Degraded rivers and streams caused by disturbances have created a need for reliable tools to assess the ecological status of such ecosystems. Numerous methods and programs have been developed to assess ecological status using biological indicators, benthic macroinvertebrates are the most commonly used biotic indicator. The Hester-Dendy multi-plate sampler is a commonly used tool for sampling benthic macroinvertebrates, but its effectiveness under different environmental conditions has not been adequately tested. The aim of this study was to investigate if HD samplers assess the benthic macroinvertebrate community equally under different flow conditions. I investigated if the colonization of BMI in a constant flow differed from that of a variable flow (simulating a hydropeaking flow regime). This was studied using six aquariums, three as control with constant flows and three with variable flow conditions. One Hester-Dendy sampler and 50 benthic macro invertebrates from five different taxonomic orders were place in each aquarium. After five days of colonization the Hester-Dendy samplers were retrieved and benthic macroinvertebrates colonizing the Hester-Dendy samplers and still remaining in the aquariums were collected, preserved and analysed. Results showed that the mean sampling efficiency did not differ between the two treatments. On the other hand species diversity calculated from Shannon-Wiener index was significantly higher in the control treatment than in the variable flow treatment. The lower species diversity in the variable flow treatment is consistent with previous research on benthic macroinvertebrates affected by hydropeaking powerplants. These results can be seen as an indication of how a variable flow regime might affect the samples collected by HD samplers in a natural environment. As the artificial environments created are greatly different from a natural environment, this result might not therefore be representative in a natural environment. / Vattendrag kraftigt påverkade av antropogena störningarna har skapat ett behov av tillförlitliga verktyg för att kunna bedöma dessa vattendrags ekologiska status. Många olika metoder och program har utvecklats genom att använda olika biologiska indikatorer. Bentiska makroevertebrater är en av de vanligaste biotiska indikatorerna. En vanlig metod för att prov ta bentiska makroevertebrater är Hester-Dendy provtagaren. Syftet med denna studie var således att testa om provtagningseffektiviteten för Hester-Dendy provtagare påverkas olika av ett variabelt vattenflöde jämfört med ett jämnt vattenflöde. Detta studerades i sex akvarium, där tre akvarium agerade kontroll och utsattes för ett jämt flöde samt tre akvarium med variabelt flöde. En Hester-Dendy provtagare och 50 bentiska makroevertebrater från fem olika taxonomiska ordningar placerades i varje akvarium. Efter fem dagars koloniserings tid hämtades Hester-Dendy provtagarna och de bentiska makroevertebrater som koloniserade provtagaren såväl som akvariet bevarades i etanol och analyserades i labbet. Resultaten visade att den genomsnittliga provtagningseffektiviteten inte skilde sig åt mellan de två behandlingarna. Däremot var artdiversiteten beräknad med Shannon-Wiener-index signifikant högre i kontrollbehandlingen. Den lägre artdiversiteten i behandlingen med variabelt flöde stämmer överens med tidigare forskning om bentiska makroevertebrater påverkade av korttidsreglerande vattenkraftverk. Resultaten i denna studie bör ses som en indikation av hur ett varierande flöde kan påverka provtagnings effektiviteten hos en Hester-Dendy-provtagare. Detta med anledning av att den konstgjorda miljön som försöket utfördes i är vitt skilt från organismernas naturliga miljö vilket kan ha påverkat resultatet.

