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Anoxia/high temperature double whammy during the Permian-Triassic marine crisis and its aftermath.

Song H, Wignall PB, Chu D, Tong J, Sun Y, Song H, He W, Tian L - Sci Rep (2014)

Bottom Line: The relative tolerance of groups to this double whammy provides the first clear explanation for the selective extinction losses during this double-pulsed crisis and also the fitful recovery.Thus, high temperature intolerant shallow-water dwellers, such as corals, large foraminifers and radiolarians were eliminated first whilst high temperature tolerant ostracods thrived except in anoxic deeper-waters.Limited Early Triassic benthic recovery was restricted to mid-water depths and coincided with intervals of cooling and deepening of water column anoxia that expanded the habitable mid-water refuge zone.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China.

ABSTRACT
The Permian-Triassic mass extinction was the most severe biotic crisis in the past 500 million years. Many hypotheses have been proposed to explain the crisis, but few account for the spectrum of extinction selectivity and subsequent recovery. Here we show that selective losses are best accounted for by a combination of lethally warm, shallow waters and anoxic deep waters that acted to severely restrict the habitable area to a narrow mid-water refuge zone. The relative tolerance of groups to this double whammy provides the first clear explanation for the selective extinction losses during this double-pulsed crisis and also the fitful recovery. Thus, high temperature intolerant shallow-water dwellers, such as corals, large foraminifers and radiolarians were eliminated first whilst high temperature tolerant ostracods thrived except in anoxic deeper-waters. In contrast, hypoxia tolerant but temperature intolerant small foraminifers were driven from shallow-waters but thrived on dysoxic slopes margins. Only those mollusc groups, which are tolerant of both hypoxia and high temperatures, were able to thrive in the immediate aftermath of the extinction. Limited Early Triassic benthic recovery was restricted to mid-water depths and coincided with intervals of cooling and deepening of water column anoxia that expanded the habitable mid-water refuge zone.

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Biodiversity curves in the platform, slope, and basin habitats near the PTB in South China.Diamonds show raw data whereas circles show subsampling data corrected for variation in sampling intensity by using UW method25. Plankton and benthos only found in shallow-water habitats completely disappeared during the latest Permian extinction, whereas nekton and eurytopic benthos underwent two pulses of extinction. Water-depth data and biotic data see Table S4. Diamond = raw species richness data and circle with bar = subsampling data with 95% confidence intervals. Green colour = data from pre-latest Permian extinction, blue colour = data from middle interval, and orange colour = data from post-earliest Triassic extinction.
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f3: Biodiversity curves in the platform, slope, and basin habitats near the PTB in South China.Diamonds show raw data whereas circles show subsampling data corrected for variation in sampling intensity by using UW method25. Plankton and benthos only found in shallow-water habitats completely disappeared during the latest Permian extinction, whereas nekton and eurytopic benthos underwent two pulses of extinction. Water-depth data and biotic data see Table S4. Diamond = raw species richness data and circle with bar = subsampling data with 95% confidence intervals. Green colour = data from pre-latest Permian extinction, blue colour = data from middle interval, and orange colour = data from post-earliest Triassic extinction.

Mentions: The interval between the two extinction pulses was characterised by unusual marine communities that lacked shallow-water specialists and diverse radiolarians in low latitudes (Fig. 3), although this planktonic group remained diverse and abundant in higher latitude, cooler southern oceans26. Nonetheless benthic communities diversified at this time in South China, notably amongst groups tolerant of high temperatures (ostracods, gastropods and bivalves). The second pulse of extinction – the ETE – brought this radiation to an end. The wide spread of anoxic facies at this time was enough to cause the demise of the high-temperature (but not hypoxia) tolerant ostracods. Only species tolerant of both high temperature and hypoxia, namely bivalves and gastropods (Fig. 1), were able to thrive in large numbers (but not high diversity) in the aftermath of this second extinction event (Fig. 3).


