Buried in the sand: Uncovering the ecological roles and importance of rays

Rays (superorder Batoidea) are the most diverse group of elasmobranchs, and many are threatened with extinction. However, there remain areas where research on the ecology of this group is lacking, from trophic interactions to their importance to ecosystem structure and function. Such ecological insights are critical for predicting the potential consequences of changes in their population sizes. Our aim was to synthesize the existing ray ecology literature and identify key knowledge gaps in order to provide a framework for future research. Numerous studies describe ray diets, and the number of studies using biochemical methods to address ray trophic interactions is increasing. The implications of ray predator-prey interactions on population dynamics of prey and how ray foraging might influence ecosystem dynamics through bioturbation remain relatively unexplored, despite claims that rays are ecologically important because they are bioturbators and because of their potential to deplete stocks of commercially important bivalves. Therefore, to better integrate rays in our understanding of marine community dynamics, there is a need to: (i) combine behavioural data with dietary information to describe predator-prey interactions; (ii) understand how ray bioturbation affects biogeochemical cycles and infaunal communities; (iii) elucidate conditions under which rays might initiate or transmit trophic cascades through consumptive and non-consumptive pathways; and (iv) consider anthropogenic influences on the ecological roles and importance of rays.