Benthic macroinvertebrates are heavily relied on to indicate stream condition because of their ease of sampling, broad span of sensitivities to pollution among taxa, and diverse life histories that utilize various habitats and environmental conditions. Surface-coal mining in central Appalachia often results in salinization of headwater streams, with documented responses in macroinvertebrate communities across streams that vary in specific conductance (SC), an index of degree of salinization. Mining-influenced headwater streams can also exhibit within-stream spatial variation in SC, frequently via dilution with downstream distance from mining. However, the extent to which coal-mining alters downstream patterns in water chemistry and macroinvertebrate communities is largely unknown. This study aimed to determine macroinvertebrate community responses to physical and chemical gradients within six Appalachian headwater streams (four mining-impacted, two reference). Streams were sampled for benthic macroinvertebrates, habitat characteristics, and water chemistry in fall 2021 and spring 2022 at six-to-nine locations per stream over a range of 1.5 – 3 km. Mining-impacted streams exhibited greater spatial variation in macroinvertebrate community composition compared to reference streams, particularly in spring. Bray-Curtis Community similarity determined highly-impacted streams experienced the greatest within-stream shifts in community similarity. Metrics of macroinvertebrate communities and community similarity showed some correlation with SC at within-stream scales, particularly in highly impacted streams in spring; however, such trends were much fewer and weaker compared to relationships among streams when collectively examining communities. Redundancy Analysis (RDA) and Variation Partitioning (VP) indicated water quality, habitat, and location do overlap in explanation of community variation although they often additionally explain variance in unique ways. Significant variables identified by RDA within at least two of the six streams include channel slope, streamwater nutrients and hardness, stream channel embeddedness, and percent fines comprising the streambed. Redundancy Analysis also indicated 18 key macroinvertebrate taxa in study streams responding to location within stream, habitat, and water quality. Of those 18 taxa shredders, collectors, and clingers were most frequently impacted. Improved understanding of the spatial scale of coal-mining influences on headwater stream characteristics will help inform bioassessment protocols to most accurately assess stream condition, and inform remediation efforts within the central Appalachian region and in other salinized stream systems. / Master of Science / Small streams (or headwater streams) originating in the central Appalachian Mountains harbor a variety of unique organisms and are essential to the quantity and quality of downstream freshwater for fishing, recreation, and other uses. Coal mining processes, including disturbance of coal-bearing bedrock, often increases the streams salinity by adding pollutants that elevate dissolved minerals, or salts. Salinization of streams can come from a variety of sources in addition to coal mining such as de-icing road salts and crop irrigation and is of growing concern regarding its impacts to the quality of freshwater available for wildlife and human use. A common way to determine stream health is by identifying which aquatic insects (or macroinvertebrates) are present in a stream, because different groups are present based on the type and intensity of a variety of pollutants. Previous studies determined stream health by identifying insects from one location in a stream and comparing it to others. Stream's habitat and water quality naturally change as they join with larger rivers and flow to lower elevations causing different macroinvertebrates to be present at locations within streams. This study aimed to determine how changes along stream distances may be different in streams salinized from coal mining. The objectives of this study were to determine if one sample is adequate to represent the entire condition of a headwater stream. Six streams were sampled for macroinvertebrate, water quality, and habitat at six-to-nine locations within each stream over distances of ca. 2,000 m. Four streams were impacted by mining, of which two were highly impacted and two were impacted to a low-level; the last two streams were unimpacted to represent reference condition. The study found the type and number of macroinvertebrates within streams were changing least within reference streams and most in highly impacted streams. Macroinvertebrate communities in highly-impacted streams changed more within streams because they had high concentrations of dissolved salts upstream near the source of coal-mining pollution and these salts diluted with distance downstream, most likely due to fresh spring water contributions with minimal dissolved salts. Therefore, highly-impacted headwater streams experience greater environmental and macroinvertebrate variability indicating more than one sample location may be helpful in accurately assessing what macroinvertebrates inhabit the stream length of interest. Ensuring accurate sampling technique to determine stream condition is essential to our understanding of stream health and how to remediate and monitor impacts of salinization on our freshwater resources.

