Browsing by Author "Soucek, David J."

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    Benthic macroinvertebrate community structure responses to multiple stressors in mining-influenced streams of central Appalachia USA
    Drover, Damion R. (Virginia Tech, 2018-06-25)
    Headwaters are crucial linkages between upland ecosystems and navigable waterways, serving as important sources of water, sediment, energy, nutrients and invertebrate prey for downstream ecosystems. Surface coal mining in central Appalachia impacts headwaters by burying streams and introducing pollutants to remaining streams including excessive sediments, trace elements, and salinity. Benthic macroinvertebrates are widely used as indicators of biological conditions of streams and are frequently sampled using semi-quantitative methods that preclude calculations of areal densities. Studies of central Appalachian mining impacts in non-acidic streams often focus on biotic effects of salinity, but other types of pollution and habitat alteration can potentially affect benthic macroinvertebrate community (BMC) structure and perhaps related functions of headwater streams. Objectives were: 1) use quantitative sampling and enumeration to determine how density, richness, and composition of BMCs in non-acidic central Appalachian headwaters respond to elevated salinity caused by coal surface mining, and 2) determine if BMC structural differences among study streams may be attributed to habitat and water-quality effects in addition to elevated salinity. I analyzed BMC structure, specific conductance (SC, surrogate measure of salinity), and habitat-feature data collected from 15 streams, each visited multiple times during 2013-2014. BMC structure changed across seasonal samples. Total benthic macroinvertebrate densities did not appear to be impacted by SC during any months, but reduced densities of SC-sensitive taxa were offset by increased densities of SC-tolerant taxa in high-SC streams. Total richness also declined with increasing SC, whereas BMCs in high-SC streams were simplified and dominated by a few SC-tolerant taxa. Taxonomic replacement was detected in high-SC streams for groups of benthic macroinvertebrates that did not exhibit density or richness response, showing that taxonomic replacement could be a valuable tool for detecting BMC changes that are not evident from analyses using conventional metrics. Specific conductance, water-column selenium concentration, large-cobble-to-fines ratio of stream substrate, and relative bed stability were associated with changes in BMC structure. These results suggest multiple stressors are influencing BMCs in mining-influenced Appalachian streams. These findings can inform future management of headwater streams influenced by mining in central Appalachia.
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    Benthic Macroinvertebrate Community Temporal Dynamics and Their Response to Elevated Specific Conductance in Appalachian Coalfield Headwater Streams
    Boehme, Elizabeth A.; Schoenholtz, Stephen H.; Zipper, Carl E.; Soucek, David J.; Timpano, Anthony J. (Virginia Tech. Powell River Project, 2013)
    Protecting integrity of benthic macroinvertebrate communities, which are used to assess stream condition in Appalachian coalfield headwater streams, is essential. Previous studies have suggested elevated total dissolved solids (TDS) and closely related specific conductance (SC) in streamwater have negative effects on sensitive benthic macroinvertebrates (Timpano 2011, Bernhardt et al. 2012, Cormier et al. 2013a, Cormier et al. 2013b), although effects varied based on selected metric, chosen effect level, and in some cases, potential influence of confounding water-quality- or physical-habitat conditions. Most importantly, previous studies have relied on point-in-time measurements of SC, which may not be representative of exposure levels in the days, weeks, or months prior to sampling of benthic macroinvertebrates.
