乌伦古湖外来鱼类池沼公鱼对土著鱼类河鲈影响的生态学机理研究

There is a fast development of pond smelt (Hypomesus olidus) population since its introduction to Lake Ulungur. Meanwhile, the catch of a piscivorous fish pike (Esox lucius) has increased tremendously, and endemic fish perch (Perca fluviatilis) has decreased in its population. The hypothesis of the proposed study are: there is some extend overlap in ecological niche between pond smelt and perch, therefore competition between these two species exist; Meanwhile, pike obtained additional food source due to pond smelt introduction, and thus increase its population. The predation of pike on perch is then increased and leads to a decrease in perch population. We will study the ecological niches of pond smelt and perch using approaches of gut content and stable isotope analyses (13C and 15N), and calculate the niche overlap index. Meanwhile, food habit of pike is also analyzed and the predation pressure of perch by pike will be evaluated. Using historical data of pike in the lake, the changes in predation pressure of perch by pike can be established. Thus the proposed study evaluates ecological mechanisms of the impact of the introduced pond smelt on endemic perch from the angles of competition and predation. The results also shed light on understanding the impact of species invasion on ecosystems.

池沼公鱼引入乌伦古湖后得到迅速发展，同时肉食性鱼类白斑狗鱼的产量也大幅提高，而土著鱼类河鲈种群规模不断下降，其生态学机理尚不清楚。本研究的假设是：池沼公鱼与河鲈的生态位有一定的重叠，从而存在竞争关系；池沼公鱼为白斑狗鱼提供充足食物，促进其种群的发展，从而增强了狗鱼对河鲈的捕食压力。本项目通过野外调查，运用肠道内含物分析和稳定同位素（13C和15N）技术，分析池沼公鱼与河鲈的食物生态位特征，结合两者种群的空间分布调查，分析其空间生态位特征，并计算两种鱼类种群生态位重叠指数；同时，通过野外调查白斑狗鱼的食物来源，分析白斑狗鱼对河鲈的捕食压力；结合白斑狗鱼历史数据，分析白斑狗鱼对河鲈捕食压力的历史变化，从而从竞争和捕食两个角度，分析池沼公鱼对河鲈影响的生态学机理，结果有助于揭示外来种入侵对生态系统的影响。

池沼公鱼引入乌伦古湖后得到迅速发展，同时肉食性鱼类白斑狗鱼的产量也大幅提高，而土著鱼类河鲈种群规模不断下降，其生态学机理尚不清楚。本研究的假设是:池沼公鱼与河鲈的生态位有一定的重叠，从而存在竞争关系;池沼公鱼为白斑狗鱼提供充足食物，促进其种群的发展，从而增强了狗鱼对河鲈的捕食压力。本项目通过野外调查，运用肠道内含物分析和稳定同 位素(13C和15N)技术，分析池沼公鱼与河鲈的食物生态位特征，结合两者种群的生态位特征，计算两种鱼类种群生态位重叠指数;同时，通过野外调查白斑狗鱼的食物来源，分析白斑狗鱼对河鲈的捕食压力，从而从竞争和捕食两个角度，分析池沼公鱼对河鲈影响的生态学机理，结果有助于揭示外来种入侵对生态系统的影响。研究结果显示：池沼公鱼的主要食物为浮游动物（98.4%），而河鲈成鱼对浮游动物的利用比较相对较低（0.9%），而对池沼公鱼和底栖动物的利用比例相对较高，分别为83.9%和16.1%。池沼公鱼与河鲈间的食性生态位重叠指数为0.49，处于较高水平。白斑狗鱼的食物来源多样，但主要以河鲈为食（56.3%），池沼公鱼贡献了狗鱼食性的13.9%。河鲈的另一重要捕食者梭鲈对其利用的比例高达87.4%。本研究从竞争和捕食两个方面解析了乌伦古湖外来鱼类池沼公鱼对土著鱼类河鲈影响的生态学机理，对乌伦古湖土著鱼类河鲈种群保护与恢复，及其它具有相似渔业资源问题湖泊土著鱼类保护具有重要的参考价值，这也为发展乌伦古湖可持续渔业提供重要的理论依据。