Hylander Samuel, Farnelid Hanna, Fridolfsson Emil, Hauber Marc M, Todisco Vittoria, Ejsmond Maciej J, Lindehoff Elin
Department of Biology and Environmental Science, Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden.
Institute of Environmental Science, Faculty of Biology, Jagiellonian University, Cracow, Poland.
PLoS One. 2024 Dec 2;19(12):e0308844. doi: 10.1371/journal.pone.0308844. eCollection 2024.
Micronutrients such as vitamins are transferred from lower to higher trophic levels, but no general ecological concept describes the factors regulating this process. Here, we investigated thiamin (thiamine, vitamin B1), which is an example of a metabolically important water-soluble micronutrient. Thiamin is produced by organisms such as bacteria and phytoplankton, and all consumers, such as zooplankton and fish, rely on a continuous intake of thiamin through their diet and possibly from de novo-synthesized thiamin by gut microbiota. A deficiency in thiamin negatively affects reproduction in fish and bird populations worldwide. The aim of this study was to quantify thiamin transfer in a planktonic food web in response to thiamin and/or nutrient addition, using an outdoor mesocosm system (an approximately 1.9 m3 bag submerged in sea water). These estimates were then compared with literature data on thiamin concentrations at different trophic levels. The results showed that thiamin was rapidly taken up by phytoplankton in both the ambient and nutrient-amended treatments. However, large differences in thiamin concentrations in phytoplankton did not lead to any significant changes in community composition or abundance. Nitrogen addition led to changes in the abundance and community composition of picoplankton and phytoplankton but there were no additional major effects of thiamin addition. Differences in thiamin concentrations in phytoplankton were not detected at the next trophic level in zooplankton. Although the concentrations did not change, a greater abundance of some zooplankton taxa were developed in the thiamin treatments. Comparing the mesocosm results with literature data demonstrated a gradual reduction in thiamin concentrations along the food chain, with six percent of the concentration in producers occurring in top consumers (i.e., piscivorous fish). Overall, these observations illustrate the concept of trophic dilution of micronutrients where concentrations decrease along the food web from phytoplankton via zooplankton and planktivorous fish to piscivorous fish.
维生素等微量营养素会从营养级较低的生物向营养级较高的生物转移，但尚无通用的生态学概念描述调节这一过程的因素。在此，我们研究了硫胺素（维生素B1），它是一种具有重要代谢意义的水溶性微量营养素。硫胺素由细菌和浮游植物等生物产生，所有消费者，如浮游动物和鱼类，都依赖通过饮食持续摄入硫胺素，也可能依赖肠道微生物群重新合成的硫胺素。硫胺素缺乏会对全球鱼类和鸟类种群的繁殖产生负面影响。本研究的目的是利用室外中宇宙系统（一个约1.9立方米、浸没在海水中的袋子），量化浮游生物食物网中硫胺素的转移对硫胺素和/或营养添加的响应。然后将这些估计值与不同营养级硫胺素浓度的文献数据进行比较。结果表明，在环境处理和营养添加处理中，浮游植物都能迅速吸收硫胺素。然而，浮游植物中硫胺素浓度的巨大差异并未导致群落组成或丰度发生任何显著变化。添加氮导致了微微型浮游生物和浮游植物的丰度及群落组成发生变化，但添加硫胺素没有产生额外的主要影响。在浮游动物的下一个营养级未检测到浮游植物中硫胺素浓度的差异。虽然浓度没有变化，但在硫胺素处理中，一些浮游动物类群的丰度有所增加。将中宇宙实验结果与文献数据进行比较表明，硫胺素浓度沿食物链逐渐降低，生产者中6%的浓度出现在顶级消费者（即食鱼性鱼类）中。总体而言，这些观察结果说明了微量营养素的营养级稀释概念，即浓度沿着食物网从浮游植物经浮游动物和食浮游生物的鱼类到食鱼性鱼类逐渐降低。
