Evidence for limited microbial transfer of methane in a planktonic food web
Evidence for limited microbial transfer of methane in a planktonic food web
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DOI：
10.3354/ame01349
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发表时间：
2009-01-01
影响因子：
1.4
通讯作者：
Lennon, Jay T.
中科院分区：
文献类型：
--
作者：
Jones, Stuart E.;Lennon, Jay T.
甲烷衍生的碳可能是一种重要的、但被忽视的能源，为各种水生生态系统的食物链提供燃料。尽管人们普遍认为甲烷衍生碳的流动是由水生无脊椎动物对甲烷氧化细菌(MOB)的消耗来调节的，但很少有研究表征这种营养相互作用。我们利用稳定同位素分析、生物测定实验和基于聚合酶链式反应的分子技术，在美国密歇根州西南部的一个腐殖湖的中上层区域研究了水蚤和MOB之间的相互作用。我们观察到浮游生物中C-13的适度消耗，但这些数据本身并不能提供达赫尼亚对MOB的消耗的证据。利用定量聚合酶链式反应，我们发现MOB在水柱中达到了较高的密度(占细菌群落的3%)，但我们没有发现它们被Dajohnia捕食的证据。此外，我们的结果并不支持水蚤藏匿共生黑帮的假设。因此，水蚤的同位素组成不能通过与浮游动物的直接营养相互作用来解释，这表明间接营养相互作用(例如，捕食浮游动物的原生生物的消耗)或其他改变浮游动物资源同位素组成的过程(例如，二氧化碳循环)具有潜在的重要性。
Methane-derived carbon may be an important, but overlooked source of energy fueling food webs in a variety of aquatic ecosystems. Although it is commonly assumed that the flow of methane-derived carbon is regulated by aquatic invertebrate consumption of methane-oxidizing bacteria (MOB), few studies have characterized this trophic interaction. We used stable isotope analysis, bioassay experiments, and PCR-based molecular techniques to investigate the interactions between Daphnia and MOB in the pelagic region of a humic lake located in southwestern Michigan, USA. We observed moderate depletion of C-13 in the plankton, but these data alone could not provide evidence for the consumption of MOB by Dajohnia. Using quantitative PCR, we determined that MOB attained relatively high densities in the water column (3% of the bacterial community), but we found no evidence that they were grazed upon by Dajohnia. Moreover, our results do not support the hypothesis that Daphnia harbored symbiotic MOB. Therefore, the isotopic composition of Daphnia could not be explained by direct trophic interactions with MOB, suggesting the potential importance of indirect trophic interactions (e.g. consumption of MOB-feeding protists) or other processes that alter the isotopic composition of zooplankton resources (e.g. CO2 recycling).