DNA and Diet Analysis of Lontra canadensis in the Possession Sound Estuary and the Snohomish River

• Main Author: Kisela, Jamie
• Format: Text
• Language: English
• Published: Western CEDAR 2014
• Subjects: Terrestrial and Aquatic Ecology; Orca; Alaska; Lontra
• Online Access: https://cedar.wwu.edu/ssec/2014ssec/Day2/127

During the 2012-2013 school year, foundational research on the diet of the Possession Sound river otter (Lontra canadensis) population was performed by students and faculty 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. Though no protozoa were found, the diet analysis showed the otter population to have a primarily marine crustacean diet. Because river otters are opportunistic feeders, this could be due to abundance of crustacean organisms like Mytilus edilus, coating pilings in the Everett Marina. The distribution of M. edilus is such that river otters have easy access to it at any tidal stage. The foundational study is now carried on by a small group of students, each with a different focus. This study focused on gathering information about river otter abundance and biodiversity though DNA and diet analysis of scat samples from communal “latrine sites.” Because river otters have been used as an indicator species for environmental issues such as the Exxon Valdez oil spill in Alaska, gaining an understanding of local populations and their health offers insight into ecosystem stability. This study aims to compare results from two latrine sites regularly studied in the Everett Marina to a new site established by this study 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 the same group of otters transit up and down river with the tidal cycle, resulting in the same groups of otters frequenting all the camera locations. Therefore, it is expected that these otters will show relatedness through DNA sequencing, and diet analysis between marina sites and Langus will have limited variation.