Impacts of the end Pliocene marine megafaunal extinction on North Atlantic trophic structure

Amy Shipley , Andrew P Beckerman, Catalina Pimiento, Jack Shaw, Jennifer A Dunne, Tracy Aze, Alexander M Dunhill

Marine megafauna are experiencing widespread population declines and these losses are expected to have cascading effects, impacting ecosystem structure and function. However, quantifying these ecological consequences at a global scale remains challenging, requiring an understanding of long-term trophic dynamics. Palaeoecology can provide useful insights into how communities respond to taxonomic losses through reconstructing food webs across extinction events. Here, we investigate the end Pliocene marine megafaunal extinction (~2.6 Ma) which saw the loss of one third of marine megafaunal genera globally, including the large apex predator Otodus megalodon. The trait-based Paleo Food web Inference Model (PFIM) is used to assess the impact of these extinctions on North Atlantic food web structure and function in the Pliocene and Pleistocene alongside the consequences of apex predator loss on other top predator trophic positions. Despite substantial taxonomic loss, no major structural changes were found, with the trophic positions of top predators being unaffected by the extinction of O. megalodon. Minor shifts in food web structure suggest more densely connected post-extinction communities characterised by a larger proportion of generalists. These findings suggest that, contrary to expectations, the Pliocene marine megafaunal extinction had minimal impact on long-term trophic structure and function in the North Atlantic.