Ocean-bottom seismometers (OBSs) are known to record puzzling signals termed short-duration events (SDEs) at frequencies of 4-18 Hz. SDEs are harmonic and usually have a duration of < 1 s, lack the P and S waves of local earthquakes, and individual events are never recorded on multiple OBSs. These signals have been attributed to either biological activity from animals bumping the seismic sensors or gas bubbles moving beneath the sea floor. In this study, we assess these explanations for SDEs using data from the Cascadia Initiative, a major OBS experiment along the continental margin of the Pacific Northwest that lasted from 2011-2015. After manually calibrating the acceptable trigger amplitude for each station, I ran a recursive short term/long term detector over the year they were deployed. Some shallow stations show a clear diurnal signal with more SDEs during the day, which is consistent with a biological origin, while others show no such pattern. SDEs are also observed on some of seismic stations on the Ocean Observatories Initiative Regional Cabled Array where the sensors are buried and protected from the biological bumps. I categorized the SDEs on representative stations based on parameters including the average frequency, bandwidth, number of peaks, and duration. This data will be used to determine whether the characteristics of the events show a pattern consistent with the biological or gas bubble hypotheses.

Possession Sound, located in Everett, Washington, includes the second largest source of freshwater in Puget Sound from the Snohomish River. This salt-wedge estuary serves as a home to a wide selection of phytoplankton, which provide energy to a variety of organisms farther up the food chain. Water chemistry often determines where phytoplankton accumulate prior to their recycling as nutrients. Ocean Research College Academy students utilize water chemistry data (temperature, salinity, dissolved oxygen, pH, turbidity and chlorophyll concentration) from two sensors deployed in Possession Sound: One in the river and one two miles away at Mukilteo. While plankton samples are collected in the Sound, rarely are plankton collected in the river and compared to chlorophyll concentrations. This study will look at abundance and diversity of phytoplankton collected in the river at various tide stages and compare these to Mukilteo samples. I hypothesize that flood tide samples will be similar, while ebb tide phytoplankton and chlorophyll levels will decrease. The preliminary data revealed that chlorophyll and temperature levels did not vary significantly between the two sites despite the widely differing salinity levels. The next steps of the study are to determine the plankton density of phytoplankton species across the two most recent years of data. Results will enable us to explore further into plankton presence in relation to chemical variance in water systems. 

Pugettia producta, native to the Salish Sea, alter their diet seasonally based on availability, shifting from algae in spring and summer to mussels in fall and winter. Our hypothesis was that when presented with both algae and mussels simultaneously, the kelp crabs would prioritize one food over another. Additionally, the environmental conditions of a tank may also have an effect on the amount of food consumed. We also hypothesized that by mimicking the seafloor, the consumption rate would be higher. Crabs were placed in two tanks, one with sediment and one without, and were accompanied by a measured amount of bull kelp and mussels. Tanks were covered nightly at sunset to mimic outdoor lighting conditions, and salinity, pH, water flow, and temperature were regulated evenly for both tanks. Measurements were taken daily of the remaining food supply, and each trial was run for 48 hours. We found that the tank with the sediment had less food remaining, and in both tanks, more algae was consumed than mussels. Algae may have been preferred because it takes less energy to consume, which may mean that kelp crabs spend more energy eating in the winter, and likely suffer a tradeoff with less energy to spend on other factors, such as growth and reproduction. Imitating the sea floor may have made a difference in alleviating stress levels in the crabs, which led to more consumption. Understanding dietary preferences is important when considering the potential future effects of anthropogenic climate change and ocean acidification on marine ecosystems.  Additionally, mimicking field conditions in a laboratory in conjunction with manipulating variables of interest for any experiment likely provides more accurate results than an empty tank, and may be a viable option wherever possible to obtain results representative of a natural environment when field experiments are not possible.  

