The median lethal concentrations (LC50s) of aldrin, fenvalerate, captan and diazinon were determined for Clarias batrachus by trimmed Spearman-Karber method. The potency ratios of toxicity among them were analysed by ...The median lethal concentrations (LC50s) of aldrin, fenvalerate, captan and diazinon were determined for Clarias batrachus by trimmed Spearman-Karber method. The potency ratios of toxicity among them were analysed by parallel-line bioassay with quantal responses. The LC50s for 40 day of exposure of aldrin, fenvalerate, captan and diazinon were 0.00036,0.0094, 0.5473 and 2.4186 ppm respectively. These values were lower than those obtained for an exposure of 96 hour. It shows the greater toxicity of the pesticides in a long-term exposure. The relative toxic potency of aldrin fenvalerate, captan and diazinon was in a ratio of 6807:241:4:1 respectively. Thus the chemically different groups of pesticides exhibit an order of toxicity as aldrin > fenvalerate >captan > diazinon for the freshwater catfish, Clarias batrachus. It infers that the catfish is most sensitive to aldrin and least sensitive to diazinon. The comparison of the sensitivity of various species tested against these pesticidal chemicals has also been done to review the available information.展开更多
作为海洋生态系统的关键组成部分,鱼类在食物网中的相对重要性直接影响着整个生态系统的稳定性。目前已使用了多个复杂网络中心性指标如Katz指数、PPR指数等来评估鱼类的重要性,但这些指标侧重点各不相同,为确保不同中心性指标对鱼类重...作为海洋生态系统的关键组成部分,鱼类在食物网中的相对重要性直接影响着整个生态系统的稳定性。目前已使用了多个复杂网络中心性指标如Katz指数、PPR指数等来评估鱼类的重要性,但这些指标侧重点各不相同,为确保不同中心性指标对鱼类重要性刻画的适用性,并能够综合评价鱼类对食物网稳定性的影响,本研究系统性定义了包括鱼类度中心性、鱼类信息中心性等的鱼类中心性指标,并提出一种多中心性指标相似度融合(Multi-centrality Index Similarity Fusion,MISF)方法。该方法构建包含多种网络中心性指标的鱼类特征矩阵,提出基于余弦相似度、欧氏距离和相对熵融合的鱼类相似度计算并使用熵权法确定各指标权重,最终实现鱼类综合重要性排序。本研究以2016—2018年珠江口海域鱼类捕食关系网数据为研究对象,开展了鱼类重要性评估,实验结果表明,与Katz指数、PPR指数等方法相比,该方法可以有效评估鱼类在食物网中的相对重要性。在2016和2018年数据集中,MISF方法的精确率和召回率分别达到1.0和0.5,显著优于其他方法,而在2017年数据集中,尽管网络规模增大导致精确率略低于Katz和PPR指数,但召回率表现更佳。此外,根据鱼类在食物网中的不同重要性级别,讨论了它们由于数量变动对网络稳定性产生的影响差异。本研究为鱼类资源管理提供了新的视角。展开更多
文摘The median lethal concentrations (LC50s) of aldrin, fenvalerate, captan and diazinon were determined for Clarias batrachus by trimmed Spearman-Karber method. The potency ratios of toxicity among them were analysed by parallel-line bioassay with quantal responses. The LC50s for 40 day of exposure of aldrin, fenvalerate, captan and diazinon were 0.00036,0.0094, 0.5473 and 2.4186 ppm respectively. These values were lower than those obtained for an exposure of 96 hour. It shows the greater toxicity of the pesticides in a long-term exposure. The relative toxic potency of aldrin fenvalerate, captan and diazinon was in a ratio of 6807:241:4:1 respectively. Thus the chemically different groups of pesticides exhibit an order of toxicity as aldrin > fenvalerate >captan > diazinon for the freshwater catfish, Clarias batrachus. It infers that the catfish is most sensitive to aldrin and least sensitive to diazinon. The comparison of the sensitivity of various species tested against these pesticidal chemicals has also been done to review the available information.
文摘作为海洋生态系统的关键组成部分,鱼类在食物网中的相对重要性直接影响着整个生态系统的稳定性。目前已使用了多个复杂网络中心性指标如Katz指数、PPR指数等来评估鱼类的重要性,但这些指标侧重点各不相同,为确保不同中心性指标对鱼类重要性刻画的适用性,并能够综合评价鱼类对食物网稳定性的影响,本研究系统性定义了包括鱼类度中心性、鱼类信息中心性等的鱼类中心性指标,并提出一种多中心性指标相似度融合(Multi-centrality Index Similarity Fusion,MISF)方法。该方法构建包含多种网络中心性指标的鱼类特征矩阵,提出基于余弦相似度、欧氏距离和相对熵融合的鱼类相似度计算并使用熵权法确定各指标权重,最终实现鱼类综合重要性排序。本研究以2016—2018年珠江口海域鱼类捕食关系网数据为研究对象,开展了鱼类重要性评估,实验结果表明,与Katz指数、PPR指数等方法相比,该方法可以有效评估鱼类在食物网中的相对重要性。在2016和2018年数据集中,MISF方法的精确率和召回率分别达到1.0和0.5,显著优于其他方法,而在2017年数据集中,尽管网络规模增大导致精确率略低于Katz和PPR指数,但召回率表现更佳。此外,根据鱼类在食物网中的不同重要性级别,讨论了它们由于数量变动对网络稳定性产生的影响差异。本研究为鱼类资源管理提供了新的视角。
