Life Sciences Commons^™

Comparing Alternative Developmental Modes: Structure And Gene Expression In The Olfactory System Of Plethodontid Salamanders, Giuseppina S. Lanzilli

Cal Poly Humboldt theses and projects

The olfactory system of extant amphibians changes as the animal transitions from a fully aquatic to a terrestrial lifestyle at metamorphosis. Cellular morphology of the nose and expression patterns of olfactory genes in the nasal cavity have been examined for a variety of frogs and salamanders, but among plethodontid salamanders, molecular data are available only for Plethodon shermani. Using standard histology and micro-CT reconstruction, I investigated the structure of the olfactory organs of larvae, juveniles, and adults of six plethodontid species, with terrestrial, streamside, semiaquatic, and aquatic adults. The overall structure of the olfactory cavity was generally similar across …

Characterizing The Habitat Use Of Pacific Coast Feeding Group Gray Whales (Eschrichtius Robustus) And The Spatial And Temporal Variability Of Their Benthic And Planktonic Invertebrate Prey In Northern California, Robyn E. Norman

Cal Poly Humboldt theses and projects

As opportunistic foragers, the Eastern North Pacific population (~20,000) of gray whales (Eschrichtius robustus) feed on diverse benthic and planktonic invertebrates in northern Alaska foraging grounds before they undertake one of the largest yearly migrations of any mammal to breed in Baja California, Mexico. While most of the population travels to the summer foraging grounds in Alaska, a sub-group of whales (~230) called the Pacific Coast Feeding Group (PCFG) summer between British Columbia, Canada, and northern California. The diet of PCFG whales typically includes high-density and/or high-caloric prey items like mysids and diverse species of amphipods, yet a …

Comparative Morphology And Ultrastructure Of Olfactory Epithelia In Plethodontid Salamanders: Effect Of Life History Variation, Emily Gremling

Cal Poly Humboldt theses and projects

Many amphibian species rely on olfaction for locating prey and for social interactions during different life stages. Despite the importance of the olfactory system, research on its structure has been taxonomically limited. The most diverse family of salamanders, the Plethodontidae, has been largely excluded from research efforts to describe olfactory morphology. Although several histological studies have been conducted, no studies have yet looked at morphology at the level of ultrastructure using electron microscopy. The primary goal of my research was to examine olfactory morphology and ultrastructure in plethodontid species with a range of life history strategies, to better understand the …

Evaluating The Utility Of Tracers To Characterize Environmental Dna Transport And Inform Detection Of Fishes In Small Streams, Gavin B. Bandy

Cal Poly Humboldt theses and projects

This study was motivated by the need to develop a noninvasive and highly sensitive monitoring tool for determining local occupancy of an endangered aquatic species To make inference into the occupancy of fishes within small stream sites, we developed a method to determine whether environmental DNA (eDNA) concentrations from a target species were elevated relative to a tracer, formulated to mimic eDNA and introduced at a single location. We examined patterns in the observed distribution of the tracer to account for the effects of site-specific transport processes and sampling on distributions of naturally occurring eDNA at small spatial scales (400 …

Pond Characteristics That Influence Oviposition Site Selection By Two Pond-Breeding Amphibians, Northern Red-Legged Frog (Rana Aurora) And Northwestern Salamander (Ambystoma Gracile), Jessica Jones

Cal Poly Humboldt theses and projects

Pond-breeding amphibians connect aquatic and terrestrial habitats through their biphasic life cycle, and understanding pond characteristics that support oviposition sites for multiple species is important for amphibian conservation. Two common amphibians in the Pacific Northwest, Northern red-legged frog (Rana aurora) and Northwestern salamander (Ambystoma gracile) often oviposit in the same pond; however, prior studies have focused on pond use by one species or the other, but not both together. I surveyed pond and oviposition site characteristics of 26 ponds in Humboldt County, CA, 10 of which were used only by R. aurora and 16 of which …

Effects Of Habitat Selection And Individual Quality On The Reproductive Success Of Barn Owls (Tyto Furcata), Jaime E. Carlino

Cal Poly Humboldt theses and projects

The hypothesis of adaptive breeding habitat selection proposes congruence between the evolved selection of habitats and fitness components such as reproductive success. However, mismatches between habitat selection and observed fitness outcomes are not unusual and can arise for multiple reasons. Variation in individual qualities of animals has also been found to affect reproduction and survival. I examined associations between barn owl nest box selection, reproductive output, and plumage characteristics previously shown to correspond to individual quality. I found that barn owls selected tall nest boxes made of wood, mounted high off the ground, and with increased proportions of grassland around …

