Ecology and Evolutionary Biology Commons^™

Patterns In Winter Stonefly Distribution Along A River Continuum And Land-Use Gradient In Northwest Arkansas Streams, Zachary Tipton

Graduate Theses and Dissertations

Freshwater ecosystems are facing a crisis with extinction rates of aquatic species exceeding those of their terrestrial counterparts by up to fivefold. This decline is predominantly attributed to evolving land use patterns within watersheds, leading to chemical and physical transformations in freshwater habitats. Northwest Arkansas (NWA) represents one of the fastest-growing regions in the United States, undergoing substantial shifts in land use. Consequently, the status of aquatic life in this region remains uncertain. Addressing this concern, the latest Arkansas Wildlife Action Plan emphasizes the necessity of distribution and population data to guide conservation efforts for Species of Greatest Conservation Need …

How Flow Regime Affects Predator-Prey Relationships Of Stream Darter And Shiner Species, Anna E. Richardson

Biological Sciences Undergraduate Honors Theses

Analysis of the interactions between abiotic and biotic factors of environments and ecosystems is a highly valued area of research. This study focuses on the interactions between the biotic component of predation and foraging of certain stream fish species and the abiotic component of the flow regime that those species reside in. Gut content analysis followed by statistical calculations in the form of t-tests and chi -quared tests were performed on two fish species who both inhabited a stream with a groundwater flashy flow regime as well as a stream with a runoff flashy flow regime. The research showed that …

Analysis Of Edna To Assess Effects Of Water Quality On Freshwater Fungal Diversity In A Virginia Coastal Watershed, Lauren French

Undergraduate Honors Theses

Freshwater fungi comprise a phylogenetically and functionally diverse group which contributes to wide-ranging ecosystem processes in aquatic systems. Saprotrophic fungi convert detritus into nutrient-rich food sources for fish and invertebrates, whereas pathogenic and parasitic fungi can cause disease and population declines of other aquatic organisms. With their diverse and important roles, changes in freshwater fungal community structure may have far-reaching impacts on ecosystems. To understand how natural and anthropogenic stressors to freshwater systems impact fungal-mediated ecosystem processes, a greater understanding of the taxonomic and functional composition of freshwater fungal communities is needed. We assessed relationships among freshwater habitat types, water …

Transport And Fate Of Phosphorus In The Nearshore Zone Of Lake Michigan, Nathan Van Ee

Theses and Dissertations

Bioavailable phosphorus loads exported to Lake Michigan from the Milwaukee and Sheboygan River Watersheds appear to have increased in the last 40 years despite meeting total phosphorus (TP) loading goals set by the Great Lakes Water Quality Agreement (GLWQA).Overall, bioavailability of P delivered from the Milwaukee and Sheboygan Rivers was highest during the warmer months, which coincides with the nearshore nuisance algae growth season. However, first order loss rates of SRP calculated during baseflow recession were also greatest during the summer, suggesting that increased river residence time during the summer could reduce export of bioavailable P. Observations of phosphorus partitioning …

Phragmites Australis Dieback In The Mississippi River Delta: Chemical Profiles Of Soil Types And Restoration Potential, Herie Lee

LSU Master's Theses

Since 2016, there has been widespread dieback of P. australis in the Lower Mississippi River Delta (hereafter referred to as Lower MRD, which is defined as the Birds Foot Delta) with relatively little to no signs of recovery. The cause of the current dieback is not fully understood. This thesis explores P. australis with emphasis on chemical profile characterization of different soil types and its effects on plant growth and the potential for restoration in the Lower MRD.

In chapter 2, I characterized the chemical profiles of soils collected from healthy and dieback stands of Phragmites, and from newly …

Plant Community Response To The Combined Effects Of Elevation, And Simulated Nutrient And Sediment Loading In Sagittaria Lancifolia-Dominated Wetlands, Donnie Day

LSU Master's Theses

Coastal wetlands are experiencing threats to their long-term sustainability brought about by the combined effects of relative sea-level rise and human modifications to hydrology, sediment delivery and nutrient loading. Restoration and management strategies can include adding sediment to the surface of deteriorating marshes to facilitate positive feedbacks among elevation, plant productivity, sediment trapping, and accretion; however, if delivered using nitrate-enriched river waters, belowground biomass and soil organic matter pools may be negatively affected, resulting in the acceleration of wetland loss. Overall, there is limited information on the combined effects of nutrient loading, sedimentation, and flooding dynamics in regulating feedbacks among …

