Lontra canadensis, more commonly known as the North American river otter, is a resident in many riparian and coastal ecosystems across the continent. The behaviors of mainland populations – the inhabitants of freshwater lakes and rivers – have been well documented and studied over the years. The impact of tides on coastal and estuarine populations, however, is still largely unknown. Therefore in 2012, members of the Ocean Research College Academy, a dual enrollment program run through Everett Community College, began studying otters in Possession Sound. Preliminary diet analysis of scats retrieved from local latrine sites revealed target prey consisting of mostly saltwater species. Due to the high metabolic rate of otters necessitating large daily food intake and prey availability in estuaries being driven by tidal cycles, it was then hypothesized a correlation existed between tides and the presence of otters in the sound. Specifically, it was predicted otters would be present at high salinity tides when the water chemistry could sustain their prey species. To test this, game cameras were installed at latrine sites on Jetty Island and the Hat Island ferry dock in Everett, Washington. Visits by otters were documented and time stamped, with corresponding tide stages and heights recorded. The majority of visitations occurred at tide heights above 4 feet (81% of visits) with considerably fewer camera captures during low salinity tides. Further research is currently being done into the possible impacts of other local factors on river otter behavior, including spring-neap tidal cycles and river discharge.

During the 2012-2013 school year, foundational research on the diet of the Possession Sound river otter (Lontra canadensis) population was performed by students of the Ocean Research College Academy (ORCA), a dual enrollment program at Everett Community College. This study included diet analysis of scat samples, visual surveys using motion-sensing game cameras, and tests for protozoa presence. The diet analysis showed the otter population to have a primarily marine crustacean diet. Further research during the 2013-2014 school year focused on gathering information about river otter abundance though camera traps and diet analysis of scat samples from communal “latrine sites.” This research aims to compare results from two latrine sites regularly studied in the Everett Marina to a new site established three miles up the Snohomish River, at Langus Riverfront Park. The highest number of river otters observed on camera simultaneously has been seven. It is hypothesized that these otters form one group which transit up and down river with the tidal cycle, resulting in the same groups of otters frequenting all the camera locations. It is assumed that otters will frequent upriver sites at high tide, following the marine species from Possession Sound with the more saline water. This will result in the upriver site having increased visitation at high tide noted in the camera trap data and no significant variation in prey types compared to the marina.

The Snohomish River flows through an area where anthropogenic factors may affect the water chemistry due to industry and agriculture. The lower reaches of the Snohomish River are near industrial sources. At the Ocean Research College Academy (ORCA) in Everett, Washington, students are encouraged to derive and conduct independent research studies in the Snohomish River estuary system on monthly State of Possession Sound (SOPS) research cruises. It is expected that data will change in relation to distance from anthropogenic influences and the mouth of the Snohomish River. The pH up river is expected to be, overall, lower than that of the salt water, and even lower with the influence of farm waste and factory runoff. The waste from these sources releases CO2 into the river causing the pH to decrease. Sampling sites for the data collection of this study were selected with consideration to farms and factories along the river. The data collected includes dissolved oxygen (D.O.), salinity, temperature, and pH. A handheld YSI 650 and YSI 85 were used. Nutrient samples were collected at approximately half a meter below the surface. From the data it can be determined how farms and other anthropogenic factors affect pH. Further research on how these factors affect the marine life in the Snohomish River estuary system and Possession Sound are planned for future studies to determine how changes in water chemistry may have a negative impact on estuarine ecosystems.
 

Possession Sound is located between the coastline of Snohomish county and Southeast of the Whidbey Island Basin within the Puget Sound. The freshwater Snohomish River is the second greatest input to the Puget Sound and greatly affects the overall health of Possession Sound. Monthly since 2009, the Ocean Research College Academy (ORCA) students collect samples in the Possession Sound with a Niskin bottle, to send to the University of Washington Marine Chemistry Lab which provides nutrient concentrations which can fluctuate with season, weather, river discharge, marine organisms, and anthropogenic influences, specifically waste water outfall. Focal analysis of a site close to the Snohomish River were compared to other locations up river. Discharge data corresponds with fluctuating levels of nitrates, nitrites (NOx) and ammonia throughout the year. NOx data corresponds with river discharge with an exception to spring where there is a general decrease. In April of 2013, for example, the discharge is at a high 18,300 ft³/second, but the NOx concentrations are at lows, at 3.04 μm/L. The subtle changes in ammonia concentrations seem to correlate with the extremes in river discharge. For example, between May and June of 2010, the river discharge data increases from 12,550 ft³/second to 15,090 ft³/second. Ammonia concentration follows, in May the concentration is 36.8 μm/L, which increases in June to 49.8 μm/L. The hypothesis was partially supported. Ammonia data correlated with river discharge, raising as river discharge flow increases. Comparatively, the NOx data varied independently of river discharge. Further research into ammonia concentrations and waste water outfall in addition to utilization of NOx by plankton species such as Thalassiosira spp. and Copepod spp. populations is yet to be conducted.