Monitoring Hydrologic Factors Influencing Bog Turtle Persistence at a Site in Connecticut

A calcareous fen that supported one of the few populations of bog turtles (Glyptemys muhlenbergii) in Connecticut has been shown by the Connecticut Department of Energy and Environmental Protection (DEEP) to have declined with no sitings reported since 2004. This study evaluates the current hydrology of the fen in question to provide insight as to why it may be no longer habitable. Possible reasons for turtle decline identified at the outset of the project included salt contamination from deicing of a state road, periodic flooding from seasonal storms, nutrient and pesticide runoff from the draining farms, potential drying conditions due to succession and changes in water table depth. A one-year monitoring program was instituted to investigate these issues and produce a hydrologic characterization of the site. Parameters monitored continuously were groundwater depth, stream stage, flood height across the wetland, soil moisture, soil temperature, soil bulk conductivity, stream conductivity, precipitation, and barometric pressure. Measurements made during periodic site visits were depth to groundwater, stream height and width, stream velocity, water quality parameters (temperature, specific electrical conductivity, dissolved oxygen, pH, ORP), and water chemistry parameters (metals, pesticides, fertilizers). The study focuses on the following conditions: extent of stream flooding, surface and subsurface water quality, groundwater discharge, and the impacts of pollution and succession. Observations from the study conclude that a receding water table, periodic flooding, and a subsurface infiltration of salt are likely causes for disturbance at the site