Pacific herring (Clupea pallasii) play a critical ecological role in the Puget Sound food web and are experiencing declines throughout the Sound. Presently, no single cause has been identified, and consequently, no policy action has been implemented to reverse the declines. Here we evaluate the hypothesis that terrestrial landscape features govern the trends in local stocks (defined by aggregations during reproduction) through run-off, noise, light, and other indirect effects. We predicted that status of local stocks would show associations with terrestrial landscape features such as land use and human density. To test these predictions, we gathered a time series of spawning biomass estimates for sub-stocks throughout Puget Sound and used multiple metrics to evaluate the population status of each subpopulation. We then related these metrics with information on local land-use and other localized anthropogenic disturbances. Across all metrics, a majority of the 22 stocks showed impaired status over the past 15 years. However, we found no association between local status and landscape metrics. This result indicates that landscape level effects are not solely responsible for the impaired status of Pacific herring, but we caution that this may be because there are multiple, interacting causes for declines that need to be addressed to recover this valuable species.

A novel freshwater methane seep with unique physics and chemistry was discovered off the Oregon coast in 2014. This seep, called Pythia’s Oasis, is located ~20 km east from where the Juan de Fuca plate subducts beneath the North American plate along the Cascadia Margin. Studying microorganisms from deep within subduction zones is difficult and requires deep-sea drilling expeditions that can disrupt the ecosystem. Recent analyses of Pythia’s Oasis fluids suggests that they likely originate from high temperatures deep within the Cascadia Margin, providing a window into the region where deep subduction-zone fluids are formed. The Pythias’s plume has a vent-orifice temperature of 12.08˚C, ~3 times warmer than background seawater and is characterized by low-salinity and methane-saturated fluids. Nothing is currently known about the microorganisms that inhabit this type of system. In August of 2021, the deep-sea remotely operated vehicle Jason collected 5 L of fluid emanating from the Pythia’s Oasis’s orifice. The goal of this project is to extract and sequence community-genomic DNA to identify the dominant taxa present in this system and to elucidate the diversity of functions present. The resulting metagenomic data will be analyzed using established bioinformatic tools that can assess diversity and genetic potential. Results of this research will provide new insights into the chemical and biological conditions within the subsurface of the Cascadia Margin and similar systems in the deep subsurface.

In vertebrates, differences in limb morphology are often the result of adaptions to locomotion. While previous researchers have examined the external shape of skeletal elements, there have been relatively fewer studies examining internal bone structure despite its potential significance to locomotor biomechanics. This study aims to help fill this gap by quantifying internal differences in forelimb skeletal morphology of squirrels (Sciuridae) across three locomotor ecologies: ground, tree, and gliding. We test the hypothesis that forelimb internal bone structure reflects adaptations to these ecotypes. To test our hypothesis, we micro-CT scanned the humeri of 61 species of squirrels and conducted bone structure analyses in the open-source software 3D Slicer. We assessed cortical bone composition by measuring material properties including global compactness (bone density), diaphysis (shaft) elongation, and second moment of area (bending ability). Based on biomechanical demands,we predict that A) gliders will have relatively less compact long bones with more elongated diaphyses due to the gravitational/aerodynamic constraints of gliding and B) ground squirrels will exhibit highly compact long bones with more robust diaphyses to gain more force while digging burrows​​. Preliminary results support our prediction that larger ground squirrels exhibit relatively more compact, robust, and bend-resistant humeri in accordance with their digging locomotion. This research furthers the understanding of diversity in forelimb morphology across mammals and the connection between forelimb morphology and locomotion. This study also lays the groundwork for future biomechanical and behavioral work to examine the evolutionary ties between form and function.

