2013 Wrigley Institute Summer Graduate Fellows


James Askew – USC Department of Biological Sciences, Program in Integrative and Evolutionary Biology
Wrigley Institute Summer Fellow
Project Title: “A monitoring study of Catalina’s mice populations”

James grew up in Bristol, England, where he studied Marine Biology and Coastal Ecology at the University of Plymouth, and pursued a Masters at the University of Exeter studying orangutan behavior in Borneo. During his thesis he collaborated with USC primatologist Dr. Roberto Delgado, and this collaboration eventually led to James selecting USC for his Ph.D. studies in the fall 2011. Eventually, James hopes his research will take him back into the jungle; in the meantime, he is studying the demographics, distributions and ecological roles of endemic mice populations on Catalina Island. His research will help understand the roles these mice play as predators and prey for other endangered island taxa, the threats posed to them by the island’s invasive rat species, and how these small mammals relate to the overall management of Catalina Island’s conservation, ecology and tourism.


Meghan Hall – USC Department of Biological Sciences, Program in Marine Biology and Biological Oceanography
Wrigley Institute Summer Fellow
Project Title: “Effect of copper on development and physiology of the mussel, Mytilus spp. and implications for EPA saltwater copper toxicity”

During Meghan’s undergraduate studies at Duke University, she took a week-long field course called “Marine Ecology of the Pacific Coast of California”. The class brought her to the USC Wrigley Marine Science Center, where the facility helped put USC at the top of her list for graduate programs. Now a Trojan, Meghan’s current graduate summer research involves studying how sub-lethal exposure to copper in larval mussels can ultimately affect their later successful growth and ecology.  Copper is a problematic pollutant in Southern California coastal waters and can be present in high concentrations in enclosed water bodies, especially after heavy rainfall brings increased runoff and associated metal pollution. Although EPA protocols set acceptable copper limits partially based on copper’s acute affects on mussel mortality and development, it is still a very coarse measure and doesn’t indicate how exposing mussels to sub-lethal concentrations of copper will affect their subsequent life history stages. Meghan is utilizing the expanding field of transcriptomics (gene expression studies), along with traditional physiological and developmental techniques, to examine effects of sub-lethal copper exposure on mussels from embryo through settlement and young adult stages.


Ben Higgins – University of California, Santa Cruz, Department of Ecology and Evolutionary Biology
Wrigley Institute Summer Fellow
Project Title: “Ecology and movement patterns of the California Moray Eel (Gymnothorax mordax) around Catalina Island”

Ben is a PhD student at University of California Santa Cruz, where his doctoral research addresses the ecology, distribution, and movement patterns of the California moray eel. The combination of a cryptic lifestyle and lack of a commercial fishery has enabled morays in general to remain virtually undetected in standard species surveys and elusive to scientific studies. Thus, many basic biological and ecological have yet to be asked about these likely apex consumers. Ben’s goal is to study the movement patterns, density, growth, and predator-prey dynamics of the California moray eel around Santa Catalina Island as a means of understanding the role of morays within southern California kelp forest ecosystems.


Jenny Hofmeister – University of California, Berkeley, Integrative Biology Program
Wrigley Institute Summer Fellow
Program Title: “Factors influencing distribution and abundance of octopus inside and outside of a marine protected area in a kelp forest rocky reef ecosystem”

Based at University of California Berkeley, Jenny has been a summer fellow at USC’s Wrigley Institute for three years in a row investigating local octopus predator dynamics. Her dissertation research examines the behavioral and foraging impacts of octopus on a Catalina rocky reef kelp forest ecosystem. Jenny measures the population density and feeding selection of local octopus via their middens (the leftover shells from their feeding) and stable isotope analysis to reveal octopus diets and trophic position in the local food web. Jenny’s work will improve scientific understanding of the effects of octopus density on kelp forest ecosystems and biodiversity.


Johanna Holm – USC Department of Biological Sciences, Program in Marine Biology and Biological Oceanography
Wrigley Institute Summer Fellow
Project Title: “Identification and physiology of the endosymbiotic algae of the soft coral Muricea californica”

Johanna came to USC specifically to work with Dr. Karla Heidelberg at the Wrigley Marine Science Center, where her ability to stay at Catalina Island and access both the ocean and the laboratory in the same day motivated her decision to join the Trojan Family. This summer she is a Wrigley Fellow, studying microbial eukaryotic organisms she recently discovered in a soft coral species found along the southern California coast. Dinoflagellate endosymbionts (also referred to as zooxanthellae) are typical of many corals, living inside the coral and sharing the products of its photosynthetic carbon fixation with the coral host. Currently, the only species known to establish this relationship with corals are of the dinoflagellate genus Symbiodinium. However the species that Johanna has found living inside the local coral is different: it does not appear to be a dinoflagellate, yet it still appears to exhibit photosynthetic capabilities and may be performing a similar role. Her summer research is dedicated to identifying this organism and testing its ability to photosynthesize in the lab.


