In this study of energy pathways in karst groundwater the first chapter examines spatial and temporal patterns of bacterial density and activity in the Dorvan-Cleyzieu karst aquifer, France. During baseflow, bacterial density and activity in the water column was similar in upper and lower zones of the aquifer. Floods apparently scoured inactive bacteria from the aquifer matrix but had little effect on respiring cells. Dissolved organic carbon was more abundant at the base of the aquifer, probably because of patchy distribution of particulate organic matter in upper aquifer zones that leached dissolved organic carbon. The temporal sequence of flooding and drying in the aquifer appears to play an important role in the maintenance of biofilms which should be important energy sources to higher trophic levels in the aquifer. The ecosystem expansion and contraction model, originally developed to describe surface streams, may be a good descriptor of spatial and temporal patterns of microbial films in karst aquifers. The process of leaf and wood breakdown in cave streams in Organ Cave, West Virginia is examined in Chapter 2. Leaf and wood breakdown rates and microbial biomass and respiration on leaves and wood were compared between cave streams with and without coarse particulate organic matter (CPOM) input from the surface to examine the role of CPOM input in leaf and wood breakdown. Breakdown rate and pattern of microbial colonization of leaves and wood were typical of results reported for surface streams. Unlike in surface streams, CPOM input did not influence breakdown rate or microbial colonization on leaves and wood, apparently because nutrients are not limiting in cave streams. Nutrient addition had little effect on microbial films on wood in either stream type. Gammarus minus is an important shredder in Organ Cave streams and G. minus colonization accelerated leaf breakdown rates. Leaf and wood transport rates were low and, when combined with breakdown rates, suggest that CPOM will be retained and transformed to fine particles near its entry point to the subsurface. In chapter 3 I examine cave stream food web structure and the role various organic matter sources in stream trophic dynamics. I used stable isotope (13C and 15N) natural abundance analysis and a 13C-acetate tracer release to establish feeding relationships and to trace the use and importance of bacterial carbon in cave streams with and without CPOM input. Cave streams contained three trophic levels consisting of organic matter sources, primary consumers, and predators. Patterns of 13C labeling in the stream were similar to that in similar studies of surface streams. 13C acetate was incorporated into epilithic biofilms and fine benthic organic matter (FBOM). Some primary consumers, Fontigens tartarea, Gyraulus parvus, and Physa were highly labeled and showed a longitudinal labeling pattern consistent with the consumption of epilithic biofilms. An epigean caddisfly, Dolophilodes, was highly labeled and probably feeds on suspended organic matter. Other primary consumers, Gammarus minus and Caecidotea holsingeri, feed on FBOM and epilithon. Two amphipods, Stygobromus emarginatus and S. spinatus, and a planarian, Macrocotyla hoffmasteri, are predators in the streams. Leaves and wood were not major energy sources directly used by stream animals. Dissolved organic matter (DOM) originating from soils appears to be the primary energy source for stream food webs by fueling bacterial production that is then used by higher trophic levels. Because epilithon C turnover times were relatively long (12.7 - 17 days), DOM can be immobilized in cave stream biofilms, enhancing the efficiency with which the microbial loop may transfer energy to higher trophic levels. / Ph. D.

Streams are constantly subject to downstream movement of materials. The role of fallen leaves in resisting downstream transport of particulates is largely unquantified. The litter exclusion study at Coweeta presented the opportunity to study a stream without litter input. I expected removal of leaf litter to reduce the capacity of the stream to retain fine particulate organic matter, FPOM. However, leaves are also a major source of FPOM. I studied the effect of leaf exclusion on FPOM transport by field sampling and by generating computer simulations of particle transport in the stream. Sampling of suspended particles during storms showed that although litter inputs and subsequent particle generation were greatly decreased (Wallace et al. 1997), storm exports did not differ significantly from those of the reference stream. This suggested that the effect of litter exclusion was to reduce FPOM retention. Although there was no new organic matter entering the stream during the exclusion period, entrainment of stored material compensated for it. The computer simulations predicted higher concentrations of FPOM for storms after litter exclusion than I actually measured except during heavy rains that greatly increased discharge. These results suggested that after litter exclusion, low-intensity storms exported lower concentrations than before exclusion. However, after exclusion, intense storms that greatly increased discharge entrained higher concentrations of FPOM. Both field studies and computer models indicated that stability of the litter-excluded streambed was lower compared to the reference and pre-treatment streams, and stability was further reduced with increased discharge. / Master of Science

Macroinvertebrate assemblage structure was compared from 12 streams differing in urbanization type and degree. Urbanization, both historical and current, was measured using several variables generated from GIS overlays of land cover, aerial photographs, and field exploration in the study watersheds. Quantitative benthic macroinvertebrate samples were taken, and a variety of physicochemical characteristics were measured. Increasing urbanization resulted in a decline in diversity and abundance of intolerant organisms. Streams in industrial areas had greater invertebrate density due to large increases in a few tolerant groups. Urbanization in the watersheds was coupled with changes in the physical and chemical structure of the streams suggesting some possible mechanisms for urbanization impact on stream biota. Multivariate analysis grouped streams based on a number of pollution-sensitive taxa suggesting the utility of this type of approach in analyzing community data. Primary funding for this project was from the Coweeta Hydrologic Lab NSF-LTER grant. Additional funding was provided through a Graduate Research and Development Project grant from the Graduate Student Assembly of Virginia Polytechnic Institute and State University. Matching funds were provided by the Biology Department. / Master of Science

