Terrestrial–marine teleconnections in the collapse and rebuilding of Early Triassic marine ecosystems

Abstract

The latest Permian mass extinction (LPE), just prior to the Permian–Triassic boundary at ~ 252 Ma, resulted in the disappearance of ~ 90% of skeletonized marine taxa and the replacement of the Paleozoic Fauna by the Modern Fauna. In the immediate aftermath of the extinction, shallow-marine ecosystems were dominated by microbial communities and diminutive disaster taxa (“Lilliput faunas”), and the post-crisis period in general was characterized by high-abundance, low-diversity marine communities occupying a reduced ecological space. The recovery of marine ecosystems was a protracted process, lasting throughout the ~ 5-Myr-long Early Triassic. Some clades failed to recover and subsequently went extinct (“dead clades walking”), while others recovered only to suffer secondary crises during the Early Triassic. Profound environmental changes accompanied these biotic developments. Deep oceans experienced sustained hypoxia or anoxia for at least several million years following the boundary event. Anoxia was also widespread in shallow-marine areas, especially at the time of the LPE, but it was more episodic and abated more rapidly than in the deep ocean, making it an unlikely factor in the delayed recovery of Early Triassic marine ecosystems. The development of anoxia was due at least in part to a sharp temperature rise following the LPE but may have been stimulated by changes in marine nutrient inventories and productivity rates as well. These conditions may have been the result of a concurrent increase in subaerial weathering rates that was sustained into the Early Triassic. In addition to increasing nutrient fluxes to marine areas, rapid weathering caused a massive influx of sediment to shallow-marine systems, subjecting marine biotas to siltation stress. This scenario implies close teleconnections between terrestrial and marine environments during the Permian–Triassic boundary crisis, with perturbations of the terrestrial realm contributing to the marine crisis.