PhD Student UC Santa Barbara and STRI Fellow
Reconstructing shark communities using dermal denticles preserved in reef sediments
What were shark communities like before humans? Ecological surveys and historical records demonstrate significant declines in Caribbean shark populations, yet pre-exploitation baselines are nonexistent. Dermal denticles – tiny, tooth-like scales lining the skin of elasmobranchs – can offer insight into shark communities on reefs. We have found denticles to be beautifully preserved in fossil and modern reef sediments, allowing morphometric analysis and classification. Denticle traits are also closely associated with shark ecology and can paint a picture of shark community composition. Evaluating the relative abundances of different denticle morphotypes in sediment samples across time and space can both supplement existing survey data – using time-averaged modern sediments – and assist in the reconstruction of pre-human shark baselines – using the recent fossil record. This previously unexplored data source may reveal what shark communities looked like prior to the advent of fishing, facilitating exciting and important assessments of the magnitude and ecological consequences of global shark declines and producing more meaningful conservation targets.