Sarah Hu – USC Department of Biological Sciences, Program in Marine Biology and Biological Oceanography
Wrigley Institute Summer Fellow
Project Title: “Changes in gene expression of key mixotrophs isolated from the water column”

Born and raised in San Diego, California, Sarah went to the University of Washington in Seattle for a B.S. in Aquatic and Fishery Sciences and a Minor in Microbiology. With an interest in marine microbiology she worked primarily with oysters and marine bacteria. Sarah came to USC to continue marine microbiology as a doctoral student in Dave Caron’s lab, focusing on the diversity and ecology of microbial eukaryotes, but with a broader focus on ecology and understanding the functional diversity of microbial communities in the ocean. In her Wrigley Summer Fellowship, Sarah is taking a closer look at the mixotrophic behavior of the potentially toxic protist Prymnesium parvum. Microbial eukaryotes are an important part of the microbial food web, but the exact mechanisms of these roles are not fully characterized. Many protists are mixotrophs – they can both photosythensize and feed heterotrophically. Studying mixotrophic physiology will give us insight into the ecological niches that microbial eukaryotes fulfill, and Sarah hopes eventually science will be able to apply such knowledge to use microorganisms as bioindicators of ocean ecosystem health.


Joyce Kao – USC Department of Biological Sciences, Program in Computational Biology and Bioinformatics
Wrigley Institute Summer Fellow
Project Title: “Adaptation of the North American gooseneck barnacle, Pollicipes polymerus to contrasting environments.”

A Ph.D. candidate of computational biology at USC, Joyce is working in the laboratory of Wrigley Professor Sergey Nuzhdin. Her research interests in evolutionary biology mainly cluster around the topics of population differences and speciation. As a Wrigley Summer Fellow, Joyce will be looking at genetic differences between populations of gooseneck barnacles in southern California, specifically those living in different high and low tide environments. She is interested in how organisms adapt to rapidly changing environments at the molecular level. Barnacles are sessile organisms, and they must cope with variable and changing conditions in their habitats once settled since they cannot relocate. Joyce is collecting DNA and RNA from barnacles across sites and sequencing their whole genomes to look for genetic differentiation between low tide and high tide groups. By doing so, she is searching for genomic signatures of adaptation between these two environments and hopefully can identify some of the key genes involved in such adaptation.


Bonita Lam – USC Department of Biological Sciences, Program in Marine Biology and Biological Oceanography
Wrigley Institute Summer Fellow
Project Title: “Exploring extracellular electron transport by microorganisms in marine sediments”

Bonita’s summer research project is to characterize (phylogenetically and physiologically) microorganisms capable of extracellular electron transport (EET) from marine sediments collected from sites around Two Harbors, Catalina Island. Her project will focus on discovering microorganisms that may not be found through traditional culturing methods, because of specialization in one particular mechanism of EET and/or a limited set of electron donors or acceptors. The elucidation of EET is redefining the way we look at microbial respiration. Although EET has been characterized in metal-reducing microorganisms, these mechanisms could be more widespread in nature and across phylogenies. EET may also play a significant role in global biogeochemical cycles. By using electrochemical techniques and chemical micro-profiling, Bonita hopes that this project can potentially develop and refine a way to culture microorganisms that were once thought to be a part of the 99.9% unculturable faction.


Ryan Lesniewski – USC Department of Biological Sciences, Program in Marine Biology and Biological Oceanography
Wrigley Institute Summer Fellow
Project Title: “Investigating the microbial ecology and nutrient dynamics of soilless plant growing systems”

Ryan’s research interests are focused on the microbial ecology of sustainable food production systems.  Providing safe, healthy food for people living in arid urban environments will require new farming strategies that are soil-less, high-density, and water-efficient. One such method of cultivation is called aquaponics, which is the combined cultivation of fish and plants in a recirculating water system. Correctly balanced, this ecosystem can provide a healthy environment for plants and fish to grow; but the system also runs the risk of developing host pathogens and parasitic relationships that inhibit or decrease plant productivity and limit nutrient uptake. Ryan is dedicating his Wrigley Summer Fellowship to initiating a multi-year doctoral research project investigating the microbial ecology of an aquaponics system he is building at the Wrigley Marine Science Center. This summer will involve the preliminary work required to design, build, and test his system; microbial community membership, succession, and function will all be studied in experiments over the next several years. 