Invasions from coho salmon were first reported in the Cape Horn Biosphere Reserve (CHBR) in 2019 which is the most southern distribution registered to date. The CHBR is known for its high number of endemic species and unique biodiversity, such as the native fishes Galaxias maculatus and Aplochiton taeniatus. There are now three invasive salmonid species in the rivers of CHBR and are a potential threat to the native fish taxa. Stable isotope and gut content analysis were used to understand resource utilization by both native galaxiid and invasive salmonid taxa, as well as aquatic macroinvertebrates and riparian spiders. The natural laboratory study approach applied to this research, allowed for comparisons of differences within streams that contain conditions in which fish do not occur naturally, to sites in which high densities of invasive salmonid exist. Analysis of the trophic niche and diet in this study showed the importance of marine resource use by the native galaxiid and coho salmon juveniles supported with elevated δ15N and δ34S ratios. Diet analysis also confirmed there was the highest similarity between the coho salmon juveniles and the native fish. Altered behavior and habitat use was shown through the isotope and diet analysis for the galaxiid in snow melt streams which could be due to the high density of invasive salmonids in these streams. The invasive salmonids were found to impact aquatic macroinvertebrate populations, specifically larger bodied Trichoptera abundance. Aquatic insect emergence was negatively correlated to salmonid densities. The aquatic insect emergence revealed alterations with significantly higher biomass of aquatic insect emergence in upstream sites without invasive fish. Lastly, aquatic insect predator (Hydrobiosidae: Rheochorema sp.) exhibited a suppressed trophic position in rivers with invasive salmonids. An unexpected finding from the study was the refugium stream habitat conditions that has been shown to be important for conserving the native fish in the CHBR. We conclude that the impacts from invasive species are significant enough to disrupt lower trophic levels especially aquatic insects. The altered aquatic emergence and insect behavior have the potential to disrupt food webs and ecosystem functioning in the southernmost protected ecoregion in the world.

The Dallas-Fort Worth International (DFW) Airport is located in a densely urbanized area with one of the fastest-growing populations in the U.S.A. The airport property includes a large tract of "protected" riparian forest that is unique to the urban surroundings. This dissertation explores variables that influence the benthic macroinvertebrate community structure found in urbanized prairie streams that were initially assessed by the University of North Texas (UNT) Benthic Ecology Lab during four, non-consecutive biomonitoring studies (2004, 2005, 2008, and 2014) funded by the DFW Airport. Additionally, land use analysis was performed using 5-meter resolution satellite imagery and eCognition to characterize the imperviousness of the study area watersheds at multiple scales. Overall, flow conditions and imperviousness at the watershed scale explained the most variability in the benthic stream community. Chironomidae taxa made up 20-50% of stream communities and outperformed all other taxa groups in discriminating between sites of similar flows and urban impairments. This finding highlights the need for genus level identifications of the chironomid family, especially as the dominant taxa in urban prairie streams. Over the course of these biomonitoring survey events, normal flow conditions and flows associated with supra-seasonal drought were experienced. Prevailing drought conditions of 2014 did not negatively influence stream communities, allowing this study to capture the long-term natural (temporal) variability of urban prairie stream communities. Such long-term studies are imperative for discerning between stream impairment versus natural variation, especially as droughts become more frequent and severe.

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An increase in public environmental awareness and a decrease in resources within government regulatory agencies have led to a larger interest in volunteer biomonitoring programs. Government agencies are currently using volunteer data for official purposes with increasing frequency, but questions have been raised about the validity of the data collected by volunteers who have only limited training and experience. Therefore, we conducted a detailed study to assess, modify, and validate the Virginia Save-Our-Streams (SOS) program, which is a volunteer organization collecting macroinvertebrate data. Sites were sampled using professional methods concurrently with volunteers who utilized the SOS protocol. The volunteer samples were retained for further laboratory analysis. In addition, numerous sites previously sampled by volunteers were re-sampled using professional methods. The data were statistically analyzed to determine if the results of volunteers and professional aquatic biologists were correlated and if they arrived at the same conclusions about ecological condition. It was determined that the Virginia SOS method, and probably other similar volunteer methods, consistently overrate ecological condition. This means that streams impaired by pollution could go unreported, if they are monitored exclusively by volunteers. The cause of this overestimation was determined to be the overly simplistic SOS metric, which is based solely on the presence or absence of taxa. The SOS protocol for data analysis was made more quantitative by developing a multimetric index that is appropriate for use by volunteers. The SOS sampling protocol was modified slightly to obtain actual counts of the different kinds of macroinvertebrates, which allowed for calculation of metrics. Sorting effort and taxonomic level of identification were not changed so that currently participating volunteers would not be excluded because of the need for expensive equipment or advanced technical training. The modified SOS protocol was evaluated by a different set of concurrent samples taken by volunteers and professionals, but using the same statistical techniques. The modified SOS protocol proved to be feasible for volunteers. The new SOS multimetric index correlated well with a professional multimetric index. The conclusions about ecological condition derived from the volunteer multimetric index agreed very closely with those made by professional aquatic biologists. This study demonstrated that volunteer biomonitoring programs can provide reliable data, but every volunteer program needs to be thoroughly validated by statistical comparisons to the professional methods being used in that area. / Master of Science

