Primary productivity is the basis of energy production in marine ecosystems and is primarily dependent on nutrients and sunlight to occur, specifically the 400-700nm range of light that is used in photosynthesis, known as photosynthetically active radiation (PAR). In the Possession Sound estuary, nutrient input from the Snohomish River and seasonal daylight patterns lead to high productivity in spring, summer, and fall. These patterns provide an opportunity to investigate the influence of PAR against the influence of nutrients, which would allow for a greater understanding of the potential effects of PAR from artificial light at night (ALAN) in an estuarine system. We utilized existing and ongoing data from the paired deployments of a Seabird 19+ and a YSI EXO 2-Sonde to obtain water column profiles of PAR, chlorophyll, turbidity, and dissolved oxygen from July 2022 to April 2024 at Mt. Baker Terminal (MBT) in Mukilteo, and data from a moored MiniDOT PAR logger at MBT and moored EXO sensors at MBT and the Everett Marina from October 2023 to April 2024. The moored PAR logger and EXO sensors were set to collect data at 1 and 15 minute intervals, respectively. Additionally, we collected a concurrent total of 30 plankton samples at MBT and Everett Marina after sunset using a 1.7L Niskin bottle and a 20µm plankton filter. Preliminary analysis shows no measurable PAR at night, though Marina potentially has more productivity at night than MBT based on plankton data. Due to the small timeframe of our research, future explorations should expand the available analysis of temporal variation along with increasing the scope of sites throughout the Possession Sound and greater Salish Sea.

Noise pollution from recreational boats, industry, and shipping can be an issue for marine life. This is especially important in an estuary with a lot of wildlife and human activity such as Possession Sound, Washington. This started out with the question of how noise levels change based on the time of day and season. Also knowing if those noises are related to humans or animals. Before assessing noise impacts it is important to understand baseline noise levels. This study uses data collected from a moored Soundtrap Hydrophone at Mount Baker Terminal near Mukilteo. MBT is good because it is near a waterway and railroad. The hydrophone takes readings for 15 minutes every hour. I downloaded and analyzed data from 48 periods for each season from 2022 to 2024. Using RavenPro, I found the average Root Mean Square Amplitude (RMSA) for each 15-minute file. I identified anomalies/spikes and determined their duration. Early analysis shows the average RMSA to be 364.21. The spikes have an average RMSA of 5850.07 lasting an average of 277.23 seconds. Excluding spikes gives an average RMSA of 207.97. I found the noise level in decibels with the equation 20*log(RMSA/0.001). The third spike is about equal to 135 decibels or about an aircraft taking off. The baseline is around 106 decibels or a snowblower. Similar hydrophone studies in estuaries will help determine the normalcy of these levels. I am continuing to gather data through the year to find a pattern. Hopefully this study or a future iteration of it can be used in mapping activity through time based on noise for a civil project Future studies can compare baseline RMSA at specific frequencies to frequencies known to affect marine life common in the area.

As primary producers, plankton play an important role in the marine environment as the basis of the food chain. Because of this, plankton biodiversity can be an indicator of the health of the ecosystem. As weather patterns change, rising salinity has been documented in marine environments across the globe. This has shown harmful effects in several organisms, including plankton. This study focuses on examining the correlation between salinity and plankton biodiversity across different seasons in Possession Sound located in Everett, Washington. For each site and season I compared biodiversity values with halocline salinity data for each plankton tow. Plankton were collected using horizontal plankton net tows at the halocline and identified based on morphology. I used the Shannon Diversity Index to examine biodiversity of phytoplankton and zooplankton. I collected this data on research cruises held by the Ocean Research College Academy and used historical data collected by previous students. The collected data encompass three sites visited from 2014-2024. Preliminary analysis suggests that biodiversity and salinity will have an inverse relationship. By examining the correlation between salinity and plankton biodiversity, we can begin to understand the potential impacts of rising salinity levels in marine ecosystems.

