When fast-moving water flows into a basin with weaker tides, a highly stratified salt-wedge estuary occurs. Calculating the travel time of water in an estuary can be useful when predicting pollutant spills, erosion, and depositional effects at the river mouth. This study examines the Snohomish River, which is part of a salt-wedge estuary that encompasses the Port of Everett Marina and deposits into Possession Sound in the Whidbey Basin of the Salish Sea. When the tide floods, water goes north. River travel time calculated by previous Ocean Research College Academy (ORCA) students was nearly 10 hours of delay between a United States Geological Survey monitor located 12 miles upriver and water quality data at the river mouth. This previous research shows there will be less travel time and less water speed during high tides. A more accurate travel time can be found by cross-correlating river discharge with water speed. Through retrieving water speed and direction at the river mouth, one can develop current vectors to compare with tide stage. Using the distance to the water's surface from the Acoustic Doppler Current Profiler (ADCP) near the riverbed, one can determine the tidal effect on river speed and travel time through extreme water levels correlating to low and high tides. This study investigates July 2020 ADCP North/South vectors at the river mouth and correlates them to river discharge upriver. Using RStudio statistical analysis, this correlation is then compared to ADCP water height to model for tides. It is predicted that the faster the river discharge and the larger the Southern vectors, then the more drastic decrease in ADCP’s height in the river. Further research would include adding more ADCP data and precipitation to consider seasonal patterns. Since runoff feeds the Snohomish River, examining precipitation would create a more accurate model.

All natural features that make up river systems are created through erosion. The energy in the water column that causes this erosion is called turbulence. Turbulence isn’t limited to river systems, but the focus of this paper is on turbulence, specifically within the possession sound. Depending on how water is flowing within a local ecosystem, the terrain and biological components in that ecosystem can change drastically. In this study I examine how turbulent flow in the mouth of the Snohomish River in Everett, Washington changes relative to river discharge. I defined turbulence for this study as the relationship of the direction and magnitude of two vertically adjacent water particles. I also used a variation of the Reynolds number (Re) to more clearly define the difference between Transitional and Turbulent flow. In this study, data were collected with a 3-beam Aquadopp 1MHz Acoustic Doppler Current Profiler (ADCP), which measures the speed of passing particles in the water column at 1-meter increments starting at 1.4-meters above the river bed. I processed the data in RStudio and Excel. From preliminary research I know that during periods of high flow, the difference of adjacent flows is more dramatic at depth than it is anywhere else in the water column. I also have observed constant random direction of water flow towards the surface. It is expected that this will also be observed while doing tests with the Re, meaning that there will be continuous high Re at the surface due to outside influences, with low Re at depth during periods of normal flow rate. It is also expected that there will be prolonged high Re throughout the water column during and after periods of high flow rates.

 As global ocean temperatures rise, there has been a worldwide increase in frequency, intensity, and geographic range of harmful algal blooms (HABs). HABs can have detrimental effects on both natural and anthropogenic factors. Diatoms of the genus Pseudo-nitzschia are known to cause HABs in Puget Sound, Washington. This toxigenic diatom is a particularly concerning species, as they produce domoic acid (DA), which can be transferred up the food web through biomagnification, resulting in illness and death of birds and mammals in the surrounding area. The goal of this project is to identify trends in the relationship between the population density of Pseudo-nitzschia and water quality indicators such as surface temperature, dissolved oxygen (DO) levels, chlorophyll, and pH. This study focuses on data collected by the Ocean Research College Academy (ORCA) during State of Possession Sound (SOPS) cruises from the five sites in Puget Sound from the years 2016 to 2020. Students from ORCA conduct vertical plankton tows using a 335-micrometer net and horizontal plankton tows using a 20-micrometer net. Plankton enumeration is conducted in the lab, and plankton density is calculated. Surface temperature, DO, chlorophyll, and pH data are collected during EXO2 Sonde deployments during SOPS cruises. Based on preliminary research, a greater population density of Pseudo-nitzschia is expected during years with higher surface temperatures and lower DO levels. Researching the conditions that allow Pseudo-nitzschia to thrive may allow for increased accuracy in predicting the locations and time in which harmful blooms are most likely to develop. Understanding the impact and expected severity of Pseudo-nitzschia blooms can aid in signifying whether concern should be raised regarding water quality within the Puget Sound ecosystem.

As dam removals become more frequent across the United States and globally, understanding kelp forest response to coastal dam removals, in particular, is critical for managing nearshore habitat. Dam removals impact flow and sediment regimes of rivers, both of which can influence coastal kelp forests. The removal of the Elwha River, WA dams released ~19 Mt of sediment into marine ecosystems. This sediment flux dramatically influenced the turbidity of the nearshore water column and permanently increased the amount of sediment released from the river. The objectives of this study were two-fold. First, I developed methods to remotely sense and quantify the abundance of canopy forming kelps from aerial images. Next, I determined how changes in suspended sediment concentration and light attenuation during and following a major dam removal event in the Elwha River impacted the growth of nearshore bull kelp, Nereocystis luetkeana. By incorporating remote sensing to quantify the relative abundance of bull kelp in the area, my study observed that following dam removal, bull kelp abundance declined in the study area. This was an unexpected finding because I calculated that suspended sediment concentration decreased following dam removal, thus improving conditions for kelp growth. Although suspended sediment concentration decreased after the dam removals, other factors, such as an increase in herbivorous predation, could have played a large role in suppressing bull kelp abundance. The supervised classification scheme that I developed for remotely monitoring kelp abundance will make analyzing larger areas feasible in future studies, which may help to better identify regional trends in kelp abundance. Marine aerial monitoring remains an important avenue to better predict and manage future kelp forest response to dramatic changes in the ecosystem.

Salinity is a fundamental component of all estuarine environments, affecting water chemistry and density-driven flow dynamics. In the Snohomish River Estuary in Washington State, saltwater from Possession Sound and freshwater from the Snohomish River stratify, forming a partially-mixed salt-wedge estuary. Haloclines, zones of rapid salinity-change, vary in depth depending on season, temperature, and freshwater influx. Above and below the halocline, the water column displays relative homogeneity in salinity. An established relationship between tide height and salinity may allow researchers to use accessible tide data as an indicator of salinity. If such a relationship were to change, any difference from the baseline relationship may be used as a measure of change in the ecosystem to track climate change and other factors. I examined salinity data collected throughout the water column, at surface, halocline, and deep zones, to detect the influence of tides on salinity. I anticipated increased tide height, paired with corresponding saltwater encroach, to correspond to an increase in the salinity of brackish water at the halocline. I expected surface and deep zones would be relatively unaffected, owing to their separation from this immediate area of change. I predicted any relationship between tide height and salinity to strengthen with increased distance from the Snohomish River, as saltwater would be less diluted by freshwater, implying a more noticeable influence on it. My analysis of readings taken at field sites in Possession Sound from 2017-2020, restricted according to site and season, did not present any consistent correlation between degree of tide-salinity correlation and distance from the Snohomish river. I detected varying correlation between salinity at restricted depths and tide height. Further research will entail further elimination of confounding variables.