Linking larval chironomids to methane:: seasonal variation of the microbial methane cycle and chironomid δ13C
Linking larval chironomids to methane:: seasonal variation of the microbial methane cycle and chironomid δ13C
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DOI：
10.3354/ame046273
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发表时间：
2007-03-13
影响因子：
1.4
通讯作者：
Eller, Gundula
中科院分区：
文献类型：
--
作者：
Deines, Peter;Grey, Jonathan;Eller, Gundula
在几项利用稳定同位素对湖泊生态系统进行的研究中，甲烷衍生碳已被证明是大型无脊椎动物的重要碳源。此外，季节和湖泊地貌似乎影响了甲烷作为碳源的重要性。然而，甲烷循环的动态很少与摇蚊幼虫的同位素特征同时测量。我们研究了两个不同混合模式(多相和一水相)的湖泊中的甲烷动态，同时监测了摇蚊幼虫Delta C-13在一个年度周期中的相应变化。二辉绿岩湖甲烷周转率和甲烷氧化细菌丰度都较高，相应地，幼虫的平均增量C-13值较低，为-44.2-61.7‰。都被记录下来了。相比之下，多相湖中潜在的甲烷生产和氧化速率以及甲烷氧化细菌的细胞数量总是较低；相应的幼虫增量C-13值在-32.3%到-29.6‰之间。此外，C-13幼虫在水成湖的季节变化(-50.1+/-5.9‰)比多水成湖(-31.1+/-1.2‰)更明显，反映了周转速率的幅度。这有力地表明，湖泊特征对甲烷周转率有影响，并与季节一起，影响随后通过大型无脊椎动物将甲烷衍生的碳并入淡水食物网。
Methane-derived carbon has been shown to be an important carbon source for macroinvertebrates in several studies of lake ecosystems using stable isotopes. Furthermore, season and lake morphology appear to influence the importance of methane as a carbon source. However, rarely have the dynamics of the methane cycle been measured concurrently with the isotope signatures of chironomid larvae. We examined the methane dynamics in 2 lakes with contrasting mixing regimes (polymictic and dimictic), while monitoring corresponding changes in chironomid larval delta C-13 throughout an annual cycle. Both methane turnover rates and abundance of methane-oxidising bacteria were higher in the dimictic lake, where correspondingly lower mean larval delta C-13 values of -44.2 to -61.7 parts per thousand. were recorded. In contrast, potential methane production and oxidation rates, as well as cell numbers of methane-oxidising bacteria were always lower in the polymictic lake; corresponding larval delta C-13 values ranged from -32.3 to -29.6 parts per thousand.. Furthermore, seasonal variation in larval delta C-13 was more pronounced in the dimictic lake (-50.1 +/- 5.9 parts per thousand) compared to the polymictic lake (-31.1 +/- 1.2 parts per thousand), reflecting the amplitude of turnover rates. This suggests strongly that lake characteristics have an influence on methane turnover rates and, in conjunction with season, affect the subsequent incorporation of methane-derived carbon into freshwater food webs via macroinvertebrates.