Baggini, C

Buhl, D

Griesshaber, E

Hahn, S

Hall-Spencer, J

Immenhauser, A

Rodolfo-Metalpa, R

Schmahl, WW

English

Hall-Spencer, Jason

Plymouth Electronic Archive and Research Library

Geophysical Research AbstractsVol. 13, EGU2011-7130, 2011EGU General Assembly 2011© Author(s) 2011Exploring the geochemistry and shell ultrastructure of bivalves asarchives of past ocean acidification events: recent Mytilidae in a naturalacidic setting in Ischia (Italy, Mediterranean Sea)Sabine Hahn (1), Riccardo Rodolfo-Metalpa (2), Erika Griesshaber (3), Wolfgang W. Schmahl (3), Dieter Buhl(1), Jason Hall-Spencer (2), Cecilia Baggini (2), and Adrian Immenhauser (1)(1) Institute of Geology, Mineralogy and Geophysics, Ruhr-University Bochum, Germany (sabine.hahn@rub.de), (2) MarineInstitute, Marine Biology and Ecology Research Centre, University of Plymouth, United Kingdom, (3) Department of Earthand Environmental Science; Ludwig Maximilian University, Munich, GermanyThis study assesses the impact of future ocean acidification on the biomineralization performance of calcitic andaragonitic bivalves by analysing past ocean acidification events. However, to accomplish this goal, an archive forrecent bioperformance and calcification of bivalves is necessary. In a first approach we focus on recent Mytilusgalloprovinciales specimen from naturally acidic seawater (mean pH 7.4) and normal conditions (mean pH 8.15)near the Island of Ischia. These mussels were transplanted from the port of Ischia into the different settings. Ischia[Mediterranean Sea (Thyrrenian Sea), Italy)] allows for an investigation of the effects of ocean acidification ina natural setting. These effects were investigated on various specimen of the benthic ecosystem like corals, seagrass, sea urchins, serpulid polychaetes, gastropods, bivalvia (Hall-Spencer et al., 2008) & (Cigliano et al., 2010),foraminifera (Dias et al., 2010) and bryozoans (Martin et al., 2008). Now we extend the findings in regard tobivalves, investigating the bivalve shell in more detail. Since, bivalves are sensitive recorders of environmentalchange in epeiric-neritic and coastal water masses. For the analysis of the bivalves, we use two methods for thequantification of bivalve calcification and bioperformance under acidic seawater conditions: (i) geochemistry andhere mainly stable isotope systems (C, O, trace elements) that are affected by the bivalve bioperformance and (ii)shell ultrastructure analysis focussing in textural differences between shell material precipitated under ‘normal’with such precipitated under acidic seawater conditions. The first results of the geochemical analyses of the carbonand oxygen isotope show, that these proxies illustrate both milieus and the sudden transition between them verywell. Furthermore, by a specific and detailed sampling it was possible to prove, that the various components orlayers of the shell have different isotope values. This contributes to the understanding of shell construction. Theresults of the shell ultrastructure analyses are very complex and it is yet not possible to distinguish the variablefactors (pH, general milieu differences, etc.) and their individual influence on construction of the shell structure.Thus, it is possible to observe differences in the shell ultrastructure between the growth in the ’normal’ milieu and inthe ‘acidic’ milieu. For example one observable effect of the new acidic milieu around Ischia is the distinct thinningof the calcite layer by about ∼40% relative to normal shell growth. However, in all likelihood, this has nothing todo with the acidic milieu, but depends on the low nutrient supply or the individual for the shell completely alteredhabitat. These difficulties show the limits of a natural laboratory. The next steps are to use cultured bivalves toclearly distinguish between the individual and various effects like pH. Furthermore, the main goal is to obtain abasis for improving the interpretation of shell archives for environmental changes of the past. However, Mytilidaeare generally bivalves that are particularly tolerant to less-than-normal marine aquatic environments. Thus, morework with more sensitive species may reveal a more pronounced effect of acidic seawater on bivalve metabolismand performance.

Exploring the geochemistry and shell ultrastructure of bivalves as archives of past ocean acidification events: recent Mytilidae in a natural acidic setting in Ischia (Italy, Mediterranean Sea)

Exploring the geochemistry and shell ultrastructure of bivalves as archives of past ocean acidification events: recent Mytilidae in a natural acidic setting in Ischia (Italy, Mediterranean Sea)

Abstract

Similar works

Full text

Available Versions

Plymouth Electronic Archive and Research Library