Impact of trace metal concentrations on coccolithophore growth and morphology : species-specific responses in past and present ocean
Abstract
Data di Pubblicazione:
2017
Citazione:
Impact of trace metal concentrations on coccolithophore growth and morphology : species-specific responses in past and present ocean / G. Faucher, L. Hoffmann, L.T. Bach, E. Erba, C. Bottini, U. Riebesell. - In: GEOPHYSICAL RESEARCH ABSTRACTS. - ISSN 1029-7006. - 19:(2017 Apr). ((Intervento presentato al convegno EGU (European Geosciences Union) General Assemblies nel 2017.
Abstract:
The Cretaceous witnessed intervals of profound perturbation named “Oceanic Anoxic Events (OAEs)” characterized
by volcanic injection of large amounts of CO2, ocean anoxia, eutrophication, and introduction of biologically
relevant metals. Some of these extreme events were characterized by size reduction and/or morphological changes
of a number of nannofossil species. To detect the cause/s of such changes in the fossil record is challenging. Evidence
of a correspondence between intervals of high trace metals concentrations and nannofossil dwarfism may be
suggestive for a negative effect of these elements on nannoplankton biocalcification process.
In order to verify the hypothesis that anomalously high quantities of essential and/or toxic metals were the cause of
coccolith dwarfism, we explored the toxicities of a mixture of trace metals on four living coccolithophores species,
namely Emiliania huxleyi, Gephyrocapsa oceanica, Pleurochrysis carterae and Coccolithus pelagicus. The trace
metals tested were chosen based upon concentration peaks identified in the geological record and upon known
trace metal interaction with living coccolithophores algae.
Our results demonstrate a species-specific response to trace metal enrichment in living coccolithophores: E. huxleyi,
G. oceanica and C. pelagicus showed a decrease in their growth rate with progressively and exponentially
increased trace metal concentrations, while P. carterae is unresponsive to trace metal content. Furthermore, E.
huxleyi, G. oceanica and C. pelagicus evidenced a decrease in the cell diameter. Smaller coccoliths were detected
in E. huxleyi and C. pelagicus, while coccolith of G. oceanica showed a decrease in size only at the highest trace
metal concentrations tested. P. carterae size was unresponsive for changing trace metal concentration.
Our results on living coccolithophore algae, demonstrate that elevated trace metal concentrations not only affect
growth but also coccolith size and/or weight and that there are large differences between different species. These
species-specific differences must be considered before morphological features of coccoliths are used to reconstruct
paleo-chemical conditions.
Following the laboratory experiment results, elevated trace metal conditions in the past oceans could have caused
at least part of the observed morphological changes detected during some Mesozoic OAEs.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
coccolithophore algae, trace metal, morphology
Elenco autori:
G. Faucher, L. Hoffmann, L.T. Bach, E. Erba, C. Bottini, U. Riebesell
Link alla scheda completa:
Link al Full Text: