Stable isotopes reveal that chironomids occupy several trophic levels within West Greenland lakes: Implications for food web studies
Stable isotopes reveal that chironomids occupy several trophic levels within West Greenland lakes: Implications for food web studies
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DOI：
10.4319/lo.2013.58.3.1023
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发表时间：
2013-05
影响因子：
4.5
通讯作者：
Nina S. Reuss;L. Hamerlík;G. Velle;A. Michelsen;O. Pedersen;K. Brodersen
中科院分区：
文献类型：
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作者：
Nina S. Reuss;L. Hamerlík;G. Velle;A. Michelsen;O. Pedersen;K. Brodersen
对北极低海拔湖泊中的摇蚊个体进行了氮(δ15N)和碳(δ13C)的稳定同位素分析，以调查这一不同昆虫类群所覆盖的营养水平的范围。采集了5个湖泊的样本，其中2个为淡水湖，2个为低盐湖，1个为冰川影响湖，代表了格陵兰西南部的主要湖泊类型。不同湖泊类型间的同位素偏移量差异较大。在低盐湖泊中，我们将低δ13C值归因于循环二氧化碳的使用，而高δ15N信号可能是由微生物过程控制的。为了进行湖泊间的比较，将摇蚊类的δ15N信号归一化到属于直枝亚科的低δ15N值的常见初级消费者(Psectrocladius sordidellus组和Psectrocladius limbatellus组)。归一化的δ15N值跨度超过5‰，表明摇蚊群落在这些低北极湖泊中至少覆盖了两个营养级别。同一生境内不同摇蚊类群的δ15N值相差1‰~5‰。结果表明，在食物网研究中，摇蚊不应被视为一类。即使在亚科水平上对营养位置的解释也可能是有问题的，因为它们在δ15N值上观察到了巨大的差异。关于个别摇蚊分类群的详细营养信息在此之前没有报道过。摇蚊是北极湖泊中丰富而重要的生物群，其营养水平的变化表明北极湖泊的食物网络结构具有高度的复杂性。
Stable isotope analyses of nitrogen (δ15N) and carbon (δ13C) were conducted on individual chironomid taxa from low arctic lakes to investigate the range in trophic levels covered by this diverse insect group. Five lakes were sampled, including two freshwater, two oligosaline, and one glacier influenced lake, representing the major lake types in southwest Greenland. There was a large difference in the offset of isotopic values among the different lake types. In the oligosaline lakes, we ascribe low δ13C values to the use of recycled CO2, while the high δ15N signal is possibly controlled by microbial processes. In order to compare among lakes, the δ15N signal of the chironomid taxa was normalized to common primary consumers (Psectrocladius sordidellus group and Psectrocladius limbatellus groups) that show consistently low δ15N values and belong to the subfamily Orthocladiinae. Normalized δ15N values spanned more than 5‰, indicating that the chironomid community covered at least two trophic levels in these low arctic lakes. The δ15N values of different chironomid taxa within a single habitat differed by 1‰ to 5‰. The results suggest that chironomids should not be considered as one group in food web studies. Even interpretation of trophic position on subfamily level can be problematic as a result of the large differences observed in their δ15N values. The level of detailed trophic information on individual chironomid taxa presented here has not previously been reported. Chironomids are an abundant and important group of organisms in arctic lakes, and the observed variation in their trophic level indicates a high complexity of the food web structure of arctic lakes.