Periphyton support for littoral secondary production in a highly humic boreal lake
Periphyton support for littoral secondary production in a highly humic boreal lake
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附生植物对高腐殖质北方湖泊沿岸二次生产的支持
DOI：
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发表时间：
2016
影响因子：
1.8
通讯作者：
Roger I. Jones
中科院分区：
文献类型：
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作者：
Jussi Vesterinen;J. Syväranta;Shawn P. Devlin;Roger I. Jones
在高度腐殖化的湖泊中，陡峭的分层和较差的透光性通常限制了含氧的沿岸的区域，使其局限于狭窄的湖缘。然而，在某些情况下，周围的漂浮植被垫可以维持高生产力的附着生物和更多样化的无脊椎动物社区比远洋地区。人们对这些沿岸的食物网如何发挥作用或中上层和沿岸的食物网相互联系的程度知之甚少。我们将15 N标记的硝酸铵添加到Mekkojärvi的沿岸的区域周围的漂浮苔藓垫中，Mekkojärvi是芬兰南部一个高度腐殖化且无鱼的小湖泊。我们的目标是增加浮游生物的δ 15 N值，以研究沿岸的无脊椎动物的饮食和可能的中上层-沿岸的耦合在湖泊。我们用一个塑料帘子把湖分成两半，在一个盆地里增加了欧洲鲈鱼（Perca fluviatilis），而另一个盆地则没有鱼。附着生物和大多数沿岸的无脊椎动物的δ 15 N增加远高于自然丰度水平。浮游水蚤的δ 15 N总体上没有增加，除了在引入鱼类的流域出现突然和短暂的增加。在33条重新捕获的鲈鱼中，只有一条的δ 15 N明显增加。δ 13 C值最低的是远洋无脊椎动物。大多数沿岸的无脊椎动物的价值接近那些附着生物，这显然有助于显着的饮食大多数沿岸的无脊椎动物群体，是一个重要的基础资源，在沿岸的食物网。摇蚊和蜉蝣的δ 13 C值低得令人惊讶，这可能反映了它们的食物中含有高度13 C耗尽的甲烷氧化细菌，这些细菌是湖中水蚤的食物。我们的研究结果表明，远洋和沿岸的栖息地没有强烈的耦合在没有鱼，但食虫鱼类可能会增加耦合的驱动浮游动物进入沿岸的区寻求庇护捕食。
Steep stratification and poor light penetration in highly humic lakes typically restrict oxygenated littoral areas to narrow lake margins. However, in some instances, surrounding floating vegetation mats can sustain highly productive periphyton and more diverse invertebrate communities than pelagic areas. Little is known about how these littoral food webs function or the extent to which the pelagic and littoral food webs are coupled. We added 15N-labeled ammonium nitrate to the floating moss mat surrounding the littoral zone of Mekkojärvi, a small highly humic and fishless lake in southern Finland. Our goal was to increase the δ15N values of periphyton to investigate the diets of littoral invertebrates and possible pelagic–littoral coupling in the lake. We divided the lake in 2 with a plastic curtain and added European Perch (Perca fluviatilis) to 1 basin while the other remained fishless. δ15N of periphyton and most littoral invertebrates increased well above the natural abundance levels. δ15N of pelagic Daphnia generally did not increase, except for a sudden and transitory increase in the basin where fish were introduced. Only one perch of the 33 recaptured following their introduction showed clearly increased δ15N. The lowest δ13C values were found in pelagic invertebrates. Most littoral invertebrates had values closer to those of periphyton, which clearly contributed significantly to the diets of most littoral invertebrate groups and was an important basal resource in the littoral food web. Chironomids and ephemeropterans had surprisingly low δ13C values, which may reflect inclusion in their diets of highly 13C-depleted methane-oxidizing bacteria, which were known to contribute to the diets of Daphnia in the lake. Our results indicate that the pelagic and littoral habitats are not strongly coupled in the absence of fish but that zooplanktivorous fish may increase coupling by driving zooplankton into the littoral zone to seek refuge from predation.