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Trophic Dynamics Of The Lake Superior Fish Community, Ariel Edwards

All NMU Master's Theses

The Lake Superior food web has undergone many changes in recent decades, including the rehabilitation of the native apex predator lake charr (Salvelinus namaycush) and the introduction of several nonnative species. The trophic linkages and ecological requirements of the entire fish community, including predators and prey fishes, has not been assessed on a whole-lake scale in over a decade. Here, I investigated the trophic dynamics across multiple regions of the lake, and estimated the consumptive effect of lean lake charr in one region of Lake Superior. From April to October of 2021, a total of five predator, four …

Cell Volume As A Determinant Of Virus-Mediated Population Growth In Ciliates, Jace Miller, John Paul Delong Phd

Honors Theses

Many protists and other small aquatic organisms consume virus particles, a behavior known as virovory. Some species of protists, such as the ciliate Halteria grandinella, can grow and divide using viruses as their sole food source. Other ciliate species have previously been shown to consume large quantities of viral particles, but it is unclear if they are able to support population growth with viruses alone. Because large ciliates have a higher energy demand, we hypothesize that they will be unable to support population growth on a virus-only diet. We fed nine ciliate species a diet of chloroviruses and found …

Host-Parasite Interactions Within Food Webs, Adam Zvanut Hasik

Graduate Theses and Dissertations

Parasitism is one of the most common life history strategies employed in nature, yet the effects of parasites are often thought to be minimal, and the vast majority of studies fail to consider parasites and their effects on host organisms. This is likely a problem, as the magnitude of parasite-mediated effects on their hosts can be quite large. Additionally, the effects of parasites are known to extend beyond the host to affect other species interactions. I used a series of approaches to gain a more integral understanding of host-parasite interactions by studying (1) the effects of parasites on biotic interactions …

How Wildlife Respond To Natural Noise, Dylan G. E. Gomes

Boise State University Theses and Dissertations

Animal sensory systems have evolved in a natural din of noise since the evolution of sensory organs. Anthropogenic noise is a recent addition to the environment, which has had demonstrable, largely negative, effects on wildlife. Yet, we know relatively little about how animals respond to natural sources of noise, which can differ substantially in acoustic characteristics from human-caused noise. Here we review the noise literature and suggest an evolutionary approach for framing the study of novel, anthropogenic sources of noise. We also push for a more quantitative approach to acoustic ecology research.

To build a better foundation around the effects …

Role Of Reptile-Invertebrate Interactions In Enigmatic Reptile Declines, Meredith Swartwout

Graduate Theses and Dissertations

Reptile populations are declining world-wide and the mechanisms behind many of these declines remain enigmatic. Food web interactions (i.e., reduced prey availability or increased predation) have been implicated behind some reptile declines. However, relatively little is known about predation on lizard and snake eggs, despite egg survival being important for population dynamics of some species. Ants are important predators of squamate reptile eggs in tropical and temperate systems. In Costa Rica, long-term declines in terrestrial anole lizards were linked with reduced leaf litter depth, a factor that could influence egg vulnerability to ant predation. Fire ants (genus Solenopsis) are aggressive …

Vignette 02: Lower Trophic Levels In The Salish Sea, Ian Perry

Institute Publications

Plankton form the base of the pelagic marine food web in the Salish Sea, and are eaten by fishes, marine mammals, and seabirds. Plankton include microscopic plants (phytoplankton) and very small animals (zooplankton). This vignette presents an overview of monitoring observations of phytoplankton and zooplankton distribution and biomass in the Strait of Georgia. Climate change may lead to unusual and unexpected patterns of phytoplankton and zooplankton in the future.

Vignette 10: Biological Repercussions From Microplastics In The Salish Sea, Ashley Bagley, Iris Kemp

Institute Publications

Microplastic (< 5 mm) consumption and the movement of microplastic through the marine food web is an emerging concern in the Salish Sea. Upon consumption, marine plastics can physically and chemically affect marine organisms. Effects from plastics may be unique among species, types of contaminants, and types and sizes of plastics. Existing research indicates that current microplastic concentrations within the Salish Sea are not a significant threat to marine organisms. However, factors such as increasing urbanization and climate change may create or exacerbate microplastics impacts on Salish Sea species.

