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首页> 外文期刊>Marine ecology progress series >Size at sex change in protogynous labroids, prey body size distributions, and apex predator densities at NW Hawaiian atolls
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Size at sex change in protogynous labroids, prey body size distributions, and apex predator densities at NW Hawaiian atolls

机译：西北夏威夷环礁的原生雌性类胡萝卜体的性别变化大小，猎物的身体大小分布和先端捕食者密度

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摘要

Body sizes at protogynous (sequential, female-to-male) sex change are described for 8 species of labroid fishes (4 labrids, 4 scarids) based on in situ diver observations of the sizes of sex-related color morphs for populations at atolls in the NW Hawaiian Islands. Sizes at sex change are deduced from the median overlap in size distributions of initial phase (IP: female or female and precocious male) and terminal phase (TP) male individuals for each labroid species and from the median sizes of transitional morph individuals of the endemic, spectacled parrotfish Chlorurus perspicillatus. Relative (to maximum) sizes at sex change vary significantly among 4 major species and, within these species, among the 6 reef populations, a finding that contrasts with a recent model of invariant relative size at sex change in protogynous fishes. Overall median size at sex change is compared to the density of a large carangid (giant trevally Caranx ignobilis, the biomass-dominant apex predator) and to that of the respective labroid species population at each atoll. Size at sex change is inversely related to the density of giant trevally but not meaningfully related to the density of the respective labroid population. The size distributions of the labroids—like those of all other prey reef fishes—are strongly skewed toward smaller and larger fish at atolls with higher and lower densities, respectively, of giant trevally. Altogether these observations strongly suggest that higher mortality from predation at greater predator densities, rather than slower growth rates under greater intraspecific competition at higher prey densities, is the cause of the observed differences among atolls in prey attributes. We suggest that prey body size distribution can potentially provide a sensitive measure, complementary to predator density, for assessing changes in the abundance of apex predators on coral reefs. Pheno-typic indices of size at sex change from adult female to male in sexually dimorphic labroids with striking differences in coloration (that facilitate underwater observations) have great potential as nondestructive alternatives to gonad examination requiring specimen sacrifice. Labroid color change thus represents a potentially useful index for assessing changes in the functional structure of coral reef fish assemblages and reef ecosystems.
机译：根据原住民对环礁环礁种群性别相关颜色形态的大小的原位观察，描述了8种唇形鱼类（4种唇齿，4种猩猩）的原性（顺序，雌性至雄性）性别变化。西北夏威夷群岛。性别变化的大小是根据每种唇形物种的初始阶段（IP：雌性或雌性和早熟的雄性）和末期（TP）雄性个体的大小分布的中值重叠以及地方性过渡性形态个体的中值大小推导得出的，眼镜鹦嘴鱼Chlorurus perspicillatus。在4个主要物种之间以及在这些物种内的6个珊瑚种群中，性别变化的相对（最大）大小差异很大，这一发现与最近的原生鱼类性别变化的相对大小不变的最新模型形成了鲜明对比。将性别变化时的总体中位大小与大型类肉食蟹动物（tr大的Caranx ignobilis，以生物量为主的食肉动物）的密度以及各个环礁物种种群的密度进行比较。性别变化时的大小与三叶草巨人的密度成反比，但与各个唇齿种群的密度却无意义。像所有其他pre类鱼类一样，类唇的大小分布也强烈偏向于大型或蝶形密度较高的环礁的较小和较大的鱼类。总而言之，这些观察结果强烈表明，在较高的食肉密度下，较高的食肉动物密度导致较高的捕食死亡率，而不是在较高的种内竞争下，由于较高的食肉动物密度而导致环礁差异的原因。我们建议，猎物的体型分布可以潜在地提供一种敏感的措施，以补充捕食者的密度，以评估珊瑚礁上的先天捕食者数量的变化。具有性别差异的两性性类人形动物中，成年雌性到雄性的表型大小指数从成年女性变为男性（有助水下观察），作为性腺检查的无损替代品，需要牺牲标本，具有很大的潜力。因此，唇形生物的颜色变化代表了一种潜在有用的指标，可用于评估珊瑚礁鱼群和珊瑚礁生态系统功能结构的变化。

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