Tesfaye Million, Souza Allan T, Šmejkal Marek, Jůza Tomáš, Sajdlová Zuzana, Draštík Vladislav, Kočvara Luboš, Symonová Radka, Meador Travis B, Vašek Mojmír, Kubečka Jan
Biology Centre of the Czech Academy of Sciences Institute of Hydrobiology České Budějovice Czechia.
Faculty of Fisheries and Protection of Waters, South Bohemian Research Centre for Aquaculture and Biodiversity of Hydrocenoses University of South Bohemia in České Budějovice Vodňany Czechia.
Ecol Evol. 2025 Aug 19;15(8):e71973. doi: 10.1002/ece3.71973. eCollection 2025 Aug.
Intraspecific competition is a fundamental selective force in animals, leading to various specializations that influence ecological interactions. Diet composition and trophic position at the early life stages substantially influence fish growth, survival, and recruitment success. Yet, most studies focus disproportionately on adult stages, leaving critical knowledge gaps in our understanding of early life history. To address this, we used young of the year (YOY) pikeperch () as a model species and investigated the intraspecific interaction and degree of trophic partitioning between three intra-annual cohorts (extremely small (ES), ordinary and piscivorous YOYs) using stable isotope (SI) and gut content analysis (GCA). Analysis of SI metrics unveiled that an ontogenetic diet shift was linked to increasing body size, leading to significant trophic niche variation among intra-annual cohorts. The piscivorous cohort occupied the highest trophic position, followed by the ordinary and ES cohorts. There was no overlap in the isotopic niche between the intra-annual cohorts, considering the 40% standard ellipse area. The GCA showed two distinct feeding patterns: the ES cohort exclusively consumed zooplankton, while the ordinary cohort had a more diverse diet, feeding on zooplankton and benthic macroinvertebrates. The piscivorous cohort (≥ 80 mm) predominantly fed on their conspecifics and YOY perch (). Our study demonstrates that YOY pikeperch intra-annual cohorts exhibit a broad size range and unique ontogenetic feeding patterns, with vital implications for population dynamics and ecological interactions. These differences are likely due to different hatching dates, environmental factors, and individual ability to become predatory. Furthermore, this work emphasizes the need for comparative studies to better understand trophic dynamics and uncover the ecological factors shaping the early life stages of fish.
种内竞争是动物的一种基本选择力量，会导致各种影响生态相互作用的特化现象。鱼类幼体阶段的饮食组成和营养级对其生长、存活及补充成功有着重大影响。然而，大多数研究过度关注成年阶段，使得我们在理解早期生活史方面存在关键的知识空白。为解决这一问题，我们以当年幼鱼（YOY）梭鲈（）作为模式物种，利用稳定同位素（SI）和肠道内容物分析（GCA），研究了三个年内同龄组（极小（ES）、普通和食鱼幼鱼）之间的种内相互作用和营养分配程度。对SI指标的分析表明，个体发育过程中的饮食转变与体型增大有关，导致年内同龄组之间出现显著的营养生态位差异。食鱼同龄组占据最高营养级，其次是普通同龄组和ES同龄组。考虑到40%的标准椭圆面积，年内同龄组之间的同位素生态位没有重叠。GCA显示出两种不同的摄食模式：ES同龄组仅摄食浮游动物，而普通同龄组的饮食更为多样，以浮游动物和底栖大型无脊椎动物为食。食鱼同龄组（≥80毫米）主要以同种个体和幼鱼（）为食。我们的研究表明，当年梭鲈的年内同龄组表现出广泛的体型范围和独特的个体发育摄食模式，这对种群动态和生态相互作用具有重要意义。这些差异可能是由于不同的孵化日期、环境因素以及个体成为捕食者的能力不同所致。此外，这项工作强调了进行比较研究的必要性，以便更好地理解营养动态并揭示塑造鱼类早期生活阶段的生态因素。