Impacts of climate change, such as warming ocean temperatures and increased prevalence of disease, greatly affect intertidal marine environments within the Puget Sound. These impacts can alter behaviors of marine invertebrates, resulting in ecological cascade effects within rocky intertidal zones. The goal of this study was to observe variation in growth and feeding behaviors of organisms within a trophic cascade including plankton, pacific blue mussels (Mytilus trossulus), and sea stars (Crossaster papposus and Pisaster ochraceus) as a representation of the rocky intertidal zone in the Puget Sound. Experiments were conducted under two temperatures, 11.8°C and 20.7°C, to simulate a control similar to current water conditions and an increased temperature similar to recent heat wave conditions. Plankton growth rate was measured by counting the change in number of individuals per 1 mL sample over a four day period. Mussel feeding behavior was measured by recording change in fluorescence over a four day period, both with and without the presence of a predator (sea star). Sea star feeding behavior was measured by counting the number of mussels consumed over a 24 hour period. The results showed decreased plankton growth in the increased temperature treatment (t-test, p=0.065). Mussel feeding rate decreased as a result of both increased temperature and presence of a predator (two-way ANOVAp=0.040). Sea star feeding rate additionally decreased under increased temperature (t-test p=0.090). Because these organisms are integral to rocky intertidal zones, we can use their behaviors as bioindicators and conclude that these ecosystems are impacted by climate change. Variation in behavior could result in significant changes in species abundance and ecosystem structure; it is essential to research how ecosystems within the Puget Sound will adapt to future environmental conditions.

Given the upper-trophic nature of marine mammals, their population numbers can be indicators of marine ecosystem health. For pinnipeds - including seals, sea lions, and fur seals in Washington State - one method of population assessment is documentation of stranded individuals, or dead animals that wash up on beaches. Due to the lack of a comprehensive stranding program along the Washington coastline, with some carcasses being reported to official stranding networks while others are noted on citizen science websites, I explored whether the citizen science photo-platform iNaturalist could be used to augment the Marine Mammal Stranding Network (MMSN) stranding database managed by the National Oceanic and Atmospheric Administration (NOAA). I searched for pinniped photographs on iNaturalist between the years 2015 through 2020, limited to Washington waters. After removing duplicates, I cross-referenced iNaturalist data with MMSN strandings. After compilation of the high-quality data, I calculated the ratio of unreported to reported strandings over the entire dataset, as well as annually, by species, and as a function of carcass freshness. I found there were unreported strandings throughout Washington waters, with a ~1:3 ratio of unreported-to-reported strandings overall (27% of the total). My findings suggest that some species were much more common than others, with an order of magnitude difference between the most common species (harbor seals) and rarest (fur seals). However, species-specific unreported-to-reported ratios were not dissimilar (22-30%). Unreported carcasses also crossed all freshness categories ("fresh" through "skeletal"). These analyses prove that stranding cases often go unreported to stranding networks, and suggest no biases in space, species, or carcass condition in citizen science data. Based on these conclusions, I recommend that citizen science stranding data be incorporated into national stranding databases to allow for the largest dataset possible from which to analyze and manage marine mammals and marine ecosystem health.

Aerial surveys are a tool commonly used to estimate population abundance for many species, yet little is known about how aircraft presence impacts animal behavior. The National Oceanic and Atmospheric Administration (NOAA) periodically conducts surveys in the U. S. waters of Alaska to monitor Arctic seal populations. These surveys are important as trends show reductions in the sea ice that these pinniped species depend on. Quantification of ringed seal (Pusa hispida) and bearded seal (Erignathus barbatus) rates of flushing from the sea ice into the water in response to aircraft overflights is necessary to strengthen population estimates and implement sound policy measures for activities in Alaska that may impact these pinnipeds. In the spring of 2021, NOAA conducted aerial surveys over the sea-ice of the Beaufort Sea. As an intern I separated the video into trials that captured seals before, during, and after the plane passed overhead. For each individual seal I then recorded species, weather, group size, distance from the plane, and seal behavior changes and geographic locations and analyzed which factors influence seal flushing behavior. In 161 trials, we recorded 266 ringed seals and 21 bearded seals. Only one bearded seal flushed (4.8%) while 47.8% of all ringed seals flushed. Most ringed seals flushed before the plane passed overhead. Generalized linear models indicated that distance from flight path and group size exerted the greatest influence on flushing behavior while weather and plane altitude were less important. Less distance from the flight path and larger group sizes led to higher ringed seal flushing rates. Understanding ice seal behavior will improve population estimates in future surveys. Overall flushing rates are important indicators of the disturbance ringed and bearded seals experience as a result of commercial and scientific activity in the Arctic and may be useful for permitting processes.