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Trophic Ecology And Mercury Concentrations Of Canary Rockfish (Sebastes Pinniger) In The California Current System, Michaela M. Melanson
Trophic Ecology And Mercury Concentrations Of Canary Rockfish (Sebastes Pinniger) In The California Current System, Michaela M. Melanson
Master's Theses
Canary rockfish are a profitable fishery resource that has failed and successfully recovered in the 21st century. This study aimed to evaluate their trophic ecology through stomach content and stable isotope analysis and relate these to their mercury concentrations, biological traits, and environmental conditions. Canary rockfish consume mostly krill and teleosts with their geographic location affecting the proportion of prey items, suggesting regional environmental effects: chlorophyll-a, relief, port, and depth impact dietary choices. Mean ??13C values (-17.18 ± 0.54) significantly increased in individuals residing in deeper depths, higher latitudes, higher productivity, and higher temperatures, and in sexually mature individuals. Mean …
Research Handling Effects On Stress Hormones, Blood Parameters, And Heart Rate In Juvenile Northern Elephant Seals (Mirounga Angustirostris), Lauren A. Cooley
Research Handling Effects On Stress Hormones, Blood Parameters, And Heart Rate In Juvenile Northern Elephant Seals (Mirounga Angustirostris), Lauren A. Cooley
Master's Theses
Wildlife researchers must balance the need to safely capture and handle their study animals to sample tissues, collect morphological measurements, and attach dataloggers while simultaneously ensuring their results are not confounded by stress artifacts caused by handling. To determine the physiological effects of research activities including chemical immobilization, transport, instrumentation with biologgers, and overnight holding on a model marine mammal species, I collected hormone, blood chemistry, hematology, and heart rate data from 19 juvenile northern elephant seals (Mirounga angustirostris) throughout a translocation experiment. Across my six sampling timepoints, cortisol and aldosterone data revealed a moderate hormonal stress response to handling …
Epiphyte-Host Dynamics Between Pyropia And Nereocystis In Central California, Daniel Joseph Gossard
Epiphyte-Host Dynamics Between Pyropia And Nereocystis In Central California, Daniel Joseph Gossard
Master's Theses
Macroalgal epiphytism is widespread, but many unique epiphyte-host interactions remain poorly understood. Pyropia nereocystis is an annual northeastern Pacific species that has evolved to primarily epiphytize the annual kelp Nereocystis luetkeana. I examined three aspects of Pyropia-Nereocystis epiphyte-host dynamics in the southern extent of the host’s range: (1) temporal variation in epiphtyte presence; (2) growth of gametophyte and sporophyte (conchocelis) stages using transplantation experiments; and (3) effects of epiphyte depth and host characteristics on the recruitment and biomass of the epiphyte. Pyropia exhibited a shift in presence on Nereocystis that differed interannually as a function of Nereocystis density and Nereocystis …
Hook-Billed Kite, Chondrohierax Uncinatus, Southbound Autumn Migration In Belize And Mexico, Ryan Anthony Phillips
Hook-Billed Kite, Chondrohierax Uncinatus, Southbound Autumn Migration In Belize And Mexico, Ryan Anthony Phillips
Master's Theses
The Hook-billed Kite (Chondrohierax uncinatus) is a specialized Neotropical raptor with a wide distribution that has received little research attention. The species is considered non-migratory across most of its distribution, but there are scattered records of Hook-billed Kite migration. The present research describes, for the first time, the largest southbound autumn migration of Hook-billed Kite in Belize and Mexico and evaluates the effects of environmental conditions on this phenomenon. Eight years of count data were collected in Belize and 25 years in Mexico. During a total of 3093.1 count hr from 2013-2020 in Belize, 39928 Hook-billed Kites were counted on …
Detecting Feeding And Estimating The Energetic Costs Of Diving In California Sea Lions (Zalophus Californianus) Using 3-Axis Accelerometers, Mason Russell Cole
Detecting Feeding And Estimating The Energetic Costs Of Diving In California Sea Lions (Zalophus Californianus) Using 3-Axis Accelerometers, Mason Russell Cole
Master's Theses
