The diversity of centric diatoms is documented for the transitional zone of the lower part of the Southern Bug River (Ukraine) just before entering the Dnipro-Bug Estuary and compared to earlier results from the upstream sampling sites of the same river system. Benthic samples of the following sites were investigated: north of Mykolaiv City (approximately 5 km), in Mykolaiv City (near Varvarivskyi Bridge), and 5 km south of the city. Twenty-four centric diatom taxa belonging to 11 genera were identified, analysed, and documented by scanning electron microscopy (SEM) and light microscopy (LM). Among them, Aulacoseira nivalis is the first report for Ukraine, A. islandica and is the first confirmed record for the studied area since the 1930s. The maximum number of centric diatom taxa found in one station was 21, the minimum 10. Melosira subglobosa was the most common (documented in 57–80% of sites with centric diatoms) and abundant species 7.3–15.7% in relative abundance to all diatom taxa. The discovered diversity of taxa and its comparison with previous results is discussed with regard to the relevance of estuary zones in the research of diatoms.

中文翻译：

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南部布格河（乌克兰）下部的中心硅藻多样性：迈科拉夫市的过渡带

在进入第聂伯河-布格河口之前，南部布格河下游（乌克兰）的过渡带记录了中心硅藻的多样性，并将其与同一河流系统上游采样点的早期结果进行了比较。调查了以下地点的底栖动物样本：Mykolaiv市以北（约5公里），Mykolaiv市（Varvarivskyi桥附近）和市以南5公里。通过扫描电子显微镜（SEM）和光学显微镜（LM）鉴定，分析和记录了11个属的24个中心硅藻类群。其中，Aulacoseira nivalis是乌克兰A. islandica的第一份报告，也是自1930年代以来该研究区域的第一份确凿记录。一个站点中发现的最大中心硅藻类群数量为21，最小数量为10。Melosira subglobosa是最常见的（在有中心硅藻的站点中有57-80％的记录），相对于所有硅藻类而言相对丰富的物种是7.3-15.7％。关于河口带在硅藻研究中的相关性，讨论了已发现的分类单元的多样性及其与以前的结果的比较。