Cattle exclusion from streams is believed to improve riparian vegetation, in-stream habitat, and composition of aquatic organisms. Yet research on the effects of cattle exclusion have yielded conflicting results. The goal of this study was to examine relationships between physical habitat and benthic macroinvertebrate populations with increasing downstream distance from cattle-impacted stream segments, and determine which physical habitat and chemical water quality parameters are affected by cattle presence. Macroinvertebrates from 24 sites in Rockingham County, VA were used to calculate bioassessment metrics. Fourteen sites made up 4 longitudinal studies where improvement of biotic condition with distance from cattle impact was examined. Linear regression and multilevel modeling results indicated improving macroinvertebrate assemblage with increasing distance downstream from cattle-impacted reaches. Presence of riparian trees and distance from impact had a positive influence on bioassessment scores. A total of 39 stream sites in the Shenandoah Valley were classified using the Rapid Habitat Assessment (RHA) which is based on 10 visual evaluations of physical characteristics. Four of the ten RHA parameters, embeddedness, bank stability, vegetative protection, and riparian vegetative zone width, along with the total RHA score, were associated with cattle presence. This study found that a) RHA factors reflect direct cattle impacts on the riparian zone, but RHA has limitations as a general predictor of cattle impact, b) cattle influence on benthic macroinvertebrates extends hundreds of meters beyond the immediate pasture boundary, and c) improvement in Virginia Stream Condition Index can be predicted as a function of distance downstream. / Master of Science

Measurements in paired stream reaches with and without livestock access in southwestern Virginia suggest that livestock exclusion practices installed on short, isolated stream reaches result in improved geomorphic and riparian vegetation condition, but do not significantly improve the benthic macroinvertebrate assemblage. Detailed longitudinal and cross-sectional surveys, pebble counts, and rapid geomorphic assessments were conducted on contiguous, paired stream reaches (5 pairs) with and without active livestock access across a range of time since livestock exclusion was implemented. In addition, bank characteristics were quantified by measuring groundcover biomass, shrub crown volume, tree density and diameter, soil bulk density, and particle-size analysis. Benthic macroinvertebrates were collected with a D-frame dip net and quantified using the Virginia Stream Condition Index (SCI), and other benthic macroinvertebrate metrics. We determined that: 1) small lengths of livestock exclusion can significantly increase channel depth and decrease the width to depth ratio, and increase groundcover vegetation growth, but do not significantly alter benthic macroinvertebrate assemblages; and, 2) qualitative geomorphic assessment results showed trends over time since exclusion (0 to greater than 50 years), but not in any of the other parameters evaluated. These observations suggest that a more targeted and holistic approach that addresses watershed-wide impacts must be implemented to restore aquatic habitat. (Key Words: CREP, stream channel morphology, livestock exclusion, agriculture, benthic macroinvertebrates, riparian buffers.) / Master of Science

The goal of the Aquatic Indicators of Land Condition (AILC) project is to develop analytical tools that integrate land condition information with stream condition for improved watershed management within the United States Bureau of Land Management (BLM). Based on the goal of the AILC, two objectives for this study were: to determine the effect of four GIS-derived distance measurements on potential relationships between common BLM landscape stressors (mining and grazing) and changes in benthic macroinvertebrate community structure; and to assess the effectiveness of individual questions on a commonly-used Bureau-wide qualitative stream assessment protocol, the proper functioning condition (PFC) assessment. The four GIS distance measurements assessed for biotic relevance included: straight-line distance, slope distance, flow length, and travel time. No significant relationships were found between the measured distance to stressor and macroinvertebrate community structure. However, the hydrological relevance of flow length and travel time are logically superior to straight-line and slope distance and should be researched further. Several individual questions in the PFC assessment had statistically significant relationships with the final reach ratings and with field-measured characteristics. Two of the checklist questions were significantly related to the number of cow droppings. This may indicate a useful and efficient measure of stream degradation due to grazing. The handling and use of the PFC assessment within the BLM needs further documentation and examination for scientific viability, and the addition of quantitative measurements to the PFC in determining restoration potential would be desirable. / Master of Science