Heinrichs Anna Lena, Hardorp Onja Johannes, Hillebrand Helmut, Schott Toni, Striebel Maren
Institute for Chemistry and Biology of the Marine Environment (ICBM) Carl-von-Ossietzky University of Oldenburg, School of Mathematics and Science Oldenburg Germany.
Helmholtz Institute for Functional Marine Biodiversity (HIFMB) Carl-von-Ossietzky University of Oldenburg Oldenburg Germany.
Ecol Evol. 2024 Jul 31;14(8):e70073. doi: 10.1002/ece3.70073. eCollection 2024 Aug.
Temperature and resource availability are pivotal factors influencing phytoplankton community structures. Numerous prior studies demonstrated their significant influence on phytoplankton stoichiometry, cell size, and growth rates. The growth rate, serving as a reflection of an organism's success within its environment, is linked to stoichiometry and cell size. Consequently, alterations in abiotic conditions affecting cell size or stoichiometry also exert indirect effects on growth. However, such results have their limitations, as most studies used a limited number of factors and factor levels which gives us limited insights into how phytoplankton respond to environmental conditions, directly and indirectly. Here, we tested for the generality of patterns found in other studies, using a combined multiple-factor gradient design and two single species with different size characteristics. We used a structural equation model (SEM) that allowed us to investigate the direct cumulative effects of temperature and resource availability (i.e., light, N and P) on phytoplankton growth, as well as their indirect effects on growth through changes in cell size and cell stoichiometry. Our results mostly support the results reported in previous research thus some effects can be identified as dominant effects. We identified rising temperature as the dominant driver for cell size reduction and increase in growth, and nutrient availability (i.e., N and P) as dominant factor for changes in cellular stoichiometry. However, indirect effects of temperature and resources (i.e., light and nutrients) on species' growth rates through cell size and cell stoichiometry differed across the two species suggesting different strategies to acclimate to its environment.
温度和资源可用性是影响浮游植物群落结构的关键因素。许多先前的研究表明它们对浮游植物的化学计量、细胞大小和生长速率有显著影响。生长速率反映了生物体在其环境中的生存能力，与化学计量和细胞大小相关。因此，影响细胞大小或化学计量的非生物条件变化也会对生长产生间接影响。然而，这些结果存在局限性，因为大多数研究使用的因素和因素水平有限，这使我们对浮游植物如何直接和间接响应环境条件的了解有限。在这里，我们使用组合多因素梯度设计和两个具有不同大小特征的单一物种，测试了其他研究中发现的模式的普遍性。我们使用了结构方程模型（SEM），使我们能够研究温度和资源可用性（即光、氮和磷）对浮游植物生长的直接累积影响，以及它们通过细胞大小和细胞化学计量变化对生长的间接影响。我们的结果大多支持先前研究报告的结果，因此一些影响可被确定为主要影响。我们确定温度升高是细胞大小减小和生长增加的主要驱动因素，而养分可用性（即氮和磷）是细胞化学计量变化的主要因素。然而，温度和资源（即光和养分）通过细胞大小和细胞化学计量对物种生长速率的间接影响在两个物种中有所不同，这表明它们适应环境的策略不同。