Seasonal Growth, Movement, And Survival Of Juvenile Coho Salmon (Oncorhynchus Kisutch) Utilizing Restored Rearing Habitat, Monica S. Tonty

Cal Poly Humboldt theses and projects

The Scott River supports the most robust population of threatened Coho Salmon Oncorhynchus kisutch remaining in the Klamath River basin. Even in the Scott River, low quality and restricted extent of juvenile rearing habitat limits the Coho Salmon population to a small fraction of historic abundance. To support persistence and recovery of Scott River Coho Salmon, the Scott River Watershed Council (SRWC) has constructed a portfolio of restoration projects to improve juvenile rearing habitat, including beaver dam analogs (BDAs). The Scott River BDAs were the first implemented anywhere in California. This study compares juvenile Coho Salmon responses associated with production …

Carnivore And Ungulate Occurrence In A Fire-Prone Region, Sara J. Moriarty-Graves

Cal Poly Humboldt theses and projects

Increasing fire size and severity in the western United States causes changes to ecosystems, species’ habitat use, and interspecific interactions. Wide-ranging carnivore and ungulate mammalian species and their interactions may be influenced by an increase in fire activity in northern California. Depending on the fire characteristics, ungulates may benefit from burned habitat due to an increase in forage availability, while carnivore species may be differentially impacted, but ultimately driven by bottom-up processes from a shift in prey availability. I used a three-step approach to estimate the single-species occupancy of four large mammal species: mountain lion (Puma concolor), coyote …

A Return To The Staging Grounds: Reassessment Of Aleutian Cackling Goose Spring Distribution In North Humboldt Bay, Shaun W. Thornton

Cal Poly Humboldt theses and projects

After a 15-year interval in research, spatial and temporal patterns of the Aleutian cackling goose during spring staging was assessed again in 2022. During my study, 3,389 goose flocks were recorded in Arcata Bottoms staging site, 1 January to 21 April 2022, amounting to an estimated total of 2,248,512 goosedays, which was 336.8% higher than 2007 estimates of 667,485 goosedays. Geese continued to use pastures with a wide range of landscape characteristics primarily represented by livestock grazing practices. Goose use was greater than availability on beef-cattle fields early in the season and dairy-cow fields later in the season. Human disturbances …

Genetic Evaluation Of The Current Distribution And Possible Diffrentations Between Lasiurus Borealis And Lasiurus Frantzii In Southwestern North America, Zeinab M. Haidar

Cal Poly Humboldt theses and projects

Several recent accounts of overlap and historic misidentifications regarding two species of the genus Lasiurus, Western red bat (Lasiurus frantzii) and Eastern red bat (Lasiurus borealis), have cast doubt on our understanding of their distribution, assumed spatial allopatry, and interactions in the United States Southwest. With the use of morphometrics and genetic sequencing, utilizing tissue collected from specimens throughout California and adjoining states, we have reassessed the current distribution, best practices for field identification, and genetic differentiation between both species. Appropriate species classification by region was achieved utilizing mitochondrial DNA, targeting the cytochrome c oxidase …

Host-Microbe Interactions In Non-Native Estuarine Anemones: Biogeography And Temperature, Parker K. Lund

Cal Poly Humboldt theses and projects

Non-native species are increasing in prevalence around the world, resulting in negative economic and ecological impacts. However, the broad distributions of non-native species also offer a system for investigating the response of host-associated microbial communities to environmental factors across a range of ecological scales. At the broadest scale, I investigated the geography of microbial communities in the non-native estuarine anemone Diadumene lineata on the west coast of the United States of America. Across latitudes, microbial community composition was very similar and displayed a high percentage of Klebsiella spp. at all sites. However, the communities in California tended to exhibit higher …

Inferring Exposure To Harmful Pseudo-Nitzschia Blooms From Ocean-To-Estuary Gradients In Domoic Acid Concentrations In Humboldt Bay Bivalves, Natasha Hope Ficzycz Winnacott

