Secondary production connects primary producers with higher-order consumers. The response of secondary production to seasonal variation in primary producers can influence trophic flows that underpin key ecosystem functions and services. Within the canopy-forming macroalgal meadows of Ningaloo Reef, Western Australia, we quantified the secondary production generated by Sargassum-associated epifauna across seasons and seascapes. We found a strong positive correlation between overall epifaunal production and Sargassum canopy size. Variation in epifaunal production was predominantly driven by seasonal changes in Sargassum canopy size. However, these seasonal effects were not uniform across the seascape. Key predictors of spatial and temporal variation in epifaunal production were the presence of invertivorous fish families, as well as daily and monthly fluctuations in sea temperature. Areal estimates of epifaunal productivity were much higher in summer than in winter, due to higher Sargassum canopy size and percent cover in summer. Epifaunal production was estimated to be more sensitive to Sargassum percentage cover than to canopy height. Modeling a 45% reduction in canopy height and percent cover of Sargassum associated with a marine heatwave event revealed a potential 81% drop in the areal rate of secondary production by Sargassum epifauna in this tropical fringing reef ecosystem. Disturbances to Sargassum canopy structure driven by global change can therefore significantly alter the productivity of these tropical macroalgal meadows and their ability to support higher level consumers within the food web, including important fisheries species. Our results highlight the importance of including epifaunal production estimates in predictive modeling when managing macroalgal-dominated marine ecosystems.

中文翻译：

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量化热带大型藻类草甸的表层动物次生生产：季节性和对冠层结构的敏感性

二次生产将初级生产者与更高阶的消费者联系起来。次级生产对初级生产者季节性变化的响应可以影响支撑关键生态系统功能和服务的营养流。在西澳大利亚宁格鲁礁的形成树冠的大型藻类草甸内，我们量化了马尾藻相关的附生动物群在不同季节和海景中产生的二次生产。我们发现整体表皮动物产量与马尾藻冠层大小之间存在很强的正相关关系。表皮动物生产的变化主要是由马尾藻的季节性变化驱动的树冠大小。然而，这些季节性影响在整个海景中并不统一。表皮动物生产时空变化的关键预测因素是反食鱼类家族的存在，以及海水温度的每日和每月波动。由于夏季马尾藻的冠层尺寸和覆盖百分比较高，夏季的表层动物生产力的面积估计值远高于冬季。据估计，外生动物生产对马尾藻百分比覆盖率比对冠层高度更敏感。模拟与海洋热浪事件相关的树冠高度和马尾藻覆盖百分比下降 45% 的模型显示，马尾藻的二次生产面积率可能下降 81%在这个热带边缘礁生态系统中的外生动物。因此，由全球变化驱动的对马尾藻冠层结构的干扰可以显着改变这些热带大型藻类草甸的生产力及其支持食物网中更高级别消费者的能力，包括重要的渔业物种。我们的研究结果强调了在管理大型藻类主导的海洋生态系统时将表皮动物生产估计纳入预测模型的重要性。