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    Combined effects of copper, nickel, and zinc on growth of a freshwater mussel (Villosa iris) in an environmentally relevant context
    Timpano, Anthony J.; Jones, Jess W.; Beaty, Braven; Hull, Matthew; Soucek, David J.; Zipper, Carl E. (Elsevier, 2022-01)
    Trace metals rarely contaminate freshwaters independently, hence regulatory limits based on single-metal toxicity may be underprotective of aquatic life. This could be especially the case for rare and sensitive fauna like freshwater mussels, such as those suppressed in the Clinch and Powell Rivers in eastern USA where trace metals are long-term contaminants but at concentrations below regulatory limits. We hypothesized metal mixtures may be exerting combined effects on mussels, resulting in greater toxicity than would be predicted based on single-metal exposures. To test that hypothesis, we conducted two experiments exposing juvenile rainbow mussels (Villosa iris) for 42 days to dissolved copper, nickel, and zinc, individually and in three-metal mixtures, in an environmentally-relevant context of water with chemistry (hardness 155 mg/L as CaCO3, dissolved organic carbon 1.7-2.3 mg/L, pH 8.4) similar to that of the Clinch River, which receives alkaline mine drainage. We used a toxic unit approach, selecting test concentrations based on literature values for the lower of 28-day survival or growth (length) effect concentrations for Villosa iris or Lampsilis siliquoidea (fatmucket). Our first experiment confirmed survival and growth effects when acute and chronic water quality criteria, respectively, are approached and/or exceeded. Our second experiment, at lower concentrations, showed no effects on survival but combined effects on growth were evident: a mixture of Cu, Ni, and Zn (7.2 +/- 1.2, 65.3 +/- 6.1, 183 +/- 32 mu g/L, respectively) inhibited growth (dry weight) by 95% versus 73%, 74%, and 83% inhibition for single-metal exposures to Cu, Ni, and Zn of similar concentration (8.0 +/- 1.1, 63.5 +/- 4.8, 193 +/- 31 mu g/L, respectively). Furthermore, a mixture of Cu, Ni, and Zn with individual concentrations 21%, 29%, and 37% of their water quality criteria (3.4 +/- 1.2, 21.8 +/- 1.8, and 62.1 +/- 8.4 mu g/L, respectively) inhibited growth (dry weight) by 61% relative to controls. Our observation of combined effects suggests that regulatory limits based on single-metal toxicity may be underprotective of freshwater mussels when multiple metals are present.
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    Comparison of benthic macroinvertebrate assessment methods along a salinity gradient in headwater streams
    Pence, Rachel A.; Cianciolo, Thomas R.; Drover, Damion R.; McLaughlin, Daniel L.; Soucek, David J.; Timpano, Anthony J.; Zipper, Carl E.; Schoenholtz, Stephen H. (Springer, 2021-12-01)
    Benthic macroinvertebrate community assessments are used commonly to characterize aquatic systems and increasingly for identifying their impairment caused by myriad stressors. Yet sampling and enumeration methods vary, and research is needed to compare their abilities to detect macroinvertebrate community responses to specific water quality variables. A common assessment method, rapid bioassessment, uses subsampling procedures to identify a fixed number of individual organisms regardless of total sample abundance. In contrast, full-enumeration assessments typically allow for expanded community characterization resulting from higher numbers of identified organisms within a collected sample. Here, we compared these two sampling and enumeration methods and their abilities to detect benthic macroinvertebrate response to freshwater salinization, a common stressor of streams worldwide. We applied both methods in headwater streams along a salinity gradient within the coal-mining region of central Appalachia USA. Metrics of taxonomic richness, community composition, and trophic function differed between the methods, yet most metrics exhibiting significant response to SC for full-enumeration samples also did for rapid bioassessment samples. However, full-enumeration yielded taxonomic-based metrics consistently more responsive to the salinization gradient. Full-enumeration assessments may potentially provide more complete characterization of macroinvertebrate communities and their response to increased salinization, whereas the more cost-effective and widely employed rapid bioassessment method can detect community alterations along the full salinity gradient. These findings can inform decisions regarding such tradeoffs for assessments of freshwater salinization in headwater streams and highlight the need for similar research of sampling and enumeration methodology in other aquatic systems and for other stressors.