Vignette 17: Salish Sea Jellyfish, Correigh Greene

Institute Publications

The Salish Sea is home to a diverse community of gelatinous zooplankton (or "jellies"). In their adult forms, jellies comprise a relatively large proportion of biomass in the Salish Sea. Questions regarding jellyfish abundance and climate variation in the Salish Sea have been difficult to address, in part because of a lack of consistent monitoring. Research presented in this vignette suggests that jellyfish are sensitive to climate signals like marine water temperatures, but do not appear to be systematically increasing in abundance over time. Due to advances in modeling, we may gain a better perspective on the roles jellies play …

Oyster Reef Restoration: Impacts On Infaunal Communities In A Shallow Water Estuary, Katherine Harris

The Pegasus Review: UCF Undergraduate Research Journal

Oyster reefs are important estuarine ecosystems that provide habitats to many species, including threatened and endangered wading birds and commercially important fishes and crabs. Infaunal organisms (i.e. aquatic, sediment-dwelling organisms) are also supported by oyster reef habitats. Infaunal organisms are critical to oyster-based food webs and are consumed by many important estuarine species. Due to their critical role in coastal food webs, infauna are hypothesized to be strong indicators of habitat productivity. With the dramatic global loss of intertidal oyster reefs, organisms that depend on oyster reef infauna are likely negatively impacted. Fortunately, oyster reef restoration is currently underway in …

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 …

Food Web Effects Of Lake Trout (Salvelinus Namaycush) Invasion In Northwestern Montana, Charles Wainright

Graduate Student Theses, Dissertations, & Professional Papers

Around the turn of the 20th century, lake trout (Salvelinus namaycush) were widely introduced in several lakes and reservoirs outside their native range in western North America. Since then, lake trout have become problematic in many lakes where they were introduced, causing significant declines in popular sport fishes and native species, most notably federally protected bull trout (Salvelinus confluentus). Despite evidence that invasive fish can cause cascading trophic effects in aquatic communities, the impacts of lake trout introduction / invasion on aquatic food webs remain poorly understood. Moreover, native fish restoration programs tend to focus on suppression …

Spatial And Temporal Patterns Of Arctic Nearshore Fish Community And Food Web Structures, Mark B. Barton

FIU Electronic Theses and Dissertations

Climate change and increasing anthropogenic activities are causing rapid changes to environmental and ecological processes in the Arctic Ocean. To better understand these changes, scientists have increased research efforts in these regions, but to date the number of studies on Arctic nearshore habitats are lacking. My dissertation responds to the paucity of information and investigates patterns in Arctic nearshore fish communities and food webs to gain insight to how these ecosystems may shift as these changes continue. I used multivariate statistical analysis to examine patterns in community structure and composition to determine that Arctic nearshore fish communities are largely driven …

Simulating Eutrophication Effects In Puget Sound Using Qualitative Network Models, Christopher James Harvey, Kathryn Sobocinski

Salish Sea Ecosystem Conference

Ecosystems are complex, dynamic networks of interacting physical, chemical, biological and social components. A stressor such as eutrophication thus can cause responses throughout the system via direct and indirect pathways and feedbacks. Ecosystem models are typically designed to account for as many critical components, functions and pathways as possible in order to reasonably simulate how a system may respond to a stressor; however, many aspects of ecosystem structure and function are poorly studied and too data-poor to represent in a quantitative, mechanistic model. Qualitative network models (QNMs) assume comparably simple (i.e., positive or negative) relationships between interacting components, and allow …

Trophic Roles Of Tadpoles In Tropical Australian Streams, Katrin Schmidt, Melanie L. Blanchette, Richard G. Pearson, Ross A. Alford, Aaron M. Davis

Research outputs 2014 to 2021

Tadpoles can be abundant consumers in stream ecosystems, and may influence the structure and function of streams through their feeding activities and interactions with other organisms. To understand the contribution of tadpoles to stream functioning, and the potential impact of their loss, it is necessary to determine their diets and how they might influence food-web structure. Using gut-content analysis and stable-isotope analysis of N and C, we determined the main food sources and trophic positions of tadpoles of five native frog species, invertebrates, and fish in upland and lowland Australian Wet Tropics streams. Omnivory was prevalent among the tadpoles and …

Green Sea Turtles (Chelonia Mydas) In Bermuda Exhibit An Ontogenetic Diet Shift Despite Overexploitation Of Resources In Their Developmental Habitat, Claire Margaret Burgett

FIU Electronic Theses and Dissertations

Green sea turtles in Bermuda are overgrazing the seagrasses on which later life stages are thought to specialize. I hypothesized that larger green turtles in Bermuda would display individual diet specializations during seagrass scarcity. Stable isotope methods were used to determine the diet composition of green sea turtles from the Bermuda Platform as a function of size class and in turtles captured in successive years. Individual turtles had a wide range of diets, however, the variation in diets was driven by differences among size class rather than within the size classes of larger turtles, indicating that green turtles undergo a …

Marine Disease Impacts, Diagnosis, Forecasting, Management And Policy, Kevin D. Lafferty, Eileen E. Hofmann

CCPO Publications

(First paragraph) As Australians were spending millions of dollars in 2014 to remove the coraleating crown of thorns sea star from the Great Barrier Reef, sea stars started washing up dead for free along North America’s Pacific Coast. Because North American sea stars are important and iconic predators in marine communities, locals and marine scientists alike were alarmed by what proved to be the world’s most widespread marine mass mortality in geographical extent and species affected, especially given its mysterious cause. Investigative research using modern diagnostic techniques implicated a never-before-seen virus [1]. The virus inspired international attention to marine diseases, …

