IFREMER, HMMN - Unité halieutique Manche-Mer du Nord, 62200, Boulogne sur mer, France.
Univ. Lille, CNRS, Univ. Littoral Côte d'Opale, IRD, UMR 8187 - LOG - Laboratoire d'Océanologie et de Géosciences, 59000, Lille, France.
Sci Rep. 2024 Jan 19;14(1):1684. doi: 10.1038/s41598-024-52256-4.
Knowledge of the trophic structure and variability of planktonic communities is a key factor in understanding food-web dynamics and energy transfer from zooplankton to higher trophic levels. In this study, we investigated how stable isotopes of mesozooplankton species varied seasonally (winter, spring, autumn) in relation to environmental factors and plankton size classes in a temperate coastal ecosystem. Our results showed that spring is characterized by the strongest vertical and size-structured plankton food-web, mainly fueled by the phytoplankton bloom. As a result, spring displayed the largest isotopic niche space and trophic divergence among species. On the contrary, both pelagic and benthic-derived carbon influenced low productive seasons (winter and autumn), resulting in more generalist strategies (trophic redundancy). Stable isotope mixing models were used to explore how different seasonal structures influenced the overall food web up to predatory plankton (i.e., mysids, chaetognaths, and fish larvae). Different feeding strategies were found in spring, with predators having either a clear preference for larger prey items (> 1 mm, for herring and dab larvae) or a more generalist diet (sprat and dragonets larvae). During low productive seasons, predators seemed to be more opportunistic, feeding on a wide range of size classes but focusing on smaller prey. Overall, the food-web architecture of plankton displayed different seasonal patterns linked to components at the base of the food web that shaped the main energy fluxes, either from phytoplankton or recycled material. Additionally, these patterns extended to carnivorous plankton, such as fish larvae, emphasizing the importance of bottom-up processes.
浮游动物的营养结构和变异性的知识是理解食物网动态和从浮游动物向更高营养级传递能量的关键因素。在本研究中，我们调查了温带沿海生态系统中，浮游动物季节性（冬季、春季、秋季）与环境因素和浮游动物大小类别的关系如何变化。我们的研究结果表明，春季的垂直和大小结构的浮游动物食物网最强，主要由浮游植物繁殖提供动力。因此，春季表现出最大的同位素生态位空间和物种之间的营养差异。相反，浮游生物和底栖生物衍生的碳都影响了低生产力季节（冬季和秋季），导致更普遍的策略（营养冗余）。稳定同位素混合模型被用来探索不同的季节结构如何影响整个食物网，直至捕食性浮游动物（即糠虾、箭虫和鱼类幼虫）。在春季发现了不同的摄食策略，捕食者对较大的猎物（>1 毫米，如鲱鱼和鲈鱼幼虫）有明显的偏好，或者采用更普遍的饮食策略（鲱鱼和幼鱼）。在低生产力季节，捕食者似乎更具机会主义，摄食各种大小的食物，但主要关注较小的猎物。总的来说，浮游动物的食物网结构显示出与食物网底部成分相关的不同季节性模式，这些模式塑造了主要的能量流动，无论是来自浮游植物还是再循环物质。此外，这些模式还扩展到了肉食性浮游动物，如鱼类幼虫，强调了底栖过程的重要性。
