Oxygen, ecology, and the Cambrian radiation of animals

Sperling, Erik A.; Frieder, Christina A.; Raman, A. V.; Girguis, Peter R.; Levin, Lisa A.; Knoll, Andrew H.

doi:10.1073/pnas.1312778110

Cited by 315 publications

(249 citation statements)

References 51 publications

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“…Cloud, 1968;Runnegar, 1982). Experimental work has also shown that the oxygen levels necessary to support small, primitive metazoans such as sponges (Porifera) are far lower (Mills et al, 2014) than those required for large, active, and A c c e p t e d M a n u s c r i p t 7 ecologically-important animals such as carnivorous predators (Sperling et al, 2013b;Knoll and Sperling, 2014).…”

Section: Introductionmentioning

confidence: 99%

Dynamic redox conditions control late Ediacaran metazoan ecosystems in the Nama Group, Namibia

Wood

Poulton

Prave

et al. 2015

Precambrian Research

172

194

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A c c e p t e d M a n u s c r i p t 3 ABSTRACTThe first appearance of skeletal metazoans in the late Ediacaran (~550 million years ago; Ma) has been linked to the widespread development of oxygenated oceanic conditions, but a precise spatial and temporal reconstruction of their evolution has not been resolved. Here we consider the evolution of ocean chemistry from ~550 to ~541 Ma across shelf-to-basin transects in the Zaris and Witputs Sub-Basins of the Nama Group, Namibia. New carbon isotope data capture the final stages of the Shuram/Wonoka deep negative C-isotope excursion, and these are complemented with a reconstruction of water column redox dynamics utilizing Fe-S-C systematics and the distribution of skeletal and soft-bodied metazoans. Combined, these inter-basinal datasets provide insight into the potential role of ocean redox chemistry during this pivotal interval of major biological innovation.The strongly negative  13 C values in the lower parts of the sections reflect both a secular, global change in the C-isotopic composition of Ediacaran seawater, as well as the influence of 'local' basinal effects as shown by the most negative  13 C values occurring in the transition from distal to proximal ramp settings. Critical, though, is that the transition to positive  13 C values postdates the appearance of calcified metazoans, indicating that the onset of biomineralization did not occur under post-excursion conditions. Significantly, we find that anoxic and ferruginous deeper water column conditions were prevalent during and after the transition to positive  13 C that marks the end of the Shuram/Wonoka excursion. Thus, if the C isotope trend reflects the transition to global-scale oxygenation in the aftermath of the oxidation of a large-scale, isotopically light organic carbon pool, it was not sufficient to fully oxygenate the deep ocean. Page 4 of 74A c c e p t e d M a n u s c r i p t 4 Both sub-basins reveal highly dynamic redox structures, where shallow, inner ramp settings experienced transient oxygenation. Anoxic conditions were caused either by episodic upwelling of deeper anoxic waters or higher rates of productivity. These settings supported short-lived and monospecific skeletal metazoan communities. By contrast, microbial (thrombolite) reefs, found in deeper inner-and mid-ramp settings, supported more biodiverse communities with complex ecologies and large skeletal metazoans. These long-lived reef communities, as well as Ediacaran soft-bodied biotas, are found particularly within transgressive systems, where oxygenation was persistent. We suggest that a mid-ramp position enabled physical ventilation mechanisms for shallow water column oxygenation to operate during flooding and transgressive sea-level rise. Our data support a prominent role for oxygen, and for stable oxygenated conditions in particular, in controlling both the distribution and ecology of Ediacaran skeletal metazoan communities.Keywords: Oxygenation; Neoproterozoic; Biomineralisation; Metazoans; Ediacaran; Ecosystems Introductio...

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Section: Introductionmentioning

confidence: 99%

Dynamic redox conditions control late Ediacaran metazoan ecosystems in the Nama Group, Namibia

Wood

Poulton

Prave

et al. 2015

Precambrian Research

172

194

View full text Add to dashboard Cite

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“…These environmental data also showed that although small animals may be present at very low O 2 concentrations, the ecological richness associated with the Cambrian biota (particularly carnivory) requires O 2 concentrations perhaps closer to 10% PAL ( Fig. 1) (11,12). Under the hypothesis that animal evolution and O 2 are inexorably linked, these physiological and ecological constraints make a set of predictions for the geological record-specifically, that stable atmospheric O 2 concentrations did not rise above 1% PAL until relatively late in the Proterozoic Eon.…”

mentioning

confidence: 66%

Breathing room for early animals

Fischer

2016

Proc. Natl. Acad. Sci. U.S.A.

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“…In places where sea-floor oxygen levels are a bit higher -about 0.5-3% of concentrations at the sea surface -animals are more abundant but their food webs remain limited: the animals still feed on microbes rather than on each other. But around somewhere between 3% and 10%, predators emerge and start to consume other animals 4 .…”

Section: Modern Mirrorsmentioning

confidence: 99%