Department of Ecological Studies and International Centre for Ecological Engineering, University of Kalyani, Kalyani, West Bengal, 741235, Nadia, India.
Department of Zoology, Sreegopal Banerjee College, Bagati, Mogra, West Bengal, 712148, Hooghly, India.
Environ Monit Assess. 2023 Jun 7;195(7):818. doi: 10.1007/s10661-023-11411-6.
The nature and intensity of water pollution determine the effects on aquatic biota and aquatic ecosystem health. The present study aimed at assessing the impact of the degraded physicochemical regime of river Saraswati, a polluted river having a historical legacy, on the parasitic infection and the role of fish parasite as a bioindicator of water quality. Two Water Quality Indices (WQIs) were adopted as useful tools for assessing the overall water quality status of polluted river based on 10 physicochemical parameters. Total 394 fish (Channa punctata) were examined. Ectoparasite Trichodina sp., Gyrodactylus sp., and endoparasites Eustrongylides sp. were collected from the host fish. Prevalence, mean intensity and abundance for each sampling period were calculated for the determination of parasitic load. The parasitic load of Trichodina sp. and Gyrodactylus sp. was significantly (p < 0.001) higher in winter, whereas the parasitic load of Eustrongylides sp. showed no significant (p > 0.05) seasonal fluctuation. The parasitic load of ectoparasites was negatively correlated with temperature, free carbon dioxide, biochemical oxygen demand, and WAWQI but positively correlated with electrical conductivity and CCMEWQI. Fish health was found to be adversely affected by degrading water qualities and parasitic infection. A 'vicious cycle' develops as a result of the interplay among deteriorating water quality, withering fish immunological defence, and amplifying parasitic infection. Since parasitic load was strongly conditioned by the combined influence of a suite of water quality parameters the fish parasites can be used as a powerful indicator of deteriorating water quality.
水污染的性质和强度决定了其对水生生物和水生生态系统健康的影响。本研究旨在评估受污染河流 Saraswati 退化的物理化学状况对寄生虫感染的影响，以及鱼类寄生虫作为水质生物指标的作用。采用了两个水质指数（WQIs）作为有用的工具，根据 10 个物理化学参数评估污染河流的整体水质状况。共检查了 394 条鱼（Channa punctata）。从宿主鱼中采集了外寄生虫 Trichodina sp.、Gyrodactylus sp. 和内寄生虫 Eustrongylides sp.。计算了每个采样期的总感染率、平均强度和丰度，以确定寄生虫负荷。冬季 Trichodina sp. 和 Gyrodactylus sp. 的寄生虫负荷显著（p < 0.001）更高，而 Eustrongylides sp. 的寄生虫负荷没有显著（p > 0.05）季节性波动。外寄生虫的寄生虫负荷与温度、游离二氧化碳、生化需氧量和 WAWQI 呈负相关，与电导率和 CCMEWQI 呈正相关。发现鱼类健康受到水质恶化和寄生虫感染的不利影响。由于水质恶化、鱼类免疫防御功能下降和寄生虫感染加剧之间的相互作用，形成了一个“恶性循环”。由于寄生虫负荷受到一系列水质参数的综合影响，鱼类寄生虫可以作为水质恶化的有力指标。
