Guislain Alexis L N, Nejstgaard Jens C, Köhler Jan, Sperfeld Erik, Mischke Ute, Skjelbred Birger, Grossart Hans-Peter, Lyche Solheim Anne, Gessner Mark O, Berger Stella A
Department of Plankton and Microbial Ecology, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin, Germany.
Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany.
Ecology. 2025 Mar;106(3):e70043. doi: 10.1002/ecy.70043.
Understanding the mechanisms driving community structure and dynamics is crucial in the face of escalating climate change, including increasing incidences of extreme weather. Cell size is a master trait of small organisms that is subject to a trade-off between resistance to grazing and competition for resources, and thus holds potential to explain and predict community dynamics in response to disturbances. Here, we aimed at determining whether cell size can explain shifts in phytoplankton communities following changes in nutrient and light conditions resulting from storm-induced inputs of nutrients and colored dissolved organic matter (cDOM) to deep clearwater lakes. To ensure realistic environmental conditions, we used a crossed gradient design to conduct a large-scale enclosure experiment over 6 weeks. Cell size explained phytoplankton community structure when light availability declined as a result of cDOM supply. Initially unimodal, with small-celled species accounting for up to 60% of the total community biovolume, the cell-size distribution gradually shifted toward large-celled species as light levels declined following cDOM addition. Neither nutrients nor mesozooplankton affected the shift in cell-size distribution. These results suggest a distinct competitive advantage of larger over smaller species at reduced light levels following cDOM inputs during storm events. Importantly, the clustering of species in two distinct size classes implies that interspecific size differences matter as much as cell size per se to understand community dynamics. Given that shifts in cell-size distribution have strong implications for food-web structure and biogeochemical cycles, our results point to the importance of analyzing cell-size distributions of small organisms as an essential element to forecast community and ecosystem dynamics in response to environmental change.
面对不断升级的气候变化，包括极端天气事件的增加，了解驱动群落结构和动态变化的机制至关重要。细胞大小是小型生物的一个主要特征，它在抵抗捕食和资源竞争之间存在权衡，因此有潜力解释和预测群落对干扰的动态响应。在此，我们旨在确定细胞大小是否能够解释在风暴将营养物质和有色溶解有机物（cDOM）输入到清澈深水湖泊后，营养和光照条件变化所导致的浮游植物群落的变化。为确保环境条件符合实际情况，我们采用交叉梯度设计进行了为期6周的大规模围隔实验。当由于cDOM供应导致光照可用性下降时，细胞大小能够解释浮游植物群落结构。细胞大小分布最初呈单峰型，小细胞物种占总群落生物量的比例高达60%，随着添加cDOM后光照水平下降，细胞大小分布逐渐向大细胞物种转变。营养物质和中型浮游动物均未影响细胞大小分布的变化。这些结果表明，在风暴事件期间cDOM输入后光照水平降低的情况下，较大物种相对于较小物种具有明显的竞争优势。重要的是，物种聚集在两个不同的大小类别中意味着，种间大小差异对于理解群落动态与细胞大小本身同样重要。鉴于细胞大小分布的变化对食物网结构和生物地球化学循环具有重要影响，我们的结果指出，分析小型生物的细胞大小分布作为预测群落和生态系统对环境变化响应的一个关键要素具有重要意义。
