Determination of the burrow shapes of Cardisoma guanhumi on Vieques, Puerto Rico

Objective: To determine the burrow morphology of Cardisoma guanhumi and to determine if a battery-powered fiber optic camera could be used to investigate these burrows. Methods: A portable fiber optic camera was used to investigate 116 active burrows. All burrows were categorized according to shape. The diameter of each burrow was also recorded and biomass calculations were completed at each study site. Results: Analysis showed that different study sites were more likely to have particular burrow shapes than expected. Three main types of burrows were classified as horizontal slide, short and shallow, and inverted-S. A Pearson Chi-square analysis revealed that burrow shape was not equally distributed across study sites (χ2 = 61.05, df = 18, P < 0.000 1). Biomass calculations showed that different sized animals inhabited different study sites (ANOVA; df = 7, MS = 158.3, F = 13.9, P < 0.000 1). The fiber optic camera was useful in determining burrow morphology and occupancy non-destructively. Conclusions: As the locations of juvenile individuals of this species are poorly known, and the species is both ecologically and economically important where it occurs, a greater understanding of burrow morphology and size segregation may help agencies be responsible for managing this natural resource to do so effectively