广东从化地区不同生境食蚊鱼种群的繁殖生物学特征

本文从繁殖群体的环境条件、形体特征、卵巢发育与繁殖力方面对广东从化地区溪流、池塘、农田3种不同生境的食蚊鱼(Gambusia affinis)种群展开比较研究。结果发现,无论流动水体溪流还是静水水体池塘和农田,食蚊鱼的繁殖期均在3~12月份,繁殖群体中雌鱼占比明显高于雄鱼(Chi-Square test,P0.01)。雌鱼周年平均体长及体重,池塘生境的显著大于农田和溪流生境。农田生境中雌鱼的个体怀卵量(24.1±12.1)粒,体重相对繁殖力(57.5±31.0)粒/g,二者均明显高于溪流生境(16.6±11.6)粒,(40.8±15.5)粒/g]与池塘生境(18.9±16.3)粒,(35.7±19.1)粒/g],但农田生境雌鱼成熟卵子的卵径显著小于溪流和池塘生境。结果表明,在环境稳定的池塘生境中,食蚊鱼的繁殖策略偏向k-对策特性;在人为干扰较大的农田生境中,食蚊鱼的繁殖策略偏向r-对策特性。不同类型生境中食蚊鱼的繁殖特性存在一定差异,主要与其栖息环境的稳定性和饵料生物的丰富度有关。

Reproductive Biology of Mosquito Fish (Gambusia affinis) in different Habitats in Conghua, Guangdong

This research assessed morphology, ovarian development, fecundity, etc. of the breeding population of mosquito fish, Gambusia affinis, found in streams, ponds, and farmlands of Conghua City, Guangdong. It was found that in no matter the water flow or the static water bodies, mosquito fish breeding season were from March to December, and there were more females than males. Female fish in ponds had significantly larger one-year means of body length and body mass than those in farmlands, but in the breeding season,their gonad indexes, brood amounts, body mass relative fecundity were significantly lower than those of farmlands, except for the larger egg sizes. Females in streams in the breeding season had the gonad indexes and body mass relative fecundity between those of ponds and farmlandsbut closer to those of the ponds, they conceived less but larger eggs.The results showed that there were different reproductive characteristics in different groups of G. affinss, and they were related to the environmental stability and food supply conditions.