Jacki Lin – USC Department of Biological Sciences, Program in Marine Biology and Biological Oceanography
Wrigley Institute Summer Fellow
Project Title: “Investigating the molecular basis of circatidal biological rhythms in the mussel, Mytilus californianus”

Similar to the circadian clock, which runs with a 24-hour rhythm and controls the daily physiological processes of most terrestrial organisms, it has been suggested that there is also a “circa-tidal” clock in marine organisms that runs with the 12-hour rhythm of the tides. This circatidal clock governs the pulsation of RNA, proteins and other physiological changes that marine organisms produce to tolerate their fluctuating tidal environment. But although this physiological rhythm is somehow internally regulated, the molecular mechanism running the clock is currently unknown. Jacki is working this summer to elucidate the molecular mechanism of the circatidal clock. Using California mussels, she will monitor protein level cycling and test protein-protein and protein-DNA interactions in the mussels under field (i.e. tidal and subtidal) and laboratory (i.e. no tide) conditions to determine the genes, proteins and metabolic cycles underlying this process.


Yungshen Luo – USC Department of Biological Sciences, Program in Marine Biology and Biological Oceanography
Wrigley Institute Summer Fellow
Project Title: “The assimilation of domoic acid in primary consumers in the acidified ocean”

Yungshen works in the research group of Wrigley Professor Dr. Dave Hutchins, with a focus on ocean acidification and climate change. During his Wrigley summer fellowship, he is studying the response of algae to elevated carbon dioxide levels. Increasing atmospheric carbon dioxide is resulting in higher sea surface temperatures and lowering oceanic pH. Recently, harmful algae blooms, or the rapid accumulation of dense populations of toxic or harmful phytoplankton in the water, have shown a synergistic relationship with these elevated carbon dioxide conditions where “fertilization” by carbon dioxide very likely exacerbates toxic algae blooms. The impact of these toxic algae blooms on higher trophic levels in the food web is still unknown. Yungshen is investigating the effect of changing carbon dioxide levels on accumulation and assimilation of toxic algae in primary consumers. By comparing the ways that mussels and copepods take in these toxins under current and future carbon dioxide concentrations, Yungshen’s research will help determine how toxic algal blooms could affect marine food chains in the future, an important question since human-beings are also consumers in marine food webs.


Melissa Madison – USC Department of Biological Sciences, Program in Marine Biology and Biological Oceanography
Wrigley Institute Summer Fellow
Project Title: “Analysis of benthic nitrous oxide production by nitrifying microbial communities in coastal environments”

Melissa is a PhD graduate student studying biogeochemistry in Dr. Wiebke Ziebis's laboratory at USC. Much of Melissa’s work is focused on nitrogen cycling in changing environments. Nitrous oxide is a powerful greenhouse gas, and coastal zones and estuaries are important sources of nitrous oxide emissions. But specific details of nitrous oxide production and consumption in coastal environments, including the associated microbial communities, are still not well characterized. This summer, Melissa’s project will be focused on evaluating nitrification rates and characterizing microbial communities in different sediment types across Catalina Harbor. Detailed investigation of these benthic microbial populations and emission dynamics will contribute to a greater understanding of nitrogen cycling and nitrous oxide production in benthic coastal ecosystems.


Natalie Martinez-Takeshita – USC Department of Biological Sciences, Program in Marine Biology and Biological Oceanography
Wrigley Institute Summer Fellow
Project Title: “Studies of inbred lines of the oyster, Crassostrea gigas with respect to growth, mortality, sex ratios, shell color and survival rates

With grandparents who owned a sushi bar, it is perhaps no surprise that Natalie has an interest in fisheries biology today. Natalie is a PhD student with Wrigley Professor Dr. Dennis Hedgecock, conducting genetic research on fisheries and aquaculture species. Natalie’s summer fellowship research ties in with one of the Wrigley Institute’s current initiatives, the Future of Food from the Sea. Using Pacific oysters, she will investigate the role of potential deleterious mutations in the oyster genome that may be associated with early life history mortality. Determining which specific pathways are being disturbed in the metamorphosis/settlement process, and the timing between mortality and gene expression during metamorphosis, may help explain some of the high mortality observed during oyster settlement. Natalie will also be investigating whether there is a relationship between shell color and survival rates of individuals exposed to heat and desiccation stresses. The results of these studies could have direct applications for the commercial oyster aquaculture industry, leading to an increase in the yield of hatchery seed and hatchery stocks, thus providing a more profitable, efficient and sustainable food source.


