Thesis Defense by Ann Bishop – February 23 Livestream


"Feeling the heat: Reproductive Competition between Macrocystis pyrifera and Sargassum horneri"
A Thesis Defense by Ann Bishop

The Phycology Lab

MLML Live-Stream | February 23, 2021 at 4 pm

Ann is a masters student in the Phycology and has been working under the co-advisement of Dr. Mike Graham and Dr. Diana Steller. She grew up in the forests and on the water of the Great Lakes in northern Michigan, but the lakes weren’t quite enough to satisfy her curiosity. While studying Natural Resource Management and Conservation at Colorado State University she explored policy and research in rangelands, forestry, and anthropology. This led to opportunities to study in Australia focusing on tropical ecology and how to take terrestrial research techniques and apply them to managing natural resources above and below the water. After achieving her Bachelor of Science, she crisscrossed the country working for the National Park Service as a sea turtle technician and for the Catalina Environmental Leadership Program teaching students and sharing her love of nature, ecology, and- especially- seaweed and plants. During her time on Catalina, Ann watched kelp forests on the island disappear in a matter of months and be replaced with a thicket of invasive sargassum. A desire to understand what happened to Catalina’s kelp forests drove her to pursue a masters and became the topic of her thesis. At Moss Landing Marine Labs in addition to her thesis work, she has traveled to study kelp forests in Baja Mexico and Chile, interned at the Monterey Bay Aquarium as their herbarium technician, and assisted with the marine botany course. She has also has been the curator for the MLML Research Museum, which included cataloging and caring for MLML’s historic collections, presenting at conferences on behalf of the museum and her own research, and working to develop the education and outreach side of the collection. Ann hopes to continue working where everything – research, management, outreach – is connected.

Thesis Abstract:

Off the south west coast of North America, kelp forests are facing both warmer waters and introductions of new species. This study examined how the reproductive strategies of giant kelp, Macrocystis pyrifera, and the invasive fucoid Sargassum horneri may have contributed to the interactions of these species on Catalina Island during the 2014 heatwave and 2015/16 El Niño. In 2018-2019 monthly field surveys were conducted to observe current density, demography, temporal variability of vegetative vs. reproductive biomass investment, and temporal variation in gamete release for both species. Field observations were complimented with experimental lab cultures growing M. pyrifera with and without S. horneri. The lab experiments sought to test the effect of temperature on competition between these two species at their microscopic life stages, and what role temperature plays in gamete genesis. Peaks in Macrocystis biomass occurred in summer and coincided with peaks in zoospore production, however there was only a weak correlation between individual size and zoospore production. Conversely, Sargassum biomass and reproductive output peaked between February and April when this seaweed invests heavily in reproduction before the end of its lifespan. Macrocystis produced more propagules per individual at its peak reproductive period than Sargassum. Sargassum released all of its gametes in the spring and grew quickly from the microscopic to juvenile stage. In the lab Macrocystis development was affected mostly by temperature and less by settlement density. Macrocystis sporophyte production decreased with higher temperatures whereas Sargassum zygotes developed more quickly with increases in temperature. The results and observations of this study would indicate that temperature plays a large role in the developmental success of each of these species. The unique events that preceded the record 2015-16 El Niño likely contributed to Sargassum dominating the seascape. If temperatures are anomalously high this will be exacerbated in the future if Macrocystis gametophytes are unable to complete fertilization and develop sporophytes. The high propagule production of Macrocystis and its potential for large area dispersal could provide influxes of gametophytes to deforested areas, particularly in La Niña years, regenerating these habitats. Further research focused on how high ocean temperatures impact Macrocystis resilience and kelp forest connectivity could inform how these ecological processes are changing due to climate change. This can aid in better understanding to manage the trajectory of current and future introduced species, such as invasive Sargassum horneri.

Ann Bishop Presents: Feeling the heat: Reproductive Competition between Macrocystis pyrifera and Sargassum horneri

Thesis Defense by Daniel Gossard – December 18th Livestream


"Epiphyte-host dynamics between Pyropia and Nereocystis in central California"
A Thesis Defense by Daniel J. Gossard