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    Comparison of Quantitative and Semi-Quantitative Assessments of Benthic Macroinvertebrate Community Response to Elevated Salinity in central Appalachian Coalfield Streams
    Pence, Rachel A. (Virginia Tech, 2019-01-18)
    Anthropogenic salinization of freshwater is a global concern. In freshwater environments, elevated levels of major ions, measured as total dissolved solids (TDS) or specific conductance (SC), can cause adverse effects on aquatic ecosystem structure and function. In central Appalachia, eastern USA, studies largely rely on Rapid Bioassessment Protocols with semi-quantitative sampling to characterize benthic macroinvertebrate community response to increased salinity caused by surface coal mining. These protocols require subsampling procedures and identification of fixed numbers of individuals regardless of organism density, limiting measures of community structure. Quantitative sampling involves enumeration of all individuals collected within a defined area and typically includes larger sample sizes relative to semi-quantitative sampling, allowing expanded characterization of the benthic community. Working in central Appalachia, I evaluated quantitative and semi-quantitative methods for bioassessments in headwater streams salinized by coal mining during two time periods. I compared the two sampling methods for capability to detect SC-induced changes in the macroinvertebrate community. Quantitative sampling consistently produced higher estimates of taxonomic richness than corresponding semi-quantitative samples, and differences between sampling methods were found for community composition, functional feeding group, dominance, tolerance, and habit metrics. Quantitative methods were generally stronger predictors of benthic community-metric responses to SC and were more sensitive for detecting SC-induced changes in the macroinvertebrate community. Quantitative methods are advantageous compared to semi-quantitative sampling methods when characterizing benthic macroinvertebrate community structure because they provide more complete estimates of taxonomic richness and diversity and produce metrics that are stronger predictors of community response to elevated SC.
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    Integrative Bioassessment of Acid Mine Drainage Impacts on the Upper Powell River Watershed, Southwestern Virginia
    Soucek, David J. (Virginia Tech, 2001-05-14)
    Acid mine drainage (AMD), a result of oxidation of minerals containing reduced forms of sulfur (pyrites, sulfides) upon exposure to water and oxygen, is an environmental problem associated with abandoned mined lands (AML). Numerous studies have documented the impacts of AMD upon aquatic communities within acidified stream reaches; these impacts include reduced taxonomic richness and abundance, and/or a shift from pollution sensitive to pollution tolerant species. This dissertation comprises a number of integrative assessments and experiments conducted to investigate the nature of AMD ecotoxicity in the upper Powell River watershed. Emphasis was placed upon bioassessment methodologies and AMD impacts beyond the zone of pH depression. Major findings and processes developed included: 1) an Ecotoxicological Rating (ETR) system was developed that integrates chemical, toxicological, and ecological data into a single value depicting the relative environmental integrity of a given station within a watershed; 2) water column chemistry rather than sediment toxicity was the major factor causing acute toxicity to aquatic biota in close proximity to AMD discharges; 3) solid ferric hydroxide can cause acute toxicity to standard test organisms in the absence of dissolved iron; 4) Asian clams (Corbicula fluminea) can be used to detect both acutely toxic AMD inputs and nutrient loading in low order streams, and clam responses of survival and growth reflect those of indigenous communities to the two contaminant types; 5) aluminum (Al) in transition from acidic to neutral pH waters can cause acute toxicity to aquatic invertebrates, and may be the cause of impaired benthic macroinvertebrate communities in neutral pH (>7.0) waters downstream of an acidic tributary; 6) in the larger river system (North Fork Powell and Powell mainstem), urban inputs appear to have a greater influence upon aquatic communities than metal loading from AMD impacted tributaries; 7) the use of individual level assessment endpoints, such as Asian clam growth in in situ toxicity tests, eliminates variables that may confound attribution of community level impacts to contaminants; and 8) the near elimination of predatory stoneflies (Plecoptera) downstream of the Stone/Straight Creek tributary to the North Fork Powell River was associated with water column Al concentrations. This research was funded by the Virginia Department of Mines, Minerals, and Energy, Division of Mined Land Reclamation, and by the Powell River Project.
