Undergraduate Student Research

Published research from BML undergraduate students, featured in Explorations, the UCD undergraduate research journal.

The effects of UV radiation on adult and larval behavior and chromatophore size in Octopus rubescens. 

By Wyatt Brown, Spring 2014

Ultraviolet (UV) radiation—especially UV-B radiation—can have detrimental effects on marine larvae and elicit behavioral changes in many adult marine organisms. Although there has been a considerable amount of research on chromatophores in marine organisms, little is known about the relationship between cephalopod chromatophores and exposure to UV-B radiation. This study investigates the effects of 280 nm, 330 nm and 488 nm wavelengths on paralarva Octopus rubescens, as well as the behavior and chromatophore changes of adult Octopus rubescens under non-specific UV-B conditions. Paralarvae chromatophore size significantly increased after exposure to each wavelength but there was no significant difference in average percent change between the respective wavelengths. Adult octopuses exhibited no significant behavioral changes or chromatophore color changes in response to UV-B conditions; however, they tended to spend more time in darker conditions when given the chance. 

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The effects of dissolved organic matter on the survival and behavior of red abalone (Haliotis rufescens) larvae.

By Grace Ghrist, Spring 2014

Abalone species in California have drastically declined since the first commercial and recreational fisheries. Although aquaculture helps by supplementing abalone fisheries and supporting populations of endangered species, the process is still developing. An estimated 90% of cultured abalone die in the first three months post-settlement. Abalone larvae are capable of absorbing and metabolizing energy in the form of dissolved organic matter (DOM) during pre-settlement and early post-settlement larval stages. In this study, pre-settled and post-settled larvae were supplemented with various forms of DOM in an effort to increase the survival at these sensitive stages. Larvae were exposed to varying concentrations of a 16 amino acid mix, a sugar mix, and a combined amino acid and sugar mix. Pre-settled larvae were exposed to a salinity stress of 40mM KCl in order to expedite mortality so that survival data could be collected in a timely manner. No significant differences in survival were found between treatments of both the pre-settled and post-settled larvae, however, behavioral changes were observed in the post-settled larvae. In particular, the treatments with high amino acid concentrations (1000nM) had a higher percentage of crawling larvae (p<0.001) and a lower percentage of metamorphosed larvae (p=0.001) compared to the other treatments. Significant differences between high sugar and low sugar concentrations were also observed.

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Anti-predator behavior of juvenile black rockfish, Sebastes melanops.

By Sharea Giger, Spring 2014

The influence of visual and chemical cues in anti-predator behavior was studied using juvenile black rockfish (Sebastes melanops), and cabezon (Scorpaenichthys marmoratus). In a lab experiment, the prey, S. melanops, and the predator, S. marmoratus were subjected to four treatments of visual and chemical cues. S. melanops spent more time in the eelgrass (Zostera marina), and less time on the side with the predator when S. marmoratus was visually present. When a chemical cue of the predator was present, the prey spent more time near the walls of the aquariums. This study helps in understanding fish behavior, including prey detection and risk assessment.

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Relationships between aquatic primary productivity and flow regime in regulated and unregulated rivers of the Sierra Nevada, California.

By Alyssa Obester, Summer 2012

Disturbance as a result of a flood flow is considered to be one of the driving variables influencing aquatic and riparian community structure. However, the demand for water, power and flood control in California has resulted in the construction of dams on nearly every major river in the state. Dams compromise the natural flow regime by altering the magnitude and timing of flow. While the majority of current literature focuses on the effects of flow alteration on consumers and higher trophic levels, fewer studies have focused on impacts to basal aquatic resources and primary producers, particularly periphytic algae. In an effort to better understand the impacts of flow-related disturbance on algal resources, this study examines the relationship between algal ash free dry mass (AFDM) and the timing and magnitude of peak flow and water temperature in four regulated and unregulated streams of the Sierra Nevada across wet and dry water years. Results support previous findings that flow disturbance can reset algal community succession, and that growth patterns are related to water temperature. Following high flow disturbance, AFDM increases to a peak when water temperatures are highest, and then decreases as senescence occurs. Given the ease in collection and analysis, AFDM can provide a simple quantitative measure for monitoring aquatic primary production in regulated and unregulated streams.

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Effects of Wrack Composition, Age, and Cover on the Spatial Distribution of Beach Arthropods

By Bryan Nguyen

To test for resource partitioning in wrack-associated sandy beach macrofauna, I examined the effects of wrack pile age, composition, cover, and distance from the swash zone on Diptera (flies)and talitrid amphipod (Megalorchestia spp.) distributions on a Northern California sandy beachusing a factorial experiment and observational surveys. Ephydrid flies were correlated with localwrack pile size while Fucellia rufitibia flies appeared to be correlated with broader algal cover on thebeach. While both presumably feed on algae, algal cover on different spatial scales determined thedistribution of these flies. The effect of wrack pile age on animal abundances depended on the typeof wrack, with the older piles of certain algae harboring more flies. Amphipods were found closerto the swash zone, where fresher, moister wrack tends to be located. These differences in animaldistribution patterns imply that talitrid amphipods and beach flies exhibit resource partitioningas a result of how their natural histories and traits interact with tidal and diurnal cycles. Spatialdistributions of sandy beach macrofauna appear to be determined by many various abiotic andbiotic factors.

