Carbon sources and trophic structure in a macrophyte-dominated polyculture pond assessed by stable-isotope analysis
Carbon sources and trophic structure in a macrophyte-dominated polyculture pond assessed by stable-isotope analysis
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DOI：
10.1111/fwb.12821
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发表时间：
2016-08
影响因子：
2.7
通讯作者：
Zhigang Mao;X. Gu;Qingfei Zeng;Huijun Chen
中科院分区：
文献类型：
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作者：
Zhigang Mao;X. Gu;Qingfei Zeng;Huijun Chen
淡水混养系统应有效地利用天然食物资源和池塘栖息地，从而降低成本和提高生产力。然而，了解初级碳源和食物网内混养池塘，特别是大型植物为主的池塘，仍然有限。利用稳定同位素分析技术研究了固城湖混养池塘中主要碳源的来源，并对淡水动物的营养格局进行了描述。同位素混合模型（SIAR）也被用来估计四个基本来源（悬浮颗粒有机质[SPOM]，沉积有机质[SOM]，大型植物和附生植物）的无脊椎动物和不同的鱼类营养组的相对贡献。基底资源显示出不同的δ 13 C值，范围从−24.3 ‰到−20.5‰，这使得碳源的区分能力很强。消费者的δ 13 C也有很好的分离（无脊椎动物为−24.0至−20.0‰，鱼类为−24.4至−18.9‰），表明碳的最终来源存在相当大的差异。SIAR模型结果表明，附生植物是甲壳类、草食性鱼类、杂食性鱼类和食鱼性鱼类最重要的碳源，而SPOM对浮游动物、摇蚊、软体动物、环节动物、食鱼性鱼类和底栖性鱼类的贡献最大。平均δ 15 N值，结合计算的食物源贡献，被用来阐明这个混养池塘的食物网结构，这表明初级生产者固定的碳可以通过四个主要的营养途径向上运输到食鱼鱼类的食物链：一种是以SPOM为主，一种是SPOM和SOM相结合，一种是SPOM、SOM、水生植物和附生植物相结合，一种是水生植物和附生植物相结合。我们的研究结果强调了附生植物对沉水植物的营养重要性，沉水植物是混养池塘的关键组成部分，主要养殖物种：中华绒螯蟹（中华绒螯蟹：Varunidae），淡水虾（日本沼虾：Palaemonidae），和高价值的食鱼鱼类。这项研究还揭示了混养池塘食物网的高度复杂性，并表明，主要营养途径的多样性可能是一个特点的大型植物为主的水生生态系统。
Summary Freshwater polyculture systems should efficiently utilise natural food resources and pond habitats with the consequent effects of reducing costs and increasing productivity. However, understanding of the primary carbon sources and food web within polyculture ponds, and especially macrophyte-dominated ponds, remains limited. Stable-isotope analysis was used to identify the main carbon sources and describe the trophic patterns of freshwater fauna in a polyculture pond around Lake Gucheng, China. An isotope mixing model (SIAR) was also used to estimate the relative contribution of four basal sources (suspended particulate organic matter [SPOM], sedimentary organic matter [SOM], macrophytes and epiphytes) to invertebrates and different fish trophic groups. Basal resources showed distinct δ13C values, ranging from −24.3 to −20.5‰, which allowed for a powerful discrimination of carbon sources. Consumers were also well separated in δ13C (−24.0 to −20.0‰ for invertebrates and −24.4 to −18.9‰ for fish), suggesting considerable differences in ultimate sources of carbon. Results from the SIAR model indicated that epiphytes were the most important carbon sources for crustaceans, herbivorous fish, omnivorous fish and piscivorous fish, while SPOM made the highest contribution to zooplankton, chironomids, molluscs, annelids, planktivorous fish and benthivorous fish. Mean δ15N values, combined with calculated food source contributions, were used to elucidate the food-web structure of this polyculture pond, which suggested that carbon fixed by primary producers could be transported up the food chain to piscivorous fish through four main trophic pathways: one based mainly on SPOM, one on both SPOM and SOM, one on SPOM, SOM, macrophytes and epiphytes, and one based on both macrophytes and epiphytes. Our results emphasised the trophic importance of epiphytes on submerged macrophytes, a key component in the polyculture ponds, for the main culture species: Chinese mitten crab (Eriocheir sinensis: Varunidae), freshwater shrimp (Macrobrachium nipponense: Palaemonidae), and high-value piscivorous fish. This study also revealed the high level of complexity of polyculture pond food webs, and suggests that a diversity of major trophic pathways may be a characteristic of macrophyte-dominated aquatic ecosystems.