Hassanine R M El-S, Al-Hasawi Z M, Hariri M S, Touliabah H El-S
Biological Sciences Department,Rabigh-Faculty of Science and Arts,King Abdulaziz University,PO Box 344,Rabigh 21911,Saudi Arabia.
J Helminthol. 2019 Mar;93(2):177-186. doi: 10.1017/S0022149X18000044. Epub 2018 Feb 7.
Currently, fish helminth parasites, especially cestodes and acanthocephalans, are regarded as sentinel organisms to elucidate metal pollution in aquatic ecosystems. Here, 34 specimens of the fish Siganus rivulatus were collected in the Red Sea, from a seriously polluted, small lagoon named Sharm-Elmaya Bay, at Sharm El-Sheikh, South Sinai, Egypt; 22 (64.7%) were infected by Sclerocollum saudii (Acanthocephala: Cavisomidae). Thus, 22 natural infrapopulations (26-245 individuals) of this parasite were collected from infected fish. Samples of water and sediments from the bay, samples of muscle, intestine and liver from each fish, and samples from the parasite were taken for analysis of heavy metals (cadmium (Cd) and lead (Pb)). Both Cd and Pb concentrations in sediments were higher than those in water. The concentration of these metals were significantly higher in tissues (intestine, liver and muscle) of non-infected fish than those in infected fish, with Pb concentrations consistently higher than those of Cd, and both were drastically decreased in the order: liver > intestine > muscle. Metal concentrations in this acanthocephalan were much higher than those in its fish host. There were strong negative relationships between metal concentrations in tissues (intestine, liver and muscle) of infected fish and infrapopulation size, and between metal concentrations in the acanthocephalan and its infrapopulation size. These relationships strongly suggest competition for these metals between the fish host and its acanthocephalan parasite, and intraspecific competition among acanthocephalan individuals for available metals in the fish intestine. Bioconcentration factors were relatively high, since the mean Cd concentration in S. saudii was 239, 68 and 329 times higher than those in intestine, liver and muscle tissues, respectively, of its fish host. Also, mean Pb concentration was 55, 13 and 289 times higher than those in these tissues, respectively. The host-parasite system described here seems to be promising for biomonitoring of metal pollution in the Red Sea.
目前，鱼类蠕虫寄生虫，尤其是绦虫和棘头虫，被视为阐明水生生态系统中金属污染的指示生物。在此，从埃及西奈半岛南部沙姆沙伊赫一个名为沙姆 - 埃尔玛雅湾的严重污染小泻湖的红海区域采集了34份条纹篮子鱼样本；其中22条（64.7%）感染了沙特硬棘头虫（棘头虫纲：腔吻棘头虫科）。因此，从受感染的鱼中收集了该寄生虫的22个自然感染群体（26 - 245个个体）。采集了该海湾的水和沉积物样本、每条鱼的肌肉、肠道和肝脏样本以及寄生虫样本，用于分析重金属（镉（Cd）和铅（Pb））。沉积物中Cd和Pb的浓度均高于水中的浓度。这些金属在未感染鱼的组织（肠道、肝脏和肌肉）中的浓度显著高于感染鱼，Pb浓度始终高于Cd，且二者均按肝脏＞肠道＞肌肉的顺序急剧下降。这种棘头虫体内的金属浓度远高于其鱼类宿主。感染鱼组织（肠道、肝脏和肌肉）中的金属浓度与感染群体大小之间，以及棘头虫体内的金属浓度与其感染群体大小之间均存在强烈的负相关关系。这些关系有力地表明鱼类宿主与其棘头虫寄生虫之间对这些金属存在竞争，以及棘头虫个体之间在鱼肠道内对可用金属存在种内竞争。生物富集系数相对较高，因为沙特硬棘头虫体内Cd的平均浓度分别比其鱼类宿主的肠道、肝脏和肌肉组织中的浓度高239倍、68倍和329倍。此外，Pb的平均浓度分别比这些组织中的浓度高55倍、13倍和289倍。此处描述的宿主 - 寄生虫系统似乎有望用于红海金属污染的生物监测。