Anoxia/high temperature double whammy during the Permian-Triassic marine crisis and its aftermath.

Song H, Wignall PB, Chu D, Tong J, Sun Y, Song H, He W, Tian L - Sci Rep (2014)

Biodiversity curves in the platform, slope, and basin habitats near the PTB in South China.Diamonds show raw data whereas circles show subsampling data corrected for variation in sampling intensity by using UW method25. Plankton and benthos only found in shallow-water habitats completely disappeared during the latest Permian extinction, whereas nekton and eurytopic benthos underwent two pulses of extinction. Water-depth data and biotic data see Table S4. Diamond = raw species richness data and circle with bar = subsampling data with 95% confidence intervals. Green colour = data from pre-latest Permian extinction, blue colour = data from middle interval, and orange colour = data from post-earliest Triassic extinction.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3928575&req=5

f3: Biodiversity curves in the platform, slope, and basin habitats near the PTB in South China.Diamonds show raw data whereas circles show subsampling data corrected for variation in sampling intensity by using UW method25. Plankton and benthos only found in shallow-water habitats completely disappeared during the latest Permian extinction, whereas nekton and eurytopic benthos underwent two pulses of extinction. Water-depth data and biotic data see Table S4. Diamond = raw species richness data and circle with bar = subsampling data with 95% confidence intervals. Green colour = data from pre-latest Permian extinction, blue colour = data from middle interval, and orange colour = data from post-earliest Triassic extinction.
Mentions: The interval between the two extinction pulses was characterised by unusual marine communities that lacked shallow-water specialists and diverse radiolarians in low latitudes (Fig. 3), although this planktonic group remained diverse and abundant in higher latitude, cooler southern oceans26. Nonetheless benthic communities diversified at this time in South China, notably amongst groups tolerant of high temperatures (ostracods, gastropods and bivalves). The second pulse of extinction – the ETE – brought this radiation to an end. The wide spread of anoxic facies at this time was enough to cause the demise of the high-temperature (but not hypoxia) tolerant ostracods. Only species tolerant of both high temperature and hypoxia, namely bivalves and gastropods (Fig. 1), were able to thrive in large numbers (but not high diversity) in the aftermath of this second extinction event (Fig. 3).

Bottom Line: The relative tolerance of groups to this double whammy provides the first clear explanation for the selective extinction losses during this double-pulsed crisis and also the fitful recovery.Thus, high temperature intolerant shallow-water dwellers, such as corals, large foraminifers and radiolarians were eliminated first whilst high temperature tolerant ostracods thrived except in anoxic deeper-waters.Limited Early Triassic benthic recovery was restricted to mid-water depths and coincided with intervals of cooling and deepening of water column anoxia that expanded the habitable mid-water refuge zone.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China.

ABSTRACT
The Permian-Triassic mass extinction was the most severe biotic crisis in the past 500 million years. Many hypotheses have been proposed to explain the crisis, but few account for the spectrum of extinction selectivity and subsequent recovery. Here we show that selective losses are best accounted for by a combination of lethally warm, shallow waters and anoxic deep waters that acted to severely restrict the habitable area to a narrow mid-water refuge zone. The relative tolerance of groups to this double whammy provides the first clear explanation for the selective extinction losses during this double-pulsed crisis and also the fitful recovery. Thus, high temperature intolerant shallow-water dwellers, such as corals, large foraminifers and radiolarians were eliminated first whilst high temperature tolerant ostracods thrived except in anoxic deeper-waters. In contrast, hypoxia tolerant but temperature intolerant small foraminifers were driven from shallow-waters but thrived on dysoxic slopes margins. Only those mollusc groups, which are tolerant of both hypoxia and high temperatures, were able to thrive in the immediate aftermath of the extinction. Limited Early Triassic benthic recovery was restricted to mid-water depths and coincided with intervals of cooling and deepening of water column anoxia that expanded the habitable mid-water refuge zone.

Show MeSH
Related in: MedlinePlus