ABSTRACT: Prey availability and predation pressure are thought to be key constraints on larval growth, especially in low-productivity, subtropical environments. Yet, measuring their effects on larval fishes has been challenging, given the dynamic biophysical drivers of plankton distributions and small scales of interactions. We integrated fine-scale net tows (10s of meters) with in situ imaging to explore how predator-prey interactions influence larval fish growth in the Straits of Florida. Otolith-derived recent growth was analyzed for 3 ecologically important fishes: 2 coral reef labrids (Thalassoma bifasciatum and Xyrichtys novacula) and 1 tuna (Katsuwonus pelamis), with differing mean growth rates (labrids 0.25 mm d^-1, K. pelamis 0.44 mm d^-1) and prey (labrids-copepods; tuna-appendicularians). We used generalized additive models to examine the interactive effect of background density and frequency of elevated (>2 SD above background) prey and predators on recent (last 3 d) larval growth. For all taxa, recent growth increased with prey background density. Recent growth of labrids was also higher when copepod densities were more often elevated (14% of transect >20 ind. m^-3) above otherwise low background densities (2 ind. m^-3). Predators (chaetognaths and hydromedusae) had a growth-selective effect: stronger selection in transects with high-density predator patches, although the direction of the effect was species-specific. The effect of temperature was taxa-specific: growth increased with temperature for the labrids and peaked at an optimum (28°C) for the rapidly growing tuna. Integration of these fine-scale sampling methods improves our understanding of the variable influence of prey and predators on larval growth and, consequently, larval survival.

中文翻译：

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食物网限制了亚热带珊瑚礁和中上层鱼类的幼体生长

摘要：猎物的可利用性和捕食压力被认为是幼虫生长的关键限制因素，尤其是在低生产力的亚热带环境中。然而，考虑到浮游生物分布的动态生物物理驱动力和小范围的相互作用，测量它们对幼体鱼类的影响一直是具有挑战性的。我们将小型网状拖网（10米长）与原位成像相结合，以探索捕食者与猎物之间的相互作用如何影响佛罗里达海峡中幼鱼的生长。对3种具有生态学意义的重要鱼类的耳石最近生长情况进行了分析：2条珊瑚礁长鳍金枪鱼（Thalasoma bifasciatum和Xyrichtys novacula）和1条金枪鱼（Katsuwonus pelamis），平均生长率不同（长0.25 mm d^-1，K. pelamis 0.44 mm d ^-1）和猎物（金龟类-脚足类；金枪鱼-附录）。我们使用广义加性模型来研究背景密度和高频率（比背景高> 2 SD）的猎物和掠食者频率对最近（最后3天）幼虫生长的相互作用的影响。对于所有分类单元，最近的增长都随着猎物背景密度的增加而增加。labrids的最近的增长也较高时桡足类的密度更经常升高（断面的14％> 20 IND。米^-3）以上，否则低的背景密度（2 IND。米^-3）。捕食者（美洲鳄和水产杜鹃）具有生长选择性的作用：在高密度捕食者斑块的样带中选择强度更高，尽管作用的方向是特定于物种的。温度的影响是特定于分类群的：金龟子的生长随着温度的升高而增加，并在快速生长的金枪鱼达到最佳温度（28℃）时达到峰值。这些精细采样方法的整合使我们更好地了解了猎物和捕食者对幼虫生长以及因此对幼虫存活的各种影响。