McKenzie Prudence F, Bellgrove Alecia
School of Life and Environmental Sciences, Deakin University, PO Box 423, Warrnambool, Victoria 3280, Australia.
J Phycol. 2008 Oct;44(5):1108-15. doi: 10.1111/j.1529-8817.2008.00563.x. Epub 2008 Sep 3.
Drifting, fertile thalli are well documented to be the primary long-distance dispersal vector for many marine macroalgae, but little information about reproductive viability of drift is known. This study examined the reproductive viability and longevity of floating fragments of the intertidal Australasian fucoid Hormosira banksii (Turner) Decne. Beach wrack surveys and field experiments were conducted to test the model that long-distance dispersal is achieved in H. banksii via floating, fertile fronds. High densities of beach wrack fragments were evident during summer compared to autumn. The majority of beach wrack occurred on sandy beaches rather than rocky shores. Both male and female fragments were present in the beach wrack. Detached fronds were capable of releasing gametes up to 8 weeks after detachment. Beach wrack produced high fertilization rates and recruited successfully onto artificial panels. Results suggest that detached fragments are reproductively viable and that floating, fertile fronds may be an important mechanism for facilitating long-distance dispersal in this species. Nevertheless, the frequency of fronds reaching a suitable habitat and contributing to gene flow between populations, or colonizing new populations, may not be proportional to the total density of beach wrack.
漂浮的、具繁殖力的叶状体是许多海洋大型藻类主要的长距离传播媒介，这一点已有充分记录，但关于漂浮叶状体的繁殖活力却知之甚少。本研究调查了潮间带澳大利亚岩藻Hormosira banksii（特纳）德克内漂浮碎片的繁殖活力和寿命。进行了海滩残骸调查和野外实验，以验证H. banksii通过漂浮的具繁殖力的叶状体实现长距离传播的模型。与秋季相比，夏季海滩残骸碎片的密度明显更高。大部分海滩残骸出现在沙滩而非岩石海岸。海滩残骸中既有雄体碎片也有雌体碎片。脱离母体的叶状体在脱离后长达8周仍能释放配子。海滩残骸产生了高受精率，并成功附着在人工板上。结果表明，脱离的碎片具有繁殖活力，漂浮的具繁殖力的叶状体可能是促进该物种长距离传播的重要机制。然而，叶状体到达适宜栖息地并促进种群间基因流动或定殖新种群的频率，可能与海滩残骸的总密度不成正比。
