ABSTRACT The composition and patterns of spatial and season variability of epiphytic diatom assemblages of five intertidal species of Gelidiales (Rhodophyta) from three sampling sites off Gran Canaria (Canary Islands, Atlantic Ocean) were investigated during summer (2007) and winter (2008) seasons using scanning electron microscopy (SEM). Dominant species included Cocconeis scutellum var. scutellum, C. scutellum var. posidoniae, Grammatophora oceanica, Lichmophora eherembergi, Navicula sp. and Tabularia fasciculata and these represented 78% of the total diatom assemblage on Gelidiales. Eight of the diatom taxa, Cocconeis maxima, Amphicocconeis debesii, Cocconeis convexa, C. neothumensis var. marina, C. scutellum var. scutellum, C. scutellum var. posidoniae, Gomphonemopsis obscura and Pseudohimantidium pacificum, found in the present study represent new records for the Canary Archipelago. These species showed two distinct patterns of zonation, one in relation to their position at the intertidal area and the other relative to position on the host thalli. Although the vertical distribution of host thalli at the intertidal zone was important when considering the assemblage structure of epiphytic diatoms, the results showed that the cell abundance distribution changed more significantly when considering season rather than spatial distribution. Moreover, even though morphology of host thalli was not a determining factor, their aggregation mode had a significant influence on the abundance and distribution of microalgae. Finally, considering the growth forms of diatom communities, adnate diatoms were more abundant in turf than in clump species.

中文翻译：

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来自大加那利岛（西班牙）的 Gelidiales (Rhodophyta) 上的附生硅藻

摘要 在夏季（2007 年）和冬季（2008 年）季节调查了大加那利岛（加那利群岛、大西洋）三个采样点的五种潮间带藻类（红藻）的附生硅藻组合的空间和季节变化的组成和模式。使用扫描电子显微镜 (SEM)。优势种包括 Cocconeis scutellum var. 盾片，C. 盾片变种。posidoniae, Grammatophora oceanica, Lichmophora eherembergi, Navicula sp. 和 Tabularia fasciculata，它们占 Gelidiales 硅藻总组合的 78%。八种硅藻类群，Cocconeis maxima、Amphicocconeis debesii、Cocconeisconvexa、C. neothumensis var. marina, C. scutellum var. 盾片，C. 盾片变种。posidoniae、Gomphonemopsis obscura 和 Pseudohimantidium pacificum，在本研究中发现的代表了加那利群岛的新记录。这些物种显示出两种不同的分区模式，一种与其在潮间带的位置有关，另一种与其在宿主菌体上的位置有关。虽然在考虑附生硅藻的组合结构时，潮间带寄主菌体的垂直分布很重要，但结果表明，考虑季节而不是空间分布时，细胞丰度分布变化更显着。此外，尽管宿主菌体的形态不是决定因素，但它们的聚集方式对微藻的丰度和分布有显着影响。最后，考虑到硅藻群落的生长形式，草坪中的贴生硅藻比丛种中更丰富。