The stable carbon isotopic composition of Daphnia ephippia in small, temperate lakes reflects in-lake methane availability

Schilder, Jos and Bastviken, David and van Hardenbroek, Maarten and Leuenberger, Markus and Rinta, Paeivi and Stoetter, Tabea and Heiri, Oliver. (2015) The stable carbon isotopic composition of Daphnia ephippia in small, temperate lakes reflects in-lake methane availability. Limnology and Oceanography, 60 (3). pp. 1064-1075.

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Official URL: https://edoc.unibas.ch/69351/

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Daphnia can ingest methane-oxidizing bacteria and incorporate methanogenic carbon into their biomass, leading to low stable carbon isotope ratios (expressed as delta C-13 values) of their tissue. Therefore, delta C-13 analysis of Daphnia resting eggs (ephippia) in lake sediment records can potentially be used to reconstruct past in-lake availability of methane (CH4). However, detailed multilake studies demonstrating that delta C-13 values of recently deposited Daphnia ephippia (delta C-13(ephippia)) are systematically related to in-lake CH4 concentrations ([CH4](aq)) are still missing. We measured delta C-13(ephippia) from surface sediments of 15 small lakes in Europe, and compared these values with late-summer [CH4](aq). delta C-13(ephippia) ranged from -51.6 parts per thousand to -25.9 parts per thousand, and was strongly correlated with [CH4](aq) in the surface water and above the sediment (r -0.73 and -0.77, respectively), whereas a negative rather than the expected positive correlation was found with delta C-13 values of carbon dioxide (CO2) (r -0.54), and no correlation was observed with [CO2](aq). At eight sites, offsets between delta(13) C-CO2 and delta C-13(ephippia) exceeded offsets between delta C-13(CO2) and delta C-13(algae) reported in literature. delta C-13(ephippia) was positively correlated with delta C-13 values of sedimentary organic matter (r 0.54), but up to 20.7 parts per thousand lower in all except one of the lakes (average -6.1 parts per thousand). We conclude that incorporation of methanogenic carbon prior to ephippia formation must have been widespread by Daphnia in our study lakes, especially those with high [CH4](aq). Our results suggest a systematic relationship between delta C-13(ephippia) values and [CH4](aq) in small temperate lakes, and that delta C-13(ephippia) analysis on sediment records may provide insights into past changes in in-lake [CH4](aq).
Faculties and Departments:05 Faculty of Science > Departement Umweltwissenschaften > Geowissenschaften > Geoökologie (Heiri)
UniBasel Contributors:Heiri, Oliver
Item Type:Article, refereed
Article Subtype:Research Article
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:24 May 2020 18:21
Deposited On:24 May 2020 18:21

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