Diatom community composition and abundances on different thallus parts of adult and juvenile specimens of Eckloniamaxima and Laminariapallida were examined in False Bay, South Africa, using light and scanning electron microscopy. Altogether, 288 thallus portions were analysed. Diatom abundances ranged from 0 to 404 cells mm⁻² and were generally higher on E. maxima and juvenile thalli than L. pallida and adult specimens. Moreover, diatom abundances differed between the various thallus parts, being highest on the upper blade and lowest on the primary blade. A total of 48 diatom taxa belonging to 28 genera were found. Gomphoseptatum Medlin, Nagumoea Witkowski and Kociolek, Cocconeis Ehrenberg, and Navicula Bory were the most frequently occurring genera, being present in 84%, 65%, 62.5%, and 45% of the analysed samples, respectively. Among these, Cocconeis and Gomphoseptatum were the most abundant, contributing 50% and 27% of total diatom cells counted collectively across all samples. Permutational multivariate analysis of variance (PERMANOVA) revealed that all investigated main factors (kelp species and age and thallus part), as well as their two- and three-way interactions, except for the interaction between the host species and age, were significant. The high residual variance (72%) indicated that the sum of other unexamined factors contributed the largest component of the variation observed in the kelp-associated diatom communities, and grazing and possible defence strategies utilised by kelps are proposed as processes playing an important role in the structuring of epiphytic diatom communities. Possible endophytism of tissue-boring diatoms colonizing both kelp species is briefly discussed.

中文翻译：

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寄主种类，年龄和生殖器官部分对海带相关硅藻的影响评估

对成年和少年标本的不同部位叶状体硅藻群落组成与丰度Ecklonia最大值和海带淡紫在福尔斯湾，南非，检查使用光线和扫描电子显微镜。总共分析了288个肛门部位。硅藻的丰度范围从0到404个细胞mm ^-2，并且在最大的E. maxima和幼体thalli上比P. pallida和成年标本更高。此外，硅藻的丰度在各个th部之间是不同的，在上部叶片上最高，而在初级叶片上最低。共发现28个属的48个硅藻类群。Gomphoseptatum梅德林，Nagumoea Witkowski和Kociolek，Cocconeis Ehrenberg和Navicula Bory是最常见的属，分别存在于被分析样品的84％，65％，62.5％和45％中。其中，球藻和线虫是最丰富的，在所有样品中共同计数的硅藻细胞总数中分别占50％和27％。变异多变量方差分析（PERMANOVA）显示，除宿主物种和年龄之间的相互作用外，所有调查的主要因素（海藻物种，年龄和th体部分）以及它们的双向相互作用和三向相互作用均很显着。较高的残留方差（72％）表明，其他未检查因素的总和是海带相关硅藻群落中观察到的最大变化，海藻的放牧和可能的防御策略被认为是在海藻中起重要作用的过程。附生硅藻群落的结构。简要讨论了定居于两种海带物种的无聊的硅藻可能的内生性。