Harbouring the enemy: kelp holdfasts protect juvenile sea urchins from predatory crabs
Harbouring the enemy: kelp holdfasts protect juvenile sea urchins from predatory crabs
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庇护敌人：海带固着物保护幼年海胆免受捕食性螃蟹的侵害
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
R. Scheibling
中科院分区：
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作者：
Colette J. Feehan;F. T. Francis;R. Scheibling
捕食是海胆定居后死亡率的一个重要因素，这是由空间避难所的可用性和适用性介导的，特别是在脆弱的少年阶段。在实验室和野外的笼舍实验中，我们发现，一种占主导地位的海带-在大西洋西北部的海带床生态系统中，被认为是海胆的主要捕食者。在处理与个别螃蟹的任一物种，holdfasts的存在减少捕食幼海胆~20至30%相比，没有避难所的治疗。螃蟹消耗幼奈尔斯（从5至19毫米），在每三个5毫米大小的阶级，其丰度成比例，不考虑治疗。在加拿大新斯科舍省的圣伯茨湾的海带床中，每个固着器中的幼海胆数量从0.3到0.9不等，固着器中的幼海胆占一个地点的总海胆种群密度的三分之二。多达4个少年发生在一个单一的固着器，有一个显着的正相关关系少年大小（但不是数量）和固着体积。小的成年海胆没有发现在海带床的holdfasts内，很少占用holdfasts在实验室的笼子里给他们。我们的研究结果表明，海胆海带相互作用的个体发生学转变，海带促进其主要食草动物的招聘。
Predation is an important agent of post-settlement mortality of sea urchins that is mediated by the availability and suitability of spatial refuges, particularly during the vulnerable juvenile stage. In laboratory and field caging experiments, we show that holdfasts of a dominant kelp, Saccharina latissima, provide a spatial refuge for juvenile sea urchins Strongylocentrotus droebachiensis (< 20 mm, test diameter) from crabs Cancer borealis and C. irroratus, considered to be the dominant predators of sea urchins in kelp-bed ecosystems in the northwestern Atlantic. In treatments with individual crabs of either species, the presence of holdfasts reduced predation on juvenile sea urchins by ~20 to 30% compared to treatments with no refuge. Crabs consumed juve- niles (from 5 to 19 mm) in each of three 5 mm size classes in proportion to their abundance, regard- less of treatment. In kelp beds in St. Margarets Bay, Nova Scotia, Canada, the number of juvenile sea urchins per holdfast ranged from 0.3 to 0.9, with juveniles in holdfasts accounting for two- thirds of the total urchin population density at one site. Up to 4 juveniles occurred within a single holdfast, and there was a significant positive relationship between juvenile size (but not number) and holdfast volume. Small adult sea urchins were not found within holdfasts in kelp beds and rarely occupied holdfasts presented to them in laboratory cages. Our findings indicate an ontoge- netic shift in sea urchin-kelp interactions, whereby kelp facilitates recruitment of its major grazer.