Depth distribution and abundance of a coral-associated reef fish: roles of recruitment and post-recruitment processes
Depth distribution and abundance of a coral-associated reef fish: roles of recruitment and post-recruitment processes
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珊瑚相关礁鱼的深度分布和丰度：招募和招募后过程的作用
作者：
P. Smallhorn‐West;T. Bridge;P. Munday;G. Jones
许多珊瑚礁鱼类的丰度随深度而变化，但影响这种模式的人口统计过程仍不清楚。此外，虽然高度专业化的珊瑚鱼的分布通常与它们的栖息地紧密匹配，但尚不清楚随深度的分布模式的变化是否是栖息地可用性变化的结果，还是种群参数（例如补充和死亡率）与深度相关的独立变化的结果。在这里，我们表明，与珊瑚相关的虾虎鱼（Paragobiodon xanthosoma）分布的深度相关模式与补充和性能（生长和生存）的变化密切相关。深度分层调查显示，虽然珊瑚寄主 Seriatopora hystrix 延伸到更深的水域（>20 m），但 P. xanthosoma 对栖息地的利用随着深度的增加而减少，并且成虫和幼体 P. xanthosoma 在 20 m 以下都不存在。三个深度（5、15 和 30 m）的 S. hystrix 丰度标准化表明，P. xanthosoma 的补充并非由其栖息地的可用性决定。将 P. xanthosoma 相互移植到三个深度（5、15 和 30 m）的 S. hystrix 菌落，然后确定个体性能（生存和生长）在更深的水中最低；移植到 30 m 的个体死亡率高出三倍，且生长大大降低。从 15 m 深处采集的个体的生长率也比从浅水深处采集的鱼类低 50%。这些结果表明，该物种的深度分布不仅受到其珊瑚栖息地的可用性的限制，而且受到与生活在更深水域相关的人口成本的限制。
The abundance of many reef fish species varies with depth, but the demographic processes influencing this pattern remain unclear. Furthermore, while the distribution of highly specialized reef fish often closely matches that of their habitat, it is unclear whether changes in distribution patterns over depth are the result of changes in habitat availability or independent depth-related changes in population parameters such as recruitment and mortality. Here, we show that depth-related patterns in the distribution of the coral-associated goby, Paragobiodon xanthosoma, are strongly related to changes in recruitment and performance (growth and survival). Depth-stratified surveys showed that while the coral host, Seriatopora hystrix, extended into deeper water (>20 m), habitat use by P. xanthosoma declined with depth and both adult and juvenile P. xanthosoma were absent below 20 m. Standardization of S. hystrix abundance at three depths (5, 15 and 30 m) demonstrated that recruitment of P. xanthosoma was not determined by the availability of its habitat. Reciprocal transplantation of P. xanthosoma to S. hystrix colonies among three depths (5, 15 and 30 m) then established that individual performance (survival and growth) was lowest in deeper water; mortality was three times higher and growth greatly reduced in individuals transplanted to 30 m. Individuals collected from 15 m also exhibited growth rates 50% lower than fish from shallow depths. These results indicate that the depth distribution of this species is limited not by the availability of its coral habitat, but by demographic costs associated with living in deeper water.