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    Levels of Dissolved Solids Associated with Aquatic Life Effects in Headwater Streams of Virginia Central Appalachian Coalfield Region
    Timpano, Anthony J.; Schoenholtz, Stephen H.; Zipper, Carl E.; Soucek, David J. (Virginia Tech. Powell River Project, 2011)
    Benthic macroinvertebrate communities in headwater streams influenced by Appalachian coal mining often differ from communities in minimally disturbed streams. Elevated levels of total dissolved solids (TDS) associated with mining have been suggested as stressors to these communities. In studies of such streams conducted to date, both non-TDS stressors and elevated TDS have been present as potential influences on biota. In the study reported here the association between dissolved salts and benthic macroinvertebrate community structure was examined using a familylevel multimetric index and genus-level taxa sensitivity distributions. Test sites were selected along a gradient of elevated TDS, with non-TDS factors of reference quality. Virginia Stream Condition Index (VASCI) scores were regressed against log-transformed measures of TDS, specific conductance, and sulfate (SO4 2-) using ordinary least squares and quantile regression techniques. Biological effects, as defined by VASCI scores <60 indicating stressed or severely stressed conditions, were observed with increasing probability from 0% at ≤ 190 mg/L TDS to 100% at ≥ 1,108 mg/L TDS, with 50% probability of effects observed at 422 mg/L TDS. Associations between water quality measures and biological condition were variable, with approximately 48% of the variance explained by TDS. Genus-level analysis using a field sensitivity distribution approach indicated 95% of reference genera were observed at sites with TDS ≤ 281 mg/L, and 80% of genera were observed at sites with TDS ≤ 411 mg/L. This is evidence that TDS, specific conductance, or SO4 2-can be used to establish dissolved solids levels for streams influenced by Appalachian coal mining above which aquatic life effects are increasingly probable.
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    Levels of Dissolved Solids Associated with Aquatic Life Effects in Headwater Streams of Virginia's Central Appalachian Coalfield Region
    Timpano, Anthony J. (Virginia Tech, 2011-03-16)
    Benthic macroinvertebrate communities in headwater streams influenced by Appalachian coal mining often differ from communities in minimally distrubed streams. Total dissolved solids (TDS) associated with mining have been suggested as stressors to these communities. In studies of such streams conducted to date, both non-TDS stressors and elevated TDS have been present as potential influences on biota. Here the association between dissolved salts and benthic macroinvertebrate community structure was examined using a family-level multimetric index and genus-level taxa sensitivity distributions. Test sites were selected along a gradient of elevated TDS, with non-TDS factors of reference quality. Virginia Stream Condition Index (VASCI) scores were regressed against log-transformed measures of TDS, specific conductance, and sulfate (SO42-) using ordinary least squares and quantile regression techniques. Biological effects, as defined by VASCI scores indicating stressed or severely stressed conditions, were observed with increasing probability from 0% at ≤ 190 mg/L TDS to 100% at ≥ 1,108 mg/L TDS, with 50% probability of effects observed at 422 mg/L TDS. Associations between water quality measures and biological condition were variable, with approximately 48% of the variance explained by TDS. Genus-level analysis using a field sensitivity distribution approach indicated 95% of reference genera were observed at sites with TDS ≤ 281 mg/L, and 80% of genera were observed at sites with TDS ≤ 411 mg/L. This is evidence that TDS, specific conductance, or SO42- can be used to establish dissolved solids levels for streams influenced by Appalachian coal mining above which aquatic life effects are increasingly probable.
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    Selenium Dynamics in Headwater Streams of the Central Appalachian Coalfields: An Investigation of Enrichment and Bioaccumulation
    Whitmore, Keridwen McLeyne (Virginia Tech, 2017-02-06)
    Surface coal-mining is a source of selenium (Se) contamination in streams of the Appalachian coalfields. Selenium dynamics in aquatic systems are complex and largely controlled by site-specific factors, but have been understudied in Appalachian headwater streams. In this study, we evaluated the degree and dynamics of Se enrichment and bioaccumulation in headwater streams influenced by coal-mining. Based on Se concentrations in macroinvertebrates collected from 23 headwater streams, nine sites were selected for further study: three reference streams with no history of coal-mining, and six streams influenced by coal mining. Mining-influenced streams were further separated into high-Se and low-Sestreams based on macroinvertebrate tissue Se concentrations. Water-column, sediment, biofilm, leaf detritus, and prey and predator macroinvertebrates were collected and analyzed for Se concentration during two sample periods, Sept. - Oct. 2015 and Feb.-March 2016. Selenium concentrations in all media were found to be elevated in mining-influenced over reference streams and in high-Se over low-Se streams. Selenium dynamics, enrichment in particulate media (sediment, biofilm and leaf detritus) and trophic transfer of Se to prey from particulate media and to predators from prey, did not exhibit major differences among streams of differing Se levels. Water column Se concentrations were predicative of Se concentrations in macroinvertebrate tissues. Findings from this study indicate headwater streams influenced by coal-mining are capable of a high degree of Se bioaccumulation in macroinvertebrate populations.