The Phycology Lab

MLML Live-Stream | December 18, 2020 at 1 pm

Dan didn't really care for seaweeds until he started working at a seaweed farm in 2016 and everything changed. He realized that the complexity of these (primarily) sessile organisms requires lifetimes of study to even marginally understand, and that they're much more interesting than fish ever could be. His appreciation for the ecology of seaweeds grew as he realized that seaweeds can play an important foundational role for ecosystems. As seaweed biogeographic distributions have been known to rely on ocean temperatures, how will this foundational role change in reaction to a changing climate? What will be the trophic consequences? Can seaweeds potentially mitigate greenhouse (CO2 and methane) emissions? The answer is yes, but can the application be scaled in practical purposes on a global scale? Is seaweed farming a sustainable and scalable US industry that can alleviate the country's import deficit, feed livestock and fertilize fields, and be used as a biological filter to mediate industrial runoff alleviating the effects of eutrophication? (Yes). Despite all these pressing issues related to seaweeds, Dan chose to study an esoteric algal epiphyte for his Master's thesis. After graduating, Dan hopes to continue research in the fields of seaweed ecology and/or aquaculture.

Thesis Abstract:

Epiphytism is widespread in the marine environment across macroalgal taxa. However, despite being geographically ubiquitous, many unique epiphyte-host interactions remain poorly understood. Radiation within the bladed Bangiales (Rhodophyta), presumably brought on by a heteromorphic life history coupled with exceptional tolerance of stressors, led to many subtidal species of Pyropia occupying the epiphytic subtidal niche with their annual gametophyte stage. Pyropia nereocystis is a northeastern Pacific species that has evolved to primarily epiphytize the annual kelp Nereocystis luetkeana, which has a large latitudinal range from central California to the Aleutian Islands. There is a complete lack of tested hypotheses regarding the spatial and temporal dynamics of this epiphyte-host interaction and a lack of understanding of whether environmental heterogeneity drives recruitment and growth of Pyropia. I tested three aspects of Pyropia-Nereocystis epiphyte-host dynamics in the southern extent of the host’s range: (1) spatial and temporal variation in epiphtyte presence as a function host canopy densities at five sites for two cohorts; (2) empirical tests of the effects of depth on growth of gametophyte and sporophyte (conchocelis) life history stages through transplantation experiments; and (3) evaluation of the effects of depth and host characteristics on the recruitment and biomass of the ephiphyte over two seasons.

Pyropia epiphytism exhibited a shift in presence on Nereocystis that was attributed to an increase in the proportion of hosts that were epiphytized over the first two sampling periods. These dynamics differed interannually as a function of Nereocystis density. Additionally, testing the coefficient of variation of densities of epiphytized versus non-epiphytized Nereocystis over time (for sampling periods where Pyropia was present) indicated greater clumping of unepiphytized Nereocystis and more regularly arranged epiphytized Nereocystis. Pyropia gametophyte transplants showed no significant differences in growth when transplanted below their primary habitat (on the upper portions of Nereocystis stipes), but Pyropia conchocelis transplants showed a significant positive correlation between growth (change in area occupied) and depth. Intraregional environmental heterogeneity was reflected in significant intraregional differences among Nereocystis host characteristics that affected Pyropia recruitment. Additionally, significant associations between Nereocystis stipe characteristics and Pyropia's lower limit and abundance (biomass) were present for epiphytized Pyropia and their Nereocystis hosts. Nereocystis holdfast depth did not set the lower limit of Pyropia recruitment, but the PC (principal component) associated with longer host apophyses were correlated with a deeper Pyropia recruitment lower limit. Pyropia abundance in the upper meter was a strong predictor of Pyropia biomass on the whole Nereocystis stipe, but only during the peak period of Pyropia abundance. Furthermore, Pyropia abundance was positively correlated with the surface area of Nereocystis, hosts with longer stipes and more cylindrical apophyses, and thresholded by hosts characterized by greater SL:HD (stipe length:holdfast depth). These results suggest that the distribution of epiphytism of Nereocystis is more regular than it is clumped, gametophyte growth is not limited by depth, and that conchocelis can grow successfully depths at least up to 20 m. Additionally, in the presence of environmental heterogeneity, Pyropia may be regulated by Nereocystis stipe characteristics relating to host apophyses, stipe surface area, and ecological effects experienced by individual Nereocystis. The epiphyte-host interaction between the macroscopic stages of these heteromorphic algae highlights: (1) Nereocystis mediates Pyropia's persistence on a cohort sub-population scale, (2) Nereocystis likely influences Pyropia's abundance and lower limit by interactions on an individual host scale, and (3) Pyropia persists in the face of interannual hetereogeneity of host Nereocystis persistence.

