Authors:	Fröhlich, Lukas Siebert, Valentin Huang, Qian Thébault, Julien Jochum, Klaus Peter Schöne, Bernd R.
Title:	Deciphering the potential of Ba/Ca, Mo/Ca and Li/Ca profiles in the bivalve shell Pecten maximus as proxies for the reconstruction of phytoplankton dynamics
Online publication date:	5-Jul-2022
Year of first publication:	2022
Language:	english
Abstract:	Shells of the fast-growing bivalve Pecten maximus serve as a geochemical archive for the reconstruction of past phytoplankton dynamics. Specifically, high-resolution, temporally accurately aligned molar barium-to-calcium (Ba/Cashell), molybdenum-to-calcium (Mo/Cashell) and lithium-to-calcium ratios (Li/Cashell) of the shell calcite revealed distinct peaks which are closely linked to phytoplankton dynamics. Yet, the development and applicability of these geochemical proxies is still at an early stage and needs further calibration. In this study, we examined the relationship between the timing and magnitude of Ba/Cashell, Mo/Cashell and Li/Cashell peaks of P. maximus and the occurrence of various phytoplankton species (diatoms and dinoflagellates) from a statistical perspective. Studied shell samples (three specimens per calendar year) as well as detailed phytoplankton observation data were derived from the well-studied costal ecosystem of the Bay of Brest (France) over three years (2011, 2012 and 2019). An algorithm-based pseudo-random sampling simulation technique was established that analyzed the complex phytoplankton datasets with respect to the profiles of Ba/Cashell, Mo/Cashell and Li/Cashell to identify potential patterns between phytoplankton and trace element time-series. The simulation results indicate that the timing and magnitude of Ba/Cashell, Mo/Cashell and Li/Cashell peaks agreed best with the occurrence of specific phytoplankton blooms that developed ca. one to two weeks earlier. The data suggest that the formation of transient Ba/Cashell peaks had a plurispecific origin, i.e., potentially linked to blooms of ingestible diatom, dinoflagellate and flagellate species enriched in Ba that occurred 8 to 12 days earlier. Observed peaks in Mo/Cashell profiles demonstrably followed the timing and intensity of blooms of the dominant dinoflagellate genus Gymnodinium spp. after a short time lag of around 8 days, potentially linked to an enhanced enzyme activity of nitrate reductase that requires the presence of Mo in the dinoflagellate cells. In addition, Mo/Cashell peaks agreed with periods of diatom aggregate formation which were hypothesized to induce the formation of Mo/Cashell peaks in scallop shells. Li/Cashell profiles revealed similar patterns as large blooms of the diatom Chaetoceros spp. as well as to neurotoxin producing diatoms of the genus Pseudo-nitzschia when considering a short time lag of 8 to 12 days. These findings highlight the great potential of using Ba/Cashell, Mo/Cashell and Li/Cashell chronologies in P. maximus shells as proxies of past phytoplankton dynamics.
DDC:	500 Naturwissenschaften 500 Natural sciences and mathematics 540 Chemie 540 Chemistry and allied sciences 550 Geowissenschaften 550 Earth sciences 560 Paläontologie 560 Paleontology 570 Biowissenschaften 570 Life sciences 590 Tiere (Zoologie) 590 Zoological sciences
Institution:	Johannes Gutenberg-Universität Mainz
Department:	FB 09 Chemie, Pharmazie u. Geowissensch.
Place:	Mainz
ROR:	https://ror.org/023b0x485
DOI:	http://doi.org/10.25358/openscience-7298
Version:	Published version
Publication type:	Zeitschriftenaufsatz
Document type specification:	Scientific article
License:	CC BY-NC-ND
Information on rights of use:	https://creativecommons.org/licenses/by-nc-nd/4.0/
Journal:	Ecological indicators 141
Pages or article number:	109121
Publisher:	Elsevier Science
Publisher place:	Amsterdam u.a.
Issue date:	2022
ISSN:	1470-160X
Publisher DOI:	10.1016/j.ecolind.2022.109121
Appears in collections:	DFG-491381577-G