摘要:
溢油污染对近岸生态系统的平衡与稳定危害极大。本研究以石油水溶性成分(water-accommodated fraction,WAF)为目标，研究其对海洋浮游动物褶皱臂尾轮虫(Brachionus plicatilis)生殖、发育和种群动态变化的影响，以期为阐明或评估海洋溢油污染的潜在威胁提供依据。研究结果表明,(1) WAF抑制褶皱臂尾轮虫的种群增长，随着胁迫时间的延长抑制作用不断增强，呈现显著剂量-毒性效应的正相关，其48、72和96 h的半数有效抑制浓度(EC50)分别为5.42、4.81和4.39 mg·L-1。(2) WAF能显著影响褶皱臂尾轮虫的生殖和发育过程，缩短轮虫的平均寿命和生殖周期，使得进入生殖期的时间滞后，个体发育延迟；基于生命表的研究发现，其内禀增长率(rm)、周限增长率(λ)、净生殖率(R0)和生命期望(E0)显著降低，世代周期(T)延长，其中rm、λ和R0变化较其他指标明显，可作为灵敏指示褶皱臂尾轮虫响应WAF胁迫的指示指标。
Abstract:
The noxious impacts of oil spill have aroused worldwide attentions. Water-accommodated fraction (WAF) of oil was suggested to present more serious toxicity compared to crude oil. Therefore, we focused on WAF in the present study and applied the marine rotifer Brachionus plicatilis as the experimental target, aiming at elucidating the potential toxic effects of WAF on the reproduction, development and population dynamics of B. plicatilis. Results showed that: (1) WAF inhibited the population increase of B. plicatilis, and the toxicity increased with the prolongation of stress time in a clearly concentration-dependent manner. The half effective concentration (EC50) of 48, 72 and 96 h was 5.42, 4.81 and 4.39 mg·L-1, respectively. (2) WAF significantly affected the reproductive and developmental process of B. plicatilis, which shortened the average life span, delayed the henogenesis and the time entering reproductive period and retarded the development. The life table was set based on the above observation, and key parameters of intrinsic rate of increase (rm), finite rate of increase (λ), the net reproductive rate (R0) and life expectancy (E0) decreased while the generation time (T) was prolonged. We also found that the changes of rm, λ and R0 were more sensitive than the other parameters, inferring the possibility of being used as the bio-indicators for the response of rotifers to WAF stress. Results in the present study would bring evidences to further elucidate the potentially negative impacts of oil spill on coastal marine system.
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