Abstract Multicellular zooplankton, such as copepods, are the main link between primary producers and fish. Most models of plankton communities, such as NPZ-type models, ignore the life-cycle (ontogeny) of multicellular zooplankton. Ontogeny has profound implications on population dynamics and community structure. Our aim is to provide a generic food-web framework of planktonic communities that accounts for zooplankton ontogeny. We propose a model framework along the Nutrient-Unicellular-Multicellular axis – a “NUM” framework – as an alternative to the NPZ modelling paradigm. NUM is a mechanistic size- and trait-based model based on traits and trade-offs at the individual level. Here the multicellular component describes the population dynamics of key copepod groups, characterized by their adult size and feeding mode. The unicellular compartment accounts for auto- mixo- and heterotrophic protists. We also consider nitrogen dynamics and carbon export from copepod fecal pellets. All parameters have been fitted to cross-species data. By approximate analytical solutions and dynamic simulations, in both constant and seasonal environments, we investigate the patterns of body sizes and traits that emerge within the community. We show that copepods of several adult sizes and feeding modes commonly coexist, and that competition and predation by large copepods on small/juvenile copepods is an important factor in shaping the community. We also show competition between heterotrophic protists and small copepods through intraguild predation. Finally, we discuss how copepods can attenuate the fecal pellet export. This conceptually simple, yet realistic framework opens the possibility to improve end-to-end size-structured models of marine systems and investigate biogeochemical processes.

中文翻译：

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基于大小和特征的浮游生物群落的一般模型

摘要 桡足类等多细胞浮游动物是初级生产者与鱼类之间的主要纽带。大多数浮游生物群落模型，例如 NPZ 型模型，都忽略了多细胞浮游动物的生命周期（个体发育）。个体发育对人口动态和社区结构具有深远的影响。我们的目标是提供一个解释浮游动物个体发育的浮游生物群落的通用食物网框架。我们提出了一个沿营养-单细胞-多细胞轴的模型框架——一个“NUM”框架——作为 NPZ 建模范式的替代方案。NUM 是一种基于大小和特征的机械模型，基于个体层面的特征和权衡。这里的多细胞成分描述了关键桡足类群的种群动态，以它们的成年体型和进食方式为特征。单细胞室是自混和异养原生生物的原因。我们还考虑了桡足类粪便颗粒的氮动力学和碳输出。所有参数都已拟合到跨物种数据。通过近似解析解和动态模拟，在恒定和季节性环境中，我们研究了社区内出现的体型和特征的模式。我们表明，几种成年尺寸和进食方式的桡足类通常共存，并且大型桡足类对小型/幼年桡足类的竞争和捕食是塑造社区的重要因素。我们还通过群内捕食展示了异养原生生物和小型桡足类之间的竞争。最后，我们讨论桡足类动物如何减弱粪便颗粒的出口。这个概念很简单，