Lakes offer a multitude of ecosystem services, including numerous recreational opportunities and aesthetically pleasing views. As a result, lakes have long been the site of residential anthropogenic development. This development is associated with changes to riparian and littoral habitat, with documented negative effects on aquatic organisms. This development has also been associated with the invasion of exotic species such as the detrimental zebra mussel (Dreissena polymorpha). Zebra mussels are prolific reproducers, often attaining large population sizes and filtering much of the phytoplankton from the water column. These attributes can lead to increased water clarity and primary productivity in littoral zones. Thus, both lakeshore residential development and zebra mussels have the potential to greatly affect lake ecosystems.My dissertation research investigated the effects of lakeshore development and zebra mussel invasion on lake ecosystems and lakefront property values. In the first chapter, I looked at the effects of lakeshore residential development on population parameters such as sex ratios, size/age distributions, and incidence of human-related injuries of a long-lived species, the painted turtle (Chrysemys picta). My results suggest that some in-lake habitat features (e.g., vegetation, coarse woody habitat) may be important sites of refuge while anthropogenic features, such as piers, may pose a threat to male painted turtles. In my second chapter, I investigated how lakeshore development affects in-lake habitat use for female northern map turtles (Graptemys geographica). Turtles selected for shallow areas with submersed and floating vegetation. Turtle home ranges included a lower percentage of developed shoreline as compared to the lake, yet turtles demonstrated a preference for piers, developed shores, and bulkhead seawalls within their home ranges. These patterns of habitat use can provide insight into critical turtle habitat including submersed and floating vegetation.In chapter three, I studied the effects of lakeshore development and zebra mussel invasion on lake food webs. Using two species of fish (bluegill [Lepomis macrochirus] and largemouth bass [Micropterus salmoides]) and two food web metrics (proportion of the fish's diet coming from benthic sources and fish trophic position), I found that shoreline development had a negative effect on bluegill trophic positions. Contrary to expectations, I found no further relationships between food web metrics and these two anthropogenic stressors, nor any interactions between the two stressors. These results may be due to a lack of effect or to the opposing effects of these two benthic zone stressors cancelling out the effects of each other.In chapter four, I studied the effect of zebra mussels on lakefront property values. Although zebra mussels have a number of negative ecological and economic effects, they are also associated with increased water clarity and with features that make lakes desirable for recreational boating (the source of most zebra mussel introductions). I found that lakefront property values were positively related to zebra mussel presence in the lake and the time since zebra mussels first invaded the lake. Including potential confounding variables in the models did not change these positive relationships, indicating that we may be missing additional covariates or that there is a positive relationship between this invasive species and property values.The results of my dissertation show that anthropogenic changes to lakes can affect both the organisms within the lake and the ecosystem services these lakes provide to humans. Lake management plans that are designed to minimize the effects of lakeshore residential development and zebra mussel invasion could protect lake organisms and what humans enjoy about lakes.
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