DO FISH LIKE IT HOT? ENHANCED FISH PRODUCTION DURING A PERIOD OF EXTREME GLOBAL WARMTH

Marine ecosystem models predict a decline in fish production with anthropogenic ocean warming, but how fish production equilibrates to warming on long timescales is unclear. We report a positive nonlinear correlation between ocean temperature and pelagic fish production during the extreme global warmth of the Early Paleogene Period (62-46 million years ago [Ma]). Using data-constrained food-web modeling, we find that temperature-driven increases in trophic transfer efficiency (the fraction of production passed up trophic levels) and primary production can account for the observed increase in fish production, while changes in predator-prey interactions cannot. These results provide new insight into marine upper-trophic-level processes constrained from the geological record, suggesting that warmer oceans may support more efficient food webs in subtropical pelagic ecosystems.