Life Sciences Commons^™

Phylogenetic Relationships Among Fishes In The Order Zeiformes Based On Molecular Data From Three Mitochondrial Loci, Lindsay Scarpitta

Master's Theses

The Zeiformes (dories) are mid-water or deep (to 1000 m) marine acanthomorph fishes with a global, circumtropical, and circumtemperate distribution. Some species have a near-worldwide distribution, while others appear to be regional endemics, e.g., near New Zealand. Six families, 16 genera, and 33 species are currently recognized as valid. Relationships among them, however, remain unsettled, especially in light of recent proposals concerning the phylogenetic placement of zeiforms within the Paracanthopterygii rather than allied with beryciforms or percomorphs. The present study uses mtDNA characters to investigate zeiform interrelationships given their revised phylogenetic placement and attendant changes to their close outgroups, carried …

Three-Dimensional Staging Series Of Anolis Sagrei, Lilian Epperlein

Master's Theses

With the rapid rise of Evo-devo and the concurrent development of new imaging techniques, comparative studies of development have accelerated over the last decade. Squamates, lizards and snakes, lack a traditional experimental model species for developmental investigations, yet are important for understanding fundamental evolutionary questions because of their remarkable diversity. However, several squamate species have growing communities of biologists building new resources for comparative and experimental studies of lizard development. Creation of detailed embryological atlases for these species will help promote their advancement. In the past, scientists have had to rely on destructive methods to take apart biological samples which …

Evolution Of Life-History Characteristics In Gadoidei, Joshua Hittie

Master's Theses

Life-history characteristics (e.g., age and growth) have been used extensively to understand the temporal population dynamics of fish species, but less so within a phylogenetic framework. This study investigates life-history characteristics within the suborder Gadoidei (order: Gadiformes) and to test the extent of phylogenetic signal for those characteristics. To accomplish this, a phylogeny of Gadoidei was first constructed based on both mitochondrial and nuclear genes. Within this phylogenetic framework, life-history traits, including growth rate, age at maturity, and longevity, as well as ecological data, such as water depth and diet type, were mapped to the phylogeny using parsimony analysis to …

Anthropogenic Particle (Including Microplastic And Microfiber) Transport And Retention In Streams Under Varied Environmental Conditions, Elizabeth Marjorie Berg

Master's Theses

Microplastics (plastic particles <5 mm) and other anthropogenic particles (i.e., synthetic, semi-synthetic and anthropogenically modified cellulose particles < 5mm) are pollutants of concern in aquatic ecosystems worldwide. Anthropogenic particles enter food chains, adsorb harmful chemical pollutants, and are ubiquitous in aquatic ecosystems. Streams are key sites of anthropogenic particle input, retention, and transport, and empirical measurements of particle movement in lotic ecosystems are needed to inform global budgets of anthropogenic particles and microplastics. However, factors that influence anthropogenic particle retention in lotic ecosystems are poorly understood. We demonstrate how environmental characteristics affect plastic transport and retention in streams in experimental and observational studies. In our experimental study, we used particle spiraling metrics to directly measure microplastic retention in outdoor, experimental streams at Notre Dame's Linked Experimental Ecosystem Facility (ND-LEEF). We tested the impact of stream discharge (i.e., high, low), benthic biofilms (i.e., well-established biofilms, reduced biofilms post-scouring), and benthic substrate type (i.e., cobble, pea gravel, sand, mixed substrate) on retention of microplastic fibers using pulsed releases and synchronized water sample collection at 3 sites downstream. We also collected benthic surface samples for biomass and microplastic density. Samples were filtered directly (water samples) or after peroxide digestion (benthic samples), and experimental microplastic fibers were enumerated visually using a dissecting microscope. Microplastic deposition rates were significantly higher with (1) higher discharge, (2) well established benthic biofilm (as opposed to bare substrate), and (3) larger and more homogeneous substrates. The observational study examined anthropogenic particles (including microplastics and microfibers) in the Milwaukee River during storm events. Lotic ecosystems are highly variable (e.g., seasonal changes, storm events), and most research assessing anthropogenic particle pollution extrapolates stream particle loads based on measurements during only one point in time. This limits the accuracy of anthropogenic particle and microplastic dynamics models in rivers, where frequent changes in discharge drives retention and transport of fine particles. In this study, we used automated samplers to collect water from the Milwaukee River during four distinct storm events in the spring and summer of 2018. We quantified anthropogenic particle abundance using standard methods and used nearby USGS gauges to determine discharge. Anthropogenic particle concentrations varied significantly among the four sampling periods, highlighting the temporal variability of anthropogenic particle transport across dates. When data from the sampling periods were pooled, there was a decrease in anthropogenic particle concentration in the water column after storm events, indicating that floods may "flush" microplastics from the river. Unexpectedly, anthropogenic particle concentrations were not correlated with other water quality metrics, including concentrations of total suspended solids, fecal coliform, chloride, nitrate, and sulfate, indicating that these metrics cannot be used to estimate microplastic concentrations and likely have distinct driving factors. These results provide novel insights into the environmental factors controlling anthropogenic particle and microplastic fate and are critical to understanding the role of lotic retention and transport in global plastic budgets.

