Thesis Defenses

"Spatiotemporal Dynamics and Biogeochemical Responses in a Tidally Restricted Moro Cojo Slough"

A Thesis Defense by Ryan Chiu

Physical Oceanography Lab

Zoom | Live-Stream | November 8th, 2023 at 3:00 pm PDT

Abstract

Four years of observational data for Moro Cojo Slough (MCS), a Mediterranean climate estuary in central California, linked anthropogenic nutrient loading and hydrological modifications to a shift in net ecosystem metabolism (NEM) that differs from the characteristic net heterotrophic behavior of most estuarine systems. A lack of precipitation and limited flushing during the dry seasons, as evidenced from hypersaline waters, contribute to high ecosystem respiration rates that drove NEM to nearly balanced or net autotrophic. During the wet seasons, increased runoff and nutrient loading due to precipitation elevated primary production rates within MCS, characterizing the system as net autotrophic. Box models developed for the estuary determined that: 1) salinity was primarily controlled by advection and runoff, 2) high nitrate fluxes were advected into the slough at the mouth, and 3) the processes that dominate DO fluxes were biological processes and gas exchange. Field deployments of DO loggers further reinforced this dependence on daytime primary production and nighttime ecosystem respiration, as observed in the diurnal variabilities in DO. With anthropogenic factors playing a critical role in MCS’s net autotrophic characterization, there is concern that heavily modified systems may begin to exhibit a shift in metabolic behavior and ultimately act as a net source of carbon.

"White Abalone (Haliotis sorenseni) Restoration Aquaculture: An Assessment of Formulated Diets and Probiotics"

A Thesis Defense by Kayla Roy

Aquaculture Lab

Zoom | Live-Stream | July 17th, 2022 at 12:00 pm PDT

Abstract

White abalone (Haliotis sorenseni) are an endangered species found along the California coast. They are at historically low densities, nearing extinction. Aquaculture facilities throughout California are currently involved in the captive breeding of the species and grow out of juveniles for outplanting to wild habitat. White abalone have historically suffered from an infectious bacterial disease known as withering syndrome or Ca.Xc. This disease has been treated with an antibiotic, but antibiotic treatments can lower immune functions and create antibiotic resistance genes. A probiotic treatment could be used to replace this antibiotic and increase the overall health and growth rates in white abalone. To study the use of probiotics, Bacillus licheniformis was used on macroalgae in abalone exposed to and unexposed to Ca.Xc There was no Ca.Xc detected in any of the white abalone at the end of the study indicating that white abalone may now be able to combat Ca.Xc with abacteriophage (pCXc). Shell loss during this first probiotic experiment hindered data collection on feeding and growth rates. In the first probiotic study 42% of the white abalone and 53% of the red abalone lost their shells. Two subsequent studies were conducted to understand the cause of the shell loss. These studies were inconclusive, but one of these experiments showed that low tank stocking density (588 abalone/m2) can increase feeding and growth rates compared to high tank densities (1,176 abalone/m2).

White abalone restoration activity aims to enhance the species recovery by developing self-sustaining populations. These efforts are costly because of the species’ slow growth, high early mortality rate, and reliance on seasonal macroalgae feed. These limiting factors warrant an assessment of alternative diets and probiotic treatments for the species to shorten the culture time and lower costs before outplanting. Diet administered probiotics have previously shown improved growth rates, feed digestibility, and survivorship in abalone species. Formulated feeds are known to provide adequate nutrition and reduce costs for several cultured species. The second probiotic study investigated the effects of B. licheniformis on a commercially formulated abalone feed, ABKelp®, on white abalone. Three diet treatments were assessed: formulated feed treatment, formulated + probiotic treatment, and standard fresh macroalgae diet (Devaleraea mollis and Macrocystis pyrifera). The standard fresh macroalgae treatment resulted in the highest growth rates and feed intake, while the formulated + probiotic treatment had the lowest feeding and growth rates. This could be due to a reduced palatability caused by the presence of the probiotic.

Despite comparatively inferior growth metrics, the formulated treatment still resulted in adequate growth andsurvivorship in white abalone. The use of a formulated diet is feasible for white abalone restoration aquaculture when considering additional costs associated with fresh macroalgae feeding including permits, diving, and boat operations for M. pyrifera collection and culture facilities devoted to macroalgae culture and storage. The growth rates, feeding rates, and proximate analysis suggest that formulated feed is a viable alternative diet for conservation aquaculture facilities with limited access to fresh macroalgae.

Bio

Kayla graduated from California State University Monterey Bay (CSUMB) in May of 2019 with a B.S. in Marine Science. In her undergraduate time there she served as president of the Marine Science Club and was a TA the Beginner and Advanced/Rescue SCUBA classes. She volunteered a Science Mentor for Watsonville Area Teens Conserving Habitats (WATCH) program through the Monterey Bay Aquarium.

