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.

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.

 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.

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.

Hypoxia refers to low concentrations of dissolved oxygen (DO) in a body of water, and can result in death of marine biota. Hypoxic events have increased since the 1970s in shallow coastal and estuarine areas to the point where DO has arguably changed more drastically than other environmental variables of importance to these ecosystems. Studies have found that the main drivers increasing the frequency and intensity of hypoxic events are eutrophication as a result of nutrient loading and increasing water temperatures due to climate change. Puget Sound in Washington State is particularly susceptible to hypoxia because the geological features of its basin restrict water circulation and the Sound receives a high influx of nutrients from rivers and anthropogenic activity. Studies have reported hypoxia in regions of Puget Sound, including Sisters Point, Lynch Cove, and Hood Canal. This study provides a temporal and spatial analysis of DO in Possession Sound, an inlet of Puget Sound where the Snohomish River empties, to contribute to the growing understanding of hypoxia in Puget Sound, particularly in an estuarine environment. DO data were analyzed along with water temperature data to determine if hypoxia occurred in Possession Sound and to assess where potential hypoxia is more likely to occur. These data were collected by students at the Ocean Research College Academy (ORCA) at six sites in Possession Sound from 2017 to 2020 using an EXO Sonde instrument which allows for vertical analysis of DO in the water column. Preliminary results show that potentially toxic concentrations of DO occurred at depth during the winter months with a minimum value of 4.08 mg/L. It also appears that DO concentrations vary substantially between sites, years, seasons, and depths.

Every Spring, a small group of gray whales, nicknamed the “Sounders,” come to Possession Sound and the surrounding waters to feed. Many of these individuals have been documented in this region consistently since the 1990s. Although this group of less than twenty individuals has been the subject of several research studies, little is known about their movement patterns in Possession Sound. Over the past few years, gray whales along the West Coast have been experiencing a mass mortality event. Gray whale research is essential in identifying potential contributing factors. The Sounders are benthic feeders and primarily consume ghost shrimp that live in the sediment throughout the intertidal zone. These gray whales access a handful of shallow areas for feeding which are only accessible during high tides, such as the Snohomish River delta. This research evaluates and combines fifteen years of sighting data from Ocean Research College Academy (ORCA) and thirty years of sighting data from Cascadia Research Collective (CRC) with the intent of identifying spatial patterns and possible correlations with the tides. I am creating ORCA’s sighting catalog with photographs taken during ORCA’s sightings and identifying the individuals present using reference photographs from CRC and compiling any additional available data. In this catalog, sighting data is evaluated on individual whale identification, date, time, location, and additional observational notes such as whale interactions. I am plotting this data and additional data from CRC’s sighting catalog in ArcGIS to create a map of spatial distributions. Preliminary results from ORCA’s sightings suggest that gray whales are most often sighted in Possession Sound between Hat Island and the south end of Jetty Island. Any spatial trends that I identify may lead to a better understanding of gray whale behavior, possibly including gray whale intercommunication, social structure, individual behavior, and local feeding practices.