Gilbert Beric M, Jirsa Franz, Avenant-Oldewage Annemariè
University of Johannesburg, Department of Zoology, P.O. Box 524, Auckland Park 2006, South Africa.
University of Johannesburg, Department of Zoology, P.O. Box 524, Auckland Park 2006, South Africa; University of Vienna, Faculty of Chemistry, Institute of Inorganic Chemistry, Althanstrasse 14, 1090 Vienna, Austria.
J Trace Elem Med Biol. 2022 Dec;74:127053. doi: 10.1016/j.jtemb.2022.127053. Epub 2022 Aug 3.
Elevated levels of trace elements in the aquatic environment poses risks to the health of biota and humans. Parasites are important components in ecosystems; responding to changes in the health of aquatic ecosystems and can accumulate trace elements in their tissues to higher levels than their hosts. Monogeneans are an important group of fish ectoparasites being directly exposed to the aquatic environment.
In this study concentrations of Ti, Fe, Cu, Zn, Rb, Sr and Ag were analysed in the monogenean parasite, Paradiplozoon ichthyoxanthon (by total reflection x-ray fluorescence spectrometry and graphite furnace atomic absorption spectrometry), and the muscle, liver and gills of two host fish species, Labeobarbus aeneus and Labeobarbus kimberleyensis (by inductively coupled plasma -- mass spectrometry).
Most striking was the accumulation pattern for Zn in parasites; mean levels of Zn were as high as 1448 and 1652 mg kg dw, respectively, with no significant difference between the two host-parasite groups, leading to bioconcentration factors of approximately 93 (parasite/fish muscle) and 15 (parasite/fish liver). In addition, Fe was accumulated in the parasite to a higher degree compared to the fish hosts' tissues. Cu levels were higher in P. ichthyoxanthon than in the muscle tissue of both host fishes, but lower than liver tissue.
These findings demonstrate the usefulness of this parasite species as a sentinel organism in aquatic ecosystems it inhabits for Fe and Zn. Other trace elements under investigation were not accumulated higher in the parasite compared to its fish host. Lower Rb levels in the parasite compared to its hosts indicate no biomagnification of this metal. Further investigations are required to determine if similar trends in trace element accumulation occur in other monogeneans.
All data generated in the analysis of host and parasite tissues are presented in the manuscript.
水生环境中微量元素水平升高对生物群和人类健康构成风险。寄生虫是生态系统的重要组成部分；对水生生态系统健康变化做出反应，并能在其组织中积累比宿主更高水平的微量元素。单殖吸虫是直接暴露于水生环境的重要鱼类外寄生虫类群。
在本研究中，采用全反射X射线荧光光谱法和石墨炉原子吸收光谱法分析了单殖吸虫寄生虫——黄斑副双身虫（Paradiplozoon ichthyoxanthon）中钛（Ti）、铁（Fe）、铜（Cu）、锌（Zn）、铷（Rb）、锶（Sr）和银（Ag）的浓度，并采用电感耦合等离子体质谱法分析了两种宿主鱼类——铜色野鲮（Labeobarbus aeneus）和金伯利野鲮（Labeobarbus kimberleyensis）的肌肉、肝脏和鳃中的这些元素浓度。
最显著的是寄生虫中锌的积累模式；锌的平均水平分别高达1448和1652毫克/千克干重，两个宿主 - 寄生虫组之间无显著差异，导致生物浓缩系数约为93（寄生虫/鱼肌肉）和15（寄生虫/鱼肝）。此外，与鱼类宿主组织相比，铁在寄生虫中积累程度更高。黄斑副双身虫中的铜水平高于两种宿主鱼类的肌肉组织，但低于肝脏组织。
这些发现表明，这种寄生虫物种可作为其栖息的水生生态系统中铁和锌的指示生物。与鱼类宿主相比，所研究的其他微量元素在寄生虫中积累得并不更高。寄生虫中铷水平低于宿主表明该金属没有生物放大作用。需要进一步研究以确定其他单殖吸虫中是否存在类似的微量元素积累趋势。
宿主和寄生虫组织分析中产生的所有数据均列于手稿中。
