Background
The Northeastern beach tiger beetle is a subspecies of the species Cicindela dorsalis¹.  C. d. dorsalis historically occurred on beaches from Cape Cod to the shorelines of Chesapeake Bay in Virginia².  It has been lost from much of its range.² In Massachusetts, it is limited to two naturally occurring populations, the largest of which inhabits an offshore barrier beach that is relatively pristine and undisturbed by human activity³.  The species is currently listed as endangered in Massachusetts⁴.

Northeastern beach tiger beetles are restricted to sandy beaches that are at least six meters wide².  Wider beaches are required to minimize mortality from powerful storms.  They have a two year life cycle².  Larvae burrow in the sand, where they capture small arthropods².  Adults emerge from the sand with numbers peaking in late June to early July.  Mating occurs throughout the adult period, which lasts throughout the summer before adults die².  Because they are tied to beaches and larvae are sedentary, human disturbance can greatly impact populations.  Compaction of sand through recreational vehicle or heavy foot traffic, beach stabilization for erosion control, and other forms of beach development all have been implicated in population declines⁵.

Climate Impacts
Due to their proximity to the surf, Northeastern beach tiger beetles are vulnerable to significant mortality during severe storms⁶.  Populations were significantly reduced and in some cases lost from sites in Virginia following hurricanes Isabel and Ernesto.  The populations remaining in Massachusetts have the potential to be entirely lost as a result of a severe summer storm event³.  Projected changes in climate for the Northeast indicate that the frequency of severe storm events is likely to increase in the future, increasing the possibility that the loss of these beetle populations could happen^7,8.

Sea levels are projected to rise over the next century^9,10.  Though there is uncertainty surrounding the magnitude and resulting impacts, sea level rise will probably impact Northeastern beach tiger beetles.  Impacts will likely come directly through inundation and increased beach erosion¹¹, but also indirectly through engineering projects designed to mitigate the effects of sea level rise on coastal communities¹². For instance, adult and larvae populations are generally greatest on natural beaches and become less abundant as the width and quality of the beach declines. Shoreline hardening through the placement of rip-rap (loose stone) threatens beetle habitat by disrupting the along-shore movement of sand. As erosion is halted, sand moves offshore into deeper channels, leading to complete loss of beetle habitat fronting these structures. Beach nourishment is also thought to be destructive to larvae survival. If sea level rise encroaches onto their habitat without room for beaches to migrate inland, narrowing and other changes to beach morphology could further impact the species in indirect ways ^2,6.