Effect of Transient Acid Spikes on Developmental Stages of <i>Lepomis</i>Fishes

The effects of transient acid spikes on development of Lepomis sunfish were studied by combining field work with laboratory studies. Lepomis sunfish eggs were collected from rocks on nests in two freshwater ponds and tested for their resistance to laboratory induced transient acid spikes. Fertilized eggs on rocks within the same nest were used for each pH transient experiment. Egg masses on one rock from the nest were used as a control while egg masses on another rock were exposed to transient acid spikes. Various stages of development showed different responses to the acidic effects. The major stages studied were fertilized egg, hatched with attached yolk sac, and free swimming with gills. The acid sensitivity followed development stages with the most acid sensitive stage being free swimming with gills. This fieldwork-laboratory data chain supports earlier field studies, providing the final link in an evidentiary chain showing the effects of transient acid spikes on Lepomis hatching profiles in freshwater ponds.

冬季大别山不同生境的绿太阳鱼肌肉营养组成对比

为了解冬季绿太阳鱼(Lepomis cyanellus)肌肉营养成分的空间差异,分析并比较了2016年12月采集的大别山区三个样地的绿太阳鱼肌肉营养成分。利用相似性百分比(SIMPER)分析、非参数多变量排序(NMS)和聚类分析(Cluster analysis),结果显示:大别山区栖息环境(水库、溪流)对绿太阳鱼肌肉营养成分影响较大;随后t-test的结果显示同一样地溪流环境中的绿太阳鱼丰满度K,肌肉氨基酸组成中的脯氨酸Pro、甘氨酸Gly、蛋氨酸Met、组氨酸His、精氨酸Arg、总脂肪,以及脂肪酸酸组成中棕榈酸(C_(16∶0))、硬脂酸(C_(18∶0))、油酸(C_(18∶1))均高于水库中绿太阳鱼的含量;同时水库环境中绿太阳鱼肌肉中的花生一烯酸(C_(20∶1))、二十二碳二烯酸(C_(22∶2))、二十二碳六烯酸(C_(22∶6))、十七碳一烯酸(C_(22∶6))、花生二烯酸(C_(20∶2))、花生三烯酸(C_(20∶3))、花生四烯酸(C_(20∶4))、二十二碳四烯酸(C_(22∶4))、二十二碳五烯酸(C_(22∶5))等不饱和脂肪酸高于下游溪流绿太阳鱼肌肉中的水平。

蓝鳃太阳鱼诺卡氏菌的分离鉴定及药敏分析

为探明患结节病蓝鳃太阳鱼的病因,从蓝鳃太阳鱼(Lepomis macrochirus)脾脏结节处分离获得一病原菌SD1810。通过菌落形态、细菌生理生化鉴定和16S rRNA基因序列分析,确定所得菌株为鰤鱼诺卡氏菌(Nocardia seriolae)。人工回归感染试验结果显示,注射浓度为2.8×107 CFU/mL的菌液能使蓝鳃太阳鱼患病致死,发病症状与原感染鱼相似。从死亡太阳鱼体内可重新分离到与SD1810形态特征、生理生化指标相一致的病菌。对分离获得的鰤鱼诺卡氏菌进行药敏试验分析,结果表明,鰤鱼诺卡氏菌SD1810对红霉素、利福平、庆大霉素、氯霉素、阿米卡星、氟苯尼考等10种抗生素极其敏感,对头孢唑啉,诺氟沙星,青霉素、氨苄青霉素和阿莫西林等6种抗生素具有耐药性。