Daniel Gossard Presents: Epiphyte-host dynamics between Pyropia and Nereocystis in central California

Thesis Defense by Jacoby Baker – December 4th Livestream


"Maternal environment drives larval rockfish gene expression (Sebastes spp.)"
A Thesis Defense by Jacoby Baker

The Ichthyology Lab

MLML Live-Stream | December 4, 2020 at 4 pm

Jacoby has always had an affinity for the water. Even so, he tried to escape the calling of the water and started his undergrad career first in mathematics then moved into biochemistry. Eventually, he couldn't fight it anymore and received his B.S in Biological Sciences with a concentration in Marine Biology from San Jose State University. In his final year of undergrad he found himself interning at NOAA NMFS in Santa Cruz working on a large collaborative ocean acidification and hypoxia project that Dr. Scott Hamilton and Dr. Cheryl Logan were PIs on. Here, he cultivated his interest in researching the effects of climate change stressors on marine organisms, which led to his thesis project. Jacoby is now a Research Assistant at the Monterey Bay Aquarium Research Institute (MBARI) and is applying his molecular background on a project using environmental DNA (eDNA) to help identify organisms residing within Monterey Bay.

Thesis Abstract:

Global climate change is driving shifts in ocean chemistry, which combined with intensification of coastal upwelling, reduces ocean pH and dissolved oxygen (DO) content in the nearshore habitats of the California Current System. Physiological plasticity, within and across generations, might be especially important for long-lived, late-to-mature species, like rockfishes (genus Sebastes), that may be unable to keep pace with climate change via genetic adaptation. Rockfishes exhibit matrotrophic viviparity and may be able to buffer their offspring from environmental stress through early developmental exposure or transgenerational plasticity (non-genetic inheritance of phenotypes). I pre-exposed mother gopher (S. carnatus) and blue (S. mystinus) rockfish to one of four treatments; 1) ambient conditions, 2) low pH, 3) low DO, or 4) combined low pH/DO stressor during fertilization and gestation, followed by a 5-day larval exposure after birth in either the same or different treatment. I used RNA sequencing to determine how the maternal environment affected larval rockfish gene expression (GE). I found that the maternal exposure drove larval GE patterns regardless of sampling time point or treatment. Furthermore, the maternal environment continued to strongly influence larval GE for at least the first five days after birth. These data suggest that rockfish may not be able to buffer their offspring from environmental stressors, highlighting the important role of the maternal environment during gestation.

Jacoby Baker Presents: Maternal environment drives larval rockfish gene expression (Sebastes spp.)

Thesis Defense by Lindsay Cooper – December 1st Livestream


"Compartmentalization & seasonal variability in storage compounds of Pterygophora californica"
A Thesis Defense by Lindsay Cooper

The Phycology Lab

MLML Live-Stream | December 1, 2020 at 12 pm

While other children told their parents they wanted to be ballerinas or firemen, from the get go, Lindsay claimed she would become a marine biologist. That was the only profession she ever wanted to pursue in life. Every year, her birthday request was to visit Sea World and the San Diego Wild Animal Park for the weekend. However, feeling discouraged by counselors who told her there were few career paths in marine science, she pursued a business degree as an undergrad. After enduring several unfulfilling years on this path, she threw all caution to the wind and started over in order to pursue her lifelong passion of marine science. Lindsay received her SCUBA certification and was able to spend a fall semester doing research with the Wrigley Institute of Environmental Science on Santa Catalina Island. This was her first real immersion into the field and opportunity to do independent research. During this program she developed a love for seaweeds and the drive to pursue a graduate degree.

Lindsay joined the MLML Phycology lab in 2013, where she took an active role in hosting the annual Open House and volunteering to help other students with their research. While at Moss Landing, Lindsay has acquired her scientific dive certification, gone on two research trips to Baja California Sur studying rhodolith beds as a living substrate, and conducted a subtidal study of Pterygophora californica population demographics and aging in Stillwater Cove, Carmel Bay. Her thesis research focuses on the effects of biomass loss on the seasonal variability in storage compounds of Pterygophora californica, an important local kelp species.

Thesis Description:

This study investigates the existence of nutrient compartmentalization within the thallus of Pterygophora, whether there were any seasonal effects, and how biomass loss impacted the compartmentalization of nutrients. The results of this subtidal experiment have been a long time coming; it's the second iteration. The first time Lindsay set up the experiment, she was six months into the experiment when two big winter storms hit in a row and ripped almost all of the tags off of her Pterygophora, and dislodged some of the plants. Lindsay had to redesign the tags, and move the experiment to a slightly more protected location in Stillwater Cove. The experiment began in July 2017 and ran for 15 months.