Anthropogenic Litter In Illinois Streams: Monitoring, Distribution, And Relationship To Biological Indicators Of Stream Health, Lauren Wisbrock

Master's Theses

Anthropogenic litter (i.e., trash; AL) is increasing in aquatic ecosystems worldwide. AL shows a patchy, uneven distribution in lotic ecosystems due to heterogeneity in its sources, how it moves, and mechanisms of retention. In addition, the diversity of material types, size, and mobility makes developing techniques to measure AL assemblage in rivers a challenge. In rivers, watershed land-use and riparian features likely impact AL abundance and composition, but this impact is not fully understood. Measuring AL can be time consuming and labor intensive, so rapid assessments are needed for ecosystem managers to quantify the level of AL impairment in a …

The Effect Of Plastic On Leaf Litter Breakdown In Urban Streams, Lisa Haneul Kim

Master's Theses

The plastic component of anthropogenic litter (AL) is an emerging ecological concern and has been a focus of research, as it is long-lived, mobile, interacts with physical and chemical components of aquatic ecosystems, and breaks down into smaller pieces (i.e., microplastic, <5mm particles). Rivers are considered a major source of plastic to oceans, but little is known about plastic's abundance, distribution, and effects on ecological processes in urban streams. Previous studies report plastic is abundant in freshwater systems, especially in naturally occurring debris dam structures and overhanging vegetation which accumulate high quantities of AL, especially plastic items (i.e. bags, wrappers, packaging material), along with leaf litter and other coarse particulate organic matter. in temperate, forested streams, leaf litter is a critical food source and plays an essential role in the stream food web. the rate at which leaves break down is affected by many variables such as hydrology, water chemistry, and macroinvertebrate and microbial communities. We predicted that plastic accumulation along with leaf litter can slow leaf breakdown by reducing diversity and abundance of microbial decomposers, as well as macroinvertebrate consumers. We measured leaf breakdown, and characterized macroinvertebrate and microbial (i.e., bacterial, fungal, algal) communities in 3 litter bag treatments: leaves alone, plastic alone, and leaves mixed with plastic. Although plastic did not reduce leaf breakdown rates or have a significant effect on macroinvertebrate consumer communities, it showed distinct microbial communities compared to leaf substrates. Results will provide a new understanding of how plastic and microbial communities interact, and set the framework for future studies to look at microbial succession and macroinvertebrate diversity on other synthetic substrates in freshwater systems.

Habitat Associations And Community Interactions Of Non-Native Species In The Southern Basin Of Lake Michigan, Erin O'Shaughnessey

Master's Theses

Non-native crayfishes, mollusks, and macrophytes can have large impacts on biodiversity and damage ecosystem services in freshwaters. In 2015 we discovered an established population of the globally widespread invader red swamp crayfish (Procambarus clarkii) in the North Shore Channel of the Chicago Area Waterway System. This population overlaps with a population of rusty crayfish (Faxonius rusticus), a previous invader that is widely distributed and usually the dominant crayfish species across the Great Lakes region. I studied the interactions between these two species while directly competing over shelter and food. In the field, each species was studied to determine the rate …

Microplastic In Aquatic Food Webs: Museum Specimens And Ingestion Experiments Reveal Controls On Microplastic Ingestion By Freshwater Fish, Loren Hou

