The Effects of Bulkheading on Diamondback Terrapin Nesting in Barnegat Bay, New Jersey

Abstract

As human populations continue to increase, costal development severely depletes the natural resources of Americas estuaries. Barnegat Bay, New Jersey shows the highest rate of shoreline development of any mid-Atlantic estuary in the past 30 years. Hard erosion control walls, called bulkheading cover 45% of Barnegat Bay, impeding nesting diamondback terrapins (Malacleymys terrapin) from reaching high dune habitat. This dissertations objective is to determine how diamondback terrapins behaviorally and physiologically respond to bulkheading and related anthropogenic activities while nesting. By monitoring two nesting beaches within Barnegat Bay, Conklin and Sedge Islands, I quantified the probability of terrapin nesting emergence simultaneous to environmental and anthropogenic factors. There was no significant effect of motorized boats, personal watercrafts, kayaks, or human presence on terrapin emergence. Instead, terrapins responded to environmental cues such as water (26 °C) and air (27.5° C) temperatures, time of day (13:30), and tidal stage (outgoing). To determine the effects of bulkheading on nesting terrapin movements I utilized biotelemetry to measure terrestrial and aquatic habitat use at artificial bulkheading. Terrapins showed variable, site-specific responses to bulkheading. At Conklin Island, terrapins encountering bulkheading travelled significantly further with more tortuous paths on land than females nesting at unobstructed beaches. At Sedge Island, however, terrapins spent significantly more time in the water at bulkheading instead of travelling more on land. I measured corticosterone (CORT) and testosterone (T) secretion levels to determine the stress response in reproductive females from bulkheading. After handling, terrapin profiles of acute CORT increased significantly, approaching peak levels of 8 ng/ml. There were no significant increases in CORT or T due to bulkheading, however, indicating that barriers do not cause nesting terrapin stress. Over the reproductive season, T dropped significantly while CORT levels were maintained. My results suggest that diamondback terrapins lack behavioral and physiological responses to anthropogenic stressors at nesting beaches. To conserve shorelines for terrapins and other estuarine wildlife, sustainable development, accessible enhanced artificial nesting habitats, and human beach closures must be implemented. With the high rate of bulkheading construction in Barnegat Bay and nation-wide, this research provides a novel approach to managing human-wildlife conflicts within Americas estuaries.%%%%Ph.D., Environmental Science – Drexel University, 2013