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.

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.

Over the last two decades, the threat of climate change has inspired significant research in the Salish Sea. Understanding trends and correlations between water temperature, dissolved oxygen (DO), and chlorophyll levels can help us understand how climate change and other anthropogenic activity has already affected the Salish Sea. My reseach focuses on seasonal and annual trends of water temperature, DO, and chlorophyll levels between 2019 and 2023 in Possession Sound, located in Everett, Washington. This longterm data-stream is generated by the Ocean Research College Academy, collected autonomously every 15 minutes by a pair of EXO sondes that are moored at Mount Baker Terminal and Everett Marina. My goal is to understand the relationship between water temperature, DO, and chlorophyll seasonally and historical trends over multiple years in Possession Sound. Preliminary figures and outside research have shown fairly consistent seasonal cycles for temperature and chlorophyll. DO trends are not as clear and data suggest significant variation is occurring within a short time frame. Future reseach may include comparing river discharge data to water chemistry data, however a more comprehensive understanding of specific inputs to the Snohomish River system is needed to draw solid conclusions about the affects of climate change.

Saltwater estuaries can experience high turbidity levels due to river input and tidal influences. Turbidity is a measure of inorganic and organic particles suspended in the water column. Reduced light penetration due to higher turbidity levels can contribute to decreased levels of primary production and the introduction of harmful pathogens to the environment. Understanding the relationship between river discharge, tides and turbidity levels could lead to a better understanding of the causes of turbidity in estuaries such as Possession Sound, WA. I hypothesize that higher current velocity contributes to higher turbidity levels. I analyzed data from a moored Acoustic Doppler Current Profiler (ADCP) and a Conductivity, Temperature, Depth (CTD) sensor located in the Everett Marina. ADCP and turbidity data were collected every 15 minutes, 24 hours a day, from 2017 to 2021. Preliminary results suggest that higher current velocity correlates to higher turbidity levels. Future research looks to discover how river discharge, tides and seasonal variance play into turbidity spikes.