Master's Theses

Plastic is pervasive in modern economies and ecosystems. Early research suggests freshwater fish commonly ingest microplastic (particles < 5 mm), which may influence fish digestive tissues, but no studies have examined historical patterns in microplastic consumption or rates of microplastic retention in fish. We measured microplastic in digestive tissue of specimens collected and preserved over the last century (Field Museum, Chicago). We selected Micropterus salmoides (largemouth bass), Notropis stramineus (sand shiner), Ictalurus punctatus (channel catfish), and Neogobius melanostomus (round goby) because each was well represented in the museum collection, with specimens from urban rivers. Specimens from 1900-2018 showed increases in microplastic concentration from the 1950's to present. in a second project, we collected round gobies from Lake Michigan in Chicago to conduct feeding experiments to measure microplastic ingestion and retention rates. the majority of microplastic was excreted within 72 hours of ingestion. Results will aid in understanding ecological interactions of microplastic and freshwater fish, informing further work on the movement of microplastic in aquatic food webs.

Chironomidae (Diptera) Community Structure In Lakes Of Contrasting Morphometry, Landscape Position, And Water Chemistry, Conrad Stanley Zack

Master's Theses

Chironomidae (Diptera) surface-floating pupal exuviae were collected monthly during the ice-free season in 2010-2011 from six lakes in the North Temperate Lakes Long-Term Ecological Research site in northern Wisconsin. The goal of this study was to determine whether chironomid community structure reflected differences in lake morphometry (i.e., depth, area, shoreline development, etc.), water chemistry, and/or landscape position (i.e., elevation). Forty-six genera were identified from four subfamilies: Chironominae (57%), Orthocladiinae (28%), Tanypodinae (11%), and Diamesinae (4%). Tanytarsus, Ablabesmyia, and Psectrocladius were found in all six study lakes; whereas certain genera, such as Omisus, Protanypus, and Epoicocladius were each observed in only …

Population Genetics And Distribution Of The Oriental Weatherfish, Misgurnus Anguillicaudatus, In Chicago Area Waterways, John Belcik

Master's Theses

Oriental Weatherfish (Misgurnus anguillicaudatus), native to Southeast Asia, are freshwater fish belonging to the family Cobitidae (loaches). They are benthic fish with the ability to breathe atmospheric air, and exhibit an unusual behavior of swimming vertically in the water column in response to changes in barometric pressure. Oriental Weatherfish appear to be successful invaders to North American waterways. Within the last century they have been sighted in freshwater systems throughout the United States, yet the distribution and source of this invasion are largely unknown. This study investigates the distribution patterns, surveying methods, and population genetics of the Oriental Weatherfish within …

Nutrient Removal And Vegetation Recovery Through Successive Harvesting Of The Invasive Hybrid Cattail (Typha X Glauca) In Great Lakes Coastal Wetlands, Kelsey Berke

Master's Theses

Excess nutrient levels have led to invasive hybrid cattail (Typha × glauca) dominance in many Laurentian Great Lakes coastal wetlands. Its ability to alter wetland structure and function has made T. × glauca a target invasive species with respect to Great Lakes coastal wetland

restoration. This study investigated the effect of harvesting invasive T. × glauca biomass on nutrient removal, specifically nitrogen and phosphorus, and plant diversity recovery in Great Lakes coastal wetland ecosystems. This study demonstrated that without considering external nutrient inputs and outputs, a single harvest at Cheboygan Marsh, MI could remove ~2% of the total N and …

Predicting Suitable Habitat Decline Of Midwestern United States Amphibians And Quantifying The Consequence Of Declines Using Pond-Breeding Salamanders, Brock Struecker

Master's Theses

With current declines of vertebrate taxa meeting or exceeding those of historic mass extinction events, there is a growing need to investigate the main drivers of declines. Amphibians are perhaps at greatest risk of global climate change and land-use changes than most other vertebrate classes and also have significant roles in ecosystem processes – combined, this creates a cause for concern. I designed a study that would investigate the effects of current and predicted climate change and land-use changes on amphibians using species distribution models and a field study to identify the potential consequences of amphibian species declines by investigating …

Early Round Goby (Neogobius Melanostomus) Invasion Into Lake Michigan Tributaries And Competitive Interactions With Two Native Benthic Fishes., Margaret Ann Malone

Master's Theses

The round goby is a prolific invasive species and is currently spreading into Great Lake tributary streams. There is a high potential for negative impacts on native benthic fishes in these stream habitats and the aim of this study is to assess the impacts of the round goby on two native darter species in particular (johnny darter and blackside darter). I review the history of round goby invasion in the Great Lakes and summarize hypotheses of the invasive characters of the round goby. Using game theory, I provide a G-function approach to understanding the outcomes of the round goby invasion …

