Reproductive dynamics of Lycengraulis grossidens (Clupeiformes: Engraulidae) and Platanichthys platana (Clupeiformes: Clupeidae) in a subtropical coastal lagoon

Abstract We evaluated the reproductive dynamics of two fish species, Lycengraulis grossidens and Platanichthys platana, in a subtropical freshwater coastal lagoon (Peri Lagoon) in Brazil. Samples were collected from nine sites every two months from June 2008 to April 2012. Different fishing methods were used to capture larvae, juveniles, and adults. Limnological variables were obtained using multiparameter probe. More females than males were collected of both fish species and the chi-square test (χ2) was used to confirm that the sex ratio was female-biased. Large numbers of maturing and mature fishes were observed in almost every sampling month. The gonadosomatic index (GSI) of L. grossidens was the highest in August, October, and December for females and in October for males, and no significant difference was found across years. The GSI of P. platana showed no significant difference across months for either sex; however, significant differences were recorded in year three (June 2010-April 2011) and year four (June 2011-April 2012) for females and in year three (June 2010-April 2011) for males. For both species, GSI was negatively correlated with temperature and water level. L. grossidens larvae were more abundant in October 2010, showing a positive correlation with water transparency, whereas P. platana larvae were more abundant in June 2011, showing a positive correlation with water transparency and negative correlation with temperature and precipitation. Both species were represented by different stages, including larvae, which confirm that these species reproduce in Peri Lagoon. Reproduction was more pronounced in autumn and winter; however, reproductive activity was evident throughout the sampling period. In conclusion, our results show that abiotic factors strongly influence the temporal pattern of reproductive activity and larval assemblages of both L. grossidens and P. platana in Peri Lagoon, Brazil.

摘要 本研究针对巴西亚热带淡水沿海潟湖——佩里潟湖（Peri Lagoon）中的粗齿小鳀（Lycengraulis grossidens）与普拉塔纳银汉鱼（Platanichthys platana）两种鱼类，评估其繁殖动态。研究于2008年6月至2012年4月期间，每两个月在9个采样站点采集样本，采用不同捕捞方式获取仔鱼、稚鱼及成鱼。通过多参数水质监测探头（multiparameter probe）测定湖沼学环境变量（limnological variables）。结果显示，两种鱼类的采集样本中雌性个体数量均多于雄性，经卡方检验（chi-square test, χ²）验证，其性比显著偏向雌性。几乎所有采样月份均能观测到大量处于发育中和成熟阶段的个体。粗齿小鳀的性腺成熟指数（gonadosomatic index, GSI）在雌性个体中于8月、10月及12月达到峰值，雄性个体则在10月达到峰值，且不同年份间无显著差异。普拉塔纳银汉鱼的GSI在雌雄个体的月份间均无显著差异，但雌性个体在第3年（2010年6月—2011年4月）与第4年（2011年6月—2012年4月）间存在显著差异，雄性个体则仅在第3年存在显著差异。两种鱼类的GSI均与水温及水位呈负相关关系。粗齿小鳀仔鱼在2010年10月丰度最高，其丰度与水体透明度呈正相关；普拉塔纳银汉鱼仔鱼在2011年6月丰度最高，其丰度与水体透明度呈正相关，与水温及降水量呈负相关。两种鱼类均涵盖包括仔鱼在内的不同发育阶段个体，证实二者均在佩里潟湖内完成繁殖过程。其繁殖活动在秋季与冬季更为旺盛，但整个采样期间均有繁殖活动发生。综上，本研究结果表明，非生物因子对巴西佩里潟湖内粗齿小鳀与普拉塔纳银汉鱼的繁殖活动时间格局及仔鱼群落特征均具有显著影响。