ABSTRACT: Diatom-dominated microphytobenthos (MPB) communities of 4 intertidal mudflats along the meso- and polyhaline reaches of the Loire Estuary, France, were investigated during a year cycle. They were analysed in terms of biomass, diversity, species composition and growth form distribution. The assemblages of the 2 upstream sites were characterised by high biomass and lower diversities and were mostly dominated by epipelon. The 2 downstream, most haline sites had lower biomass and higher diversities and were dominated by both epipelon and tychoplankton. Diversity did not exhibit a clear seasonal signal in the upstream mudflats, but it was higher during the first half of the study in the downstream sites. The coexistence of 2 growth forms seems to increase diversity of the mudflat assemblages. Species distribution was mainly linked to changes in sediment texture and salinity, both with a marked seasonal variability. MPB biomass was inversely related to MPB diversity and positively related to both mud content and the epipelon. MPB diversity was not, however, significantly correlated with mud content. Slight changes in sediment texture, even if causing variations in assemblage composition, did not change overall diversity. The existence of an important and even dominant tychoplanktonic fraction could be considered a distinctive feature of these benthic environments in the Loire, as well as in other macrotidal estuaries.

中文翻译：

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法国卢瓦尔河口底栖植物生物量、多样性和组合结构的时空变化

摘要：以一年为周期调查了法国卢瓦尔河口中、杂盐河沿岸 4 个潮间带泥滩的以硅藻为主的微型底栖动物 (MPB) 群落。从生物量、多样性、物种组成和生长形态分布等方面对它们进行了分析。2个上游站点的组合具有生物量高和多样性低的特点，并且主要以epepelon为主。下游的 2 个大多数盐碱地生物量较低，多样性较高，以表皮和浮游生物为主。上游泥滩的多样性没有表现出明显的季节性信号，但在研究的前半段，下游站点的多样性更高。两种生长形式的共存似乎增加了泥滩组合的多样性。物种分布主要与沉积物质地和盐度的变化有关，两者都具有明显的季节性变化。MPB 生物量与 MPB 多样性呈负相关，与泥浆含量和外皮呈正相关。然而，MPB 多样性与泥浆含量没有显着相关性。沉积物质地的轻微变化，即使导致组合组成的变化，也不会改变整体多样性。存在重要的甚至占主导地位的浮游部分可以被认为是卢瓦尔河以及其他大潮河口这些底栖环境的一个显着特征。与含泥量显着相关。沉积物质地的轻微变化，即使导致组合组成的变化，也不会改变整体多样性。存在重要的甚至占主导地位的浮游部分可以被认为是卢瓦尔河以及其他大潮河口这些底栖环境的一个显着特征。与含泥量显着相关。沉积物质地的轻微变化，即使导致组合组成的变化，也不会改变整体多样性。存在重要的甚至占主导地位的浮游部分可以被认为是卢瓦尔河以及其他大潮河口这些底栖环境的一个显着特征。