Aquatic Insect Community Structure And Secondary Production In Southcentral Alaska Streams With Contrasting Thermal And Hydrologic Regimes, Samantha D. Hertel

Master's Theses

Streams along the Copper River Delta, southcentral Alaska, exhibit contrasting thermal and hydrologic variability associated with being primarily groundwater-fed (GWF) or surface water-fed (SWF). Groundwater-fed streams are predictable both thermally and hydrologically year round, whereas SWF streams are unpredictable and exhibit more variable thermal and hydrologic regimes. These differences may strongly influence aquatic insect community structure and secondary production. Four streams, two GWF and two SWF, were sampled twice monthly from late April 2013 through August 2013 and once seasonally in fall (September) and early winter (November). Aquatic insect community structure differed markedly in both hydrologic types. Taxa richness was …

Anthropogenic Litter And Microplastic In Urban Streams: Abundance, Source, And Fate, Amanda Rae Mccormick

Master's Theses

The accumulation and ecological effects of anthropogenic litter (AL) and microplastic are well-documented in marine ecosystems, but these materials’ abundances in rivers is unknown. AL enters rivers from recreation, runoff, and illegal dumping. Microplastic fibers and pellets are abundant in wastewater treatment plant (WWTP) effluent which enters rivers. Our objectives were to: (1) quantify AL abundance and composition in urban streams, (2) measure AL flux, accumulation, and export, and (3) measure riverine microplastic concentration and analyze its bacterial communities. We collected AL from 5 urban streams and observed greater AL density in riparian habitats and greater mass in benthic habitats. …

Denitrification In Urban Coastal Environments: A Functional Gene Study, Samantha Denise Lindemann

Master's Theses

Eutrophication is a major anthropogenic stressor on aquatic ecosystems worldwide. Jamaica Bay is located in the southeastern portion of New York City, NY (NYC). Like many other estuaries, Jamaica Bay is impacted by anthropogenic N inputs from various sources. Despite eutrophic conditions, improvements in water quality over the last few decades have prompted government agencies to promote oyster restoration to help reduce anthropogenic N in NYC waters. The effect of eastern oysters on sediment bacterial communities responsible for denitrification in Jamaica Bay was previously unknown. Those samples exposed to oysters were predicted to have high denitrification gene abundances, and thus …

History Of Freshwater Invasions In Illinois: Learning From The Past To Inform The Future, Abigail Jacobs

Master's Theses

Rates of introduction and spread of non-native species continue to increase worldwide, with freshwater ecosystems highly impacted. Many non-native species crossed between the Great Lakes and Mississippi watersheds by traveling through waterways in Illinois. I assembled a comprehensive database of occurrences of aquatic non-native species (n=99) in Illinois inland waters. The arrival of non-native species accelerated since 1873. The Great Lakes Basin was the main source of established species into Illinois. From 1990-2012 the dominant vector was unintentional release of established species non-native to North America. Sixty of the 99 introduced species established. Eighteen established species had high or very …

Life Histories, Diets, And Secondary Production Of Odonata Along A Temperature Gradient On The Copper River Delta, Alaska, Nicole Emilie Furlan

Master's Theses

Dragonflies (Odonata: Epiprocta) and damselflies (Odonata: Zygoptera) are a conspicuous aspect of the biota in ponds on southcentral Alaska's Copper River Delta (CRD). Odonate densities, secondary production, and diets were assessed in sixteen ponds classified by delta region (east vs. west) and landscape type (outwash plain (OP) vs uplifted marsh (UM)).

Enallagma boreale (Coenagrionidae) comprised 48.5% of collected odonates. Leucorrhinia hudsonica (Libellulidae) and Aeshna juncea (Aeshnidae) comprised 36.6% and 10.4% of collected odonates, respectively. L. hudsonica densities and secondary production were significantly higher (p<0.001) in west UM ponds than in other pond types. Ostracods (Ostracoda) and water boatmen (Corixidae) dominated west OP A. juncea diets. Midge larvae (Chironomidae) dominated A. juncea diets in remaining pond types, occurring in 68% of foreguts. 27% of A. juncea foreguts demonstrated intraguild predation, and 6% of foreguts demonstrated cannibalism. Foreguts containing threespine stickleback (Gasterosteus aculeatus) revealed A. juncea's apex predator role in CRD ponds.

