Life Sciences Commons^™

Stamp Sand Along The Keweenaw Shoreline: Solid And Dissolved Copper & Effects On Biota, Gary Swain

Dissertations, Master's Theses and Master's Reports

Stamps sand refers to the regional colloquialism for the mine-tailing byproducts generated from copper (Cu) ore processing mills located in Michigan’s Keweenaw Peninsula. In the Keweenaw region, copper extracted from basalt ores resulted in a legacy of 100’s of millions of metric tonnes of stamp sand wastes, including 22.7 million metric tonnes at Gay, MI. Trace amounts of Cu persist in stamp sands and when leached have toxic enough concentrations to influence aquatic biota. To better understand stamp sands’ properties, we ran experiments and compiled data about the solid and dissolved phases of Cu. Solid phase concentration of Cu was …

Methyltransferase Mystery: Epigenetic Mechanisms Induced By Food Limitation In Daphnia Pule, Trenton C. Agrelius

Theses and Dissertations

Daphnia are ecologically important organisms that have been well studied in the context of evolution, ecology, ecotoxicity, and genomics. Daphnia have strong maternal effects in which the environment experienced by the mother can alter offspring disease resistance, life history traits, and morphology, as well as gene expression and methylation for multiple generations. Coupled with their ability to reduce genetic differences via parthenogenesis, Daphnia are an ideal system for epigenetic studies involving the transmission of maternal effects. Using two clones of Daphnia pulex, we investigated the plasticity of life history and DNA methyltransferase (Dnmt) gene expression with respect to food …

An Elevational Gradient In Thermal Tolerance Among Daphnia From Western Maine Lakes, Wheeler Lowell

HON 499 Honors Thesis or Creative Project

With climate change threatening biodiversity worldwide, it is important to understand species’ physiological responses to changing thermal environments. This study examined whether thermal tolerance (measured as time to immobilization, Timm) in the zooplankton Daphnia catawba and D. schødleri varied along an elevational gradient in Western Maine. Specimens collected from five lakes were subjected to heat stress trials to look for inter-population variation. Thermal tolerance was strongly correlated with several elevation-driven lake temperature variables, with the percent of variation explained ranging from 13-37%. Daphnia from cooler, high-elevation lakes were more sensitive to elevated temperatures. While latitudinal gradients have been examined extensively, …

Daphnia Pulex: The Mixed Messages Of Mutations , Matthew Randall Bruner

Theses and Dissertations

While mutations are almost universally considered to be more often deleterious than beneficial, their precise interactions between different populations and individual lines have been largely overlooked. Using mutation accumulation lines of four clones of obligately asexual Daphnia pulex, this research is intended to investigate the degree to which spontaneous mutation would affect fitness-related traits after roughly 100 generations. The expectation was that there would be a visible decrease in juvenile specific growth rate, the surrogate measurement used for fitness, across all four clones due to the deleterious nature of mutation in a selection free environment. Through measuring birth mass in …

Optimizing The Delivery Of A Gfp Gene Via A Biocompatible Nanocarrier In Daphnia And A Chironomid, Alexandra R. Job

Honors Thesis

Current pest control methods impose risks including pest resistance to insecticides, bioaccumulation of the insecticide, and ecosystem impact. There is a need for a better and more sustainable method of pest control in order to protect the environment and the populations reliant on it. Currently, an alternative method of pest control uses RNA interference (RNAi), that exploits heterologous protein expression to disable the insect pest, delivered by the use of nanoparticles. Nanocarriers show great promise in this method of use, but concerns of cytotoxicity, biodegradability, and transfer to off target organisms require careful consideration. This study focuses on optimizing a …

Effect Of Oxidative Stress On Lifespan And Cellular Survival, Benedicth Onyeka Ukhueduan

Theses and Dissertations

When cells experience oxidative stress, the integrated stress response (ISR) signaling pathway is activated. One of the first outcomes of such ISR-activated response is to temporarily halt protein synthesis, which aids in cellular recovery. However, if cells cannot recover from the stress, they activate the cell death pathways which kills the affected cells, usually by apoptosis, which can then lead to either acquisition or prevention of diseases depending on the situation. In physiological aging, a compromised stress response is observed as an organism ages, which leads to disrupted homeostasis and elevated risk of disease. Thus, longevity of an organism is …

