Habitat Preference and the Effects of Beach Nourishment on the Federally Threatened Northeastern Beach Tiger Beetle, Cicindela dorsalis dorsalis: Western Shore, Chesapeake Bay, Virginia

This study examines the habitat preference of the US federally threatened northeastern beach tiger beetle, Cicindela dorsalis dorsalis, and the effect of beach nourishment on existing habitats along two western Chesapeake Bay beaches. Winter Harbor Beach and Smith Point Beach, located approximately 100 km to the north, historically have supported large populations of C. d. dorsalis. Grain size distributions, sediment compaction at two depths, temperature, moisture, and beach width habitat parameters were analyzed by analysis of variance and Tukey's honestly significant difference multiple comparison test and related to the distribution and abundance of C. d. dorsalis. The results from this study indicate that this species prefers beaches at least 6 m wide, with moderately well–sorted sands having a mean grain size of 0.5 to 0.6 mm, and relatively compacted sediment with averages of 69 psi and 110 psi at depths of 10 and 15 cm, respectively. In addition, the two nourishment projects had a positive short-term effect on the beetle habitat despite differences in deposition location. At Smith Point Beach, deposition occurred on top of the subaerial beach with a minimal increase in beach width. At Winter Harbor Beach, nearshore deposition caused a 50-m increase on average in beach width. Within weeks of deposition, adults of C. d. dorsalis rapidly moved onto the nourished sections of both beaches and produced large numbers of larvae. Winter Harbor Beach experienced the greatest increase in beetle numbers, most likely because of the additional habitat created by nearshore deposition. However, continued erosion from natural and anthropogenic sources could produce a chronic threat to productive habitats. These findings will assist coastal engineers and developers in determining effective measures designed to aid both economic and ecologic interests.