Aquatic Macrophyte Communities In Five Sibley County (Minnesota) Lakes And The Factors That Affect Their Distribution, Samuel A. Schmid

All Graduate Theses, Dissertations, and Other Capstone Projects

The purposes of this study are to 1) quantify the shifts in the macrophyte community structure of five lakes in Sibley County, and 2) to assess the relationships between the macrophyte communities and abiotic factors in these five lakes. In both the early and late growing season of 2019, point-intercept surveys were conducted on High Island Lake, Titlow Lake, Schilling Lake, Silver Lake, and Clear Lake. At each point, water depth was recorded, and all macrophytes sampled were identified and recorded as “present.” There was not a late season survey conducted for High Island Lake in 2019 due to a …

Paleoenvironmental Reconstruction Of Quaternary Saltville, Virginia, Using Ostracode Autecology, Austin Gause

Electronic Theses and Dissertations

The Saltville valley in southwestern Virginia is home to Quaternary localities containing paleontological and archaeological remains. Historically the valley has been mined for salt and the small lakes, ponds and springs along the valley floor have a brackish signature. A preliminary report on the site’s ostracode fauna suggested that the site’s water was not always saline. This study analyzed modern and Quaternary ostracodes to understand the valley’s hydrologic and chemical evolution. Sediments contained primarily freshwater species, including the environmentally sensitive Candona crogmaniana. The presence of Pelocypris tuberculatum and a new Fabaeformiscandona species throughout a vertical section spanning the latest Pleistocene …

An Investigation Into The Trophic Magnification Of Polychlorinated Biphenyls In The Lake Michigan Food Web, Philip Hurst

Theses and Dissertations

Polychlorinated biphenyls (PCBs) are a group of persistent organic pollutants known to contribute to several adverse health conditions in humans including cancers and a suite of liver diseases. While there exist 209 unique PCB congeners, the World Health Organization has identified 12 that pose the greatest health risk to humans due to these congeners’ functional similarity to dioxins, another notoriously toxic class of contaminants. Along with methylmercury, PCBs are the primary drivers behind fish consumption advisories in the Great Lakes. These guidelines are informed primarily by surveys of contaminants in freshwater biota. However, the proliferation of invasive species, such as …

Living Upstream: Kennebec River Influence On Nutrient Regimes And Phytoplankton Communities In Harpswell Sound, Siena Brook Ballance

Honors Projects

Phytoplankton underpin marine trophic systems and biogeochemical cycles. Estuarine and coastal phytoplankton account for 40-50% of global ocean primary productivity and carbon flux making it critical to identify sources of variability. This project focuses on the Kennebec River and Harpswell Sound, a downstream, but hydrologically connected coastal estuary, as a case study of temperate river influence on estuarine nutrient regimes and phytoplankton communities. Phytoplankton pigments and nutrients were analyzed from water samples collected monthly at 8 main-stem rivers stations (2011-2013) and weekly in Harpswell Sound (2008-2017) during ice-free months. Spatial bedrock and land use impacts on river nutrients were investigated …

Spatial And Temporal Genetic Structure Of Winter-Run Steelhead (Oncorhynchus Mykiss) Returning To The Mad River, California, Steven R. Fong

Cal Poly Humboldt theses and projects

Distinct populations of steelhead in the wild are in decline. The propagation of steelhead in hatcheries has been used to boost population numbers for recreational fisheries and for use in conservation. However, hatchery breeding practices of steelhead can result in changes in genetic structure. I investigated the genetic structure of winter-run steelhead (Oncorhynchus mykiss) returning to the Mad River, California, where a hatchery has been used enhance production for recreational fisheries since 1971. Genetic variability in Mad River steelhead was evaluated using 96 single nucleotide polymorphisms (SNPs) among 4203 individuals, including the Mad River and nearby locations, and …

The Stability Of Temperate Lakes Under The Changing Climate, Aleksey Paltsev

Electronic Thesis and Dissertation Repository

There is a collective prediction among ecologists that climate change will enhance phytoplankton biomass in temperate lakes. Yet there is noteworthy variation in the structure and regulating functions of lakes to make this statement challengeable and, perhaps, inaccurate. To generate a common understanding on the trophic transition of lakes, I examined the interactive effects of climate change and landscape properties on phytoplankton biomass in 12,644 lakes located in relatively intact forested landscapes. Chlorophyll-a (Chl-a) concentration was used as a proxy for phytoplankton biomass. Chl-a concentration was obtained via analyzing Landsat satellite imagery data over a 28-year period (1984-2011) and using …

