In the Portland Metro Area, the signal crayfish (Pacifastacus leniusculus) is a keystone species. Signal crayfish consume inaccessible plant matter and detritus, feed various game fish, engineer riverbeds, and are even harvested commercially for human consumption. Recognizing signal crayfishes’ multifaceted ecological and social significance, the purpose of this study was to assess the habitat factors that impact signal crayfish health and behavior in the Tryon Creek Watershed. Data collection revealed that overall, Tryon Creek crayfish were disproportionately likely to be observed in locations with high infrastructure presence levels; substrates composed of silt/sand or a combination of boulders and cobbles; culverts, runs, and pools; and water depths between 10 and 39 cm. Meanwhile, juvenile crayfish were disproportionately likely to be observed in locations with low human impact levels, substrates composed of silt/sand and a combination of cobbles and gravel, and water depths between 0 and 19 cm. Similarly, unhealthy crayfish — specimens that were deceased, immobile, or struggling, or that consisted of severed appendages — were disproportionately likely to be observed in locations with culverts and riffles and water depths between 0 and 19 cm. The study found no evidence for an established population of invasive crayfish in Tryon Creek, although further monitoring (particularly in Tryon Cove) are necessary to ensure the watershed’s continued protection. The analysis also suggested that human-caused ecosystem disruptions can seriously decrease the health and wellness of signal crayfish populations, pointing to a need for better waterway designs that can benefit fish and crustaceans alike.
Schmitt, Kyla Marie
"Portland's Keystone Crustacean: Signal Crayfish Behavior, Health, & Habitat in the Tryon Creek Watershed,"
International Journal of Undergraduate Research and Creative Activities: Vol. 14:
1, Article 5.
Available at: https://digitalcommons.cwu.edu/ijurca/vol14/iss1/5