Knowledge of when animals feed and the energetic costs of foraging is key to understanding their foraging ecology and energetic trade-offs. Despite this importance, our ability to collect these data in marine mammals remains limited. In this thesis, I address knowledge gaps in both feeding detection and fine-scale diving energetic costs in a model species, the California sea lion (Zalophus californianus). I first developed and tested an analysis method to accurately detect prey capture using 3-axis accelerometers mounted on the head and back of two trained sea lions. An acceleration signal pattern isolated from a ‘training’ subset of synced video …
Effects Of Urbanization And Habitat On The Diet And Reproduction Of Red-Shouldered Hawks In Central California, Catherine Y. Fisher
Effects Of Urbanization And Habitat On The Diet And Reproduction Of Red-Shouldered Hawks In Central California, Catherine Y. Fisher
Master's Theses
Urbanization alters biological community interactions and trophic structures compared to natural habitats; these changes may be reflected in the diets of apex predators such as raptors. The red-shouldered hawk (Buteo lineatus) is a dietary generalist that is expanding from natural and rural habitats into urbanized areas. In this study, direct observation was used to quantify the diet and reproductive success of red-shouldered hawks in Santa Clara County, California during the 2019 breeding season. GIS methods were used to quantify the nesting habitat and level of urbanization at each nest. Hawk diet consisted of mammals (50.4% by frequency and 77.7% by …
The Energetic Cost Of Anthropogenic Disturbance On The Southern Sea Otter (Enhydra Lutris Nereis), Heather Elizabeth Barrett
The Energetic Cost Of Anthropogenic Disturbance On The Southern Sea Otter (Enhydra Lutris Nereis), Heather Elizabeth Barrett
Master's Theses
With increased human populations and tourism in coastal areas, there is greater potential for disturbance of marine wildlife. Having high metabolic rates, sea otters (Enhydra lutris nereis) are at risk of increased energetic costs due to disturbance. To investigate these effects, sea otter activity in response to potential disturbance stimuli was recorded over three years, at three California locations: Monterey, Moss Landing, and Morro Bay. A hidden Markov Model was developed to examine how activity varies as a function of location, group size, pup to adult ratio, kelp canopy, and occurrence of and proximity to disturbance stimuli. Results were combined …
Dynamics And Ecological Implications Of The Ulva-Zostera Ecotone In Elkhorn Slough, California, María Vila Duplá
Dynamics And Ecological Implications Of The Ulva-Zostera Ecotone In Elkhorn Slough, California, María Vila Duplá
Master's Theses
Ecotones are transitional areas between adjacent ecological communities that have unique ecological qualities defined by space and time scales, and by the interactions between adjacent systems. Ecotones play an essential role in supporting biologically diverse communities, and are sensitive indicators of global change. An Ulva-Zostera ecotone extends along the northern shore of Seal Bend in Elkhorn Slough, an estuary located in central California. Although previous studies have mentioned the presence of the Ulva-Zostera ecotone, this was the first study to focus on understanding its driving factors, spatiotemporal dynamics, and overall ecological implications. A combination of habitat monitoring, water quality assessments, …
Diets And Stable Isotope Signatures Of Yellowtail Rockfish (Sebastes Flavidus) In Central California, Jennifer Chiu
Diets And Stable Isotope Signatures Of Yellowtail Rockfish (Sebastes Flavidus) In Central California, Jennifer Chiu
Master's Theses
Studies of fish diets can improve the understanding of trophic distributions and the predatory role of a species in an ecosystem. Identifying the spatial and temporal variability in the diets of fishes can provide useful information for stock assessments and management. Yellowtail Rockfish (Sebastes flavidus) are a commercially and recreationally important fishery species, and abundant along the central California coast, yet the most recent studies of diets occurred over 20 years ago in Oregon and Washington. To provide current information from California, I examined the food habits of Yellowtail Rockfish collected near Cordell Bank, the Farallon Islands, and Half Moon …
Traditional Ecological Knowledge In Collaborative Forest Restoration In The Sierra Nevada, Michael Boero
Traditional Ecological Knowledge In Collaborative Forest Restoration In The Sierra Nevada, Michael Boero
Master's Theses
Forest restoration in the Sierra Nevada is receiving increased attention due to climate change, increasing populations in the wildland-urban interface, and the historical mismanagement of some forests, evidenced in part by the increasing frequency and severity of wildfires in recent years. In response to an urgency to implement restoration in the absence of consensus on the best ways to proceed, public land managers practice collaborative management approaches to ameliorate antagonism between stakeholders and allow restoration projects to proceed when agreement is difficult to achieve. Stakeholders often include representatives from local community groups, environmental organizations, private industry, and—notably—tribal groups, who hold …
