Cieri M D., McCleave J D.
School of Marine Sciences, University of Maine, 5741 Libby Hall, 04469-5741, Orono, ME, USA
J Exp Mar Biol Ecol. 2001 Mar 15;257(2):219-227. doi: 10.1016/s0022-0981(00)00333-6.
Prior to making inferences from otoliths about the residence time and growth rate of glass-phase anguillid eels Anguilla in estuaries, it is necessary to validate the deposition rate of microincrements in the otoliths. Glass-phase American eels Anguilla rostrata (Lesueur), which had been captured near the mouth of an estuary in Maine, USA, prior to freshwater exposure, deposited increments at a daily rate at ambient temperature and salinity in a field and laboratory study. The regression for glass eels not possessing a transition ring was: I=0.976(D-1)+0.434, where I is the number of otolith increments distal to a fluorescent mark placed on the otolith at the beginning of the experiment, and D is the number of days in the experiment, which ranged from 7 to 49. The slope was not significantly different than 1. Unexpectedly, many glass eels deposited the transition ring during the experiment, although this ring had previously been thought to mark entry into fresh water. The regression for these glass eels was: I=0.961(D-1)-3.880, and the slope was not significantly different than 1. The negative intercept suggests that approximately 4 days were lost from the otolith record during deposition of the ring. This study demonstrated daily deposition of increments prior to freshwater exposure and demonstrated that deposition of the transition ring is not linked to freshwater entry.
在根据耳石推断玻璃鳗鲡在河口的停留时间和生长速率之前，有必要验证耳石中微增量的沉积速率。在美国缅因州河口口附近捕获的、尚未接触淡水的玻璃鳗鲡（美洲鳗鲡Anguilla rostrata，勒叙厄尔），在一项野外和实验室研究中，其在环境温度和盐度条件下以每日速率沉积增量。对于没有过渡环的玻璃鳗鲡，回归方程为：I = 0.976(D - 1)+0.434，其中I是在实验开始时放置在耳石上的荧光标记远端的耳石增量数量，D是实验天数，范围为7至49天。斜率与1没有显著差异。出乎意料的是，许多玻璃鳗鲡在实验期间沉积了过渡环，尽管此前一直认为这个环标志着进入淡水。这些玻璃鳗鲡的回归方程为：I = 0.961(D - 1)-3.880，斜率与1没有显著差异。负截距表明在环的沉积过程中耳石记录中大约损失了4天。这项研究证明了在接触淡水之前增量的每日沉积，并表明过渡环的沉积与进入淡水无关。
