Seasonal variability in the population structure of a habitat-forming kelp and a conspicuous gastropod grazer: Do blue-rayed limpets (Patella pellucida) exert top-down pressure on Laminaria digitata populations?
Seasonal variability in the population structure of a habitat-forming kelp and a conspicuous gastropod grazer: Do blue-rayed limpets (Patella pellucida) exert top-down pressure on Laminaria digitata populations?
复制标题
DOI：
10.1016/j.jembe.2018.06.011
复制
发表时间：
2018-09-01
影响因子：
2
通讯作者：
Smale, Dan A.
中科院分区：
文献类型：
--
作者：
Hereward, Hannah F. R.;Foggo, Andrew;Smale, Dan A.
海藻森林主要分布在中高纬度海岸线上暴露在海浪中的岩礁上。海带森林的分布和结构是由在不同空间和时间尺度上进行的一系列物理和生物过程决定的。许多海带森林系统受到草食性的强烈影响，特别是海胆的过度放牧是海带森林分布和结构的公认驱动因素。然而，与海带相关的帽状物食草性的生态意义却远未受到关注。我们量化了英国德文郡北部两个岩石海岸上的海带和蓝线海带的季节性种群动态。对于海带，我们量化了密度、覆盖率、形态、现存量、伸长率和侵蚀率，以及C：N和苯酚含量。对于帽贝，我们测量了丰度、生物量和形态，对于帽贝和海带的相互作用，我们记录了叶片上可观察到的掠食损伤。两个种群都表现出典型的季节性，海带生长速率在春季达到峰值，最大现存量在夏季观察到，而侵蚀率在秋季增加。蓝光帽贝被记录在海带封斋以及柄和叶片上，在春季招募，在夏末达到高峰，长度和生物量通常全年都在增加。海带叶片被放牧破坏的面积较小(最大接近4%)，全年相对一致，放牧伤痕的数量和大小表现出有限的季节性。来自英国其他种群的调查数据表明，北德文郡记录的帽贝丰度与该地区其他地点相当。尽管放牧对海带叶片组织的影响似乎很小，但需要进一步研究海带柄上的帽状物对海带叶片组织的空腔放牧，以先前评估这些空洞对移位和骨折率的影响，特别是当占有率和放牧增加与强烈的波浪作用时期重合时。我们的结论是，虽然食草性是作用于全球许多海带种群的一个重要过程，但透明螺旋藻对指藻的放牧压力不太可能强烈地影响英国岩石海岸的种群结构。
Kelp forests dominate wave-exposed rocky reefs along mid-to-high latitude coastlines. The distribution and structure of kelp forests is determined by a range of physical and biological processes operating across varying spatial and temporal scales. Many kelp forest systems are strongly influenced by herbivory, and overgrazing by urchins, in particular, is a recognised driver of kelp forest distribution and structure. The ecological significance of herbivory by kelp-associated limpets, however, has received far less attention. We quantified seasonal population dynamics of Laminaria digitata and the blue-rayed limpet Patella pellucida on two rocky shores in North Devon, UK. For the kelp, we quantified density, percent cover, morphology, standing biomass, elongation and erosion rates, and C:N and phenol content. For the limpet, we measured abundance, biomass, and morphology, and for the limpet-kelp interaction we recorded observable grazing damage on the blade. Both populations exhibited typical seasonality with kelp growth rates peaking in spring, maximum standing biomass observed in summer and increased erosion rates in autumn. Blue-rayed limpets, which were recorded within kelp holdfasts as well as on stipes and blades, recruited in spring and peaked in abundance in late summer, with length and biomass generally increasing through the year. The area of kelp blade damaged by limpet grazing was low (a maximum of similar to 4%) and relatively consistent throughout the year, and the number and size of grazing scars exhibited limited seasonality. Survey data from other L. digitata populations in the UK suggested that the limpet abundances recorded in North Devon were comparable with other sites in the region. Although the impact of P. pellucida grazing on kelp blade tissue appears to be minimal, further research into cavity grazing by limpets on the stipe and in the holdfast is needed to formerly assess the impact these cavities have on dislodgement and fracture rates, especially when increased occupancy and grazing coincides with periods of intense wave action. We conclude that while herbivory is an important processes acting upon many kelp populations globally, the grazing pressure exerted by P. pellucida on L. digitata is unlikely to strongly influence population structure on UK rocky shores.