Cal Poly Humboldt theses and projects

Harmful algal blooms (HABs) result from outbreaks of any of several different species of toxin-producing phytoplankton and that can have major detrimental effects on marine ecosystems and pose severe health and economic threats to human communities. Of particular concern along the United States West Coast are HABs of pennate diatom genus Pseudo-nitzschia that produce the potent neurotoxin domoic acid (DA). The coastal ocean between Cape Mendocino, CA, and Cape Blanco, OR is a hotspot for Pseudo-nitzschia spp. HABs. Such blooms impact coastal fisheries and pose a potential threat to aquaculture operations in Humboldt Bay, California’s second largest estuary and largest …

Long-Line Culture Of Red Seaweed In The Pacific Northwest, Erika R. Thalman

Cal Poly Humboldt theses and projects

The goal of this study was to adapt open-water rope culture techniques to the native red seaweed Devaleraea mollis to support a new seaweed aquaculture industry in Humboldt Bay, California. The specific objectives for this study were to: 1) evaluate the growth of D. mollis cultivated at different depths and seasons (fall/winter, spring/summer), 2) estimate nutrients removed by D. mollis from the water, and 3) measure heavy metals and pesticides to determine potential health risk upon ingestion. Bundles of seaweed were inserted into 3 m long weighted vertical lines attached to two horizontal long-lines suspended by floats. Two four-month …

Olfactory Organ Morphology And Ultrastructure Of The Larval Koh Tao Island Caecilian (Ichthyophis Kohtaoensis), Jaclyn M. Patmore

Cal Poly Humboldt theses and projects

The olfactory system of living amphibians (Lissamphibia) undergoes major changes as it transitions from an aquatic to a terrestrial system during metamorphosis. Patterns of change in the cellular morphology of the nose have been examined for frogs (Anura) and salamanders (Caudata). However, it remains unknown if caecilians (Gymnophiona) have similar patterns of change in their nasal ultrastructure. In particular, no data on larval caecilian olfactory cell types are available. Here, using light microscopy and transmission electron microscopy, I examined the olfactory organ of larvae of the caecilian Ichthyophis kohtaoensis, to establish the ultrastructure of the epithelium and compare it …

Effects Of Landscape Configuration Metrics On American Barn Owl Nest Box Occupancy And Hunting, Samantha D. Chavez

Cal Poly Humboldt theses and projects

Harnessing ecosystem services, broadly defined as the benefits nature gives to people, is one approach to minimize the widespread negative impacts of agriculture on wildlife and biodiversity conservation. Conservation biological control is one such service that aims to use natural enemies to reduce crops losses from pests without the use of harmful pesticides, including rodenticides. In Napa Valley, California, human-made nest boxes are deployed on wine grape vineyards to attract barn owls (Tyto furcata) that depredate and remove thousands of rodent pests throughout the nesting season. However, the provisioning of this ecosystem service depends on whether a box …

Effects Of Oyster Aquaculture On Elasmobranch Abundance And Habitat Use In Humboldt Bay, Ca, Rose Harman

Cal Poly Humboldt theses and projects

Habitat modification from aquaculture can have large effects on natural communities, with the habitat complexity provided by aquaculture structure positively influencing benthic invertebrates and small fish abundance. However, the effects of aquaculture on larger predatory fish like elasmobranchs (i.e., sharks and rays), which use nearshore habitat to forage and provide top-down control of these ecosystems, is largely unknown. Over two years, I deployed baited remote underwater video systems (BRUVS) to examine the effects of oyster aquaculture and environmental variables such as habitat (mudflat or eelgrass), salinity (ppt), turbidity (m), temperature (°C), pH (mV), dissolved oxygen (mg · L^-1), …

Survival And Growth Of Juvenile Coho Salmon (Oncorhynchus Kisutch) In Restored Wetlands Of Humboldt Bay, California, Josh D. Cahill

Cal Poly Humboldt theses and projects

Substantial investment in habitat restoration efforts have been made to promote coho salmon (Oncorhynchus kisutch) recovery, yet sampling efforts to document the response of coho salmon populations to wetland restoration are limited. I investigated two cohorts of juvenile coho salmon growth, movement, and survival within the Humboldt Bay drainage in California. My study sites included restoration features and other sample areas in upland creek habitat and in lowland estuarine wetlands that were located in the four largest watersheds within the Humboldt Bay drainage. The objectives of this study were to: (1) determine if coho salmon are using restored, …

Winter Sandpiper Communities On Humboldt Bay: High-Tide Roost Use And Habitat Features That Influence Roost Site Selection, Chelsea Polevy

Cal Poly Humboldt theses and projects

Roosts, locations at which birds and other animals come together to rest and preen while remaining vigilant for predators, are a common facet of the nonbreeding biology of many shorebirds. Roosts fall on a continuum from traditional to ephemeral; traditional roosts are used consistently by the same individuals, whereas ephemeral roosts are used inconsistently and may be used only once or a few times. Studies show that roost habitat preference is the result of an individual shorebird’s attempt to optimize the costs and benefits associated with time constraints, energetic demands, and danger risks as they relate to overall fitness.