Aquatic Macroinvertebrate Response To Invasion And Subsequent Removal Of Typha × Glauca From Great Lakes Coastal Marshes, Kimberly Anne Greene

Master's Theses

Aquatic macroinvertebrates are important in wetland ecosystems; many fish and wildlife species depend upon them for food resources and they aid in nutrient cycling. Wetland macroinvertebrate communities are influenced by plant community composition; as such, this study examined two implications of invasive hybrid cattail, Typha × glauca (Typha), on aquatic macroinvertebrate communities in northern Great Lakes coastal wetlands: 1) how the presence of nearly monotypic stands of Typha alters wetland aquatic macroinvertebrate communities and 2) how manual removal of Typha, via mowing and manual tilling, impacts these invertebrate communities along with wetland plant communities. I found that …

The Comparative Morphology Of The Pectoral Free Rays In Scorpaenoid Fishes (Perciformes: Scorpaenoidea)), Jeremy Peter Harris

Master's Theses

The pectoral fins of many benthic taxa have evolved many unique features used to interact with the substrate. In one such group, the searobins (Triglidae: Scorpaenoidea), three of the pectoral fin rays have become separated from the fin as a whole, allowing them to operate as a separate appendage from the fin as a whole. The anatomical structure of these "free rays" was investigated and several previously unreported muscle and bone variations were found. This method was extended to include members of four other scorpaenoid families which possess free rays, which revealed important differences in the muscle, bone, and nervous …

Activity Patterns And Spatial Resource Selection Of The Eastern Garter Snake (Thamnophis Sirtalis Sirtalis), Matthew Gregory Most

Master's Theses

Snake species usually exhibit seasonal variations in activity patterns, home-range size and the use of respective habitat. Using mark-recapture protocols I marked 96 individual Thamnophis sirtalis sirtalis specimens in Lake Forest, IL to determine the independent variables that best explained habitat selection in a population of Eastern Garter Snakes (T. s. sirtalis). Specifically, I focused on the relationship between seasonal movement and home range size of male and female garter snakes. I analyzed the habitat preferences and spatial ecology of Eastern Garter Snakes during the 2011 sampling season and modeled the relationship between preferred or avoided habitat, in conjunction with …

The River Continuum Redux: Aquatic Insect Diets Reveal The Importance Of Autochthonous Resources In The Salmon River, Idaho, Kathryn Vallis

Master's Theses

Along a river network, changes in the physical characteristics of a stream - changes articulated by the River Continuum Concept (RCC) - have been predicted to influence stream food webs, particularly the resources supporting aquatic macroinvertebrates. Although diets of macroinvertebrates can track resource availability along the longitudinal gradient of streams, insect diets were not assessed in the original RCC study; rather, insects were grouped into functional feeding groups (FFGs). In addition, global climate change is increasing the frequency and spatial extent of wildfire and beetle outbreaks throughout the western United States and could affect riparian vegetation and the amount of …

Cattail (Typha X Glauca) Invasion In Wetlands Of The Great Lakes Region: Are Impacts Time-Dependent?, Mark Edwin Mitchell

Master's Theses

Some species introduced into new regions have the potential to greatly impact native diversity and ecosystem functioning. The invasive hybrid cattail, Typha X glauca, has established in wetlands across the Great Lakes region decreasing native plant diversity and altering soil and microsite characteristics. We utilized 80 years of historical aerial photographs from the Illinois Beach State Park wetland complex to map the spread and determine the age of T. X glauca stands. Floristic, edaphic, and environmental data were collected from plots across an invasion-age gradient to determine the impacts of T. X glauca and time since invasion on environmental variables. …

Community Structure And Secondary Production Of Aquatic Macroinvertebrates In Coastal Wetland Ponds Of The West Copper River Delta, Alaska, Following Tectonic Uplift, Ryan Glen Van Duzor

Master's Theses

The Great Alaska Earthquake of 1964 (magnitude 9.2) greatly altered the coastal landscape in southcentral Alaska and had particularly dramatic effects on the Copper River Delta (CRD), an ecologically and economically important area within the Chugach National Forest. The earthquake caused tectonic uplift (up to 3.5m) of the CRD coastal tidal marsh and transformed it into a perched freshwater marsh. Copper River Delta ponds, which are crucial habitat to a myriad of migrating songbirds, shorebirds, and waterfowl, are of particular interest to wildlife managers in the CRD and along the Pacific coasts of North, Central and South America. This study …

