Variability of diet-tissue isotopic fractionation in estuarine macrobenthos
Variability of diet-tissue isotopic fractionation in estuarine macrobenthos
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DOI：
10.3354/meps296115
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发表时间：
2005-07
影响因子：
2.5
通讯作者：
H. Yokoyama;A. Tamaki;K. Harada;K. Shimoda;K. Koyama;Y. Ishihi
中科院分区：
文献类型：
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作者：
H. Yokoyama;A. Tamaki;K. Harada;K. Shimoda;K. Koyama;Y. Ishihi
采用恒同位素值的微藻饲养双壳贝、菲律宾红鳍贝、日本鬼虾和哈曼迪对虾幼鱼，定量测定其饮食-组织同位素分异。动物的体重增加了70倍，导致它们的饮食同位素平衡。双壳类软组织的碳分馏值为0.6 ~ 0.9‰，氮分馏值为3.4 ~ 3.6‰，均在目前公认的分馏值（0 ~ 1‰和3 ~ 4‰）范围内。对经酸处理或未经酸处理的虾的全身、肢周和外骨骼的研究表明：(1)未经酸处理的外骨骼δ 13c变化较大，(2)酸处理的外骨骼δ 13c降低了3.5 ~ 6.2‰，(3)肌肉的δ 13c和15n含量变化范围有限（2.0 ~ 2.2‰和3.6 ~ 4.0‰），(4)酸处理对肌肉的13c和15n含量影响较小（差异≤0.3‰）。(5)经酸处理后的日本野生鱼（-0.3‰）和日本野生鱼（-1.7‰）的13 - C分异有显著差异；(6)由于外骨骼的负分异（-3.0‰~ -1.9‰），整个野生鱼的15 - N分异在2.3‰~ 3.0‰之间，小于肌肉。这些发现表明，外骨骼中的碳酸盐应该被酸去除，肌肉是最适合进行同位素分析的组织。虽然15 N分馏在上述可接受范围内，但13 C分馏不在此范围内。本研究强调，分馏是物种和组织特异性的，公认的分馏值可能并不普遍适用。
Juveniles of bivalves Mactra veneriformis and Ruditapes philippinarum, and ghost shrimps Nihonotrypaea japonica and N. harmandi were reared on a microalga of a constant isotopic value to quantify their diet-tissue isotopic fractionation. The weights of the animals increased by >7-fold, resulting in isotopic equilibria with their diet. Fractionation for bivalve soft tissues was 0.6 to 0.9‰ for carbon and 3.4 to 3.6‰ for nitrogen, which fell within the range of the currently accepted fractionation values (0 to 1 and 3 to 4‰). Examinations of acid-treated or untreated whole body, mus- cle and exoskeleton of the ghost shrimps showed (1) large variations in δ 13 C for untreated exoskele- tons, (2) reduced δ 13 C for acid-treated exoskeletons by 3.5 to 6.2‰, (3) confined ranges in 13 C and 15 N fractionations for muscles (2.0 to 2.2 and 3.6 to 4.0‰), (4) only slight effects of acid treatment on 13 C and 15 N fractionation for muscles (≤0.3‰ differences), (5) a significant difference in 13 C fractionation for acid-treated whole bodies between N. japonica (-0.3‰) and N. harmandi (-1.7‰), and (6) 2.3 to 3.0‰ of 15 N fractionation for whole bodies, which were smaller than for muscles due to negative frac- tionation for exoskeletons (-3.0 to -1.9‰). These findings suggest that carbonates in exoskeletons should be removed by acid and that muscle is the most appropriate tissue for isotopic analysis. Although 15 N fractionation for ghost-shrimp muscle was within the above-mentioned accepted range, 13 C fractionation was outside this range. The present study highlights that fractionation is species- and tissue-specific, and that the accepted fractionation values may not be universally applicable.