Nutrients play a large role in marine primary productivity, and fluctuations in concentrations can have large impacts on the health of both marine life and human populations. Phosphates, silicates, nitrates, nitrites, and ammonium are all nutrients which are naturally present and key to the functioning of marine environments; however, negative consequences such as Harmful Algal Blooms (HABs) can occur if concentrations differ too far from normal ranges. Both natural processes and anthropogenic activities influence nutrient concentrations in marine environments, and in estuarine environments, like Possession Sound–part of the Whidbey Basin–the impacts of anthropogenic activities are further magnified due to unique estuarine hydrodynamics and the close proximity to dense human populations. For this study, I analyzed three sites within Possession Sound, looking at nutrient levels in comparison with dissolved oxygen (DO) and chlorophyll concentrations (as a proxy for primary productivity). I collected data during numerous research cruises and used this in tandem with the Ocean Research College Academy (ORCA) historical data set. Water samples were sent to the University of Washington Marine Chemistry Laboratory to measure nutrient concentrations, and chlorophyll and DO data were collected through the use of a conductivity, temperature, and depth (CTD) sensor. Preliminary results suggest a strong seasonal trend in nutrient values, with the lowest abundance occurring during the summer months. I hypothesize that further analysis will suggest an inverse relationship between primary productivity and nutrients. This study can potentially offer insight into the health of the Possession Sound ecosystem by assessing the extent to which dissolved oxygen, chlorophyll, and nutrient concentrations are within normal limits and following expected seasonal patterns.

The properties of an estuary are driven largely by the vertical circulation and stratification patterns resulting from the convergence of dense salt water and less dense fresh water. These density-driven circulation patterns play an important role in the way vital nutrients are distributed throughout the environment to primary-producers. This study focuses on the seasonal variation in salinity and chlorophyll in comparison with river discharge levels of the Snohomish River, at Mount Baker Terminal, WA, within Possession Sound. This site is located 3.6 miles SW of the Snohomish River output near Mukilteo, WA. Salinity, chlorophyll, and depth data were collected from January 2020 to December 2023 using a boat based CTD (EXO SONDE). I participated in the collections from Fall 2020 to December 2023. I also reference the United States Geological Survey (USGS) streamflow data at site number 12150800. I categorized deployments by season (Winter: Dec-Feb; Spring: Mar-May; Summer: Jun-Aug; Fall: Sept-Nov) and utilized RStudio and GGPLOT2 to visualize and analyze my data. Preliminary analysis suggests well-defined haloclines and increased chlorophyll levels during spring months, corresponding with increases in river flow at this time. Decreased stratification, weak haloclines and low chlorophyll levels are conversely observed during summer months, corresponding with consistently low rates of river discharge. This raises questions concerning the impact that seasonal changes in river flow have on primary production at and around the halocline. Further analysis of chlorophyll ranges at the halocline is required to better understand this relationship. Monitoring the impact of river discharge variability and primary production is especially relevant in light of changes in seasonal weather patterns related to climate change.

Escherichia coli (E. coli) abundance is commonly used to indicate water quality and environmental health. The pH of water has been shown to affect the survival of E. coli. Possession Sound is an estuary that faces a wide range of pH (around 7.5-9.0) throughout the year due to alkaline salt water from Puget Sound mixing with acidic fresh water from the Snohomish River. Primary production, organism respiration, nutrient runoff, carbon emissions, and currents also affect pH levels. This study aims to analyze the relationship between pH and E. coli abundance in an estuarine environment. PH and E. coli data was collected from 2018 to 2023 by myself and other Ocean Research College Academy students. PH data was collected with a YSI EXO2 Sonde. E. coli data was collected using a Niskin bottle to obtain water samples which were then transferred to Petri dishes for growing and counting E. coli. My preliminary analysis shows that Possession Sound’s average pH range is around 7.5-8.5, with pH being higher in spring and summer than in fall and winter. Early analysis using Spearman’s Rank Correlation suggests that pH and E. coli have a weak, inverse relationship. There is minimal research on the relationship between pH and E. coli in a marine setting, so my study helps to provide insight into the relationship between E. coli and pH in a unique estuary.