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Relationships between macroinvertebrate assemblages and environmental stressors were assessed from fall 2002 through spring 2004 in five small streams that represented a study design that involved a gradient of increasing stress (increased cattle density). Macroinvertebrate assemblages were related to environmental factors that were quantified at the sample scale. Environmental factors and macroinvertebrates were concurrently collected so that assemblage structure could be directly related to environmental variables and so that the relative importance of stressors associated with cattle grazing in structuring assemblages could be assessed. Macroinvertebrate metrics showed significant and strong responses to cattle density during most sampling periods. The majority of metrics responded negatively to the grazing gradient, while a few (total taxa richness, number of sensitive taxa, and % collector filterers) increased along the gradient before declining at the most heavily grazed sites. Total number of sensitive taxa and % Coleoptera had the strongest relationship with cattle density throughout the study period. Based on sample-scale, quantitative measures of environmental variables, measures of physical habitat (% fines and substrate homogeneity) were most important in structuring assemblages. Detrital food variables (coarse benthic and fine benthic organic matter) were secondarily important while autochthonous food variables (chlorophyll a and epilithic biomass) were not as important in influencing assemblage structure. Based on a comparative analysis of reach-scale habitat measures and estimates, quantitative measures of % fines, collected from within an enclosed sampler concurrently with macroinvertebrates, were the best predictor of macroinvertebrate assemblages. Quantitative measures and visual estimates of riparian and channel characteristics had strong relationships with macroinvertebrate metrics but the relationships were never as strong as those detected with instream measurements of % fines. The channel characteristic, bank height, was the best predictor of % fines. / Ph. D.

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. / Ph. D.

Hollow fills are composed of excess spoil and debris produced from surface coal mining that is not returned to the original mined site. Hollow fills are often constructed in the head of hollows nearby or adjacent to the mined land area, which may be the origins of headwater streams or drain into low order systems. Eleven hollow fills were utilized in evaluating the influence fill drainages had on low order streams in Virginia and West Virginia. The study was conducted in six watersheds including; Five Mile Creek in Mingo County, West Virginia, Trace Fork in Mingo County, West Virginia, Lavender Fork in Boone County, West Virginia, Middle Creek in Tazewell County, Virginia, South Fork of the Pound River in Wise County, Virginia, and Powell River in Wise County, Virginia. Bioassessment procedures used in the evaluation of hollow fill drainages included water/sediment chemistry, acute water column toxicity testing using <i>Ceriodaphnia dubia</i>, chronic sediment toxicity testing using <i>Daphnia magna</i>, benthic macroinvertebrate surveys, and <i>in situ</i> Asian clam (<i>Corbicula fluminea</i>) toxicity testing. Common significant differences in water quality between reference and fill influenced sites, among all watersheds, were elevated conductivity and water column metal concentrations, particularly aluminum and copper. Water column and sediment toxicity testing reported limited significant mortality or reproductive impairment associated with hollow fill drainages. The West Virginia watersheds used in the study consisted of headwater streams originating directly from the settling ponds, placed at the base of the hollow fills, receiving drainages from the fills. Benthic macroinvertebrate analysis reported no significant alteration in total taxa or EPT richness downstream of the ponds. Yet, collector filterer populations, including benthic macroinvertebrates and <i>in situ</i> Asian clams, were enhanced directly downstream of the ponds due to organic enrichment originating from the ponds. A decrease in collector filterer populations and lowered clam growth suggested the organic enrichment dissipated downstream from the ponds. Chlorophyll <i>a</i> analysis of the phytoplankton community was not significantly related to the enhance collector filterer populations in the streams, however the high concentrations in the settling ponds suggest abundant algal communities. The hollow fills evaluated in Virginia drained into receiving systems, whose headwater origins were not directly related to hollow fill drainages. Low taxa richness was associated with the hollow fill and settling pond drainages, however receiving system sites were minimally influenced. Yet, as reported in the West Virginia watersheds, the settling ponds input organic enrichment that enhanced collector filterer populations, including benthic macroinvertebrates and <i>in situ</i> test clams. An analysis of the hollow fills' age, or maturity, reported no significant difference between young and old fills. In general, a common feature of among the various aged fill drainages was elevated conductivity, compared to reference sites of the watersheds. / Master of Science

