TROPHIC CHANGES IN MARINE ECOSYSTEMS FOLLOWING THE PLIOCENE MEGAFAUNAL EXTINCTION EVENT

A marine extinction event at the end of the Pliocene (~2.5-3mya) saw significant losses in marine megafauna, notably Otodus megalodon one of the largest apex predators to ever exist. The apparent relationship between extinction susceptibility and large-bodied homeotherms (species with high energy requirements) in this event is atypical among past extinctions yet is similar to trends seen in current conservation research. However, the ecological consequences of losing megafauna from marine environments, particularly a globally dominant apex predator, is not well understood. Using a trait-based inference model, we reconstructed food webs to assess the impact of this Pliocene extinction event on North Atlantic trophic community structure and dynamics. The model distributes trophic links using rules based on foraging theory and functional traits assigned to every trophic species (e.g., body size, motility, metabolic control and feeding habit). Through analysing the differences in food web topology pre- and post- megafaunal extinction event we show how trophic structure and feeding interactions were altered and identify the species that ‘replaced’ O. megalodon at the top of the food web. In addition to addressing questions in palaeoecology, these findings could be informative for conservation studies predicting the impact of future marine megafauna and apex predator losses.