Thiyagarajan Vengatesen, Lau Stanley C K, Cheung Sam C K, Qian Pei-Yuan
Department of Biology, The Hong Kong University of Science and Technology, Hong Kong SAR, China.
Microb Ecol. 2006 May;51(4):431-40. doi: 10.1007/s00248-006-9041-0. Epub 2006 Apr 28.
The potential driving force(s) of the vertical distribution of subtidal barnacle Balanus trigonus Darwin were investigated using both field and laboratory experiments. Early juveniles (approximately 24 h old) placed in intertidal [approximately 0.5 m above mean low water level (MLWL)] and subtidal (approximately 3 m below MLWL) habitats survived equally well, indicating that the intertidal absence of B. trigonus in Hong Kong waters was not determined by differential mortality. However, enhanced attachment of cyprids in subtidal habitats indicated the importance of differential larval choice in determining their vertical distribution. In the laboratory, cyprids preferred to attach in response to subtidal microbial films, which may implicate microbial films as a primary cue in driving the adult vertical distribution. Microbial films developed in these two habitats differed in their biomass (= total organic carbon), abundance of bacteria and diatoms (determined by fluorescence microscopy), and bacterial diversity (determined by DNA fingerprinting analysis). For example, 6-day films in subtidal habitat had a significantly higher biomass than in films from intertidal habitat (P < 0.05). There was no difference in the biomass of films from these two habitats in 9-day films (P > 0.05); however, bacterial abundance was greater in subtidal films than in intertidal films, irrespective of the age of the film, although there was no difference in diatom abundance in films from these two habitats. Neither the abundance of bacteria and diatoms nor the biomass correlated with the attachment preferences of cyprids. This study has not provided any data to prove the existence of inductive and inhibitive (to cyprid attachment) bacterial species in subtidal and intertidal films, respectively; however, results indicate that bacterial community provided qualitative information that might explain the preferential attachment of B. trigonus cyprids in subtidal habitat.
通过野外和实验室实验，研究了潮下带三角藤壶（Balanus trigonus Darwin）垂直分布的潜在驱动力。将早期幼体（约24小时龄）放置在潮间带（平均低潮位以上约0.5米）和潮下带（平均低潮位以下约3米）栖息地，其存活率相同，这表明香港水域潮间带没有三角藤壶并非由不同的死亡率决定。然而，潮下带栖息地中无节幼体附着增强，表明不同的幼体选择在决定其垂直分布方面很重要。在实验室中，无节幼体倾向于附着在潮下带微生物膜上，这可能意味着微生物膜是驱动成体垂直分布的主要线索。在这两个栖息地形成的微生物膜在生物量（=总有机碳）、细菌和硅藻丰度（通过荧光显微镜测定）以及细菌多样性（通过DNA指纹分析测定）方面存在差异。例如，潮下带栖息地6天的膜生物量显著高于潮间带栖息地的膜（P < 0.05）。在9天的膜中，这两个栖息地的膜生物量没有差异（P > 0.05）；然而，无论膜的年龄如何，潮下带膜中的细菌丰度都高于潮间带膜，尽管这两个栖息地的膜中硅藻丰度没有差异。细菌和硅藻的丰度以及生物量均与无节幼体的附着偏好无关。本研究未提供任何数据来证明潮下带和潮间带膜中分别存在诱导性和抑制性（对无节幼体附着）细菌物种；然而，结果表明细菌群落提供了定性信息，可能解释了三角藤壶无节幼体在潮下带栖息地的优先附着。