In …

Activity Patterns Of The Del Norte Salamander (Plethodon Elongatus): Monitoring Plethodontid Behavior Using Pit Tag Surveys, Sabrina Horrack

Cal Poly Humboldt theses and projects

Semi-fossorial plethodontid salamanders exhibit behavioral plasticity to avoid desiccation, retreating underground to shelter from adverse conditions such as low precipitation and high temperatures. In this study, I used passive integrated transponder (PIT) tag surveys to monitor this behavior in the Del Norte salamander (Plethodon elongatus), a small plethodontid native to northwestern California and southwestern Oregon. Within its range, a climatic gradient exists in which coastal areas experience milder temperatures and high precipitation, while inland areas tend to have colder winters, hotter summers, and lower precipitation. By monitoring the activity patterns of this species in inland and coastal areas, …

Geographic And Seasonal Variation Of Flying Squirrel Vocalizations In California, Travis A. Farwell

Cal Poly Humboldt theses and projects

Advancements in bioacoustics field studies have further elucidated spatial, temporal, and behavioral aspects of otherwise-cryptic species, as well as offering insights into species communication. The discovery of high-frequency vocalizations in North American flying squirrels in particular has allowed researchers to use ultrasonic acoustic recorders to detect these cryptic species in the wild. Investigations into vocalizations of northern flying squirrels (Glaucomys sabrinus) and southern flying squirrels (G. volans) have highlighted call type variation between species and the potential use of recorders as a tool to examine vocal activity patterns. However, high-frequency vocalizations had yet to be quantitatively …

Escherichia Coli And Salmonella Sp. In Domestic Cattle And Wild Roosevelt Elk: Fecal Pathogens At The Wildlife-Domestic Interface, Emily A. Buck

Cal Poly Humboldt theses and projects

Direct or indirect contact between domestic populations of animals and wildlife carries an inherent risk for transmission of pathogens that cause infectious disease. In Humboldt and Del Norte counties of northern California, ongoing conflict between ranchers and Roosevelt elk groups results from elk use of ranching pastures and pastures on private land. Fecal samples from elk in association with cattle, cattle, and from elk not in known association with cattle were assessed for the presence of bacteria Salmonella enterica and pathogenic Escherichia coli to assess whether association with cattle increases risk of infection for elk. Group identity (one of the …

A Characterization Of The Sandy Beach Surf Zone Fish Community And Their Ecology In Northern California And The Effects Of Marine Protected Areas, Katie B. Terhaar

Cal Poly Humboldt theses and projects

Historically written off as dull and homogenous, the dynamics of the sandy beach surf zone remains under studied world-wide. Northern California has been no exception to this global standard, as the sandy beach surf zone ecosystem in this region has yet to be characterized, and the effect of Marine Protected Areas (MPAs) on the fish and macroinvertebrate community fully ascertained.

Considered data-poor by local wildlife officials, commercially, recreationally and culturally important Amphistichus rhodoterus (redtail surfperch) and common Hyperprosopon ellipticum (silver surfperch) utilize the sandy beach surf zone in Northern California. Little is known about the effect of various environmental factors, …

Ecological And Social Drivers Of Mexican Gray Wolf (Canis Lupus Baileyi) Home Range Patterns Across Spatiotemporal Scales, Evelyn M. Lichwa

Cal Poly Humboldt theses and projects

Elucidating factors influencing home range size are fundamental relationships that can be described for any wildlife species, particularly those of conservation concern. The Mexican gray wolf (Canis lupus baileyi) is an endangered sub-species of the gray wolf whose home range patterns have not yet been studied. I estimated home range sizes for 22 Mexican wolf packs using Brownian Bridge Movement Models (95% UD). Generalized linear mixed effect models were used to evaluate environmental and social variables across four timeframes. Annual home range size was inversely related to human density and tree cover. During the denning period, home range …

