Scavenger richness and functional diversity modify carrion consumption in the surf zone of ocean beaches

Abstract

Abstract Ecological functions are linked to the condition and stability of coastal ecosystems. Quantifying how human disturbance and seascape context influence biodiversity and how different forms of diversity (i.e. species richness and functional diversity) influence ecological functioning is important in managing coastal ecosystems. We measured if the rates of carrion consumption by fish and crustaceans were influenced by scavenger richness and functional diversity or the abundance of key scavenger species, and which environmental factors shaped carrion consumption in surf zones at 20 beaches in eastern Queensland, Australia. Carrion consumption was positively correlated with scavenger richness, functional diversity, and the abundance of two species: weeping toadfish (Torquigener pleurogramma) and ornate wobbegong (Orectolobus ornatus). Carrion consumption was highest at sites that were near rocky headlands (<1 km) and shark control programme equipment (<1 km) and was also characterized by functional complementarity as weeping toadfish consumed more carrion at sites with a smaller area of reef nearby (<0.1 km2), whilst ornate wobbegong consumed more carrion at sites with a larger area of reef nearby (>0.3 km2). We highlight the importance of scavenger richness and functional diversity in shaping carrion consumption in surf zones, particularly when the species performing the function do this in spatially distinct areas.