North Carolina Cooperative Fish and Wildlife Research Unit, Department of Applied Ecology, Campus Box 7617, North Carolina State University, Raleigh, NC 27695, U.S.A.
J Fish Biol. 2014 Apr;84(4):913-28. doi: 10.1111/jfb.12317. Epub 2014 Feb 12.
Otolith microchemistry was applied to quantify migratory variation and the proportion of native Caribbean stream fishes that undergo full or partial marine migration. Strontium and barium water chemistry in four Puerto Rico, U.S.A., rivers was clearly related to a salinity gradient; however, variation in water barium, and thus fish otoliths, was also dependent on river basin. Strontium was the most accurate index of longitudinal migration in tropical diadromous fish otoliths. Among the four species examined, bigmouth sleeper Gobiomorus dormitor, mountain mullet Agonostomus monticola, sirajo goby Sicydium spp. and river goby Awaous banana, most individuals were fully amphidromous, but 9-12% were semi-amphidromous as recruits, having never experienced marine or estuarine conditions in early life stages and showing no evidence of marine elemental signatures in their otolith core. Populations of one species, G. dormitor, may have contained a small contingent of semi-amphidromous adults, migratory individuals that periodically occupied marine or estuarine habitats (4%); however, adult migratory elemental signatures may have been confounded with those related to diet and physiology. These findings indicate the plasticity of migratory strategies of tropical diadromous fishes, which may be more variable than simple categorization might suggest.
耳石微化学被应用于量化洄游变异和经历完全或部分海洋洄游的加勒比本地溪流鱼类的比例。美国波多黎各的四条河流中的锶和钡水化学与盐度梯度明显相关；然而，水钡的变化，以及因此鱼类耳石的变化，也依赖于河流流域。锶是热带洄游鱼类耳石中纵向洄游的最准确指标。在所研究的四个物种中，大口睡鲨 Gobiomorus dormitor、山鲻 Agonostomus monticola、西氏短鲷 Sicydium spp. 和河鲷 Awaous banana，大多数个体都是完全洄游性的，但 9-12%是半洄游性的幼鱼，它们在早期生活阶段从未经历过海洋或河口环境，耳石核心也没有海洋元素特征的证据。一个物种 G. dormitor 的种群可能包含一小部分半洄游性成鱼，这些成鱼周期性地占据海洋或河口栖息地（4%）；然而，成年洄游元素特征可能与与饮食和生理有关的特征混淆。这些发现表明热带洄游鱼类的洄游策略具有可塑性，可能比简单的分类更具变异性。