Amphibian And Reptile Community Responses To Forest And Riparian Disturbance, Jacquelyn Christine Guzy

Graduate Theses and Dissertations

Riparian zones are transitional, semi-terrestrial areas regularly influenced by freshwater. These areas serve as dispersal corridors for many animal and plant species and ultimately function as important reservoirs of biodiversity in altered landscapes. While much of the riparian habitat in the United States has been affected by anthropogenic activities, management actions may mitigate potentially negative influences of these activities. For example, Streamside Management Zones (i.e., riparian buffers; SMZs) are commonly implemented within managed forests to protect water quality, but may also provide habitat for riparian-associated wildlife. Yet, little research has rigorously addressed the value of SMZs for wildlife, particularly cryptic …

Persistence Of Stream Restoration With Large Wood, Redwood National And State Parks, California, Diedra L. Rodriguez

Cal Poly Humboldt theses and projects

The conservation and recovery of anadromous salmonids (Oncorhynchus sp.) depend on stream restoration and protection of freshwater habitats. In-stream large wood dictates channel morphology, increases retention of terrestrial inputs such as organic matter, nutrients and sediment, and enhances the quality of fish habitat. Historic land use/land cover changes have resulted in aquatic systems devoid of large wood. Restoration by placement of large wood jams is intended to restore physical and biological processes. An important question for scientists and restoration managers, in addition to the initial effectiveness of restoration, is the persistence and fate of large wood installations. In this …

Impact Of Temperature Increase On Freshwater Fish Species: Energetics And Muscle Mechanics Of Two Centrarchids, Israt Jahan

Masters Theses

Fishes have evolved physiologically to live within a specific range of environmental variation and existence outside of that range can be stressful or fatal. These ranges can coincide for fishes that evolved in similar habitats. This study investigates physiological processes limiting thermal tolerance, specifically how changes in water temperature affect the swimming energetics and muscle mechanics in largemouth bass (Micropterus salmoides) and bluegill (Lepomis macrochirus). I focused on the impact of temperature change at the muscle level in these two species and the capacity to adapt to rapid changes in the environment. Fish were housed at …

Ecological Importance Of Invader Source Population And Disturbance In Aquatic Invasions, Nicole Elizabeth Graham

Graduate Theses and Dissertations

Invasive species are a global problem and their effects on recipient ecosystems may be mediated by disturbance and intraspecific variation. Crayfish can substantially influence stream structure and function, and invasive crayfish often have differential impacts than native crayfish in aquatic ecosystems. Since species traits often vary across a distribution, it is possible that invasive crayfish from different source populations may have distinct impacts on recipient ecosystem structure and function. In the Ozark Highlands of Arkansas and Missouri, USA, invasive O. neglectus (the Ringed Crayfish) may be leading to the displacement of native O. eupunctus (the Coldwater Crayfish). The objective of …

Flight Of The Freshwater Fish, Michael H. Wilson

Capstones

Michael H. Wilson

Capstone Abstract

December 27, 2016

Flight of the Freshwater Fish

The Hudson River provides for millions of people as a path for commercial and private transportation, a source of food and energy, and perhaps most importantly for many living in the tri-state area as a destination for recreation and relaxation. The most overlooked feature of the river is how the wildlife shows clear signs of a changing climate and rapid environmental response to the impacts of global warming on the river.

Entire populations of fish species in the lower Hudson have been forced to leave the river …

Ecological Consequences Of Lost Anadromous Forage Fish In Freshwater Ecosystems, Steven R. Mattocks

Masters Theses

Beginning in the early 1600s, dam construction in New England obstructed anadromous fish access to spawning grounds during migration. As a result, anadromous forage fish populations have declined, which has impacted freshwater, marine, and terrestrial ecosystems. To determine the impacts of dams on anadromous forage fish and freshwater ecosystems, I used historical and current data to estimate population changes in alewives (Alosa pseudoharengus) from 1600-1900. A significant reduction in spawning habitat occurred in New England as a result of 1,642 dams constructed between 1600 and 1900, resulting in 14.8% and 16.6% lake and stream habitat remaining by 1900, …