This study represents the first shift in multivoltine life history of Cheumatopsyche species from a wastewater treatment plant (WWTP) in North America. Populations of C. lasia were examined upstream and downstream of the Denton’s Pecan Creek WWTP August 2009 through November 2010. C. lasia is multivoltine in Pecan Creek with three cohorts observed upstream of the WWTP and four possible cohorts downstream. A fourth generation was possible downstream as thermal inputs from WWTP effluent resulted in elevated water temperatures that allowed larval development to progress through the winter producing a cohort ready to emerge in spring. Production of C. lasia was 5 times greater downstream of the WWTP with secondary production estimates of 1.3 g m-2 yr-1 and 4.88- 6.51 g m-2 yr-1, respectively. Differences in abundance were due to increased habitat availability downstream of the WWTP in addition to continuous stream flow from inputs of wastewater effluent. Results also suggest that C. lasia is important for energy transfer in semiarid urban prairie streams and may serve as a potential conduit for the transfer of energy along with emergent contaminants to terrestrial ecosystems. These finding highlight the need for more quantitative accounts of population dynamics (voltinism, development rates, secondary production, and P/B) of aquatic insect species to fully understand the ecology and energy dynamics of urban systems.

Low streamflows and warm stream temperatures, caused mainly from agricultural diversions, currently limit available habitat and productivity of trout, including native Lahontan cutthroat trout in Nevada’s Walker River Basin. Environmental water purchases, which transfer water from willing sellers to instream uses (i.e for fish), are being evaluated to improve instream habitat. To determine which environmental water purchases to prioritize, this study was undertaken to build a computer model in order to simulate stream temperatures under differing environmental water transfer scenarios. Model runs simulate a range of environmental water transfers at major diversions and reservoirs throughout the Walker River Basin. Results indicate that low flows generally coincide with critically warm stream temperatures, cooler stream temperatures exist in the East Walker River, a tributary of the Walker River, during warm seasons which provide good habitat for fish, environmental transfers can improve stream temperatures for some highly impacted reaches by up to 3°C in dry years, and environmental water transfers have a greater effect in dry years than wet years.

The data analysis indicated that travel distance, user age, and user income level are important determinants of use of trout streams. These variables were incorporated into regression analysis to develop a use-prediction model. This use-prediction model was used to determine predicted use levels of sample streams. The predicted use levels combined with travel costs and expenditures on new fishing equipment were used to derive a statistical estimate of the demand schedules for the sample streams. These statistical demand curves were subjected to consumer surplus procedures to determine the values of the sample streams.

No description available.

Insect pests are the most widespread disturbance in Canadian forests, but resulting impacts of forest defoliation on stream ecosystem functions are poorly understood. This study investigated the effects of a spruce budworm outbreak on water quality and the structure and function of microbial communities in streams of 12 catchments across a gradient of cumulative defoliation severity in the Gaspésie Peninsula, Québec, Canada. Bi-weekly stream habitat sampling was conducted spring to fall 2019-2021, with stream flow rates measured and water samples collected and analyzed for water chemistry parameters, nutrients, and dissolved organic matter (DOM) structure and quality. Algal communities were assessed at the same time by measuring in-situ biomass. Bacteria and fungi communities on leaf packs were assessed by incubating six leaf packs for five weeks (mid-August- late September) in one stream reach per watershed. Microbial community composition of leaf packs was determined using metabarcoding of 16S and ITS rRNA genes, and functions were examined using extracellular enzyme assays, leaf litter decomposition rates, and taxonomic functional assignments. This study determined that cumulative defoliation increased stream temperatures, flow rates, and SUVA (DOM aromaticity), but not nutrients. It increased algal biomass and altered microbial community composition, with a stronger influence on bacteria than fungi. The observed increases in SUVA and algal biomass corresponded with changes to bacteria carbon cycling functions, which indicated that microbes were preferentially selecting carbohydrates produced by algae rather than the aromatic compounds from increased terrestrial inputs. There were no changes to other bacteria or fungi functions and no changes to taxonomic or functional diversity. Overall, results indicate that forest pest outbreaks alter carbon inputs to streams and the structure and function of stream microbial communities associated with carbon cycling. / Thesis / Master of Science (MSc) / Terrestrial and aquatic landscapes are tightly linked, and forest disturbances can influence stream ecosystems. Insect pests defoliate millions of hectares of forests each year, but the resulting impacts on stream ecosystems are poorly understood. This study investigated the effects of a spruce budworm outbreak on water quality and microbial communities in streams in Gaspésie, QC, Canada. Microbial communities are critical to the functioning of stream ecosystems as they convert energy (e.g., carbon) into useable forms for other organisms. Results indicate that defoliation altered stream flow rates, temperatures, and carbon composition, as well as the microbial communities involved in carbon cycling processes. Carbon is essential to aquatic food webs and this improved understanding of how carbon flow is altered by a widespread forest disturbance can inform pest management decisions for spruce budworm outbreaks.

No description available.

With the increasing number of online streaming services available in the world, it is astounding to note how radio is still around maintaining excellent ratings and listener interaction. It is essential to analyze the media industry, and while there are many outlets a person is capable of accessing music, people still turn to their local radio. The literature indicates how the business of radio still exists with the primary competition of today. The study includes interviews from twelve radio professionals at Cox Media Group (CMG) Orlando, the home of seven different format radio stations. All interviewees hold a range of job titles/responsibilities, years of experience, and perspectives in the radio industry. The findings indicate that people still appreciate radio for the locality, resources, and recreational activities radio has to offer that in many ways, a streaming service cannot. The study exemplifies how although a media format may have been around for hundreds of years, it can still be relevant if it can adapt to the changes of today