Spatiotemporal Variability In The Diet Of Nonbreeding Brandt's Cormorant (Phalacrocorax Penicillatus) In The Monterey Bay Region, Lisa Webb
Master's Theses
Brandt's Cormorant (Phalacrocorax penicillatus) diet composition was investigated using pellets (n = 285) collected on 19 sampling days at 3 locations during the 2006-07 and 2007-08 nonbreeding seasons in the Monterey Bay region. The conventional diet method was used, and the efficacy of the all-structure technique was evaluated. Although 29 species were consumed, Northern Anchovy (Engraulis mordax) dominated the diet and Speckled Sanddab (Citharichthys stigmaeus) also was important. Few rockfishes (Sebastes spp.) and Market Squid (Doryteuthis opalescens) were consumed compared with the number consumed in previous studies in the region during …
A Study Of Genetic Variability In Larval And Adult Populations Of Dungeness Crab (Cancer Magister), Cairbre Fanslow
A Study Of Genetic Variability In Larval And Adult Populations Of Dungeness Crab (Cancer Magister), Cairbre Fanslow
Master's Theses
Spatial and temporal genetic variation was assessed using mitochondrial DNA from adult and megalopae of Dungeness crabs, Cancer magister, from Fraser Delta in British Columbia, Washington, Oregon, and California. Megalopae were continuously sampled using light traps in one location, Coos Bay, Oregon, and compared with adults sampled across the species' range. While small-scale spatial and temporal variation were evident, there was no significant fit to the Isolation-by-Distance model when considering adult and larvae populations sampled over a coastal length of ~1700 km (Mantel r = 0.059, p = 0.289). Smaller bays showed higher genetic diversity than larger bays, contrary to …
Effects Of Tissue Nitrogen And Media Nitrate On Trace Metal Uptake And Trophic Transfer By Ulva Spp., Sonya Meenakshi Sankaran
Effects Of Tissue Nitrogen And Media Nitrate On Trace Metal Uptake And Trophic Transfer By Ulva Spp., Sonya Meenakshi Sankaran
Master's Theses
A general survey of trace metal content in Ulva spp. (Linnaeus) around Moss Landing, California was carried out. The next objective was to evaluate whether tissue nitrogen or media nitrate affects metal uptake (As, Pb, Mn, Zn) by Ulva spp. under eutrophic conditions. Additionally, the role of metal burden in the invertebrate Idotea resecata as a function of metal content in its diet was examined. Mean trace metal concentrations in Ulva differed significantly among sites in Moss Landing, California. Laboratory measurements using samples from 15 sites along the central California coast revealed a significant positive correlation between Ulva spp. tissue …
Distribution, Growth, And Disturbance Of Catalina Island Rhodoliths, Paul Anthony Tompkins
Distribution, Growth, And Disturbance Of Catalina Island Rhodoliths, Paul Anthony Tompkins
Master's Theses
Rhodoliths are free-living coralline algae (Rhodophyta) that form large beds on the seafloor. Rhodolith beds are globally widespread and biologically diverse shallow marine habitats. Beds are ecologically sensitive, disturbed by humans, and in Europe are protected by law. While rhodolith beds have been found in California waters at Catalina Island, no literature exists regarding their distribution or ecological significance. This study sought to (1) map the distribution and characterize the rhodolith beds around Catalina, (2) determine the seasonal growth rates, and (3) investigate the effect of common sources of disturbance. A systematic search of shallow subtidal (0-40 meters) areas revealed …
Western Pond Turtle Summer Habitat Use In A Coastal Watershed, Jae Abel
Western Pond Turtle Summer Habitat Use In A Coastal Watershed, Jae Abel
Master's Theses
Western pond turtle (Actinemys marmorata) habitat use was studied in a coastal pond, lagoon, and stream system during the summer of 1995 and 1996 at Waddell Creek, Santa Cruz County, California. Location and habitat association data were recorded for locations and sightings of radio-tagged and un-tagged turtles during the normal active season. Summary comparison of habitat associations and habitat availability provided inference of habitat preference at several habitat scales. For most of the active season the turtles were in relatively sunny aquatic habitat, in deeper, slower velocity water. In addition, the turtles were most commonly associated with exposed …