Danielle Monteverde – USC Department of Biological Sciences, Program in Marine Biology and Biological Oceanography
Wrigley Institute Summer Fellow
Project Title: “Analysis of B vitamins distribution within marine sediments”

Danielle’s research focuses on the role B-vitamins and trace metals play on marine microbes in ocean sediments.  B-vitamins are vital for many microbial species that, similar to ourselves, would not be able to perform critical metabolic processes without external sources of the vitamins.  Because sediment microbes play a critical role in many of the major biogeochemical cycles, understanding how B-vitamins are produced and consumed in sediments is critical to understanding the functioning of marine microbes. Danielle will use this summer to collect sediment cores from multiple locations around Catalina Harbor and observe how B-vitamins are distributed through the harbor and across sediment depths. Her study will be the first direct measurements of B-vitamins in coastal sediment porewaters, helping scientists understand B-vitamin production and distribution in coastal sediments, and providing insight into the dynamics of sediment microbial communities.


Becky Sawyer – USC Department of Biological Sciences, Program in Marine Biology and Biological Oceanography
Wrigley Institute Summer Fellow
Project Title: “Metabolic cost of acidification stress in larval stages of the oyster, Crassostrea gigas”

Becky is a PhD student at USC working with the Wrigley Institute’s Future of Food from the Sea initiative, a collaboration between the Manahan and Hedgecock labs. Becky’s participation in this large-scale project uses purebred genetic strains of commercial Pacific oysters to study genetic differences among various family lines. By doing so, she hopes to reveal some of the mechanistic underpinnings of the different growth rates observed under ocean acidification and ambient conditions. Recently, the genome of Pacific oysters was published, opening up new potential avenues for addressing the question of what determines larval metabolic rates in this species. Becky’s doctoral research will include an assessment of the metabolic cost of acidification stress on developmental larval stages of the Pacific oyster.  In addition to her metabolic work, she will study larval shell formation to see whether larvae in acidified conditions form shells at a slower rate than larvae in ambient conditions. All of this will help unravel the complex physiological mechanisms that are at work in determining if and how marine populations of the future will survive climate change.


Michael Schram – California State University, Northridge, Department of Biology
Wrigley Institute Summer Fellow
Project Title:“The efficts of simualted size selective harvesting on a sex changing temperate reef fish, the blackeye goby, Rhinogobiops nicholsii”

Fishermen, both recreational and commercial, typically target the largest individuals in a fish population for personal satisfaction or maximum monetary gain.  This influence has been shown to influence the life history characteristics and population ecology of the species and can truncate a population to exhibit smaller body sizes, thereby affecting reproductive success.  Previous studies have looked at the effects of harvesting pressure over large spatial or temporal scales and demonstrated a decrease in the size at maturity and, for species that change sex during their lives, their sex at sex-change; however, the causal links have not been demonstrated. Using a species that is not normally targeted by fisheries and building artificial reefs in Catalina Harbor, Michael is investigating the impact of density and size-selective harvesting on goby fish populations. His goal is to demonstrate the direct causal effects of size-selective harvesting on sex-changing species. This work will fill gaps in the current knowledge about size-selective harvesting in such species; combined with long-term observational studies, the data should allow managers to make more informed assessments of economically or ecologically important sex-changing fishes.


Patrick Sun – USC Department of Biological Sciences, Program in Marine Biology and Biological Oceanography
Wrigley Institute Summer Fellow
Project Title: “Examination of oxidative stress through the generation of reactive oxygen species in the marine copepod, Tigripus californicus in its native habitat”

With rise in population growth, anthropogenic impacts are expected to intensify in marine systems while climate change is expected to bring greater temperature extremes and a number of other undetermined changes. As a result, environmental sources of oxidative stress are expected to increase. Patrick’s research interests are centered on understanding how intertidal copepodsrespond to such oxidative stress. Catalina Island’s copepod populations show extremely high tolerance to copper exposure, despite the fact that their Catalina habitat is relatively pristine. Patrick is investigating whether this copper resistance is a byproduct of exposure to other environmental stressors that have similar pathways of toxicity, helping the Catalina copepods adapt a “cross resistance” to copper. Knowing whether adaptation to one stress will provide cross resistance to another stress will be critical in understanding how species respond to changing environmental conditions such as pollution and climate change.