Influence of water temperature and feeding regime on otolith growth in Anguilla japonica glass eels and elvers: does otolith growth cease at low temperatures?
Influence of water temperature and feeding regime on otolith growth in Anguilla japonica glass eels and elvers: does otolith growth cease at low temperatures?
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DOI：
10.1111/j.1095-8649.2009.02287.x
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发表时间：
2009-06-01
影响因子：
2
通讯作者：
Tsukamoto, K.
中科院分区：
文献类型：
--
作者：
Fukuda, N.;Kuroki, M.;Tsukamoto, K.
采用5、10、15、20、25和30℃饲养条件和盐度为32的饲喂或不饲喂条件，研究了水温和饲喂方式对日本鳗鲡和鳗鲡耳石生长的影响，并对其耳石进行了ALC标记。为了消除光学显微镜（OM）或扫描电子显微镜（SEM）观察耳石边缘的困难，在实验期间的第10、20和30天从每个水箱中取样3至10只个体，并在第二次标记耳石后在25℃下饲养10天。使用OM和SEM测量耳石生长和增量数量。在20-30℃或15℃条件下，大多数日本赤潮在10天后或20天后开始摄食，但在5℃和10℃条件下没有发生摄食。在5℃和10℃条件下，没有耳石生长，只有两个个体在10℃条件下有最小的增量沉积。在15-25℃条件下，耳石生长与水温成比例，在25℃和30℃条件下没有差异。饲喂条件下的平均耳石生长率高于未饲喂条件。不同水温(5℃和10℃时为0.00 ~ 0.01 d(-1)， 15℃时为0.43 ~ 0.48 d（-1)， 20 ~ 30℃时为0.94 ~ 1.07 d(-1)）。上述结果表明，在实验条件下，日本玻璃鳗和鳗鱼的耳石生长受温度影响，在< 10℃时停止生长。因此，未来分析野生捕获的日本玻璃鳗和鳗鱼耳石的研究需要仔细考虑幼年在野生环境中可能经历的水温。
The influences of water temperature and feeding regime on otolith growth in Anguilla japonica glass eels and elvers were investigated using individuals reared at 5, 10, 15, 20, 25 and 30 degrees C and in fed or unfed conditions at salinity 32 after their otoliths were marked with alizarin complexone (ALC). To eliminate the difficulty of observing the edges of otoliths with optical (OM) or scanning electron (SEM) microscopes, three to 10 individuals were sampled from each tank at 10, 20 and 30 days during the experiment and reared for an additional 10 days at 25 degrees C after their otoliths were marked a second time. Otolith growth and the number of increments were measured using both OM and SEM. Most A. japonica commenced feeding after 10 days at 20-30 degrees C or after 20 days at 15 degrees C, but no feeding occurred at 5 and 10 degrees C. No otolith growth occurred at 5 and 10 degrees C except in two individuals with minimal increment deposition at 10 degrees C. Otolith growth was proportional to water temperature within 15-25 degrees C and not different between 25 and 30 degrees C. At 15, 25 and 30 degrees C, the mean otolith growth rate in fed conditions was higher than in unfed conditions. The number of increments per day was significantly different among water temperatures (0.00-0.01 day(-1) at 5 and 10 degrees C, 0.43-0.48 day(-1) at 15 degrees C and 0.94-1.07 day(-1) at 20-30 degrees C). These results indicated that otolith growth in A. japonica glass eels and elvers was affected by temperature and ceased at < 10 degrees C under experimental conditions. Hence, future studies analysing the otoliths of wild-caught A. japonica glass eels and elvers need to carefully consider the water temperatures potentially experienced by the juveniles in the wild.