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    Temporal and longitudinal extent of surface coal mining influences on water quality and benthic macroinvertebrate communities in central Appalachian headwater streams
    Cianciolo, Thomas R. (Virginia Tech, 2019-06-18)
    Increased loading of dissolved ions (salinization) and trace elements from surface coal mining is a common alteration to headwater streams in the central Appalachian region. However, temporal and spatial trends of water quality and associated influences on biota in these stream systems have not been well-studied. To address this research need, I analyzed temporal trends in specific conductance, ion matrix, and benthic macroinvertebrate communities in 24 headwater streams, including 19 influenced by surface mining, from 2011-2019. There was limited evidence of recovery of water chemistry or macroinvertebrate communities in these streams, indicating lasting impacts from surface coal mining. Among benthic macroinvertebrates, Ephemeroptera and the scraper functional feeding group were most-impacted by chronic salinization in study streams. In addition, I analyzed spatial patterns of water chemistry in a subset of these streams using synoptic sampling of multiple constituents under baseflow and highflow conditions. Study results indicate that water chemistry is spatially dynamic and can be influenced by both groundwater dilution and inputs from tributaries. Lastly, I investigated patterns in selenium bioaccumulation across and within streams, from particulate matter to top trophic levels (i.e. fish and salamanders). I found that benthic macroinvertebrates had the highest concentrations of selenium in these ecosystems, with lower concentrations in salamander and fish species. However, there was limited evidence of longitudinal trends in bioaccumulation dynamics downstream of mining impacts. Collectively, this work indicates long-term (ca. decades) coal-mining influences but also highlights future research needs to better understand downstream impacts to water quality and biotic communities.
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    Temporal Dynamics of Benthic Macroinvertebrate Communities and Their Response to Elevated Specific Conductance in Headwater Streams of the Appalachian Coalfields
    Boehme, Elizabeth A. (Virginia Tech, 2013-08-27)
    Prior studies have demonstrated Appalachian coal mining often causes elevated specific conductance (SC) in streams, and others have examined SC effects on benthic macroinvertebrate communities using point-in-time SC measurements. However, both SC and benthic macroinvertebrate communities exhibit temporal variation. Twelve Appalachian headwater streams with minimally impacted physical habitat and reference-quality physicochemical conditions (except elevated SC) were sampled ten to fourteen times each for benthic macroinvertebrates between June 2011 and November 2012. In situ loggers recorded SC at 15-minute intervals. Streams were classified by mean SC Level (Reference 17-142 S/cm, Medium 262-648 S/cm, and High 756-1,535 S/cm). Benthic macroinvertebrate community structure was quantified by the Virginia Stream Condition Index and other metrics. Structural metric differences among SC Levels and month of sampling were explored. Reference-SC streams exhibited significantly higher scores on most metrics, supporting previous findings that SC may act as a biotic stressor, even in streams lacking limitations from degradation of physical habitat or other physicochemical conditions. Temporal variation was greatest in Medium-SC streams, which had the most metrics exhibiting significant differences among months and the greatest range of monthly means for six metrics. Metrics involving % Plecoptera and/or % Trichoptera were not sensitive to elevated SC, as Leuctridae and Hydropsychidae exhibited increased abundance in streams with elevated SC. Best scores for benthic macroinvertebrate community metrics differed based on selected metric, SC Level, and month. Consequently, timing of sampling is important, particularly in streams with elevated SC because community metric scores may be impacted by dominant taxa life history patterns.