Arsenic is a naturally occurring element, which is toxic to aquatic biota especially in disturbed areas where it may be found at high concentrations. A headwater stream adjacent to an 85 year-old abandoned arsenic mine was investigated to determine the influence of arsenic on stream biota and processes using an upstream (reference) and downstream (mine-influenced) comparative approach. Arsenic concentration was measured monthly at 10 sites along the stream length. Benthic macroinvertebrate surveys were conducted in both reaches five times throughout the course of a year. Leaf breakdown assays were conducted in reference and mine-influenced reaches. Leaf biofilm respiration was recorded during leaf breakdown assays and also with experimental arsenic additions to reference reach leaf biofilms. At the field site, arsenic concentrations varied from below detection limit (<2.5µg/L) to more than 12 mg/L. Macroinvertebrate density was greatly reduced down-gradient of the mine with 154 individuals/m2, while upstream there were 7869 individuals/m2. Leaf biofilm respiration rates were comparable to others found in the literature and not significantly different between reference and mine-influenced reaches. Further, experimental additions of arsenic did not alter biofilm respiration under laboratory conditions. However, shredder abundance on leaf packs was eight to twenty times greater upstream than the mine-influenced reach. Leaf breakdown rate varied two to three fold among sites distributed above and below the mine and were significantly lower in reaches of elevated arsenic concentration. Together, these data suggest that the mining operations on this headwater stream have altered organic matter processing primarily by decreasing invertebrate densities and limiting shredder abundance. / Master of Science

I investigated the relationships between historical and contemporary land cover and macroinvertebrate communities, water quality, and nutrient levels in 10 streams in a historically agricultural region of the Virginia Piedmont. Historical (1963) and contemporary (2011) impervious surface, open area, and forested cover were evaluated using aerial photos and GIS data. Macroinvertebrates were collected in the fall of 2012 and spring of 2013. Water quality parameters (temperature, conductivity, alkalinity, hardness, and DO) and nutrient concentrations (NH3+NH4, PO4-P, NO3-N, Cl, and SO4) were measured at each site. Overall, forest cover decreased by 6.29%, open area decreased by 1.46%, and impervious surface increased by 4.83% from 1963 to 2011. Macroinvertebrate communities were explored using Principal Coordinates Analysis and were found to be significantly related to 2011 percent impervious surface. Water quality parameters were not significantly related to contemporary or historical land cover. Nitrate was negatively related with 2011 forest cover and positively related with 2011 open area; chloride was positively related with 2011 impervious surface and negatively related with 2011 open area. For the 10 watersheds included in this study, contemporary land cover is a better predictor of macroinvertebrate assemblages and nutrient concentrations than historical land cover. / Master of Science

Vernal pools are often defined as seasonal pools that typically are inundated beginning in the winter and then drying out completely in summer. Though evidence of spatial and temporal variability in the macroinvertebrate communities of vernal pools has been found in previous studies, it has not been studied extensively. The primary objective of this study was to determine the extent of variability in the macroinvertebrate communities within vernal pools closely situated in a forested landscape. An effort was made to explain this variability with respect to certain physiochemical environmental variables of the pools. Significant variability was observed in the macroinvertebrate communities within the vernal pools both spatially and temporally. Water temperature, as an indicator of seasonal changes, was strongly correlated with the observed variations. Higher species richness and diversity were observed in the pools in winter than in spring 2007. Chironomidae was the most diverse family (8 genera) occurring in these vernal pools. At the beginning of inundation, amphipods and copepods were more abundant. β-diversity was low in both winter and spring 2007; α-diversity in winter was high and low in spring 2007.

The term hydropeaking refers to anthropogenically induced, short-duration, high-magnitude discharge pulses that are generated in lotic systems for electricity production. The practice of hydropeaking produces the largest source of renewable energy worldwide, and its use is projected to increase through the year 2040. The primary objective of this work was to evaluate the effects of hydropeaking on benthic macroinvertebrate assemblages, which are important components of lotic ecosystems. Results of this work show that, across a wide range of impacted systems worldwide, the consistently observed patterns of elevated benthic macroinvertebrate drift in response to hydropeaking pulses are primarily related to the rate at which discharge is increased (i.e., ramping rate) and secondarily to the time between pulses. In addition, it was shown that taxa inhabiting depositional habitat patches (i.e. fine substrates and slow water velocities) were most susceptible to peaking-induced drift, and that these taxa were also those most prevalent in hydropeaking-impacted systems. Collectively, these results suggest that increased pulse ramping rate and the resulting elevated macroinvertebrate drift may be positive selective forces, which benefit populations adapted for life in hydropeaking-impacted lotic ecosystems. These results provide a greater understanding of the factors that are most important for governing the effects of hydropeaking on benthic assemblages.

