In the shallow and landlocked northeast Adriatic Sea, environmental factors have changed in recent decades. Their influence on seasonal and inter-annual variability of phytoplankton has been documented in the recent literature. Here, we decipher the long-term variability of phytoplankton phenology at a Long-Term Ecological Research site (Gulf of Trieste, Slovenia). Structural changes in the phytoplankton community (period 2005–2017) were analysed using a multivariate protocol based on Bayesian clustering. The protocol was modified from the literature to fit the needs of the study, using correspondence analysis and k-means clustering. A novel index for ordination and selection of taxa based on frequency and evenness was developed. The Total Inertia analysis showed that this index better preserved the available information. Typical seasonal assemblages were highlighted by applying the Indicative Value index in conjunction with likelihood ratio values. We obtained a rough picture of the seasonal separation of the diatom-dominated community from the mixed community and a refined picture of the phenology of the assemblages and bloom events. The spring diatom peak proved to be inconstant and short-lived, while the autumn bloom was generally long and diverse. As expected for nearshore environments, the average life span of the assemblages was found to be short-periodic (2–4 months). The second part of the year and the last part of the series were more prone to changes in terms of typical assemblages.

中文翻译：

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亚得里亚海 LTER 地点的浮游植物时间序列：破译群落结构和指示性分类群的方法论

在亚得里亚海东北部浅海和内陆海域，近几十年来环境因素发生了变化。最近的文献记载了它们对浮游植物季节性和年际变化的影响。在这里，我们破译了长期生态研究站点（斯洛文尼亚的里雅斯特湾）浮游植物物候的长期变化。使用基于贝叶斯聚类的多变量协议分析了浮游植物群落（2005-2017 年期间）的结构变化。该协议是从文献中修改的，以适应研究的需要，使用对应分析和 k 均值聚类。开发了一种基于频率和均匀度的分类群排序和选择的新索引。总惯量分析表明该指数更好地保留了可用信息。通过应用指示值指数和似然比值来突出典型的季节性组合。我们获得了以硅藻为主的群落与混合群落的季节性分离的粗略图，以及组合和开花事件物候的精细图。春天的硅藻峰是无常和短暂的，而秋天的花期则是漫长而多样的。正如对近岸环境所预期的那样，发现组合的平均寿命是短期的（2-4 个月）。今年的第二部分和系列的最后一部分在典型组合方面更容易发生变化。我们获得了以硅藻为主的群落与混合群落的季节性分离的粗略图，以及组合和开花事件物候的精细图。春天的硅藻峰是无常的、短暂的，而秋天的花期则是漫长而多样的。正如对近岸环境所预期的那样，发现组合的平均寿命是短期的（2-4 个月）。今年的第二部分和系列的最后一部分在典型组合方面更容易发生变化。我们获得了以硅藻为主的群落与混合群落的季节性分离的粗略图，以及组合和开花事件物候的精细图。春天的硅藻峰是无常和短暂的，而秋天的花期则是漫长而多样的。正如对近岸环境所预期的那样，发现组合的平均寿命是短期的（2-4 个月）。今年的第二部分和系列的最后一部分在典型组合方面更容易发生变化。发现组合的平均寿命是短期的（2-4 个月）。今年的第二部分和系列的最后一部分在典型组合方面更容易发生变化。发现组合的平均寿命是短期的（2-4 个月）。今年的第二部分和系列的最后一部分在典型组合方面更容易发生变化。