Resolving Variability In Size Structure In An Individual-Based Model For The North Pacific Krill, Euphausia Pacifica, Roxanne Robertson

Cal Poly Humboldt theses and projects

Individual-based models (IBMs) have emerged as a powerful tool for ecological research and are particularly well suited to studies of plankton ecology. In this thesis, I develop an IBM for the North Pacific krill, Euphausia pacifica, with the goal of replicating observed variability in size-structure in the northern California Current Ecosystem. Krill, and E. pacifica in particular, are central to the structure and function of the California Current Ecosystem. Their response to environmental forcing translates climate variability to higher trophic levels and underpins broader ecosystem responses. Recent observations indicate environmental and climate-related shifts in E. pacifica size distributions, which …

Use Of Redwood Basal Hollows By Bats: A Focus On The Townsend's Big-Eared Bat On The North Coast Of California, Amon Jotesh Armstrong

Cal Poly Humboldt theses and projects

Loss of roosting resources, either through disturbance or removal, negatively affects bats. For sensitive species, such as the Townsend’s big-eared bat (Corynorhinus townsendii), determining roost requirements is a critical component in conserving their habitat. Such cavity roosting bats on the North Coast of California may use hollows in large redwood trees. In this study, I examined the factors determining the use of basal tree hollows by different bat species at eight redwood forest sites in Del Norte, Humboldt, and Mendocino Counties, California. Bat guano was collected from 179 basal hollow roosts from 2017 to 2018, and guano mass …

Do Beaver Dam Analogues Act As Passage Barriers To Juvenile Coho Salmon And Juvenile Steelhead Trout?, Christopher G. O'Keefe

Cal Poly Humboldt theses and projects

In the Pacific Northwest, the human-caused reduction of quality and quantity of freshwater rearing habitat is a limiting factor for Pacific Salmon populations. Beaver dam analogues (BDAs) increase suitable rearing habitat for juvenile salmonids and promote the restoration of critical stream processes. Installing BDAs is an increasingly popular alternative to more intensive restoration techniques, due to the relatively low cost and effort required to install BDA structures. However, widespread installation of BDAs has been slowed by regulatory agencies’ concerns that BDAs may impede fish passage. Few studies have empirically assessed the extent to which BDAs impede fish passage, and no …

Effects Of Large Wood Restoration On Coho Salmon In A Northern California Watershed: A Before-After-Control-Impact Experiment, Natalie B. Okun

Cal Poly Humboldt theses and projects

Substantial time, money, and effort are invested in river and stream restoration projects to aid in the recovery of imperiled salmonid populations, but there is little evidence that these efforts have had lasting positive impacts on juvenile fish growth and survival. To assess the effectiveness of large woody debris (LWD) restoration, which is one of the most common restoration practices, I evaluated the growth and survival response of endangered Central California Coast coho salmon (Oncorhynchus kisutch) in a paired watershed before-after impact-control (BACI) study. To determine if LWD supplementation influenced coho salmon growth and survival, two neighboring, similar …

Evaluating The Effects Of Atlantic Menhaden Management And Environmental Change On The Northwest Atlantic Ocean Ecosystem, Maxwell T. Grezlik

Cal Poly Humboldt theses and projects

Atlantic Menhaden (Brevoortia tyrannus) is an abundant forage fish species whose management has recently shifted from using single species reference points to ecological reference points. This type of management allows for the ecological role (e.g., supporting predators) of the species to be considered when making management decisions, and is part of a growing global movement towards ecosystem-based fisheries management. One model that aided in this transition from single species to ecological reference points was the Northwest Atlantic Continental Shelf (NWACS13) model created using Ecopath with Ecosim (Buchheister et al. 2017). Here, I updated and expanded the NWACS13 model …

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 …

Knemidokoptes Mites And Their Effects On The Gripping Position Of Steller’S Jay Feet, Wade M. Burris

Cal Poly Humboldt theses and projects

Steller’s jays (Cyanocitta stelleri) with swollen legs and feet resembling the signs of scaly leg have been commonly seen around Arcata, California, USA. These signs are thought to be caused by knemidokoptic mites, a group of parasites specialized at exploiting a range of avian hosts. I compared the gripping position in the feet of jays with variable signs of this condition as an index of their ability to perch, confirmed the presence of mites and identified them to the nearest species using genetic analysis, and compared the relatedness of the cytochrome oxidase subunit I (COI) gene between mites …