A High-Throughput Method To Quantify Feeding Rates In Aquatic Organisms: A Case Study With Daphnia, Jessica L. Hite, Alaina C. Pfenning-Butterworth, Rachel E. Vetter, Clayton E. Cressler

School of Biological Sciences: Faculty Publications

1. Food ingestion is one of the most basic features of all organisms. However, obtaining precise—and high-throughput—estimates of feeding rates remains challenging, particularly for small, aquatic herbivores such as zooplankton, snails, and tadpoles. These animals typically consume low volumes of food that are time-consuming to accurately measure.

2. We extend a standard high-throughput fluorometry technique, which uses a microplate reader and 96-well plates, as a practical tool for studies in ecology, evolution, and disease biology. We outline technical and methodological details to optimize quantification of individual feeding rates, improve accuracy, and minimize sampling error.

3. This high-throughput assay offers several …

The Combined Effects Of Chemicals Used In Textile Processing On Plankton Communities., Diana Wilson

Honors College Theses

Industrial discharge, such as textile effluent, is a major source of chemical mixtures to surface waters. The effects of these mixtures on interacting aquatic organisms can be difficult to predict. We hypothesized that individual chemical effects on phytoplankton and a zooplankton grazer are altered by the presence of other chemicals in mixtures. Microcosms containing a phytoplankton food source (Chlorella sp.) and a zooplankton grazer (Daphnia magna) were exposed to THPC, ammonium, and hydrogen peroxide in a fully crossed design in a greenhouse for one week. Phytoplankton abundance was quantified and zooplankton response was measured as mortality and …

Does Thermotolerance In Daphnia Depend On The Mitochondrial Function?, Rajib Hasan

Electronic Theses and Dissertations

Thermotolerance limit in aquatic organism is set by the ability to sustain aerobic scope to sudden temperature shifts. This study tested the genetic and plastic differences in thermotolerance of Daphnia that can be explained by the differences in the ability to retain mitochondrial integrity at high temperatures. Five genotypes with different biogeographic origins were acclimated to 18^ᵒC and 25^ᵒC. We developed a rhodamine 123 in-vivo assay to measure mitochondrial membrane potential and observed higher fluorescent in heat damaged tissues as the disruption of the mitochondrial membrane potential. Significant effects on temperature tolerance were observed with CCCP …

Effects Of Copper Sulfate On Mortality Rates Of Daphnia Magna, Grace Vilem

Honors Projects

Many reservoirs used for drinking water end up growing algae that needs to be removed. Copper sulfate (CuSO₄) can be used to reduce the growth of algae, however this chemical has been shown to have negative effects on invertebrates living in aquatic environment. This experiment exposed Daphnia magna, an aquatic zooplankton, to various concentrations of CuSO₄ for 48 hours to determine an LC50 value. Six sets of data were collected and averaged, finding an LC50 value of 36 ug/L. Further testing is needed to determine effects of CuSO₄ on fecundity between generations of Daphnia, as …

Temperature Drives Epidemics In A Zooplankton-Fungus Disease System: A Trait-Driven Approach Points To Transmission Via Host Foraging, Marta S. Shocket, Alexander T. Strauss, Jessica L. Hite, Maja Šljivar, David J. Civitello, Meghan A. Duffy, Carla E. Cáceres, Spencer R. Hall

School of Biological Sciences: Faculty Publications

Climatic warming will likely have idiosyncratic impacts on infectious diseases, causing some to increase while others decrease or shift geographically. A mechanistic framework could better predict these different temperature-disease outcomes. However, such a framework remains challenging to develop, due to the nonlinear and (sometimes) opposing thermal responses of different host and parasite traits and due to the difficulty of validating model predictions with observations and experiments. We address these challenges in a zooplanktonfungus (Daphnia dentifera–Metschnikowia bicuspidata) system. We test the hypothesis that warmer temperatures promote disease spread and produce larger epidemics. In lakes, epidemics that start earlier and warmer in …

