Cyanobacteria as a carbon source for zooplankton in eutrophic Lake Taihu, China, measured by 13C labeling and fatty acid biomarkers
Cyanobacteria as a carbon source for zooplankton in eutrophic Lake Taihu, China, measured by 13C labeling and fatty acid biomarkers
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DOI：
10.4319/lo.2012.57.4.1245
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发表时间：
2012-07-01
影响因子：
4.5
通讯作者：
Liu, Zhengwen
中科院分区：
文献类型：
--
作者：
de Kluijver, Anna;Yu, Jinlei;Liu, Zhengwen
采用稳定同位素和脂肪酸相结合的方法，研究了中国富营养化太湖蓝藻微囊藻向浮游动物的碳转移途径。微囊藻通常被认为是浮游动物的不良食物，我们假设大多数微囊藻的碳通过溶解有机物(DOM)-细菌和碎屑-细菌途径流向浮游动物，而不是通过直接放牧。通过对野外样品中自然丰度的C-13同位素进行分析，以及对富含C-13的微囊藻进行示踪实验，验证了这一假设。将富含C-13的微囊藻作为活的微囊藻、碎屑微囊藻或DOM微囊藻添加到湖水中与Bosmina sp.孵化。和相似蚤为优势种。根据特定脂肪酸的同位素分析，确定了Seston中微囊藻、异养菌和真核藻类的C-13同位素特征，并分析了这些脂肪酸在浮游动物消费者中的存在和标记。Bosmina和Daphnia通过所有途径消耗碳，但从微囊藻DOM转移的碳量最高，其次是碎屑微囊藻。博斯米纳摄食的活体微囊藻相对多于大型水蚤。浮游动物消费者体内细菌特异性脂肪酸的存在和C-13的高度浓缩表明，异养细菌是微囊藻和浮游动物之间的重要纽带。在蓝藻大量繁殖的富营养化湖泊中，如太湖，微生物途径主导着蓝藻到浮游动物的能量流动。
Using a combined stable-isotope and fatty-acid approach, we examined carbon-transfer routes from the cyanobacterium Microcystis to zooplankton in eutrophic Lake Taihu, China. Microcystis is generally considered poor food for zooplankton, and we hypothesized that most Microcystis carbon flows to zooplankton via dissolved organic matter (DOM)-bacteria and detritus-bacteria pathways rather than via direct grazing. The hypothesis was tested by analyzing C-13 isotopes at natural abundance in field samples and in tracer experiments with C-13-enriched Microcystis. C-13-enriched Microcystis was added as live Microcystis, Microcystis detritus, or Microcystis DOM to lake-water incubations with Bosmina sp. and Daphnia similis as the dominant species. The C-13 isotope signatures of Microcystis, heterotrophic bacteria, and eukaryotic algae in seston were determined from isotope analyses of specific fatty acids, and the presence and labeling of these fatty acids were also analyzed in zooplankton consumers. Bosmina and Daphnia consumed carbon via all pathways, but the amount of carbon transfer from the Microcystis DOM was the highest, followed by the Microcystis detritus. Bosmina consumed relatively more live Microcystis than Daphnia. The presence and high C-13 enrichment of bacteria-specific fatty acids in the zooplankton consumers showed that heterotrophic bacteria were an important link between Microcystis and zooplankton. Microbial pathways dominate the energy flow from cyanobacteria to zooplankton in eutrophic lakes with heavy cyanobacteria blooms, such as Lake Taihu.