Subfossil cladocerans as quantitative indicators of past ecological conditions in Yangtze River Basin lakes, China
Subfossil cladocerans as quantitative indicators of past ecological conditions in Yangtze River Basin lakes, China
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枝角亚化石作为中国长江流域湖泊过去生态状况的定量指标
DOI：
10.1016/j.scitotenv.2020.138794
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发表时间：
2020-08-01
影响因子：
9.8
通讯作者：
Jeppesen, Erik
中科院分区：
文献类型：
--
作者：
Dong, Xuhui;Kattel, Giri;Jeppesen, Erik
枝角类（甲壳纲：鳃足类）是浅水湖泊食物网的重要组成部分。然而，它们作为东南亚亚热带地区环境变化的哨兵的潜在意义还没有得到很好的阐明。本文对长江中下游64个浅水湖泊表层沉积物中枝藻亚化石的分布格局进行了研究。利用约束排序和多元回归树（MRT），我们探讨了枝角类的分布和当代环境变量之间的关系。结果表明，大型水生植物丰度是影响枝藻群落动态的最重要的调节因子，其次是叶绿素和全磷，它们都是枝藻群落动态的重要驱动因子。尽管在过去的几十年里，在MLYB湖泊密集的水产养殖，鱼类捕食并没有显着的影响，可能是因为鱼类捕食的压力普遍较高的枝片类群落。MRT分析表明，枝蚧群落的组成存在明显的差异，并能够确定各种胁迫的关键指示种，包括Bosminacoregoni，小Alona（A. intermedia，A. rectangula）和棘尾莱迪吉亚（Leydigia acanthocercoides）、莱迪吉亚（Leydigia leydigia）和球腔室虫（Chydorus sphaericus）。利用一种新的数值模型--提升回归树（BRT），建立了枝晶组成与环境变量之间的定量关系。以长江典型湖泊梁子湖为研究对象，利用该模型对梁子湖近60年来的水生植物覆盖度进行了重建。BRT推断的水生植物覆盖度得到了同一湖泊中大型化石记录的很好验证。使用亚化石枝角类作为MLYB湖泊过去环境变化的指标是潜在有用的，因为它们的关键生态作用。然而，由于沉积物中保存的物种特异性差异和混淆的环境过程在某种程度上可能会使结论产生偏差，因此应谨慎行事。
Cladocerans (Crustacea: Branchiopoda) are an essential component of the food webs of shallow lakes. However, their potential significance as sentinels of environmental change in subtropical regions of South-East Asia, is not well elucidated. In this study, we examined the distribution pattern of cladoceran subfossils in the surface sediments of 64 shallow lakes located in the middle and lower reaches of the Yangtze River Basin (MLYB). Using constrained ordination and multivariate regression trees (MRT), we explored the relationships between the distribution of cladocerans and contemporary environmental variables. The results indicated that macrophyte abundance is the most important regulator, followed by chlorophyllaand total phosphorus that all were important drivers of cladoceran community dynamics. Despite intensive aquaculture in the MLYB lakes over the past decades, fish predation did not have a significant influence on the cladoceran community, likely because the fish predation pressure was generally high. The MRT analysis showed distinct variations in the composition of cladoceran communities and was able to identify the key indicator species of various stressors, includingBosmina coregoni,smallAlona(A. intermedia, A. rectangula) andLeydigia acanthocercoides, Leydigia leydigiandChydorus sphaericus. Boosted Regression Tree (BRT), a novel numerical model, was employed to establish the quantitative relationship between cladoceran composition and environmental variables. The model was used to reconstruct historical macrophyte coverage over the past 60 years in a typical Yangtze lake, Liangzi Lake, based on sedimentary cladoceran records. The BRT-inferred macrophyte coverage was validated well by the macrofossil records in the same lake. Using subfossil cladocerans as indicator of the past environmental change in MLYB lakes is potentially useful given their key ecological roles. However, caution should be taken due to species-specific differences in preservation in the sediment and confounding environmental processes that to some extent may bias the conclusions.