【作者】 陈国柱；

【导师】 林小涛；

【作者基本信息】 暨南大学 ， 水生生物学， 2010， 博士

【摘要】 生物入侵是导致土著鱼类濒危的主要原因之一。食蚊鱼Gambusia affinis是世界百种恶性入侵物种之一,它的入侵导致了许多土著水生生物濒危。1927年,食蚊鱼被引入到中国,此后,大范围扩散至长江以南的淡水生境,然而,当前国内尚未对其入侵生态学开展系统研究。唐鱼Tanichthys albonubes是我国Ⅱ级重点保护水生野生动物,小型濒危鲤科鱼类,主要分布在华南丘陵地区森林Ⅰ级溪流及其附近的农田、沼泽等生境。本文研究了食蚊鱼与我国华南地区小型濒危鱼类唐鱼的种间关系,评估食蚊鱼入侵对唐鱼自然种群生存的危害性。主要研究结果如下：1.揭示了当前食蚊鱼对唐鱼栖息生境的入侵格局。对广东从化地区银林、岐田、鹿田和温泉等地的10条溪流和2个丘陵谷地农田生境的调查表明,在溪流生境,食蚊鱼已广泛入侵到唐鱼所栖息的Ⅰ级溪流的下游,并具有进一步入侵趋势；而在农田生境中,则形成与唐鱼交错分布的格局。调查同时表明,食蚊鱼很可能通过对唐鱼仔鱼的捕食而对唐鱼自然种群产生威胁。2.证实了食蚊鱼对唐鱼仔鱼具有捕食压力和对唐鱼的繁殖活动具有干扰作用。室内的捕食研究表明,食蚊鱼对唐鱼体全长在12mm以下的仔鱼均具有捕食压力,而唐鱼仔鱼未能特异性识别这一陌生捕食者。对唐鱼的繁殖行为学的研究表明,引入的食蚊鱼通过对唐鱼追咬而干扰了唐鱼的正常繁殖活动。繁殖试验则揭示了唐鱼所具有的连续产卵特点,连续产卵方式使得唐鱼在实验时间内获得最大的繁殖输出和高受精率。3.证实了食蚊鱼能显著压制唐鱼种群的增长。在微生态系统的研究显示,引入的食蚊鱼在静水生境中显著抑制了唐鱼种群的增长。而当引入的食蚊鱼被清除以后,唐鱼种群恢复正常的增长。同时证实,食蚊鱼不影响唐鱼幼鱼的性成熟,因此,在实验微生态系统中食蚊鱼对唐鱼种群的主要作用机制为对唐鱼仔鱼的捕食。4.通过周年调查,了解了唐鱼与食蚊鱼野外种群的生态学特点,并揭示了野外条件下唐鱼与食蚊鱼种间相互作用的某些特点。唐鱼和食蚊鱼种群均具有小型淡水鱼类的一般生态学特点：个体小、寿命短、性成熟时间短,种群结构复杂。两者具有近似的性腺指数变动周期,周年中的3月和8月为性腺指数的高峰期。两者野外寿命均可能不超过1年,越冬群体在春季繁殖,初夏消亡,而其后代在夏季成熟,形成新一世代的繁殖群体,并可能越冬至第二年春季再次繁殖并在初夏消亡,完成生活史周期。两者在一年中大部分时间均可繁殖。降水对两者的分布格局及相互作用有重要影响,逐月降水量与食蚊鱼入侵样点与非入侵样点唐鱼种群间的体全长的差值呈显著负相关。由于目前所了解的样地中均存在这两类样点,则水流的冲击作用很可能将未被食蚊鱼入侵样点中的唐鱼小型个体间断性的带入已被食蚊鱼入侵的样点,掩盖食蚊鱼入侵样点对唐鱼种群中仔幼鱼的危害性。更多还原

【Abstract】 Biological invasions have long been recognized as a major cause of fish species population decline. The mosquito fish Gambusia affinis, a small fish which is native to North America, is one of the world’s one hundred evil invasive species. Its invasions have led to great damages to the invaded wetland habitats. It was originally introduced to China in 1927, and dispersed rapidly since then. At present, it had occupied large scale freshwater habitats in south of Changjiang River in China. However, it was rare study concerned about its invasions ecology in China to date.Tanichthys albonubes, a native endangered small freshwater fish in South China, inhabits in headwater streams and the conjoined drainages of rice fields and marshes in small hill regions. It was suspected that its endangered would have some unconcerned relations with the invasions of G. affinis.The aim of this paper is to explore the interspecific interaction between T. albonubes and G. affinis, and to determine the invasion effects of G. affinis on Tanichthy albonubes. The results of this study may provide a new insight on the relationship of G. affinis to the native small freshwater fish species in South China, and will facilitate the theory developments of invasion ecology and conservation biology of freshwater fish species. Particularly, it will provide the critical theoretical direction to the practices of T. albonubes conservations.The main results are:1) In field conditions, it was revealed that the G. affinis had invaded into many of the habitats that T. albonubes naturally occupied in Conghua county, Guangdong province, China. Particularly, it had invaded into the lower parts of the headwater streams that are the main habitats of T. albonubes, and showed the trends to further spread in these habitats. In contrast, G. affinis had showed a co-occurring with the T. albonubes in the drainages of rice field. It suggested that G. affinis performed predation effects on the larval T. albonubes in those co-occurring sites, leading to lower ratio of total length between the T. albonubes populations in sites of invaded or un-invaded by G. affinis. 2) In laboratory conditions, firstly, it was revealed that G.affinis predated on the larval T. albonubes that were smaller than 12mm (total length) heavily, however, the larval T. albonubes did not show any recognition on this strange predator. Secondly, it was revealed that the presence of G.affinis may disrupt the reproductive behaviors of the paring adult T. albonubes, and cause failures on their reproduction by its bites. Thirdly, it was revealed that T. albonubes is a successive spawner, and daily spawning made the T. albonubes obtain the highest total eggs production and high fertilization rates in laboratory conditions.3) In micro ecosystem conditions, it was revealed that G. affinis significantly suppressed the increasing of T. albonubes populations. In contrast, after the G. affinis were eliminated, the T. albonubes populations recovered to normal increasing. On the other hand, it was proven that the presence of G. affinis did not affect the mature of the juvenile of T. albonubes in micro ecosystem conditions. Thus, the main effects of G. affinis on T. albonubes in micro ecosystem conditions should be its predation on the larval T. albonubes, not the effects on the gonads development of T. albonubes.4) The commons of wild population ecology traits in these two species are:small size of individuals, short life span, short time to mature and high complex in population constructions. In addition, these two species shared many another common population ecology traits in local conditions in Conghua, Guangdong province, China, such as the similar annual dynamics of gonadosomatic index, both no more than one year in life span, both can reproduced in most of the time of a year. On the other hand, raining had dramatic effects on their interspecific interaction in field. It bring the T. albonubes from the un-invaded sites to the invaded sites which invaded by G. affinis by the strong flow in raining seasons. Thus, the real interaction effects between G. affinis and T. albonubes will be masked, and led to the misunderstanding, that is, T. albonubes can co-inhabit with G. affinis infield.更多还原