Kayla accepted a position in Dr. Luke Gardner’s lab at MLML in the fall of 2019. Her thesis investigated multiple methods of improving white abalone aquaculture restoration work. In her thesis she assessed the use of a probiotic treatment for withering syndrome now known as Ca.Xc. She assessed a formulated diet to understand its impact on white abalone growth rates, feeding rates, and survivorship compared to their natural and seasonally limited seaweed diet. She presented her thesis work at the Aquaculture America 2023 conference in New Orleans, Louisiana. During her thesis work she mentored an undergraduate student though the CSUMB Undergraduate Research Opportunities Center (UROC) program. Kayla worked as a water quality monitoring technician and worked on the White Abalone Project during graduate school. She reared the white abalone at MLML for outplanting and helped with abalone spawning work. She served as the GA for the Invertebrate Zoology I course at MLML. During her time at MLML she participated in the 2023 research competition AlgaePrize at the National Renewable Energy Lab (NREL) in Golden, Colorado. After graduating Kayla is looking forward to continuing with aquaculture work and research.

"Influence of intrinsic factors on at-sea behavior of late chick-rearing emperor penguins (Aptenodytes forsteri) at Cape Crozier, Ross Island, Antarctica"

A Thesis Defense by Parker Forman

Vertebrate Ecology Lab

Zoom | Live-Stream | July 19th, 2022 at 12:00 pm PDT

Abstract

I described the at-sea behavior of emperor penguins (Aptenodytes forsteri) during late chick-rearing at Cape Crozier. Analyzing data from eight penguins, I investigated how intrinsic factors, including sex, size, and body condition influenced their behaviors. Penguins exhibited mean trip durations of 10.6±3.4 days, covering a daily distance of 55.7±8.0 km. Penguins predominantly performed dives within the upper 200 meters of the water column (90.7±26.5%), with a smaller proportion of dives (9.3±2.0%) reaching greater depths. Deeper dives were typically associated with shallow bathymetry. Penguins conducted an average of 1,860±681 dives with maximum depths of 455.8±32.6 m and durations of 12.9±2.4 minutes. Penguins spent 66.4±14.8% and 43.9±4.4% of their time at sea resting and diving.

Penguins with similar behaviors were categorized into groups: Group I foraged near the continent and traveled to the Ross Bank, and Group II predominantly foraged near the continent. I found significant differences in foraging behaviors between the groups and sexes. The composition of these groups was influenced by sex. Group I mostly comprised males, while Group II were females and one unknown sex. Females displayed higher dive frequencies per day (Females (F):186±17, Males (M):151±4), shallower maximum depths (F: 432.2±29.4 m, M: 476.8±12.8 m), and shorter durations (F: 3.2±0.7, M: 3.9±0.3). Possible explanations for the observed differences between male and female penguins include energetic requirements, prey preference, physical characteristics, and niche differentiation, which can shape their distinct foraging behaviors.

Furthermore, results from this study indicate that penguin behaviors were also influenced by the physical characteristics and condition of their bodies. This finding suggests that there may be an optimal body condition for achieving greater diving depths. Penguins with intermediate body conditions may possess a more efficient physiological adaptation for sustained deep diving, enabling them to access resources inaccessible to individuals with lower or higher body compositions.

This study advances our understanding of late-chick-rearing penguins and the influence of intrinsic factors on their behavior. The findings indicate that emperor penguins exhibit divergent strategies influenced by sex and physical condition, leading to variations in dive behavior and bathymetry use. These sex-based disparities in penguin behavior highlight distinct ecological roles for each sex within the species. These findings provide a novel description that underscores the remarkable adaptations of emperor penguins in successfully navigating dynamic environments at Cape Crozier.

Bio

Parker Forman is an ecologist recognized for his creative application of datalogging technology to study cryptic species. With a solid understanding of behavioral ecology, Parker illuminates the hidden complexities of these creatures' lives and their interactions with their environments.

After completing his undergraduate studies, Parker embarked on a hands-on role as a biological field technician. His work encompassed diverse demographic studies, contributing to our knowledge of marine and terrestrial vertebrates, including Northern spotted owls, native Hawaiian birds, Northern elephant seals, and fur seals.

In 2018, Parker joined the Vertebrate Ecology Lab at MLML, which marked a turning point in his career. He researched the frigid landscapes of Cape Crozier, Antarctica, focusing on studying the at-sea behavior of emperor penguins. Living in such an isolated location alongside his study subjects provided Parker with firsthand experiences of the lives of these deep-diving seabirds.

Guided by his passion for nature, data analysis, and commitment to conservation, his experiences reinforce his dedication to expanding conservation efforts in ecological discovery.