Stream Restoration In A Post-Agricultural System: Indirect Effects On Density And Secondary Production Of Aquatic Insects, Lyle Stanley Dandridge Jr

Master's Theses

Restoration of stream habitats, with the goal of increasing biodiversity through increasing habitat heterogeneity, has been an ongoing trend in recent decades. Current investigations suggest most of those projects fail to significantly influence ecological structure and function when evaluated in light of their affect on species richness. In order to assess the <&ldquo>success of restoration on a prairie stream in northern Illinois traditional metrics such as community composition and density were examined in addition to macroinvertebrate secondary production. Restoration of Nippersink Creek, McHenry County, Illinois was completed in 2000 and this study was conducted 8 years post-restoration. Benthic samples were …

Investigation Of A Pharmaceutical Compound With Artificial Streams: Effects Of The Antihistamine Cimetidine On Stream Ecosystem Function., Paul David Hoppe

Master's Theses

Pharmaceutical compounds have been widely detected in surface waters but their effects on stream ecosystems are unknown. Cimetidine (Tagamet®), a widely used H2 histamine antagonist has been detected in surface waters. To measure chronic effects of cimetidine on stream invertebrates, I conducted a long-term (83d) artificial-stream experiment. A range of cimetidine concentrations (0.07 μg L-1 to 70.0 μg L-1) were added to streams supporting populations of the amphipod Gammarus fasciatus and beetle Psephenus herricki. P. herricki individual growth rates were reduced in the presence of cimetidine, but G. fasciatus individual growth rates were not different among treatments. G. fasciatus size …

Fish Assemblage Structure In Natural, Channelized, And Restored Sections Of Nippersink Creek, Mchenry County, Illinois, Sarah Ann Zack

Master's Theses

Degradation of aquatic habitats and loss of biodiversity are growing concerns of natural resource managers and the general public. Channelization, the common historical practice of straightening streams and rivers for agricultural interests, has had profound detrimental effects on the biodiversity of lotic fish assemblages. Nippersink Creek, McHenry County, IL is a twenty-three mile stream that flows through an area valued for its fish, wildlife, and invertebrate biodiversity. Although a portion of the stream was channelized in the 1950's, restoration efforts by the McHenry County Conservation District have recently restored historical meanders. Nevertheless, efforts to restore streams and rivers to their …

Temporal Variability Of Bioassessment Indices Used To Evaluate Three Midwestern Streams, Nia M. Haller

Master's Theses

Population, community and functional measures or metrics in rapid bioassessment programs aid in establishing biological criteria for streams and rivers. Each metric measures different aspects of community structure and is important in detecting changes in macroinvertebrate community structure that are influenced by changes in water quality. In this study, temporal variation of nine commonly used bioassessment indices was examined in three midwestern streams. The indices were calculated for each of nine replicate benthic macroinvertebrate samples collected monthly for one year from Cowpie Creek (CC), Nippersink Creek (NC) and Lawrence Creek (LC), McHenry County, Illinois. In practice, the habitat sampled for …

Diet Overlap And Competition Among Native And Non-Native Small-Bodied Fishes In The Colorado River, Grand Canyon, Arizona, Sarah Ellen Zahn Seegert

Master's Theses

Introductions of non-native fishes are threatening native fish communities in streams and rivers across the United States. The Colorado River especially has experienced numerous species invasions, and native fish populations throughout the basin are in decline. The native fish community in the Grand Canyon has been particularly affected, with half of the native fishes extirpated from the canyon. Many scientists blame interactions with non-native fishes for these declines. However, to date no one has conducted a thorough diet analysis of small-bodied fishes in the system to assess overlap between native and non-native fish diets. I analyzed the diets of native …

Resource Composition And Macroinvertebrate Resource Consumption In The Colorado River Below Glen Canyon Dam, Holly Ann Alfreda Wellard Kelly

Master's Theses

Physical and biological changes to rivers induced by large dams can significantly alter downstream communities, decreasing the biotic integrity of these rivers. For example, completion of Glen Canyon Dam on the Colorado River in 1963 has altered the downstream ecosystem and contributed to the decline of native fish populations and dramatic changes in the macroinvertebrate communities. Physical changes associated with the dam may also influence the food resources supporting macroinvertebrate production, but this has not been previously measured. For example, autochthonous production is high in the clear tailwaters of the dam, but downstream tributary allochthonous carbon inputs are substantial and …