Examining Spatial Differences in pH with Variables of Snohomish River Estuary

Sophie Jenness, Josh Searle and Ardi Kveven, Ocean Research College Academy, Everett Community College, 1205 Craftsman Way Suite 203, Everett, WA 98201

Historically, variables in coastal estuaries have demonstrated uniqueness due to influences specific to individual estuaries. One variable is river discharge, which can be slightly acidic and can increase nutrient loading in estuaries. Increased nutrient loading is associated with larger phytoplankton blooms, which can potentially decrease pH through respiration. Decreases in pH pose risks to certain marine organisms that rely on calcium carbonate. This study aims to understand how different variables impact pH in the Snohomish River Estuary by examining pH relative to dissolved oxygen, chlorophyll, salinity, and temperature. It was hypothesized that at depths less than 5 meters, lower temperatures and salinity values caused by river discharge would correlate with a lower pH, while lower dissolved oxygen at depths greater than 10 meters and greater chlorophyll at the halocline, which indicates a larger abundance of phytoplankton, would correlate with a decrease in pH at depth. Furthermore, sites located closer to the river would have lower pH near surface because it is impacted more by river discharge. This study used data collected at different sites located in Possession Sound, Washington, from February 2019 through February 2020 using a YSI Exo2 Sonde. Initial results show that sites located near the mouth of the river have a lower average pH of approximately 7.49, compared to sites farther from the river with an approximate average pH of 7.54. Changes in pH near the halocline correlate with a decrease in dissolved oxygen and chlorophyll, as well as an increase in salinity and temperature. The results support the hypothesis regarding the trends near the surface. However, the trends at depth that were predicted are not present. Overall, initial results do indicate that the Snohomish River reduces pH, which, paired with other stressors that decrease pH, could create harmful conditions in future.

Additional Abstract Information

Presenter: Sophie Jenness

Institution: Everett Community College

Type: Poster

Subject: Environmental Science & Sustainability

Status: Approved

Time and Location

Session: Poster 7
Date/Time: Tue 3:30pm-4:30pm
Session Number: 5016