van den Heuvel Michael R, Landman Michael J, Finley Megan A, West David W
Department of Biology, Canadian Rivers Institute, University of Prince Edward Island, Charlottetown, Canada C1A 4P3.
Ecotoxicol Environ Saf. 2008 Feb;69(2):187-98. doi: 10.1016/j.ecoenv.2007.04.015. Epub 2007 Jun 29.
Two experiments using rainbow trout (Oncorhynchus mykiss) were conducted to examine the combined effects of energy intake as manipulated by ration and pulp and paper mill effluent exposure over either one, or two consecutive reproductive cycles. This study demonstrated that the level of energy intake affected the full range of measured parameters from energy allocation to somatic growth and the gonadal development, steroid production and hematology. Increasing ration level expectedly increased growth, condition, liver and gonad size. Female trout in the higher ration treatments produced more follicles and had larger eggs, investing the same relative proportion of total energy into ovarian development. Sex steroid levels and hematological parameters were also positively influenced by increasing ration level in males and females. By far, the most dramatic impact of reduced ration on reproduction was to substantially reduce the frequency of sexually maturing fish. The effects of effluent exposure were not as marked as those linked to ration level and typically did not manifest unless fish were exposed through two consecutive reproductive cycles. The physiological effects of pulp and paper effluent exposure observed in these experiments were not consistent between the two experiments conducted herein, nor were they consistent with previously observed impacts in similar experiments with this effluent. Effluent exposure over one reproductive cycle did not impact physiological parameters in trout. However, when effluent exposure was maintained over two reproductive cycles, a new pattern of effluent response emerged including increased condition factor in both sexes, a decrease in the potential ability of the blood of females to transport oxygen, and increased sex steroids and reproductive investment in males. Effluent was also observed to cause reduced growth in male trout over two years. The effects of ration on gonad and liver size were far more obvious and consistent when a longer exposure was employed, thus, it appears to take more than one full year for energy intake changes to be reflected in those particular physiological endpoints.
开展了两项以虹鳟（Oncorhynchus mykiss）为对象的实验，以研究在一个或两个连续繁殖周期内，由投饵量控制的能量摄入与接触制浆造纸厂废水的综合影响。本研究表明，能量摄入水平影响了从能量分配到体细胞生长、性腺发育、类固醇生成和血液学等一系列测量参数。预期增加投饵量水平会促进生长、改善鱼体状况、增大肝脏和性腺尺寸。处于较高投饵量处理组的雌性虹鳟产生更多卵泡且卵更大，在卵巢发育中投入的总能量相对比例相同。雄性和雌性虹鳟的性类固醇水平和血液学参数也受到投饵量增加的正向影响。到目前为止，投饵量减少对繁殖最显著的影响是大幅降低性成熟鱼的频率。废水暴露的影响不如与投饵量水平相关的影响显著，通常除非鱼连续两个繁殖周期都暴露于废水中，否则不会显现出来。在本研究进行的两项实验中，观察到的制浆造纸废水暴露的生理影响在两者之间并不一致，也与之前在类似废水的实验中观察到的影响不一致。在一个繁殖周期内暴露于废水对虹鳟的生理参数没有影响。然而，当在两个繁殖周期内持续暴露于废水时，出现了一种新的废水反应模式，包括两性的条件因子增加、雌性血液运输氧气的潜在能力下降、雄性的性类固醇增加和繁殖投入增加。还观察到废水会导致雄性虹鳟在两年内生长减缓。当采用更长时间的暴露时，投饵量对性腺和肝脏大小的影响更为明显和一致，因此，能量摄入变化似乎需要超过一整年的时间才能反映在那些特定的生理终点上。