Investigating Trophic Interactions Of Deep-Sea Animals (Sharks, Teleosts, And Mobile Scavengers) In The Gulf Of Mexico Using Stable Isotope Analysis, Diana A. Churchill

FIU Electronic Theses and Dissertations

The deep-sea is the largest habitat on earth, containing over 90 percent of the world’s oceans and home to over 20,000 species. Deep-sea ecosystems are increasingly impacted by human activities including fishing and oil extraction. To understand potential impacts on deep-sea food webs, it is crucial to gather baseline data in these systems. I quantified the trophic interactions of three groups of deep-water animals across a range of trophic levels living in the northern and eastern Gulf of Mexico using stable isotope analysis. First, I propose methods for correcting δ¹⁵N values for the presence of nitrogenous metabolic waste …

Distribution, Ecology, And Trophic Relationships Of A Colonial Waterbird: The Double-Crested Cormorant, Kate Sheehan

All Dissertations

The realized distribution of an organism is dependent on the environmental characteristics of the landscape, biological interactions within the communities in which it lives, and geographic barriers to dispersal. Changes in habitat can influence landscape characteristics, and consequently, the distribution of organisms within the landscape. The Double-crested Cormorant ( Phalacrocorax auritus ) is a piscivorous waterbird implicated in human-wildlife conflicts at aquaculture facilities and natural aquatic systems where they compete for resources (fish) with anglers and commercial fishing guides. Impacts of P. auritus on aquatic systems result from their consumption of fish stocks and their contamination of water and soil …

Jellyfish Identification And Quantification In The San Francisco Estuary, Amalia Borson, Lindsay L. Sullivan, Wim Kimmerer

STAR Program Research Presentations

As potential predators and competitors of plankton-eating fish, jellyfish have the potential to negatively impact fish populations. Jellyfish were collected weekly with plankton tows from the RombergTiburonCenterpier in Tiburon, CA. Since some jellyfish were too small to identify, one tow was collected and preserved to record abundances, and a second tow was collected to rear jellyfish until distinguishing characteristics were visible enough for identification. Jellyfish in the preserved tows were then identified, measured, and counted, and their abundance (number m^-3) was calculated. Jellyfish from the second tows were reared in plastic buckets that were lightly bubbled using aquarium …

Introduced Sport Fish And Fish Conservation In A Novel Food Web: Evidence Of Predatory Impact, Kevin Lee Landom

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study addressed a fundamental question in applied ecology and conservation; what is the predatory impact of introduced piscivorous sport fish on imperiled native fish populations? More specifically, which of many introduced species and size-classes represent the greatest threats and should be targeted for control? In order to explore this important question, an integrated analysis of stable isotopes, quantified observed diet analysis, and stable isotope mass-balance models were used to quantify trophic interactions. These tools were used to construct food web models that were then compared to draw inferences regarding the relative contribution of prey fish, including rare native fish, …

A Trophic Model For Kuosheng Bay In Northern Taiwan, Hsing-Juh Lin, Kwang-Tsao Shao, Jiang-Shiou Hwang, Wen-Tseng Lo, I-Jiunn Cheng, Lih-Huwa Lee

Journal of Marine Science and Technology

Using the Ecopath with Ecosim software system, a mass-balanced trophic model of Kuosheng Bay, where the Second Nuclear Power Plant is sited on the coast, was constructed. This model comprised 17 compartments, ranging from a trophic level of 1.00 for primary producers and detritus to 3.97 for piscivorous fish. The geometric mean of the trophic transfer efficiencies was 6.5%. The lower efficiencies were attributable to high flows to detritus, suggesting that the food web was more dependent on detritus than on primary producers to generate total system throughput. The total system throughput, system production, and system biomass were comparable to …

Trophic Cascades, Nutrients, And Lake Productivity: Whole-Lake Experiments, Stephen R. Carpenter, Jonathan J. Cole, James R. Hodgson, James F. Kitchell, Michael L. Pace, Darren Bade, Kathryn L. Cottingham

Dartmouth Scholarship

Responses of zooplankton, pelagic primary producers, planktonic bacteria, and CO2 exchange with the atmosphere were measured in four lakes with contrasting food webs under a range of nutrient enrichments during a seven-year period. Prior to enrichment, food webs were manipulated to create contrasts between piscivore dominance and planktivore dominance. Nutrient enrichments of inorganic nitrogen and phosphorus exhibited ratios of N:P > 17:1, by atoms, to maintain P limitation. An unmanipulated reference lake, Paul Lake, revealed baseline variability but showed no trends that could confound the interpretation of changes in the nearby manipulated lakes. Herbivorous zooplankton of West Long Lake (piscivorous fishes) …