Date of Award

2024

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biology

Abstract

Turtles are an important component of many freshwater ecosystems, yet the impact of dams on freshwater turtles is an understudied topic globally. Past studies have focused on large dams and there is no literature addressing the impact of dams on turtle species assemblages. Dams affect turtles and their habitat by altering water flow, ecological communities, nesting and basking sites, and overwintering sites, and restricting turtle movements. Indiana has many low-head dams that no longer serve their original function, are in disrepair, and are hazardous to kayakers. There are ongoing efforts to remove these dams to improve stream ecology and safety. Low-head dams are known to impact sediments, fish, and macroinvertebrate communities, and could impact turtle species assemblages, abundance, and demographics. I trapped turtles above, below, and at a control site for five dams in western Indiana during summer 2023 and captured three hundred and six turtles (two hundred and fifty-one Spiny Softshell Turtles [ Apalone spinifera ], twenty Common Snapping Turtles [ Chelydra serpentina ], twenty-three Red-Eared Sliders [ Trachemys scripta elegans ], six Painted Turtles [ Chrysemys picta ], eight Northern Map Turtles [ Graptemys geographica ], and one Common Musk Turtle [ Sternothernus oderatus ]). Across sites there was a trend of increased species richness, diversity, and evenness upstream. When excluding one site due to the presence of cattle, there was lower Spiny Softshell Turtle abundance at upstream sites, and lower evenness at downstream sites. This indicates that low-head dams can alter turtle species assemblages above and below the dams. Further research is needed to determine how low-head dam removal affects aquatic turtles.

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