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The Effects Of Anthropogenic Copper on the Native Marine Mussel Mytilus Californianus in Spud Point Marina, Bodega Bay, California

By Catherine Funk

Established marinas act as gateways for human impact on the natural environment. One of the major ways this occurs is through the leaching of biocides from antifouling paints applied to marine vessels. These paints often contain copper, which can have an effect on non-target organisms, especially those in fouling communities within marinas. In this study, I hypothesized that the level of copper in Spud Point Marina in Bodega Bay, CA., would affect the local population of the native mussel Mytilus californianus at the larval stage. I tested this by measuring the level of copper in the marina using diffusive gradients in thin films (DGTs), and exposing larvae to different copper concentrations in the laboratory. I found that while increasing copper does decrease normal larval development, increased exposure time has the same effect on development. These factors interact with each other to produce a combined influence on larval development.

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The Effect of Multidrug Resistance Transporter Activity on Mercury Bioaccumulation in Strongylocentrutus Purpuratus Pluteus Larvae From Consuming Contaminated Isochrysis Galbana

By Rae Porter-Blackwell

Mercury (Hg) contamination via prey can be significantly effected by bioacculumation of mercury through trophic levels. However, a complete understanding of how mercury bioaccumulates through trophic levels is not fully understood. This study expands on knowledge of multidrug resistance (MDR) transporters on the uptake of mercury through trophic levels and investigates whether MDR activity in algal cells may alter Hg accumulation. Four-arm pluteus stage larvae of Strongylocentrotus purpuratus were exposed to the MDR inhibitor Reversin 205 and then fed inorganic mercury-contaminated algae. Results show that at the four-arm pluteus stage, S. purpuratus is more resistant to mercury contamination. Reversin 205 exposure resulted in increased survival of plutei, with no significant difference between Reversin Only and Mercury plus Reversin treatements, although overall health was reduced as compared to controls.

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Intraspecific Competition of Pagurus Samuelis on Shell Selection and Recognition

By Ariana Mortazavi

Marine hermit crabs use gastropod shells to protect their soft abdomens. By knowing a hermit crab’s shell preference, the dynamics of hermit crab interactions within a species can be better understood for shell selection and exchanges. This research conducted three treatments on the Pagurus samuelis hermit crab to test shell recognition ability and selection. The purpose of this experiment was to test intraspecific competition of P. samuelison shell selection and recognition. The gastropod shells originally inhabited by the hermit crabs were all C. funebralis. P. samuelis females and males were presented with a choice of their original shell and another similar gastropod shell previously inhabited by a P. samuelis of the same sex. Overall, when tested individually, females preferred their own shell while males had no preference. However, when P. samuelis was presented the same shell choice in the presence of another hermit crab of the same sex, its preference changed. The location of the shell also mattered for the hermit crab’s shell choice. The experiments indicate that shell preference is dependent on the presence or absence of a conspecific of the same sex. Also, it was found that a P. samuelis hermit crab’s sex does make a difference in shell choice selection and preference.

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Invertebrate Fossil Correlation to Climate Trends in Sediment Core Md02-2504 from Santa Barbara Basin in the Past 24 KYR

By Miranda Stripe

In the Southern California Bight, the upper reaches of minimally oxygenated waters rest at a depth of ~500 m. In such environments, invertebrate communities are adapted to low-oxygen levels and can exist due to annual oxygen replenishment events. Throughout the past 24 ka, oxygenation of this area fluctuated, with higher oxygenation occurring during glacial and stadial periods and hypoxic environments manifesting in interglacial and interstadial phases. To identify patterns between community structure and oxygen levels, I quantified invertebrate assemblages in Core MD02-2504 (481 m; Santa Barbara Basin, California, 34.23°N, 119.86°W) between 0.18-24.38 ka. These assemblages included ostracods, molluscs, and echinoderms. Molluscs were also identified to their lowest taxonomic groupings, where Lucinoma aequizonata and Astyris permodesta were the most abundant species within the core. Ostracod and mollusc densities increased with cooler, more oxygenated periods (e.g. the Last Glacial Maximum) and decreased in warmer, hypoxic intervals (e.g. the Bølling Allerød).

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Gulf of Alaska and California Bamboo Corals: A New Archive of Climate Change

By Wilson Sauthoff

Deep sea bamboo coral communities form along seamounts and continental margins with near global distribution. Deep ocean trawling, coral trading, and ocean acidification threaten these corals and associated species. Much like tropical corals, bamboo corals record surrounding ocean geochemistry as the coral skeleton is precipitated outwards from an internal core, sometimes displaying growth banding similar to tree rings. Records of ocean chemistry present reliable proxy records of changes in seawater conditions, such as productivity and nutrient content. Analysis of ocean variability may provide important indications of past frequency of climate oscillations, such as El Niño or Pacific Decadal Oscillation. Bamboo coral specimens from the California margin and Gulf of Alaska provide insight into latitudinal and temporal differences in sea surface productivity and nutrient availability. Past oceanic conditions are reconstructed using trace element profiles (Ba/Ca, Sr/Ca) to interpret past ocean nutrient levels and productivity. This research adds to the scientific understanding of natural, short-term climatic variability in the Pacific Ocean, and tests for evidence of anthropogenic changes in the deep ocean environment.

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June 23, 2015: Congratulations to Malina Loeher, Bodega Marine Laboratory Summer Session 2014 student (Environmental Stress and Embryo Development course)

Malina's paper, "Phototoxicity of Titanium Dioxide Nanoparticles in the Starlet Anemone Nematostella vectensis," was one of only 20 essays chosen from 375 entries to win the honor of being included in the publication of the 2014-2015 volume of Prized Writing. Prized Writing is designed to select and publish the best expository writing produced by UC Davis undergraduates during the 2014-2015 academic year.