Philosophiae Doctor - PhD / River systems are by nature complex and dynamic systems, which vary in structure and therefore function, and are closely connected to their landscapes. The primary aim of this thesis was to develop a systems operational understanding of how river patterns and processes (geomorphology and hydrology) link to aquatic and riparian systems and biodiversity (ecology) in a framework of evolving land cover/use and management. This illustrated the hydrogeomorphic controls regulating the structure and functioning of rivers in the provision of goods and services that vegetation, especially riparian vegetation, perform as ecological infrastructure, with a focus on the Duiwe River catchment. This study used a combination of desktop and field analysis. The desktop analysis followed the spatial and temporal historical land use change detection of river sub-catchments to assess the influence on water quality and river flow. It included historical water quality, flow records, rainfall data and aerial photograph time series analysis for trend detection, which were linked to changes in land use activities. The field surveys included cross-section surveys, physical and chemical sediment analysis, vegetation distribution, ground-water depth surveys and instream biological surveys of aquatic bioindicators. The study illustrated a correlation between land cover/use, water quality and river ecological integrity. When spatial heterogeneity of the catchments was altered by human or natural events, it was reflected by changes in the water quality. The linkages between the land cover/use and ecological integrity were examined using macroinvertebrates and algae. Macroinvertebrates were indicative of habitat integrity and river condition, while the benthic filamentous algae were indicative of increased nutrients and alkalinity. Results indicated that the full consortium of algae and macroinvertebrates be used as bioindicators for ecological integrity assessments in these short, coastal rivers. The influence of riparian vegetation and its effectiveness in providing regulating (retaining sediment and nutrients) and provisioning (good water quality for humans and the aquatic environment) services was examined by relating contrasting land uses, riparian vegetation, nutrient dynamics and water quality. The land covers generated different runoff volumes, water quality parameter concentrations and associated nutrient loads. Agriculture and alien Acacia mearnsii trees had the greatest impact on nutrient loads. However, a decreasing trend in nutrient concentrations was observed in the cross-section from the pastures to the riparian zones to the river at all sites. The key findings from this study were formulated into a conceptual framework flow-chain model demonstrating the linkages between river pattern, processes and ecology in the provision of ecosystem services. This interdisciplinary investigation demonstrated strong links between climate, topography, hydrogeomorphology, land cover/use, human activities and their influence on ecological river integrity. The developed framework provides a hierarchical model to link the different disciplines. It illustrates the top-down constraints provided by the system controllers and habitat drivers, coupled with the anthropogenic impacts as controllers to determine the response of biological entities (riparian vegetation and aquatic biota) at different scales, to ultimately provide ecosystem services. It provides the basis for an understanding of the linkages, processes and interactions that allows, prevents or alters ecosystem service provision by river ecosystems and in the study context, by riparian buffer zones.

Forest management, including timber harvesting, is the primary land use activity in most of Sweden.  However, clear cutting forests (i.e., final felling) can create a number of environmental problems in aquatic ecosystems and their communities. To combat these affects, intact riparian ‘buffer zones’ are typically left along streams and lakes in the Swedish landscape. There are many ideas on how wide a buffer zone has to be, to maintain an optimal ecological and hydrological state of a stream. Not only is the width of buffer zones debated, but also their overall design, including whether un-buffered stream segments could be beneficial. This study aims to test the effects of riparian buffers on macroinvertebrate biodiversity and community composition in streams draining catchments with clear cutting.  To do this, I estimated the family richness and a variety of additional metrics from nine streams from southern Sweden in the Jönköping area. Three of the streams had intact buffers (&lt;5 meter), three had no buffers, and three were unharvested (i.e., forested) catchments that served as controls. This study used data and benthic invertebrate samples collected as part of a bigger study, which were picked and manually sorted by the author. Richness ranged from 3 families at one site to as many as 13 at another one. Total abundance ranged between sites from 19820/m2to 27920/m2individuals. Overall, the results showed no significant difference in any of the invertebrate metrics across the three stream types. However, family richness increased among sites as a function of water temperature. The lack of buffer effects reported here may reflect the extremely warm summer of 2018, which caused a massive drought and was the warmest one ever recorded in the parts of Sweden where the invertebrates were collected.