2019 Volume 24 Issue 2 Article ID: 1817
Possible factors causing the decline of the endangered horseshoe crab species Tachypleus tridentatus were revealed by interpretation of aerial photographs, interviews with residents, and field surveys at Tsuyazaki Cove, Fukuoka, Japan. The interviews confirmed that T. tridentatus had been abundant in the area from the 1940s to the 1980s; however, the species decreased gradually and was rarely seen by the locals in the early 2000s. A field survey from 2005 to 2013 confirmed that the number of breeding horseshoe crabs had decreased dramatically over the survey period. The study results suggest that the decline in T. tridentatus can be explained by reclamation of the bay mouth. This caused poor sand supply to potential spawning sites, which in turn resulted in the degradation of the habitat of local populations of T. tridentatus. The historical ecology approaches applied here could be useful as a primary analysis tool to search for clues regarding causal relationships between the population decline of rare species and coastal development.
