Life Sciences Commons^™

The Effects Of Multiple Stressors On Stream Communities: The Convergence Of Drought, Nutrient Pollution, And Invasive Species, Robert Joseph Fournier Iii

Graduate Theses and Dissertations

Freshwater systems experience multi-faceted degradation from a variety of ecological and environmental stressors. Three common stressors in these systems, drought, nutrient pollution, and invasive species, have wide-ranging effects on stream population- community- and ecosystem dynamics. We have a broad understanding of how each of these stressors works to influence stream systems independently. However, we still know relatively little about if, and how, these stressors might interact when they co-occur. Though drought is a natural part of many stream systems, all three of these stressors can be exacerbated or facilitated by anthropogenic actions. Accordingly, as human population and resource use continue …

Fish Community Composition And Structure Near A Freshwater River Diversion In Southeastern Louisiana, Rachel L. Snider

LSU Master's Theses

Gulf of Mexico estuaries, particularly in Louisiana, are among the world’s most productive, with landings of commercially- and recreationally-important species exceeding all other contiguous US states. Coastal wetlands are disappearing at an alarming rate because they have been impounded from Mississippi River water and sediment. Although controversial, one proposed solution is to re-route the Mississippi River through diversions and siphons to supply the freshwater and sediments necessary to rebuild vanishing wetlands, particularly in Barataria Bay and Breton Sound, LA. This strategy is one approach outlined in the Louisiana Coastal Master Plan. This project aimed to describe the composition and structure …

Interspecific Differences In Stressor Tolerance Drive Community-Level Changes In A Small Aquatic Ecosystem, Jennifer M. Weathered

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The global human population is expected to reach 9.8 billion by 2050 and an increase in food yield will be needed to provide for the future generations. Insects are among the biggest threats to food production and are therefore the subject of intense chemical control through the application of pesticides. The ability of insects to evolve resistance to pesticides after repeated use has been documented. However, how evolved responses affect individuals’ behaviors, their interactions with others, and how these factors impact overall patterns in distribution remains relatively unexplored in the bromeliad.

The aquatic insect communities housed in water-holding tropical plants …

Same Stone, Different Outcomes: Marine Communities On Engineered Vs. Natural Rock Shores, Lucy Anne Dando Lockwood

Graduate Masters Theses

The effort to protect coastal property and infrastructure from storm damage, erosion, and sea level rise has resulted in increased construction of coastal protection structures (CPS) worldwide. Researchers around the globe have found that the marine communities living on CPS differ from those living on natural rock outcroppings in the same area. We conducted a classic disturbance experiment to investigate possible differences in marine organism response and community assembly between natural and human-constructed rocky intertidal habitat along the Massachusetts coast. The one-year study used naturally occurring rock shores and human-made granite seawalls with both wave-exposed and wave-protected areas. Significant differences …

The Effects Of Hackberry Psyllids On Refueling Migratory Songbirds And Autumnal Seed Rain, Chance H. Hines

Biological Sciences Theses & Dissertations

Hackberry psyllids (Pachypsylla sp) are a galling insect native to North America’s hackberry trees (Celtis sp). Hackberry leaf-galling psyllids are ephemerally abundant during autumn, a period of time when migratory songbirds are traveling from their breeding areas in temperate North America south to their winter ranges. These migrations are energetically taxing and many songbirds fuel their journey with resources like insects and fruits. I captured birds with mist nets, observed foraging behaviors, and captured avian-dispersed fleshy fruit seeds (hereafter, seed rain) rain during the autumn of 2016 and 2017 to determine how hackberry psyllids, an ephemerally …

Context-Dependent Dynamics Lead To The Assembly Of Functionally Distinct Microbial Communities, Leonora S. Bittleston, Matti Gralka, Gabriel E. Levanthal, Itzhak Mizrahi, Otto X. Cordero

Biology Faculty Publications and Presentations

Niche construction through interspecific interactions can condition future community states on past ones. However, the extent to which such history dependency can steer communities towards functionally different states remains a subject of active debate. Using bacterial communities collected from wild pitchers of the carnivorous pitcher plant, Sarracenia purpurea, we test the effects of history on composition and function across communities assembled in synthetic pitcher plant microcosms. We find that the diversity of assembled communities is determined by the diversity of the system at early, pre-assembly stages. Species composition is also contingent on early community states, not only because of …

Stoichiometric And Stable Isotope Ratios Of Wild Lizards In An Urban Landscape Vary With Reproduction, Physiology, Space And Time, Andrew M. Durso, Geoffrey David Smith, Spencer B. Hudson, Susannah S. French

Ecology Center Publications

Spatial and temporal variation in stoichiometric and stable isotope ratios of animals contains ecological information that we are just beginning to understand. In both field and lab studies, stoichiometric or isotopic ratios are related to physiological mechanisms underlying nutrition or stress. Conservation and ecosystem ecology may be informed by isotopic data that can be rapidly and non-lethally collected from wild animals, especially where human activity leaves an isotopic signature (e.g. via introduction of chemical fertilizers, ornamental or other non-native plants or organic detritus). We examined spatial and temporal variation in stoichiometric and stable isotope ratios of the toes of Uta …

The Effect Of Shade Tree Species On Bird Communities In Central Kenyan Coffee Farms, Deven Kammerichs-Berke

Cal Poly Humboldt theses and projects

Shade coffee has been recognized as a well-studied example of a land-sharing management strategy that both creates habitat for tropical birds while also maintaining agricultural yield. Despite the general consensus that shade coffee is more “bird-friendly” than a sun coffee monoculture, little work has been done to investigate the effects of specific shade tree species on bird diversity and their capacity to help deliver ecosystem services. Previous studies in temperate regions have demonstrated that due to shared evolutionary histories, native plant species are better at promoting native arthropod numbers, which in turn support a greater number of birds. This study …

Impacts Of Ocean Acidification On Intertidal Macroalgae And Algivore Preference, Andrea Michelle Fieber

Cal Poly Humboldt theses and projects

Ocean acidification, a facet of global climate change, has the potential to induce changes in marine macroalgae that modify their existing interactions with algivorous invertebrates. In this study, I examined the effects of elevated carbon dioxide (pCO₂) on several species of intertidal macroalgae (Phaeophyta, Rhodophyta) and evaluated the present-day and predicted future preferences of algivores (Pugettia producta and Tegula funebralis) by assessing grazing rates on untreated algal tissue and on algae exposed to high-pCO₂ seawater. Both red and brown algae grew faster in elevated pCO₂ than in ambient seawater, …

Haemoparasite Infection And Immunogenetic Diversity In A Clade Of North American Songbirds, Naima Starkloff

Legacy Theses & Dissertations (2009 - 2024)

The persistence of an organism in a particular habitat is mediated by a complex interplay of abiotic and biotic interactions. These interactions become especially complicated for a vector-transmitted parasite as its persistence relies on its ability to colonize both ectothermic and endothermic host organisms. Host factors, rather than environmental factors, have been highlighted as key predictors of the diversity and prevalence of avian haemosporidians (malaria parasites and relatives) globally. The range of a parasite is limited by its host specificity as well as the community of hosts present. In addition, as haemosporidian infections typically have negative fitness consequences on hosts, …