Ediacaran reorganization of the marine phosphorus cycle

Abstract

The Ediacaran Period (635 to 541 Ma) marks the global transition to a more productive biosphere, evidenced by increased availability of food and oxidants, the appearance of macroscopic animals, significant populations of eukaryotic phytoplankton, and the onset of massive phosphorite deposition. We propose this entire suite of changes results from an increase in the size of the deep-water marine phosphorus reservoir, associated with rising sulfate concentrations and increased remineralization of organic P by sulfate-reducing bacteria. Simple mass balance calculations, constrained by modern anoxic basins, suggest that deep-water phosphate concentrations may have increased by an order of magnitude without any increase in the rate of P input from the continents. Strikingly, despite a major shift in phosphorite deposition, a new compilation of the phosphorus content of Neoproterozoic and early Paleozoic shows little secular change in median values, supporting the view that changes in remineralization and not erosional P fluxes were the principal drivers of observed shifts in phosphorite accumulation. The trigger for these changes may have been transient Neoproterozoic weathering events whose biogeochemical consequences were sustained by a set of positive feedbacks, mediated by the oxygen and sulfur cycles, that led to permanent state change in biogeochemical cycling, primary production, and biological diversity by the end of the Ediacaran Period.

Roles of Phosphate Solubilizing Microorganisms from Managing Soil Phosphorus Deficiency to Mediating Biogeochemical P Cycle

“…Globally-enhanced continental weathering has delivered vast amounts of P to the oceans, resulting in the increased levels of subsequent eutrophication and marine anoxia [ 12 , 36 ]. The weathering of P minerals depends on numerous environmental factors, including earth history, environmental erosion, atmospheric composition, rock P contents, soil microaggregate fractions, and biological response [ 15 , 36 , 126 , 129 , 130 , 131 ]. As soil microorganisms with P i mineral weathering abilities, PSM or phosphate-dissolving microorganisms, are environmentally widespread [ 111 , 132 ].…”

“…Thus, the largest reservoirs of P in soil and marine environment are phosphate rock (PR) and sedimentary rock, respectively. The natural P cycle is a simple one-way flow from terrestrial to aquatic ecosystems through inorganic PR denudation and sediment immobilization on medium-term timescales (10 3 years) [ 8 , 15 ].…”

Phanerozoic radiation of ammonia oxidizing bacteria

“… 8 , 9 ), suggesting that the first rock record evidence for ammonia oxidation records the activity of ammonia oxidizing archaea or other biological or abiotic processes. Our estimate for the origin of bacterial ammonia oxidation is during the time in Earth history that saw the biosphere transition from a low-productivity, exclusively microbial state characteristic of Proterozoic time 18 , 19 to a more modern system fueled by eukaryotic algae and supporting complex multicellular organisms including animals 20 , 21 possibly triggered by increased phosphate availability 22 . Net primary productivity of the biosphere is thought to have increased significantly at this time 19 , 23 , along with a rise in atmospheric oxygen concentrations to near-modern levels and the more permanent oxygenation of the deep ocean 24 .…”

Phanerozoic Radiation of Ammonia Oxidizing Bacteria

“…Garvin et al 2009, Zerkle et al 2017), suggesting that the first rock record evidence for ammonia oxidation records the activity of ammonia oxidizing archaea or other biological or abiotic processes. Our estimate for the origin of bacterial ammonia oxidation is during the time in Earth history that saw the biosphere transition from a low-productivity, exclusively microbial state characteristic of Proterozoic time (Dick et al 2018, Ward and Shih 2019) to a more modern system fueled by eukaryotic algae and supporting complex multicellular organisms including animals (Erwin et al 2011, Brocks et al 2017) possibly triggered by increased phosphate availability (Laakso et al 2020). Net primary productivity of the biosphere is thought to have increased significantly at this time (Ward et al 2019a, Ward and Shih 2019), along with a rise in atmospheric oxygen concentrations to near-modern levels and the more permanent oxygenation of the deep ocean (Sperling et al 2015).…”