Inferring Organic Content of Beach Sand from Colorhalus onaneyi (Guantánamo Striped Curlytail) and Notes on its Natural History

Relative organic content in sediment is an important determinant of ecological processes, but it can be difficult to quantify in the field. Here, we present evidence that relative organic matter content of sand may be inferred from relative coloration. For 50 sand samples collected from a beach on Long Island, Antigua, West Indies, we characterized sand color intensity (brightness) using image analysis of standardized photographs and measured percent organic matter lost on ignition with dry combustion. A linear regression provided evidence for a strong negative relationship between brightness and organic content; darker-colored sand contained more organic matter. Inferring organic content from color may provide a simple way to make field-based qualitative assessments of an important parameter in beach habitats.