入侵早期食蚊鱼仔幼鱼食物组成、摄食策略及营养状况分析

饥饿是影响鱼类仔鱼早期存活的关键因素,入侵鱼类仔鱼耐饥饿能力对其种群增长与扩散意义重大。本文对滇池流域食蚊鱼Gambusia affinis奠基种群仔幼鱼摄食及仔鱼营养状况进行深入分析,初步了解了饥饿因素在食蚊鱼入侵早期种群增长中的影响。研究结果显示,该种群食蚊鱼仔幼鱼主要以枝角类、桡足类为食物,同时能够广泛利用栖息地食物资源,包括种类较为丰富的水生昆虫幼体、弹跳虫等,具有广食性的摄食策略,许多个体食物多样性指数>1。这些特点与其口裂较大、发育较为完善的特点密切相关。尽管如此,仍有高达73.27%的食蚊鱼仔鱼存在饥饿胁迫问题,可能与奠基种群自身生物学特点、仔鱼群体内部竞争、行为特点及环境资源差异化分布格局等因素密切相关。对奠基种群而言,入侵早期仔幼鱼面临陌生的栖息地生境,其摄食与营养状况对种群的定殖有关键影响。

Food Composition,Feeding Strategy and Nutrition Conditions of Mosquitofish Larvae and Young Fish During Early Stage of Their Population Foundation

Starvation is considered to be the main factor that affects the survival of fish larvae during the early life stage. The ability of invasive fish larvae in overcoming the starvation stress has significant importance to the population invasion success of fish species. In this paper, food composition, feeding strategy and nutrition conditions of mosquitofish(Gambusia affinis) larvae and young fish were investigated in a newly invaded population around Dianchi Lake basin, Kunming city, China. The results showed that the fish larvae and young fish mainly fed on cladocera and copepod, and also consumed other food resources including water insect larvae and collembolan. Therefore, the fish larvae were revealed to be general feeders, and food diversity index of many individuals was bigger than 1. These were closely related to the large mouth gap and well-development characteristics in the starvation period. However, 73.27% of the larvae were still found to be undergoing starvation. Characteristics of foundation population, food competition in fish larvae, behavior of larvae and food resource fragmentation are considered to be the main causes for the mosquitofish larvae starvation. Finally, the conditions of feeding and nutrition of larvae may profoundly affect the colonization of mosquitofish which deserve further investigation.