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    Temporal Dynamics of Benthic Macroinvertebrate Communities and Their Response to Elevated TDS in Appalachian Coalfield Streams
    Boehme, Elizabeth A.; Schoenholtz, Stephen H.; Soucek, David J.; Timpano, Anthony J. (Virginia Tech. Powell River Project, 2012)
    Maintaining integrity of benthic macroinvertebrate communities in Appalachian coalfield headwater streams is a key concern. Total dissolved solids (TDS) are ubiquitous as dissolved constituents in surface waters and often occur at elevated levels in streams draining Appalachian coal mines. Most TDS in surface waters originate from the dissolution of rock and mineral materials that are exposed to the natural elements; this process is accelerated in mining regions, as surface mines cause large volumes of fresh, unweathered rock material to be fractured, brought to the surface, and exposed to accelerated weathering processes. The concentration of TDS is closely related to specific conductance (SC), which is the ability for water to conduct a current at 25º C. We have been conducting research to identify benthic macroinvertebrate community composition relationships with TDS in southwestern Virginia’s mining area, where geology and environmental conditions are similar to adjacent coal‐mining areas of eastern Kentucky and southern West Virginia. This report summarizes the first year of a two‐year study, aimed to expand understanding of temporal variability within the benthic macroinvertebrate community in elevated‐TDS streams. Eleven sets of benthic macroinvertebrate and water quality grab samples have been collected to date and are being analyzed; and continuous conductivity loggers have been installed in all streams. Sampling will conclude in November 2012.
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    Total Dissolved Solids in Appalachian Coalfield Streams: Current Research Approaches
    Zipper, Carl E.; Schoenholtz, Stephen H.; Soucek, David J.; Timpano, Anthony J.; Boehme, Elizabeth A. (Virginia Tech. Powell River Project, 2011)
    Issues concerning total dissolved solids (TDS) in streams affected by mining operations are important to the coal industry. In this article, we present background concerning TDS as a water quality concern, and we describe ongoing Virginia Tech research approaches to address this issue.
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    Toward improved assessment of freshwater salinization as a benthic macroinvertebrate stressor
    Timpano, Anthony J. (Virginia Tech, 2017-09-27)
    Salinization of freshwaters by human activities is of growing concern globally. Salt pollution can cause adverse effects to aquatic biodiversity, ecosystem function, ecosystem services, and human health. In many regions of the world, and in coal-mining-influenced streams of the temperate forests of Appalachia USA, specific conductance (SC), a surrogate measure for the dissolved major ions composing salinity, has been linked to decreased diversity of benthic macroinvertebrates. However, assessments used to reach this conclusion have generally not accounted for temporal variability of salinity, as most studies use "snapshot" SC data collected concurrently with biological data at a single point in time. Effective management of salinization requires tools to accurately monitor and predict salinity while accounting for temporal variability. To improve those tools, I conducted analyses of 4.5 years of salinity and benthic macroinvertebrate data from 25 forested headwater streams spanning a gradient of salinity where non-salinity stressors were minimized. My objectives were to: 1) model the annual pattern of salinity, 2) determine if salinity measures derived from continuous data are more precise than snapshot SC as predictors of aquatic biology, and 3) quantify response to salinity of the benthic macroinvertebrate community. A sinusoidal model of the annual cycle of SC using daily measurements for 4.5 years revealed that salinity naturally deviated ± 20% from annual mean levels, with minimum SC occurring in late winter and maximum SC occurring in late summer. The pattern was responsive to seasonal dilution as driven by catchment evapotranspiration dynamics. Alternative discrete sampling intervals can approximate the pattern revealed by continuous SC data if sampling intervals are ≤ 30 days. Continuous SC variables did not significantly improve precision for prediction of benthic macroinvertebrate metrics (p > 0.1) as compared to snapshot SC using generalized additive mixed models. Results suggest that snapshot SC is a capable predictor of benthic macroinvertebrate community structure if sampling is carefully timed. However, continuous SC data can quantify chronic salt exposure, which supports a hypothesis to explain how temporal variability of field-based observations of salt sensitivity of benthic macroinvertebrate taxa may be influenced by life stage. Benthic macroinvertebrate community structure diverged from reference condition as salinity increased, with stronger relationships in Spring than in Fall. Intra-seasonal variation in community structure was also revealed across sampling dates. Non-Baetidae Ephemeroptera were most sensitive to salinity, with richness and abundance lower than reference at SC > 200 =µS/cm in Spring based on snapshot SC. Equivalent effects were predicted by mean monthly SC of 250-300 µS/cm from the prior Fall. Continuous conductivity monitoring may improve assessment of salinity effects because they can describe life-cycle exposure, which may aid investigations of mechanisms driving field-based observations of benthic-macroinvertebrate community alteration.