otolith retrieval and age-length keys. Ozark Bass in Crooked Creek had greater relative condition than Ozark Bass in Buffalo River ( P < 0.001). Neither Ozark bass lengths nor log-transformed weights differed ( P > 0.05) between sexes for fish collected from only the Buffalo River. Ozark Bass mean annual survival was similar between Crooked Creek (55% ± 5% as 95% confidence interval (CI)) and the Buffalo River (50% ± 7% CI) for fish age 2 to 9. Calculated Ozark Bass lengths-at-age for fish from both streams were comparable to the Von Bertalanffy growth estimates, except the Buffalo River age 7 categor y where there was only one observation. The relationship between Ozark Bass age and length differed between sampled streams, and variability in growth rates and length-at-age were observed among Ambloplites species. Results of this study contribute to the understanding of the population dynamics of the Ozark Bass that will lead to improved fisheries management.

Arkansas↗