Calcium and strontium stable isotopes reveal similar behaviors of essential Ca and nonessential Sr in stream food webs
Calcium and strontium stable isotopes reveal similar behaviors of essential Ca and nonessential Sr in stream food webs
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DOI：
10.1002/ecs2.3921
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发表时间：
2022-02
期刊：
影响因子：
2.7
通讯作者：
K. Nitzsche;S. Wakaki;K. Yamashita;K. Shin;Y. Kato;H. Kamauchi;I. Tayasu
中科院分区：
文献类型：
--
作者：
K. Nitzsche;S. Wakaki;K. Yamashita;K. Shin;Y. Kato;H. Kamauchi;I. Tayasu
近年来的研究表明，常量营养元素钙（δ44/40 Ca）和非必需元素锶（δ88/86 Sr）的稳定同位素具有作为陆生脊椎动物和海洋硬骨鱼类营养级新指标的潜力。在这项研究中，我们测试了在大型无脊椎动物占主导地位的河流食物网中是否存在与脊椎动物相似的Ca和Sr同位素分馏趋势，尽管它们的生理差异。本文测定了日本中部琵琶湖流域两条河流上下游大型无脊椎动物和小型虾虎鱼的δ44/40 Ca和δ88/86 Sr值以及87 Sr/86 Sr比值，并分析了它们的潜在金属来源（河水、附着生物和陆生植物凋落物）。87 Sr/86 Sr比值表明，石蝇若虫、甲壳动物和虾虎鱼主要依赖水生Sr来源。一些起重机苍蝇和石蛾幼虫，蜉蝣，dobsonfly，和蜻蜓较高的87 Sr/86 Sr比值表明更大的陆地通过植物凋落物的贡献。δ44/40 Ca和δ88/86 Sr值之间的正相关关系表明，Ca和Sr来源相似，Ca和Sr稳定同位素分馏趋势相似，但Sr不是必需的。δ44/40 Ca和部分δ88/86 Sr值与Sr/Ca比值呈正相关，与δ 15 N值呈负相关，表明Ca和Sr稳定同位素具有营养效应。在大型滤食性石蛾幼虫中44 Ca和88 Sr的富集是这些营养趋势的一个显著例外。我们的数据证实，在海洋硬骨鱼和陆生脊椎动物中观察到的营养性44 Ca和88 Sr耗竭也适用于以大型无脊椎动物为主的河流食物网，尽管它们的生理学不同，表明Ca和Sr同位素分馏的共同机制可能存在于这些类群之间的细胞或分子水平。
Recent studies showed the potential of stable isotopes of the macronutrient calcium (δ44/40Ca) and nonessential strontium (δ88/86Sr) as new trophic level indicators in terrestrial vertebrates and marine teleost fishes. In this study, we tested whether similar Ca and Sr isotopic fractionation trends existed in macroinvertebrate‐dominated stream food webs compared to vertebrates despite their physiological differences. We have determined the δ44/40Ca and δ88/86Sr values as well as the87Sr/86Sr ratios of stream macroinvertebrates and small gobies and their potential metal sources (stream water, periphyton, and terrestrial plant litter) in upper and lower reaches of two streams in the Lake Biwa catchment, central Japan. The87Sr/86Sr ratios revealed that stonefly nymphs, crustacea, and gobies mostly relied on aquatic Sr sources. Higher87Sr/86Sr ratios of some crane fly and caddisfly larvae, mayfly, dobsonfly, and dragonfly nymphs indicated greater terrestrial contributions via plant litter. Positive correlations between the δ44/40Ca and δ88/86Sr values implied that similar Ca and Sr sources existed, and that Ca and Sr stable isotopes underwent similar fractionation trends although Sr was not essential. The δ44/40Ca and partly the δ88/86Sr values were positively correlated with Sr/Ca ratios and negatively with δ15N values indicating trophic effects on Ca and Sr stable isotopes. The enrichment of44Ca and88Sr in large filter‐feeding caddisfly larvae was a notable exception from these trophic trends. Our data confirm that the trophic44Ca and88Sr depletion observed for marine teleost fishes and terrestrial vertebrates also applied to macroinvertebrate‐dominated stream food webs despite their different physiologies indicating that shared mechanisms of Ca and Sr isotopic fractionation may exist at the cellular or molecular level between these taxa.