Variation in brachiopod microstructure and isotope geochemistry under low-pH–ocean acidification–conditions .

Ye, Facheng, Jurikova, Hana, Angiolini, Lucia, Brand, Uwe, Crippa, Gaia, Henkel, Daniela, Laudien, Jürgen, Hiebenthal, Claas and Smajgl, Danijela (2019) Variation in brachiopod microstructure and isotope geochemistry under low-pH–ocean acidification–conditions . Open Access Biogeosciences (BG), 16 (2). pp. 617-642. DOI 10.5194/bg-16-617-2019.

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Abstract

Throughout the last few decades and in the near future CO2–induced ocean acidification is potentially a big threat to marine calcite-shelled animals (e.g., brachiopods, bivalves, corals and gastropods). Despite the great number of studies focusing on the effects of acidification on shell growth, metabolism, shell dissolution and shell repair, the consequences on biomineral formation remain poorly understood, and only few studies addressed contemporarily the impact of acidification on shell microstructure and geochemistry. In this study, a detailed microstructure and stable isotope geochemistry investigation was performed on nine adult brachiopod specimens of Magellania venosa (Dixon, 1789), grown in the natural environment as well as in controlled culturing experiments at different pH conditions (ranging 7.35 to 8.15±0.05) over different time intervals (214 to 335 days). Details of shell microstructural features, such as thickness of the primary layer, density and size of endopunctae and morphology of the basic structural unit of the secondary layer were analysed using scanning electron microscopy (SEM). Stable isotope compositions (δ13C and δ18O) were tested from the secondary shell layer along shell ontogenetic increments in both dorsal and ventral valves. Based on our comprehensive dataset, we observed that, under low pH conditions, M. venosa produced a more organic-rich shell with higher density of and larger endopunctae, and smaller secondary layer fibres, when subjected to about one year of culturing. Also, increasingly negative δ13C and δ18O values are recorded by the shell produced during culturing and are related to the CO2–source in the culture setup. Both the microstructural changes and the stable isotope results are similar to observations on brachiopods from the fossil record and strongly support the value of brachiopods as robust archives of proxies for studying ocean acidification events in the geologic past.

Document Type: Article
Funder compliance: info:eu-repo/grantAgreement/EC/H2020/643084
Keywords: Magellania venosa, biomineral, δ13C, δ18O, primary layer, secondary layer, endopunctae, scanning electron microscopy, culturing
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
OceanRep > GEOMAR > FB3 Marine Ecology > FB3-EOE-B Experimental Ecology - Benthic Ecology
AWI
Refereed: Yes
Open Access Journal?: Yes
DOI etc.: 10.5194/bg-16-617-2019
ISSN: 1726-4170
Related URLs:
Projects: BASE-LiNE Earth
Date Deposited: 06 Sep 2018 07:11
Last Modified: 23 Sep 2019 23:41
URI: http://oceanrep.geomar.de/id/eprint/44150

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