School of the Environment, C3, Faculty of Science, University of Technology, Sydney, PO Box 123, Broadway, NSW 2007, Australia.
J Environ Radioact. 2013 Dec;126:388-98. doi: 10.1016/j.jenvrad.2012.06.002. Epub 2012 Jul 15.
Previous radiotracer experiments that compared multi-elemental whole organism: water transfer factors among chondrichthyan and teleost fishes, including an ICRP reference flatfish Psetta maxima, demonstrated distinctive contrasts in their bioaccumulation characteristics, with generally elevated bioaccumulation in chondrichthyans. These results supported a hypothesis that phylogenetic divergence may influence marine radionuclide transfer factors. This notion has been further evaluated in an amphioxus species Branchiostoma lanceolatum, sub-phylum Cephalochordata. This taxon diverged about 800 MYBP from a common ancestor of the teleosts and the chondrichthyans, which in turn diverged from each other around 500 MYBP. Our experimental results indicate that amphioxus is indeed more divergent in its multi-elemental bioaccumulation patterns from teleosts and chondrichthyans than they are from each other, consistent with our hypothesis. The experimental comparisons with the ICRP reference flatfish P. maxima also revealed an unexpectedly enhanced capacity in amphioxus to accumulate all eight tested trace elements from seawater, and for some by more than two orders of magnitude. These results have practical applications for the strategic selection of marine biota for further radioecological investigations to better guarantee the radiological protection of marine biodiversity. Such seemingly anomalous results for understudied biota like amphioxus and chondrichthyans suggest that more effort in marine radioecology be directed to assessing the bioaccumulatory capacities of other phylogenetic groups that have received less attention so far, particularly those that are phylogenetically more remote from commonly investigated taxa and those nominated as ICRP marine reference organisms.
水转移因子，包括 ICRP 参考比目鱼 Psetta maxima，其生物积累特征存在明显差异，软骨鱼的生物积累通常较高。这些结果支持了一个假设，即系统发育分歧可能影响海洋放射性核素转移因子。这一概念在文昌鱼（Branchiostoma lanceolatum）物种中得到了进一步评估，文昌鱼属于原索动物亚门。这个分类群与硬骨鱼和软骨鱼的共同祖先分化大约在 800 万年前，而硬骨鱼和软骨鱼本身又在大约 500 万年前从彼此分化出来。我们的实验结果表明，文昌鱼在其多元素生物积累模式上与硬骨鱼和软骨鱼的差异确实比它们之间的差异更大，这与我们的假设一致。与 ICRP 参考比目鱼 P. maxima 的实验比较还表明，文昌鱼从海水中积累所有 8 种测试痕量元素的能力出乎意料地增强，对于某些元素的积累能力增强了两个以上数量级。这些结果对于海洋生物群的放射性生态学研究具有实际应用价值，可以更好地保证海洋生物多样性的辐射保护。对于像文昌鱼和软骨鱼这样研究较少的生物群的这种看似异常的结果表明，海洋放射性生态学需要投入更多的努力来评估其他受到较少关注的系统发育群体的生物积累能力，特别是那些与通常研究的分类群在系统发育上相距较远的群体，以及那些被提名作为 ICRP 海洋参考生物的群体。
