PS 17-135
An urban waterway where a non-native is the primary prey of Western Pond Turtles (Emys marmorata)
Recent research indicates that urban wetland ecosystems harbor native species, a source of biodiversity worth conserving. The results of my research show that a native species of statewide concern, the Western Pond Turtle (Emys marmorata), is surviving because of the presence of a non-native prey species, the Louisiana crayfish (Procambarus clarkii). I did this 3-year study at 2 sites in Santa Rosa Creek, Santa Rosa, California; a city located approximately 69km north of San Francisco. During the project, I utilized present-day technology to record information, developed novel sampling methods, and used a sophisticated chemical restraint methodology.
Results/Conclusions
The results of my research indicate that a non-native species of crayfish Procambarus clarkii (Louisiana Crayfish) is the primary food resource of adults. They have an IRI value of 83.014/100 of the adult diet, 89.88/100 in the diet of female adults, and an IRI value of 78.054/100 of the adult male diet. In contrast, the sub-adult diet IRI values are 58.253/100 native Odonate naiads and 33.891/100 native fish. Throughout my research human modification of the waterway escalated and this affected the distribution of turtles and their main prey, P. clarkii. For example, at SCR2 the site where work was most dramatic the overall population of E. marmorata in 2010 was 26, dropped to 9 in 2011, and fell to 5 by 2012. At ACR1 where the population of E. marmorata was 12 in 2010, dropped to 2 in 2011, and rose to 18 in 2012. Furthermore, a mark and capture study in 2013 shows that the numbers of their main prey, P. clarkii were 66% higher at ACR1 (72) than SCR1 (15). Hence, in discussing my results I consider the possible negative effects of an apparently successful adaptation because of human activity. Furthermore, using tangential results I suggest the research and collaborations that may reverse these worrisome conclusions.