Stream Microbial Communities As Potential Indicators Of River And Landscape Disturbance In North-Central Arkansas, Wilson Howard Johnson

Graduate Theses and Dissertations

In the past decade, 29 shale basins have been actively developed across 20 states for extraction of natural gas (NG) via horizontal drilling/hydraulic fracturing (=fracking). This includes ~5000 wells within the Fayetteville shale of north-central Arkansas. Development often impacts both river- and landscapes, and management requires catchment-level evaluations over time, with organismal presence/absence as indicators. For this study next-generation sequencing was used to identify/characterize microbial communities within biofilm of eight Arkansas River tributaries, so as to gauge potential catchment influences. Streams spanned a gradient of landscape features and hydrological flows, with four serving as ‘potentially impacted catchment zones’ (PICZ) and …

Dietary Effects On The Stoichiometry Of Growth, Regulation, And Wastes Of Ozark Stream Insect Detritivores, Halvor Matthew Halvorson

Graduate Theses and Dissertations

A widespread stressor, anthropogenic nitrogen (N) and phosphorus (P) pollution can increase resource nutrient content and alter animal community composition in freshwater ecosystems. In this dissertation, I used ecological stoichiometry theory to examine effects of diet nutrient content and leaf litter type on growth, regulation, and wastes of aquatic invertebrate detritivores. I tested effects of leaf litter diet carbon:phosphorus (C:P) on growth and stoichiometric regulation of the detritivorous caddisfly Pycnopsyche lepida and used results to determine a threshold elemental ratio of oak litter C:P=1620 that confers peak growth of this species. This empirical, growth-based approach provided a more accurate estimate …

The Role Of Hydrologic Regimes In Driving Morphologic Divergence And The Trait Compositions Of Fish Assemblages, Lindsey A. Bruckerhoff

Graduate Theses and Dissertations

The hydrologic regime is an important determinant of the ecological integrity of a stream. Hydrologic regimes are defined by the magnitude, timing, frequency, rate of change, and duration of high and low flow events and capture long term patterns of variability and predictability of water movement in a stream. Flow regimes influence many aspects of the biophysical environment in lotic systems; therefore organisms have adapted to natural flow patterns. We investigated how fish have adapted to flow regimes at both a population and community level. In the first study presented in this thesis, we hypothesized fish exhibit phenotypic divergence to …

Juvenile Survival And Adult Return As A Function Of Freshwater Rearing Life History For Coho Salmon In The Klamath River Basin, Molly Gorman

Cal Poly Humboldt theses and projects

The Scott and Shasta rivers, Klamath River tributaries, experience spatial disparity in habitat quality in spring and summer as a result of historical and current land-use. Juvenile Coho Salmon (Oncorhynchus kisutch) born in the upper tributary reaches often rear in natal streams before migrating to sea. However, those born in the lower reaches often encounter unsuitable habitat and emigrate during their first spring to seek non-natal rearing habitats. It is assumed that these early outmigrants are population losses. This study evaluated first-summer survival, and contribution to the adult population, of non-natal rearing juveniles in the Klamath River Basin. …

A Multiscale Analysis Of The Factors Controlling Nutrient Dynamics And Cyanobacteria Blooms In Lake Champlain, Peter D. F. Isles

Graduate College Dissertations and Theses

Cyanobacteria blooms have increased in Lake Champlain due to excessive nutrient loading, resulting in negative impacts on the local economy and environmental health. While climate warming is expected to promote increasingly severe cyanobacteria blooms globally, predicting the impacts of complex climate changes on individual lakes is complicated by the many physical, chemical, and biological processes which mediate nutrient dynamics and cyanobacteria growth across time and space. Furthermore, processes influencing bloom development operate on a variety of temporal scales (hourly, daily, seasonal, decadal, episodic), making it difficult to identify important factors controlling bloom development using traditional methods or coarse temporal resolution …

Hydrology-Biology Response Relationships In The Ozark Highlands, Dustin Thomas Lynch

Graduate Theses and Dissertations

I examined flow-ecology relationships among stream communities in the Ozark Highlands, USA. I sampled fish, crayfish, and benthic macroinvertebrates during two consecutive summers, including a drought year (2012) and a flood year (2013). Biological response variables related to community structure were assessed via two different statistical methods: an Information Theoretic approach relating response variables to a priori selected predictor variables incorporating hydrology, habitat, geomorphology, and water quality, and canonical ordination using forward selection to relate these same response variables to a large assortment of hydrologic metrics. In addition to assessing metrics related to predicted natural flow, flow alteration at gaged …

