1. An undescribed diaptomid copepod probably belonging to a new Mastigodiaptomus species has been discovered and was very abundant in El Junco Lake (San Cristóbal Island, Ecuador) from 1966 until 2004. The species was not found in samples from 2007, 2008 or 2018.
2. The loss of this key species from the lake coincides with the illegal introduction of Nile tilapia to El Junco Lake in 2005 and its subsequent eradication in 2008.
3. The disappearance of this biogeographically and ecologically important copepod population may be explained by direct mechanisms of predation and competition, by a combination of both processes, and by indirect mechanisms linked to alterations in the lake ecosystem.
4. The effects of fish eradication using rotenone may have contributed to the loss of the diaptomid population and to preventing its recovery.
5. This article discusses the search for sources of propagules for recolonization and possible reintroduction scenarios and procedures.

中文翻译：

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尼罗罗非鱼的引进和灭绝后，加拉帕戈斯群岛 El Junco 湖淡水桡足类物种的消失

1. 1966 年至 2004 年间，在 El Junco 湖（厄瓜多尔圣克里斯托瓦尔岛）中发现了一种可能属于新Mastigodiaptomus物种的未描述的桡足类双足类动物。该物种在 2007、2008 或 2018 年的样本中均未发现。
2. 湖中这一关键物种的消失恰逢 2005 年将尼罗罗非鱼非法引入 El Junco 湖并随后在 2008 年被根除。
3. 这种在生物地理和生态上具有重要意义的桡足类种群的消失可以通过捕食和竞争的直接机制、这两种过程的结合以及与湖泊生态系统变化相关的间接机制来解释。
4. 使用鱼藤酮根除鱼类的效果可能导致 diaptomid 种群的损失并阻止其恢复。
5. 本文讨论了为重新定殖和可能的重新引入方案和程序寻找繁殖体的来源。