A five year look at the impacts of pH Seasonally and Spatially within Possession Sound

The ability for an ecosystem's organisms to adapt and thrive is dependent on the water chemistry. Capabilities for adaptation to the ever-changing environment are affected by the pH, or the acidity, of the water. Microorganisms, which are the foundation for a healthy ecosystem, are impacted by the pH of the water, and thus their ability to thrive depends on it. Globally, the pH of the ocean is decreasing as a result of ocean acidification caused by increasing anthropogenic CO2 emissions. Within the Salish Sea, which is home to an abundance of life, lies Possession Sound, located off the shores of Everett, Washington. Possession Sound is a salt-wedge estuary, allowing it to host a variety of organisms, all of which are affected directly and indirectly by the pH of the water. The well-being of Possession Sound was explored by examining changes in pH overtime at two locations. Early analysis of pH shows seasonal changes and spatial differences. Data were collected with a YSI EXO Sonde from 2016-2021 at two sampling location with varying distances from shore and the mouth of the Snohomish River that deposits into Possession Sound. Spatially, it was found that lower pH could be found at the site located nearer to shore. Seasonally, it was found that pH followed significant trends by increasing in the fall and winter and decreasing in the spring and summer. Overall, there was less variation in the data that came from the site located further from shore and more variation in the nearshore site. This could be attributed to the mixing that occurs within deeper water versus shallower water and several other factors. Future research examining pH would benefit from the addition of more data sites.