Lindsay Cooper Presents: Compartmentalization & seasonal variability in storage compounds of Pterygophora californica

Thesis defense by Amber Reichert – December 7th Livestream


"Habitat Associations of Catshark Egg Cases (Chrondrichthyes: Pentanchidae) off the U.S. Pacific Coast"
A Thesis Defense by Amber N. Reichert

Pacific Shark Research Center

MLML Live-Stream | December 7, 2020 at 4 pm

Thesis Abstract:

Many marine species select sites for reproduction based on habitat suitability, environmental tolerances, and oceanographic conditions, in order to enhance development or survival of their offspring. For many species living in the deep sea, it is unknown which factors influence this aspect of the reproductive process. In this study, the occurrence and influences of oviposition site selection were determined for the brown catshark, Apristurus brunneus, and filetail catshark, Parmaturus xaniurus, in the greater Monterey Bay region, providing novel insights into specific habitat preferences and depth distributions. Video footage from the Monterey Bay Aquarium Research Institute (MBARI), and the National Oceanographic and Atmospheric Administration’s Southwest Fisheries Science Center Fisheries Ecology Division (NOAA-SWFSC-FED) was utilized to predict suitable oviposition habitat using MaxEnt presence-only modeling, identify attachment substrates and faunal associations using qualitative observations, and determine depth and habitat preferences using tests of independence and Manly’s selectivity indices. The greater Monterey Bay region was determined as a nursery for both A. brunneus and P. xaniurus on the basis of meeting all oviparous nursery qualifications: high densities of egg cases deposited in the same region, habitat was benthic, oviposition sites were continually used, and no juvenile sharks were observed in the vicinity of egg cases. Complex geographic and environmental features such as rugosity and depth were shown to influence oviposition sites of A. brunneus and P. xaniurus. An increase in rugosity indicated higher predictive habitat suitability. The primary depth range of oviposition sites for both species was 150–199 m, with relatively more A. brunneus egg cases in the 100–149 m range, and more P. xaniurus egg cases observed at deeper depths (200–300 m). Depth ranges for both species are similar and were expanded based on MBARI video observations  (A. brunneus = 87–550 m, P. xaniurus = 99–524 m). Areas of greatest predicted habitat suitability were indicated on the shelf break and upper to mid slope of the Monterey Canyon and in adjacent canyons. MaxEnt model output indicated higher induration (i.e., rockier) habitat was the main driver of oviposition site selection. Structure forming marine invertebrates (SFMI) such as corals and sponges were identified as important faunal attachment structures, with egg cases of both species occurring significantly more often on sponges than other substrates. Nurseries are critically important habitat and this research is necessary for influencing habitat-based management. The vulnerability of these and other species prompts further research concerning the use of SFMI as oviparous nurseries for potential essential fish habitat (EFH) designation.

Amber Reichert Presents: Habitat Associations of Catshark Egg Cases (Chrondrichthyes: Pentanchidae) off the U.S. Pacific Coast

Thesis Defense by June Shrestha – December 9th Livestream


"Fish pee in the sea: a surprising source of limiting nutrients in California kelp forests"
A Thesis Defense by June Shrestha

The Ichthyology Lab

MLML Live-Stream | December 9, 2020 at 12 pm

Growing up, June always loved being underwater. Long summer days were spent at the local pool in Virginia, where she swam along the bottom pretending to be a SCUBA diver and scouring the “seafloor” looking for treasure: forgotten toys, hair ties, and even a coin or two. Then on a fateful snorkel trip to the ocean with her family, 10-year-old June loved swimming with the fish so much, that she decided that she wanted to be an “Oceanographer Scientist” when she grew up! Mind you, she did not know exactly what an oceanographer did, but she liked that it had the word “ocean” in it, and “scientist” sounded impressive. 

From then on, all of her academic pursuits were focused on reaching her goal of becoming an “Oceanographer Scientist”. In high school, she crashed “Take Your Daughter to Work Day” events at NOAA, conducted extra science fair projects, and even studied Latin for four years in hopes that it would help her learn scientific nomenclature. In college, June majored in Biological Sciences for her B.S. degree at Virginia Tech and learned that she was actually more interested in ecology, not oceanography! She participated on any research project she could involving the words “water”, “fish”, or “snorkel”, and spent many days surveying streams for fishes in the mountains of Virginia.

