基于地标点法的九龙江口和珠江口凤鲚和七丝鲚耳石形态学特征比较

Landmark-based morphometric comparison of otolith for Coilia mystus and C. grayii from Pearl River estuary and Jiulong River estuary

为把握珠江口、九龙江口鲚属鱼类凤鲚(Coilia mystus)与七丝鲚(C. grayii)的耳石形态特征,并了解这2种鱼类在不同河口资源群体间的关联性,文章首次引入地标点法研究了耳石形态的地理差异性。选择耳石轮廓上6个地标点和主凹槽上4个地标点并进行地标点法分析。这2个水域的2种鲚属鱼类种间及种内不同群体的判别分析正确率均达100%。其中主凹槽上的地标点相对扭曲贡献率达76.1%,余下23.9%为轮廓上地标点所贡献,说明主凹槽上的地标点位置为形态差异的主要来源,并在耳石种群形态区分中起到较大作用。2种鱼耳石形态的种间差异表现为前者较后者要宽;而种内不同河口群体间的差异表现为珠江的七丝鲚主凹槽较九龙江的更窄,而珠江凤鲚则较九龙江凤鲚的更宽。研究还发现珠江口和九龙江口凤鲚和七丝鲚群体均为互相独立的不同地理群体。

Landmark-based morphometric analysis was first used to identify the variation in the otolith and stock connectivity of Coilia mystus and C.grayii from the Pearl River estuary and Jiulong River estuary.Six landmarks in the outline of otolith and four landmarks in the sulcus were selected to extract the geometric morphometric information of otoliths.Discrimination analysis indicates that both intra-and inter-species distinguishing ratios of the two Coilia fish from two different waters were 100%.Among the 10 landmarks,those in the sulcus had main contribution(76.1%)in explaining the main source of morphological variation,while those in the outline of otolith just had 23.9%.The difference of inter-species shows that the sulcus of C.mystus was wider than C.grayii.Meanwhile,the difference of intra species shows that the C.grayii from the Pearl River estuary,had a narrower sulcus than those from the Jiulong River estuary,but the two stocks of C.mystus from these two waters were the opposite.It is revealed that the investigated stocks of either C.mystus or C.grayii from the Pearl River estuary and Jiulong River estuary are separated,which means that they may belong to different geographical stocks.