Effects Of Landscape Disturbances On Autotrophic Processes Within Arkansas Ozark Streams, Bradley J. Austin

Graduate Theses and Dissertations

Land-use change is one of the most widespread human impacts and can influence abiotic and biotic processes within surrounding streams. For example, streams in agricultural and urban watersheds receive greater light and nutrient inputs that can promote increased algal growth and primary production. Natural gas (NG) infrastructure development, a recent land use change in many regions, may also stimulate forested stream primary production, by reducing forest cover and increasing sediments and nutrient transport. I sampled streams across a NG activity gradient for algal biomass and gross primary production (GPP) to assess potential effects of this emerging land-use type. Algal biomass …

Exploration Of Spatial And Temporal Changes In Trophic Status Of Lakes In The Northern Temporal Forest Biome Using Remote Sensing, Aleksey Paltsev

Electronic Thesis and Dissertation Repository

There is a critical need for detailed surveys of lakes covering large spatial (>100 km²) and temporal scales (decades) to determine if there is an increase in the magnitude and frequency of phytoplankton blooms. Remote sensing was used to: (1) develop a regression model that relates chlorophyll a (chl-a) as a proxy of lake phytoplankton biomass to Landsat TM and ETM+ optical reflectance (r²=0.85, p

Phosphorus Recycling By Profunda Quagga Mussels In Lake Michigan, Caroline Mosley

Theses and Dissertations

Quagga mussels (Dreissena rostiformis bugensis) act as ecosystem engineers in the southern basin of Lake Michigan, altering physical habitats and biogeochemical processes. Adapted to cold and oligotrophic conditions, profunda quagga mussels thrive on the soft substrate of deeper depths. At a 55 m site (10,000 mussels m-2) offshore from Milwaukee, WI, profunda mussel biomass (g m-2) was 1/3 of biomass (g m-2) measured at a 10 m comparison site (5,000 mussels m-2). Higher densities but less biomass is due to profunda mussels having less tissue for a given length and the population per m2 comprising of mostly small mussels ( …

Plankton Trophic Structure Within Lake Michigan As Revealed By Stable Carbon And Nitrogen Isotopes, Zachery G. Driscoll

Theses and Dissertations

Zooplankton represent a critical component of aquatic food webs in that they transfer energy from primary producers to higher trophic positions. However, their small size makes the application of traditional trophic ecology techniques difficult. Fortunately, novel techniques have been developed that can be used to elucidate feeding information between zooplankton species. I used the analysis of stable carbon and nitrogen isotope ratios to estimate the trophic structure of Lake Michigan's zooplankton community. The major zooplankton species, three size classes of seston, and seston from specific water column depths were collected in 2011 and 2012 for stable isotope analysis. Trophic position …

Inter-And Intra-Population Variability Across The Transcriptome Of Lake Baikal’S Endemic Copepod With Ramifications For Adapting To Climate Change, Larry L. Bowman Jr

Electronic Theses and Dissertations

The future of Lake Baikal’s biodiversity is uncertain in response to climate change. Unlike its diverse benthos, Lake Baikal’s zooplankton is species poor, with up to 96% of its biomass being composed of a single Calanoid copepod species, Epischura baikalensis. This study characterizes the genetic differentiation and differential gene expression of E. baikalensis. Using partial-transcriptome sequences obtained by 454 Rosche and Illumina sequencing technologies, the genetic differentiation at inferred single nucleotide polymorphism (SNP) sites and differential gene expression in populations sampled from various parts of the lake were analyzed. The functional genomics of genes showed significant differential …

Fishes In Seagrass Habitats: Species Composition, Trophic Interactions, And Production, Kathryn L. Sobocinski

Dissertations, Theses, and Masters Projects

The value of habitats in terms of biological production is of interest to ecologists and resource managers. Seagrasses are a commonly occurring habitat type in shallow marine waters and have been shown to support high abundances of fish and invertebrates. In lower Chesapeake Bay, seagrasses grow in a shallow fringe in the subtidal zone. Although, ample evidence exists for the value of these habitats as foraging and rearing areas for a variety of organisms, the connectivity among species and the benefits derived from these habitats in terms of production have not been well described, especially for small, seasonally occurring finfishes. …