洞庭湖中是否存在溯河洄游型刀鲚

利用电子探针微区分析(EPMA)技术, 分析了2018年8月采自湖南省岳阳市洞庭湖畔水产市场2尾刀鲚(Coilia nasus)干制个体的矢耳石中锶和钙微化学特征。定量线分析结果显示, 2尾样本的耳石锶钙比值(Sr/Ca×1000)波动显著, 从耳石核心到边缘可分别出现对应淡水生境的锶钙比值<3的低值区, 对应于半咸水生境的3—7高值区和再次为对应于淡水生境<3的低值区。面分布分析结果更直观显示两尾刀鲚个体的耳石从核心到边缘对应于不同盐度生境的锶含量变化图谱, 即从耳石核心到边缘可分别出现对应于淡水生境的蓝色区域, 对应长江口外半咸水生境的黄绿色区域和再次对应于淡水生境的蓝色区域。这种淡水-半咸水-淡水的生境转换显示出了上述个体的典型溯河洄游生活史“履历”。研究显示目前距长江河口约1400 km的洞庭湖中仍可能存在溯河洄游型刀鲚个体。

ARE THERE STILL ANADROMOUS THE ESTUARINE TAPERTAIL ANCHOVIES COILIA NASUS IN DONGTING LAKE?

The electron probe microanalyzer (EPMA) was used to study the element Sr and Ca microchemistry patterns in sagittal otoliths of two dried individuals of Coilia nasus collected from a fish market by the Dongting Lake in Yueyang City of China in August 2018. The results of line transect analysis indicated that the ratios of Sr/Ca×1000 in the otolith of the two individuals fluctuated significantly. The ratios from otolith core to edge of the two anchovies in turn exhibited three different phases, namely low (<3, freshwater habitat), high (>3, brackish water habitat), and low (<3, freshwater habitat) Sr/Ca×1000 ratios. These three different phases could be more visually presented in sequence by the Sr intensity maps of bluish region (low Sr level, low salinity freshwater habitat), yellowish and greenish regions (high Sr level, high salinity brackish water habitat), and bluish region (low Sr level, low salinity freshwater habitat), respectively. The fluctuation patterns of Sr/Ca×1000 and Sr level demonstrated that these two C. nasus fish were typical anadromous individuals. These results revealed that there may still be anadromous C. nasus in the Dongting Lake, about 1400 km from the mouth of the Yangtze River.