黄海黑鲷仔鱼耳石的日轮以及光照对其形成的影响

DAILY GROWTH INCREMENTS AND EFFECTS OF PHOTOPERIOD ON DAILY GROWTH PATTERNS IN OTOLITHS OF SPARUS MACROCEPHALUS (BASILEWSKY) LARVAE

实验仔鱼于1986年5月,由饲养在海洋研究所室内的同一尾黄海黑鲷雌鱼在一次产卵中取得的受精卵孵化后取得的。对实验仔鱼耳石生长轮形成的周期以及光照对其形成的影响进行了观察。实验证明,黑鲷仔鱼耳石生长轮形成具有日周期性,仔鱼培育天数(D)与耳石生长轮数(N)之间的关系以回归式N=D-1.89表达之。在24h内的12h光照、12h黑暗条件下,耳石形成一个宽带和一个窄带。在6h光照、6h黑暗条件下,则形成两个宽带和两个窄带,但它们的宽度都比前者小。光照周期对耳石生长轮形成产生明显的影响。

The present study researches the deposition rate of growth increment in the otolith of black porgy, Sparus macrocephalus (Basilewsky) larvae and the effect of different photoperiod on production of daily growth increments.Black porgy larvae were reared from fertilized eggs spawned by one adult reared in the laboratory of Institute of Oceanology, Academia Sinica in May, 1986. The otolith showed a daily growth rhythm under a 12 light-12 dark photoperiod. The regression equation of chronological age based on the number of daily growth increment, N = D-2-77 was derived, where N is the number of growth increments and D the days after hatching.The otolith body-diameter length relationship varied significantly between 6L-6D and 12L-12D experimental groups. The growth rate of the 12L-12D group was higher than that of the 6L-6D group. The mean numbers of growth increments in the otoliths were highly correlated with the frequency of the L, D cycle. Opaque bands formed under 6L-6D cycles, were poorly etched and easily distinguished (by SEM) from those under 12L-12D cycles Result of experiments under various light-dark cycles suggested that a 24 h light-dark cycle was required for producing daily growth increment. Photoperiod apparently acts as a zeit-geber for the circadian rhythm.