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Abstract：
Many freshwater organisms have a life-history stage that can disperse through seawater. This has obvious benefits for colonization and connectivity of fragmented sub-populations, but requires a physiologically challenging migration across a salinity boundary. We consider the role of landscape boundaries between freshwater and seawater habitats, and evaluate their potential effects on traits and developmental histories of larvae and juveniles (i.e., dispersing life-history stages) of an amphidromous fish, Galaxias maculatus. We sampled juvenile fish on their return to 20 rivers in New Zealand: 10 rivers had abrupt transitions to the sea (i.e., emptying to an open coastline); these were paired with 10 nearby rivers that had gradual transitions to the sea (i.e., emptying into estuarine embayments). We reconstructed individual dispersal histories using otolith microstructure, otolith microchemistry, and stable isotope analysis. We found that fish recruiting to embayment rivers had distinct dispersal and foraging histories, were slower growing, smaller in size, and older than fish recruiting to nearby non-embayment rivers. Our results indicate that landscape edges can affect dispersal capabilities of aquatic organisms, potentially leading to divergent life-history strategies (i.e., limited- versus widespread-dispersal). Patterns also suggest that dispersal potential among landscape boundaries can create heterogeneity in the traits of individuals, with implications for metapopulation dynamics.
摘要：
许多淡水生物都有一个可以通过海水扩散的生命史阶段。这对分散的亚群的定殖和连通性有明显的好处，但需要在生理上具有挑战性的迁移跨越盐度边界。我们考虑淡水和海水栖息地之间的景观边界的作用，并评估其对幼虫和幼体性状和发育历史的潜在影响(即，分散两栖鱼类的生活史阶段），黄斑星系。我们采样了幼鱼返回新西兰的20条河流：10条河流突然过渡到大海（即，排空到开放的海岸线)；这些与附近10条逐渐过渡到大海的河流配对(即，排空到河口入口)。我们使用耳石微观结构重建了个体扩散历史，耳石微化学，和稳定同位素分析。我们发现，鱼群在河中的捕捞有明显的扩散和觅食历史，生长较慢，尺寸较小，并且比在附近的非捕捞河流中招募的鱼更古老。我们的结果表明，景观边缘可以影响水生生物的扩散能力，可能导致不同的生活史策略(即，有限与广泛扩散)。模式还表明，景观边界之间的扩散潜力可以在个体特征中产生异质性，对种群动态有影响。
