Environmental controls on marine ecosystem recovery following mass extinctions, with an example from the Early Triassic

Abstract

23The recovery of marine ecosystems following a mass extinction event involves an 24 extended interval of increasing biotic diversity and ecosystem complexity. The pace of 25 recovery may be controlled by intrinsic ecosystem or extrinsic environmental factors. Here, 26 we present an analysis of changes in marine conditions following the end-Permian mass 27 extinction with the objective of evaluating the role of environmental factors in the protracted 28 © 2015. This manuscript version is made available under the Elsevier user license http://www.elsevier.com/open-access/userlicense/1.0/ 2 (~5-Myr-long) recovery of marine ecosystems during the Early Triassic. Specifically, our 29 study examines changes in weathering, productivity, and redox proxies in three sections in 30 South China (Chaohu, Daxiakou, and Zuodeng) and one in northern India (Mud). Our results 31 reveal: 1) recurrent environmental perturbations during the Early Triassic; 2) a general pattern 32 of high terrestrial weathering rates and more intensely reducing marine redox conditions 33 during the early Griesbachian, late Griesbachian, mid-Smithian, and (more weakly) the 34 mid-Spathian; 3) increases in marine productivity during the aforementioned intervals except 35 for the early Griesbachian; and 4) stronger and more temporally discrete intervals of 36 environmental change in deepwater sections (Chaohu and Daxiakou) relative to shallow and 37 intermediate sections (Zuodeng and Mud). Our analysis reveals a close relationship between 38 episodes of marine environmental deterioration and a slowing or reversal of ecosystem 39 recovery based on metrics of biodiversity, within-community (alpha) diversity, infaunal 40 burrowing, and ecosystem tiering. We infer that the pattern and pace of marine ecosystem 41 recovery was strongly modulated by recurrent environmental perturbations during the Early 42Triassic. These perturbations were associated with elevated weathering and productivity 43 fluxes, implying that nutrient and energy flows were key influences on recovery. More regular 44 secular variation in deepwater relative to shallow-water environmental conditions implies that 45 perturbations originated at depth (i.e., within the oceanic thermocline) and influenced the 46 ocean-surface layer irregularly. Finally, we compared patterns of environmental disturbance 47 and ecosystem recovery following the other four "Big Five" Phanerozoic mass extinctions to 48 evaluate whether commonalities exist. In general, the pace of ecosystem recovery depends on 49 the degree of stability of the post-crisis marine environment. 50 51

Biotic and environmental dynamics through the Late Jurassic–Early Cretaceous transition: evidence for protracted faunal and ecological turnover

“…Wei et al, 2015). Distinct extinction and diversification patterns are clearly recorded in different groups, with a range of potential extrinsic abiotic controls.…”

Carbon isotopic shift and its cause at the Wuchiapingian–Changhsingian boundary in the Upper Permian at the Zhaojiaba section, South China: Evidences from multiple geochemical proxies

“…1). Al, P and Fe are the typical elements in detrital material (such as clay minerals) and thus can be use for detrial proxies (Wei et al, 2003(Wei et al, , 2015Pattan et al, 2008). Based on the Al, P and Fe T profiles, high detrital input occurred in the upper Wuchiapingian, low detrital input in the uppermost Wuchiapingian and lower Changhsingian and gradual increasing detrital input in the upper Changhsingian (Fig.…”

Expansion of photic-zone euxinia during the Permian–Triassic biotic crisis and its causes: Microbial biomarker records

“…Enhanced terrestrial erosion during the PTB transition has been documented on the basis of biomarker evidence, i.e., DBT, DBF, retene, and moretane concentrations (Sephton et al, 2005;Xie et al, 2007), sediment fluxes (Algeo and Twitchett, 2010), and Sr isotopes (Korte et al, 2003;Sedlacek et al, 2014). High riverine nutrient fluxes would have stimulated marine primary productivity during the latest Permian to earliest Triassic (Algeo et al, 2011bShen et al, 2015;Wei et al, 2015). According to paleoceanographic modeling results, widespread oceanic anoxia and PZE are likely to have developed if riverine phosphate fluxes during the PTB crisis reached~10 × the modern value Winguth and Winguth, 2012).…”