Now, as June graduates with her M.S. in Marine Science from Moss Landing Marine Laboratories and CSU Monterey Bay, she can finally say that she accomplished her childhood dream. When not conducting research, you can find June SCUBA diving - for real now - within the kelp beds of California.

Thesis Abstract:

In marine systems, fishes excrete dissolved nutrients rich in nitrogen, a biolimiting nutrient essential for regulating primary production and macroalgal growth in the ocean. Often overlooked in attempts to explain the variability in kelp forest productivity, relatively little is known about the magnitude and patterns that drive nutrient excretion from fishes, especially in temperate kelp forests. I investigated the supply of nutrients excreted by the dominant fishes (30 species representing ~85% of total fish biomass) on nearshore rocky reefs in California. Using rapid field incubations, I measured the amount of dissolved ammonium (NH4+) released per individual (n = 460) as a function of body size and developed predictive models relating mass to excretion rates at the family-level. I then combined the family-specific predictive equations with data on fish density and size structure around the northern Channel Islands characterized from visual SCUBA surveys conducted from 2005-2018. Mass-specific excretion rates ranged from 0.01 – 3.45 µmol g-1 hr-1, and per capita ammonium excretion ranged from 5.9 – 2765 µmol per individual per hr. Ammonium excretion rates scaled with fish size; mass-specific excretion rates were greater in smaller fishes, but larger fishes contributed more ammonium per individual. When controlling for body size, ammonium excretion rates differed significantly among fish families with the highest excretion by surfperches (Embiotocidae). On an areal scale, the fish community in the northern Channel Islands excreted a substantial amount of ammonium to the kelp forest (mean: 131.3 µmol · m-2 · hr-1), and spatiotemporal variability (range: 59.84 – 247.9 µmol · m-2 · hr-1) was driven by the establishment of marine protected areas (MPAs), geographic and temporal shifts in the overarching fish community structure, and environmental and habitat characteristics. Results suggest that fish-derived nutrients may provide an important and underrepresented nutrient source to kelp beds, particularly during low-nutrient periods (e.g. seasonal or climatic events), and that fishing may interfere with these nutrient cycling pathways. Areal rates of ammonium excretion – consistent with those reported for tropical reefs, but among the first measured in temperate systems – reveal that fishes may play a critical role in supporting the resiliency of kelp forest ecosystems.

June Shrestha Presents: Fish pee in the sea: a surprising source of limiting nutrients in California kelp forests

Thesis defense by Mason Cole – November 6th Livestream


"Detecting Feeding and Estimating the Energetic Costs of Diving in California Sea Lions (Zalophus californianus) Using 3-Axis Accelerometers"
A Thesis Defense by Mason Cole

The Vertebrate Ecology Lab

MLML Live-Stream | November 6, 2020 at 12 pm

     There is written evidence that when Mason was in third grade he wanted to be an "adventure biologist!", which sounds like an awesome gig. He promptly forgot this dream and ended up pursuing a pre-med undergrad track (B.S. in General Biology from UCSD in 2010), only to change his mind again after graduating. Drawn by wilderness and adventure, and hoping to somehow stumble upon a fulfilling career choice, he booked it to Chilean Patagonia and wandered northward through mountains, diverse volunteer gigs in conservation biology, and his entire bank account before crawling reluctantly back to California. Two years later, armed with experience in both tough field work and poverty, he was ready to take on grad school!  Through hard work and perfect timing he ended up in Dr. McDonald's Vertebrate Ecology Lab, where he couldn't be happier. It was during this time (2015-2020) that Mason's 3rd grade "adventure biologist!" card was unearthed like a fossil from sedimentary layers of nostalgic keepsakes in his parents' home...COINCIDENCE? I think not.
     Mason's research interests currently include the foraging ecology and energetics of large predators, with ample room for broadening this horizon in the future. Mason is also passionate about scientific outreach, outdoor education, and active conservation (habitat conservation and restoration), and has worked (or is currently working) professionally in each of these avenues.

Thesis Abstract:

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).  In Chapter 1 I 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 and acceleration data was used to build a feeding detector. In blind trials on the remaining data, this detector accurately parsed true feeding from other motions (91-100% true positive rate, 0-4.8% false positive rate), improving upon similar published methods.  In Chapter 2, I used depth and acceleration data to estimate the changing body density of 8 wild sea lions throughout dives, and used those data to calculate each sea lion’s energetic expenditure during descent and ascent at fine temporal scales.  Energy expenditure patterns closely followed the influence of buoyancy changes with depth. Importantly, sea lions used more energy per second but less energy per meter as dive depth increased, revealing high costs of deep diving.  Combined, these chapters further our understanding of California sea lion foraging ecology and provide new methods to aid similar future studies.

