有明银鱼耳石显微结构和微化学研究

摘要

Adult Ariake icefish (Salanx ariakensis) in Yalujiang river estuary were collected in September 1998. After biological measurements of the samples, the sagittae were removed from the fish. One of the sagittae from each individual was sectioned to examine its microstructure under microscope, the other one was p olis hed and coated with carbon for measurement of the concentration ratio of stronti um and calcium in otoliths by using a wavelength dispersive Xray electron micr oprobe (EMP820Q). In the analysis of Sr and Ca, CaSO4 and SrSO4 were used as standards.rnThe long radius Y(μm) of the otolith was linearly related to the fish lengt h X (SL, mm), and the equation total from 31 individuals (SL 116～157 mm) wa s Y=27216X+92292, r=09178, P<001. The mean diameters of core and prim ordum in otolith were 2255± 288 μm and 695±130 μm, respectively. The number of daily growth increments in otolith of 13 adults ranged from 305 to 354. The transition zone (mark ring)occured appromately at 45～70 days increments. The width of daily gro wth increments was from 094 μm～114 μm, the largest width at 190～220 days inc rements and the smallest width appeared after 280 increments. The first peak of S r/ Ca concentration ratio appeared at the 5th～7th measurement point that coinci ded with the time of migration of the juvenile fish to the sea for overwintering . While the second peak appeared from the measurement points 28 to 32 which coin cided well with the time of the fish anadromous migration for spawning. The chan ges of physiological and ecological condition during ontogenic development of th e fish lead to the Sr/ Ca ratio alteration in the otolith, but the drastic chan ge of salinity in habitability water that was the dominant factor causing the Sr /Ca ratio significantly increase.%1998年从鸭绿江捕取有明银鱼成鱼，生物学测量后剖出耳石。每尾鱼1对矢耳石中的1个用于制片，显微镜下观察其显微结构，另1个制片镀碳膜后，用扫描电子微探针测定Sr和Ca的浓度比率。 Sr和Ca分析的标准样用SrSO4和CaSO4。31尾鱼(体长116～157 mm)耳石长半径(Y)与鱼体长(X)成线性关系，其方程式为Y=2.7216X+9.2292, r=0.9178, P<0.01。耳石中心和耳石原基的平均直径分别为22.55±2.88 μm和6.95±1.30 μm。13尾鱼耳石上的日轮数为305～354, 大约在45～70日轮处出现过渡轮。日轮间距0.94～1.14 μm, 最大间距在190～220日轮处, 最小间距出现在280日轮之后。耳石中Sr、Ca浓度比例在第5至第7测点出现第1个高峰，这与稚鱼为了越冬洄游到海中时间相吻合。第2个高峰出现在28～32测点，这与鱼产卵上溯洄游时间相符。个体发育过程中生理和生态条件的变化，可引起耳石中Sr、Ca比率的改变，但栖息水域盐度的突然改变是导致Sr、Ca比率显著增高的主导因素。