Assessing Variation In Visual Abilities In Daphnia As A Result Of Disparity In Eye Sizes, Adrian Perez

Senior Theses

The functionality of an eye is affected by a number of structural factors, and altering any of these factors often involves inevitable tradeoffs between resolution and sensitivity. However, it has been theoretically reasoned, and tested empirically, that increasing the size of an eye allows for both of these central features of vision to be improved due to corresponding increases in lens size. This study examines the relevance of this hypothesis for the vision of Daphnia in both interspecific and intraspecific contexts. The visual capabilities of six different species of Daphnia are tested using the optomotor response—a visually mediated behavior that …

Session C-1: Modeling Stem Activities Into Classroom Practice, Sowmya Anjur

Professional Learning Day

Students understand concepts better when they have had a chance to work hands on with relevant material. Examples will be presented from my classroom where difficult concepts have been modeled into simple experiments with considerable success in enhancing student understanding. Special focus will be given to selected topics that students seem to have the most difficulty grasping. The objective is to enable students to transfer their understanding to solve complex problems with considerable ease and apply their understanding to real world scenarios on assessments. Suggestions will also be provided for implementation of various concepts into the high school classroom.

Costs Of Resistance And Infection By A Generalist Pathogen, Tad Dallas, Mathieu Holtackers, John M. Drake

Faculty Publications

Pathogen infection is typically costly to hosts, resulting in reduced fitness. However, pathogen exposure may also come at a cost even if the host does not become infected. These fitness reductions, referred to as “resistance costs”, are inducible physiological costs expressed as a result of a trade-off between resistance to a pathogen and aspects of host fitness (e.g., reproduction). Here, we examine resistance and infection costs of a generalist fungal pathogen (Metschnikowia bicuspidata) capable of infecting a number of host species. Costs were quantified as reductions in host lifespan, total reproduction, and mean clutch size as a function …

Nickel And Copper Mixture Toxicity To Daphnia In Soft Water, Prachi Deshpande

Theses and Dissertations (Comprehensive)

Industrially important metals, such as Cu and Ni, sometimes are present at elevated concentrations in lakes, including those in the Sudbury, ON region. Although they are essential metals, their divalent-cation state (Cu²⁺ and Ni²⁺) can be toxic at high concentrations in the water. The free-ion toxicity of each of these metals has been studied in isolation, but rarely as a mixture. The economic importance of Cu²⁺ and Ni²⁺ makes them essential to study in the context of mixture toxicity. The objectives were to: (1) determine Cu and Ni mixture toxicity to Daphnia through acute LC50 …

Establishing The Microcrustacean Daphnia As A Model System For Research On Aging, Charles Andrew Shumpert

Theses and Dissertations

Aging is a ubiquitous process pertaining to all biological systems around the planet. Although much has been learned from studies so far on the molecular mechanisms that lead to aging, a complete understanding of a healthy life span and longevity still eludes us. In this dissertation, we will examine the use of a freshwater microcrustacean Daphnia as a model system for studies on the biology of aging. The Introduction chapter presents a review of the general molecular alterations associated with cellular and organismal aging, and discusses the core model organisms currently used to study the aging process. The introduction chapter …

The Evolutionary Biology Of Vision In Daphnia, Christopher S. Brandon

Theses and Dissertations

Eyes have attracted the attention of evolutionary biologist since the field’s infancy. In On the Origin of Species, in fact, Darwin famously remarked on the proposition that natural selection could engineer the eye, saying “[it is] absurd in the highest possible degree.” Though, he goes on to explain, beautifully and simply, how his theory of evolution by natural selection could produce such an organ. Indeed, eyes are remarkable examples of complex information acquisition systems that have evolved from simple beginnings. Eyes allow animals to extract environmental information from light, which informs physiological and behavioral responses to resources, predation, and mates. …

