Gheorghiu Cristina, Cable Joanne, Marcogliese David J, Scott Marilyn E
Institute of Parasitology, Macdonald Campus of McGill University, 21,111 Lakeshore Road, Ste-Anne-de-Bellevue, Que., Canada H9X 3V9.
Int J Parasitol. 2007 Mar;37(3-4):375-81. doi: 10.1016/j.ijpara.2006.09.004. Epub 2006 Oct 2.
Recent reviews indicate that pollutants in the surrounding macroenvironment directly influence the population dynamics, distribution and dispersal of fish ectoparasites, often leading to increased parasitism. The aim of the current study was to explore the effects of sublethal concentrations of waterborne zinc (up to 240 microg Zn/L) on survival, reproduction and morphometrics of Gyrodactylus turnbulli, a viviparous monogenean infecting the skin and fins of the guppy, Poecilia reticulata. Parasite survival and reproduction on the fish were recorded daily for individual parasites maintained in isolated containers. Both survival and reproduction were reduced in 30 and 120 microg Zn/L, compared with 0, 15, and 60 microg Zn/L indicating direct toxic effects of Zn on the parasite. However, as generation time was unaffected by Zn, we attribute the reduced reproduction to the shorter lifespan. Parasite survival off the fish was monitored hourly. Average lifespan of the detached parasites decreased linearly from 19.5 h in 0 microg Zn/L to 17.3h in 240 microg Zn/L, further supporting the direct toxic effect of Zn to the parasite. In addition, temporal dynamics of parasite morphometrics were monitored from mini-epidemics sampled after 1, 5, 10, and 15 days exposure to various Zn concentrations. All morphological parameters decreased significantly in response both to concentration and duration of exposure to waterborne Zn. Together these data clearly indicate that concentrations as low as 120 microg Zn/L are directly toxic to G. turnbulli.
近期的综述表明，周围宏观环境中的污染物直接影响鱼类体外寄生虫的种群动态、分布和扩散，常常导致寄生虫感染率上升。本研究的目的是探究环境水体中锌的亚致死浓度（最高达240微克锌/升）对特氏三代虫（一种寄生于孔雀鱼皮肤和鳍上的胎生单殖吸虫）的存活、繁殖和形态特征的影响。对于单独饲养在隔离容器中的寄生虫个体，每天记录其在鱼体上的存活和繁殖情况。与0微克锌/升、15微克锌/升和60微克锌/升相比，在30微克锌/升和120微克锌/升条件下，寄生虫的存活和繁殖均减少，这表明锌对寄生虫有直接毒性作用。然而，由于世代时间不受锌的影响，我们将繁殖减少归因于寿命缩短。每小时监测寄生虫离开鱼体后的存活情况。脱离鱼体的寄生虫平均寿命从0微克锌/升时的19.5小时线性下降至240微克锌/升时的17.3小时，进一步支持了锌对寄生虫的直接毒性作用。此外，在暴露于不同锌浓度1天、5天、10天和15天后，从小型流行病样本中监测寄生虫形态特征的时间动态变化。所有形态学参数均因环境水体锌浓度和暴露时间的增加而显著降低。这些数据共同明确表明，低至120微克锌/升的浓度对特氏三代虫具有直接毒性。