"Composition and Distribution of Fish Assemblages in Cap de Creus Natural Park in Relation to Marine Protection, Depth, and Habitat"

A Thesis Defense by Katie Cieri

Fisheries and Conservation Biology Lab

Zoom | Live-Stream | Arpil 19th, 2022 at 4:00 pm PDT

Bio

Katie got her B.S. in Biology from the University of Virginia. After graduating, she pursued many different opportunities. She completed a Research Apprenticeship at Friday Harbor Laboratories investigating the foraging ecology and diet of Pacific Sand Lance. She also worked as an intern with the Virginia Aquarium Stranding Network in the Humpback Whale identification program. Prior to her enrollment in MLML, Katie worked as a research technician and lab manager in the Farmer Lab at the University of Utah, where she conducted investigations into the respiratory physiology of Tarpon and American Alligators. While completing her Master’s thesis, the composition and distribution of fish assemblages in Cap de Creus Natural Park in relation to marine protection, depth, and habitat, at MLML Katie worked as a research technician in the Fisheries and Conservation Biology Lab under Dr. Rick Starr. She was involved in many projects, including the Monitoring & Evaluation of Mid-Depth Rocky Reef Ecosystems, the Benthic Observation System Survey (BOSS), and the California Collaborative Fisheries Research Program (CCFRP). Through these projects and her own thesis, Katie explored how different survey methodologies including video landers, remotely operated vehicles, and hook-and-line surveys, can be utilized to assess nearshore fish and invertebrate communities and to monitor the effectiveness of Marine Protected Areas. Katie is also passionate about outreach and inclusion and continues to explore avenues to make marine science more accessible. While at MLML, she was a member of the leadership committee for the Monterey Bay Chapter of the Society for Women in Marine Science. She also contributed to MLML Open House through leading crowdfunding, participating in the puppet show, and heading up the donations committee. Katie is interested in exploring the best solutions for marine conservation through science, user engagement, and collaborations in her new position as a California Sea Grant Fellow for the California Ocean Protection Council's Biodiversity Program. In her free time, Katie enjoys kayaking, scuba diving, hiking, and adventures with her husband and dog.

"The Distribution of Microplastics in Marshlands Surrounded by Agriculture Fields: Elkhorn Slough (CA)"

A Thesis Defense by Victoria Dickey

Geological Oceanography Lab

Zoom | Live-Stream | November 30th, 2022 at 4:00 pm PDT

Bio

Victoria joined Moss Landing Marine Labs in 2018 after earning a BS in Oceanography at Hawaii Pacific University. She is in the Geological Oceanography lab under Ivano Aiello’s advisement and has enjoyed building skills in GIS, grain size analysis, and operating the Scanning Electron Microscope. Victoria came up with the idea to sample sediment to find microplastics after driving past the fields of plastic mulch on her way to school every day. She is a strong advocate for ocean conservation and has played a role in the local chapter of the Surfrider Foundation as well as on the advisory council for the Monterey Bay National Marine Sanctuary. Victoria believes strongly in the necessity of communicating science and conservation to people of all ages and demographics and hopes to continue to build that skill in her future careers.

Thesis Abstract

The wide-spread use and subsequent recycling of plastics in the agriculture industry promotes improper disposal and poses a threat to important wetland habitats. When plastics degrade, they break up into smaller pieces that pose serious threats to organisms that ingest them and to habitats they settle in. This study quantifies the estimated concentration, types, and lengths of microplastics (< 5mm plastic particles) in the marsh environments of Elkhorn Slough, California’s second largest estuary. Replicate samples of marsh soil samples were extracted from seven Elkhorn Slough marshes at varying distances from the head and the mouth of the estuary and potential sources of agricultural plastic. Using a safe and cost-effective density separation technique, microplastics were separated from the soil, identified, and counted on micro-filters using a dissecting microscope, then further analyzed with a Scanning Electron Microscope equipped with an Energy-Dispersive Spectrometer (SEM/EDS) to analyze surface microstructures and the elemental compositions of the particles. Two main microplastic morphotypes, fragments and fibers were observed. The average concentration of microplastics estimated by this study is ~1600 particles per kg of wet soil, which is comparable to the average concentration of microplastics found in the sediment of the Venice Lagoon. Fragments are statistically smaller but more abundant (making up 85% of microplastics found) than fibers and with an average length of ~85 µm and ~500 µm respectively. Fragment lengths at agriculture sites are larger than the rest of the sampling sites, indicating a shorter residence time in these locations and highlighting agriculture plastics as a potential source. All microplastics found in collected samples exhibit signs of weathering, like pitting and fractures on the surface.  This study explores the particle size distributions of microplastics and the sediment they were sampled from to highlight the similarities in the physical influences controlling their distributions. Importantly, the federally protected Monterey Bay National Marine Sanctuary exchanges an extensive tidal range with Elkhorn Slough. This study identifies potential sources of microplastics to the Monterey Bay National Marine Sanctuary and the surrounding shores with an emphasis on the agriculture industry.