Schilder Jos, van Hardenbroek Maarten, Bodelier Paul, Kirilova Emiliya P, Leuenberger Markus, Lotter André F, Heiri Oliver
Institute of Plant Sciences and Oeschger Centre for Climate Change Research, University of Bern, Altenbergrain 21, 3013 Bern, Switzerland
Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, 40014 Jyväskylä, Finland.
Proc Biol Sci. 2017 Jun 28;284(1857). doi: 10.1098/rspb.2017.0278.
Methane-derived carbon, incorporated by methane-oxidizing bacteria, has been identified as a significant source of carbon in food webs of many lakes. By measuring the stable carbon isotopic composition (δC values) of particulate organic matter, Chironomidae and spp. and their resting eggs (ephippia), we show that methane-derived carbon presently plays a relevant role in the food web of hypertrophic Lake De Waay, The Netherlands. Sediment geochemistry, diatom analyses and δC measurements of chironomid and remains in the lake sediments indicate that oligotrophication and re-eutrophication of the lake during the twentieth century had a strong impact on in-lake oxygen availability. This, in turn, influenced the relevance of methane-derived carbon in the diet of aquatic invertebrates. Our results show that, contrary to expectations, methane-derived relative to photosynthetically produced organic carbon became more relevant for at least some invertebrates during periods with higher nutrient availability for algal growth, indicating a proportionally higher use of methane-derived carbon in the lake's food web during peak eutrophication phases. Contributions of methane-derived carbon to the diet of the investigated invertebrates are estimated to have ranged from 0-11% during the phase with the lowest nutrient availability to 13-20% during the peak eutrophication phase.
由甲烷氧化细菌整合的源自甲烷的碳，已被确定为许多湖泊食物网中重要的碳源。通过测量颗粒有机物、摇蚊科及其他物种及其休眠卵（卵鞍）的稳定碳同位素组成（δC值），我们发现源自甲烷的碳目前在荷兰富营养化的德瓦伊湖的食物网中发挥着重要作用。湖泊沉积物的地球化学、硅藻分析以及摇蚊和其他物种遗骸的δC测量表明，20世纪该湖泊的贫营养化和再富营养化对湖内的氧气供应产生了强烈影响。反过来，这又影响了源自甲烷的碳在水生无脊椎动物食物中的重要性。我们的结果表明，与预期相反，在藻类生长营养可利用性较高的时期，相对于光合产生的有机碳，源自甲烷的碳对至少一些无脊椎动物变得更加重要，这表明在富营养化高峰期，湖泊食物网中源自甲烷的碳的使用比例更高。据估计，在营养可利用性最低的阶段，源自甲烷的碳对所研究的无脊椎动物食物的贡献范围为0 - 11%，而在富营养化高峰期则为13 - 20%。
