COS 49-3 - Urban stream maintenance program best practices may not be the best way to ensure that freshwaer turtles thrive

Wednesday, August 10, 2016: 8:40 AM
Floridian Blrm D, Ft Lauderdale Convention Center


Nicole M. Karres, Sonoma State University; Nicholas R. Geist, Sonoma State University


As humans continue migrating to urban centers, the nearby freshwater waterways must carry ever-increasing quantities of stormwater runoff. In order to prevent urban flooding as urbanization expands, land managers are intensifying their stream maintenance program (SMP) activities. Consequently, wildlife that persists in these waterways faces ever-increasing pressure to adapt. Our research was an effort to uncover some the demands to adapt freshwater turtles experience and its outcomes. We used the diet and foraging ecology of an assemblage of Western Pond Turtles (Actinemys marmorata) as a proxy. Our rationale for doing this is that the diet and foraging activity is a nexus between conditions in the environment and their ability to thrive in a locality. Furthermore, benthic macroinvertebrate (BMI) taxa often used to assess the robustness of aquatic ecosystems are the predominant prey of A. marmorata. Our methods included collecting foraging information by tracking turtles using radio telemetry and observing them. To study their diet we developed new methods to capture turtles and remove their stomach contents. Finally, to measure the effects of SMP activity we regularly gathered environmental data (i.e., changes in waterflow regimen). 


After doing research from 2010-2013 in 2 Northern California streams our results include the fact that a non-native crayfish was the mainstay or 71% of the diet. Yet, the dependence on 1 taxon as prey leads to the turtles abandoning one site, SRC2 by July 2012. This is because SMP activity altered the flow regimen in 2011 so that crayfish no longer could thrive at SRC2. In 2013, we found that the disparity in crayfish abundance between the sites was a ratio of 1:4.8 between SRC2 and ACR1. Furthermore, in 2010 we found that the turtles added 4 new taxa to the diet, along with adding foraging on the terrestrial landscape to their behavior. Nonetheless, by 2012 after the introduction of a new SMP in 2010 the dietary biodiversity had dropped from 9 taxa to 5, a 45% decline. Both if these results are representative of kinds of habitat losses that lead to local wildlife extinctions conventional SMP’s produce. Yet, as recent research demonstrates, these negative outcomes are unnecessary because there are alternative SMP’s that restore these ecosystems so that they are functional. In fact, restore them to the extent that they deliver even more services than conventionally managed ones offer.