Previous work indicates that a variety of microbes bloomed in the oceans after the end-Permian faunal mass extinction, but evidence is sporadically documented. Thus, the nature and geographic distribution of such microbes and their associations are unclear, addressed in this study using a series of biomarker groups. On the basis of microbial biomarker records of the 2-methylhopane index, evidence is presented for cyanobacterial bloomsin both the western and eastern TethysSea and in both shallow and deep waters, after themassextinction. The enhanced relative abundance of C28 (expressed by the C28C29 ratio of) regular steranes suggests a bloom of prasinophyte algae occurred immediately after the end-Permian faunal extinction, comparable with those observed in some other mass extinctions in Phanerozoic. Signicantly, cyanobacteria and prasinophyte algae show a synchronized onset of bloom in the shallow water Bulla section, north Italy, inferring for the rst time their coupled response to the biotic crisis and the associated environmental conditions. However, in Meishan of Zhejiang Province in south China, the bloomdeclined earlier than in Bulla. The association of increased 2- methylhopane index with a negative shift in the nitrogen isotope composition infers a scenario of enhanced nitrogen xation by cyanobacteria immediately after the faunal mass extinction. N2 xation by cyanobacteria is here interpreted to have provided prasinophyte algae with ammonium in nutrient-limited shallow waters, and thuscaused their associated blooms.

Microbial response to limited nutrients in shallow water immediately after the end-Permian mass extinction

FARABEGOLI, ENZO;PERRI, MARIA CRISTINA;
2012

Abstract

Previous work indicates that a variety of microbes bloomed in the oceans after the end-Permian faunal mass extinction, but evidence is sporadically documented. Thus, the nature and geographic distribution of such microbes and their associations are unclear, addressed in this study using a series of biomarker groups. On the basis of microbial biomarker records of the 2-methylhopane index, evidence is presented for cyanobacterial bloomsin both the western and eastern TethysSea and in both shallow and deep waters, after themassextinction. The enhanced relative abundance of C28 (expressed by the C28C29 ratio of) regular steranes suggests a bloom of prasinophyte algae occurred immediately after the end-Permian faunal extinction, comparable with those observed in some other mass extinctions in Phanerozoic. Signicantly, cyanobacteria and prasinophyte algae show a synchronized onset of bloom in the shallow water Bulla section, north Italy, inferring for the rst time their coupled response to the biotic crisis and the associated environmental conditions. However, in Meishan of Zhejiang Province in south China, the bloomdeclined earlier than in Bulla. The association of increased 2- methylhopane index with a negative shift in the nitrogen isotope composition infers a scenario of enhanced nitrogen xation by cyanobacteria immediately after the faunal mass extinction. N2 xation by cyanobacteria is here interpreted to have provided prasinophyte algae with ammonium in nutrient-limited shallow waters, and thuscaused their associated blooms.
2012
JIA C.; HUANG J.; KERSHAW S.; LUO G.; FARABEGOLI E.; PERRI M.C.; CHEN L.; BAI X. and XIE S.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/308315
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