In:
Limnology and Oceanography, Wiley, Vol. 60, No. 3 ( 2015-05), p. 1064-1075
Abstract:
Daphnia can ingest methane‐oxidizing bacteria and incorporate methanogenic carbon into their biomass, leading to low stable carbon isotope ratios (expressed as δ 13 C values) of their tissue. Therefore, δ 13 C analysis of Daphnia resting eggs (ephippia) in lake sediment records can potentially be used to reconstruct past in‐lake availability of methane (CH 4 ). However, detailed multilake studies demonstrating that δ 13 C values of recently deposited Daphnia ephippia ( δ 13 C ephippia ) are systematically related to in‐lake CH 4 concentrations ([CH 4 ] aq ) are still missing. We measured δ 13 C ephippia from surface sediments of 15 small lakes in Europe, and compared these values with late‐summer [CH 4 ] aq . δ 13 C ephippia ranged from −51.6‰ to −25.9‰, and was strongly correlated with [CH 4 ] 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 δ 13 C values of carbon dioxide (CO 2 ) ( r −0.54), and no correlation was observed with [CO 2 ] aq . At eight sites, offsets between δ 13 and δ 13 C ephippia exceeded offsets between δ 13 and δ 13 C algae reported in literature. δ 13 C ephippia was positively correlated with δ 13 C values of sedimentary organic matter ( r 0.54), but up to 20.7‰ lower in all except one of the lakes (average −6.1‰). 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 [CH 4 ] aq . Our results suggest a systematic relationship between δ 13 C ephippia values and [CH 4 ] aq in small temperate lakes, and that δ 13 C ephippia analysis on sediment records may provide insights into past changes in in‐lake [CH 4 ] aq .
Type of Medium:
Online Resource
ISSN:
0024-3590
,
1939-5590
Language:
English
Publisher:
Wiley
Publication Date:
2015
detail.hit.zdb_id:
2033191-5
detail.hit.zdb_id:
412737-7
SSG:
12
SSG:
14
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