Carbon Nanomaterials In Freshwater Ecosystems: An Chronic, Multi-Generational, And Genomic Assessment Of Toxicity To Daphnia Magna, Devrah Anne Arndt

Theses and Dissertations

Carbon nanomaterials are synthesized with a variety of core structures and surface chemistries to make them more biocompatible for application in different industries, but variation in core structure and functionalization can change the toxicity of carbon nanomaterials to organisms. In addition, current literature is dominated by data from acute toxicity assays, but meta-data is necessary to improve our understanding of nanomaterial toxicity. This project identifies specific core structures and surface chemistries that make carbon nanomaterials more and less toxic using chronic toxicity assays and multi-generational assays to generate a dataset on the sub-lethal impacts of nanomaterials to Daphnia magna. In …

The Effects Of Sodium Lauryl Sulfate On The Abundance Of Producers And Grazers In Aquatic Communities Using Freshwater Microcosms, Stephanie R. Shipley

Honors College Theses

With increases in environmental awareness, industry has responded with products that reduce negative impacts on aquatic ecosystems. Sodium lauryl sulfate (SLS), a rapidly degrading chemical commonly found in cleaners labeled as ‘environmentally friendly,’ has been shown to have low toxicity in single species toxicity tests. However, that organisms have different sensitivities to SLS suggests a need for measuring effects at the community level. We exposed communities of microalgae (Chlorella sp.) and invertebrate grazers (a benthic snail, Elimia sp. and pelagic microcrustacean Daphnia magna) to 0, 0.5 or 1.5 mgL^-1 SLS. Water quality and invertebrate abundance were measured …

Nr1l: A Novel Nuclear Receptor Group Activated By Juvenile Hormone Analogs, Yangchun Li

All Theses

Annotation of the Daphnia pulex nuclear receptors revealed a novel group of three receptors designated NR1L, and named HR97a/b/g because of their similarity to the HR96 receptors involved in xenobiotic detection. We cloned and sequenced the three receptors from a related species often used in aquatic toxicology studies, Daphnia magna, and then analyzed their genomic structure and conducted phylogenetic studies. Phylogenetic studies confirmed that the HR97s do form a distinct group with HR97g being the precursor of HR97a and b. They also confirmed that the HR97 receptors are related to the HR96 (NR1J) receptors, and the VDR/CAR/PXR (NR1I) group. Mining …

Stoichiometric Controls Of Mercury Dilution By Growth, Roxanne Karimi, Celia Y. Chen, Paul C. Pickhardt, Nicholas S. Fisher, Carol L. Folt

Dartmouth Scholarship

Rapid growth could significantly reduce methylmercury (MeHg) concentrations in aquatic organisms by causing a greater than proportional gain in biomass relative to MeHg (somatic growth dilution). We hypothesized that rapid growth from the consumption of high-quality algae, defined by algal nutrient stoichiometry, reduces MeHg concentrations in zooplankton, a major source of MeHg for lake fish. Using a MeHg radiotracer, we measured changes in MeHg concentrations, growth and ingestion rates in juvenile Daphnia pulex fed either high (C:P = 139) or low-quality (C:P = 1317) algae (Ankistrodesmus falcatus) for 5 d. We estimated Daphnia steady-state MeHg concentrations, using a …

Algal Blooms Reduce The Uptake Of Toxic Methylmercury In Freshwater Food Webs, Paul C. Pickhardt, Carol L. Folt, Celia Y. Chen, Bjoern Klaue, Joel D. Blum

Dartmouth Scholarship

Mercury accumulation in fish is a global public health concern, because fish are the primary source of toxic methylmercury to humans. Fish from all lakes do not pose the same level of risk to consumers. One of the most intriguing patterns is that potentially dangerous mercury concentrations can be found in fish from clear, oligotrophic lakes whereas fish from greener, eutrophic lakes often carry less mercury. In this study, we experimentally tested the hypothesis that increasing algal biomass reduces mercury accumulation at higher trophic levels through the dilution of mercury in consumed algal cells. Under bloom dilution, as algal biomass …