Mason Cole Presents: Detecting Feeding and Estimating the Energetic Costs of Diving in California Sea Lions (Zalophus californianus) Using 3-Axis Accelerometers

Thesis Defense by Emily Pierce – April 17th Livestream


"Emanation and Decay of Environmental DNA from Three Molluscan Species"
A Thesis Defense by Emily Pierce

The Invertebrate Zoology and Molecular Ecology Lab

MLML Live-Stream | April 17, 2020 at 4 pm

Emily has loved marine invertebrates since visiting aquariums and tide pools as a young child. When she moved away from the ocean, she had pet snails so she could continue to learn about molluscs and slimy things, even though she lived in the desert. Emily received a B.S. in Biology from Pepperdine University, where she had a chance to work as an undergraduate researcher and teaching assistant for 3 years. Her research interests include invertebrate zoology and molecular biology, but she is also passionate about education and reaching underserved populations with marine biological knowledge. Emily will move on to a Ph.D. program in collaboration with the University of Maine, University of New England, and the Bigelow Laboratories under the Maine EPSCoR project to continue working with environmental DNA, this time searching for invasive species on the Maine Coast.

Thesis Abstract:

Environmental DNA (eDNA) is nucleic acids outside of living organisms found in air, soil, water, and ice. It is shed by organisms through waste and other bodily fluids, as well as cells sloughed off the outside of an organism. eDNA breaks down over time, especially when exposed to UV, heat, and bacteria. Scientists can analyze eDNA to identify organisms in an area, though the rate at which it is emanated and decayed seem to vary from organism to organism, complicating interpretation of results. The present study sought to quantify the rates of emanation and decay through a series of in vitro experiments for three species, Mytilus californianus (the California blue mussel), Haliotis rufescens (the red abalone), and Lottia scabra (the rough limpet). I found that eDNA emanation rates varied based on species, size, and activity level, and that rates of decay can be influenced by bacterial activity and time under treatment. This data can be used by scientists and managers to interpret eDNA signals of these commercially or ecologically important molluscs to help protect these species and the communities in which they belong.

Watch Emily’s Remote Thesis Defense Below:

Thesis Defense by Miya Pavlock-McAuliffe – January 27th

Drivers of Sub-Seasonal to Interannual Shoreline Change at Sunset State Beach in Monterey Bay, CA

A Thesis Defense by Miya Pavlock-McAuliffe

The Physical Oceanography Lab

Monday, January 27th, 2020 at 4pm

MLML Seminar Room

Thesis Abstract:

This study investigates the interrelationships between the shoreline, sandbar, and wave characteristics using twenty months of half-hourly video observations and five years of biannual survey observations. The relationship between sandbar and shoreline position was investigated to evaluate whether the sandbar buffers the shoreline from incoming wave energy. The shoreline varied by approximately 60 meters while the sandbar varied by approximately 100 meters in the cross-shore direction. The 95th percentile of nearshore significant wave height (1.7m) was required to significantly erode the shoreline at the onset of winter. The investigation of sandbar buffering was inconclusive but suggests that sandbar position plays a greater role in shoreline recovery than in shoreline erosion. Next, shoreline change models were used to test the influence of cross- and alongshore sediment transport on storm-scale to interannual shoreline evolution. An equilibrium shoreline change model was used to simulate shoreline change due to cross-shore sediment transport (RMSE = 6.4m). According to the equilibrium model, the accretion timescale at Sunset State Beach was nearly four times longer than the erosion timescale. Model performance was not significantly improved by the inclusion of shoreline change due to alongshore sediment transport but was likely degraded by temporally variable sediment supply, inferred from annual fluctuations of sandbar and shoreline position. Enhanced shoreline erosion corresponded with greater average winter wave heights and when wave energy approached from more shore-normal directions. Shore-normal wave approach did not necessarily correspond with El Niño periods, but did act to enhance alongshore wave energy gradients due to the irregular bathymetry of the Monterey Submarine Canyon. The results of this study emphasize the need for accurate projections of changing wave direction in addition to wave energy to accurately predict coastal change.

Miya Pavlock McAuliffe Presents: Drivers of sub-seasonal to interannual shoreline change at Sunset State Beach in Monterey Bay, CA