Direct and indirect effects of a macroalgal canopy and limpet grazing in structuring a sheltered inter-tidal community
Direct and indirect effects of a macroalgal canopy and limpet grazing in structuring a sheltered inter-tidal community
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大型藻冠和帽贝放牧对构建受保护的潮间带群落的直接和间接影响
DOI：
10.3354/meps188081
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发表时间：
1999
影响因子：
2.5
通讯作者：
T. Norton
中科院分区：
文献类型：
--
作者：
S. Jenkins;S. Hawkins;T. Norton
对英国马恩岛南部 4 个受庇护的岩石海岸的中岸群落的主要组成部分进行了调查。在 1 个地点进行了一项双向析因实验，以调查泡叶藻（以下简称泡叶藻）树冠和 Patella vulgata 放牧的群落结构作用，并进行了为期 6 年的监测。移除树冠对林下群落产生了显着影响，包括直接和间接影响。相比之下，由于这种食草动物仅限于红藻草皮内的小块裸露基质，因此去除帽贝的效果有限。泡叶藻的树冠直接促进了中岸红藻草皮的出现；移除树冠导致草皮物种白化和死亡，随之而来的是截留淤泥的损失。草皮的退化导致帽贝放牧面积增加，随后帽贝补充量增加，与裸露基质面积的增加成比例。因此，泡叶藻冠层通过促进红藻草皮的生长间接限制了泡叶藻的数量。除去泡叶藻十八个月后，出现了墨角藻和锯齿墨角藻的混合树冠。这与原始树冠的作用类似，为草皮物种提供遮荫，从而恢复了藻类草皮和帽贝放牧之间的平衡。尽管如此，红藻草皮在最初被漂白后五年仍未完全恢复，这说明了泡叶藻冠层损失对该群落的长期影响。移除树冠也导致大量泡叶藻的补充，但这些幼年植物的生长速度缓慢，意味着在移除树冠近 6 年之后，泡叶藻树冠仍未发育。尽管如此，我们预测泡叶藻最终将在竞争中击败墨角藻属。天篷。对泡叶藻幼体分布的详细检查表明，自然种群中幼体的低密度是由于缺乏没有帽贝和占据空间的草皮的基质，而不是树冠的直接影响。
The dominant components of the mid-shore community of 4 sheltered, rocky shores in the south of the Isle of Man, UK, were surveyed. A 2-way factorial experiment to investigate the community structuring roles of Ascophyllum nodosum (hereafter Ascophyllum) canopies and Patella vulgata grazing was undertaken at 1 site and monitored over a period of 6 yr. Removal of the canopy had a marked impact on the understorey community, with both direct and indirect effects. In contrast, the effect of limpet removal was limited, owing to the restriction of this grazer to small patches of bare substrate within a turf of red algae. The Ascophyllum canopy directly facilitated the presence of the red algal turf in the mid-shore; canopy removal resulted in bleaching and death of turf species with a consequent loss of entrapped silt. This degradation of the turf resulted in an increase in the area grazed by limpets and a subsequent increase in limpet recruitment, proportional to the increased area of bare substratum. Thus, the Ascophyllum canopy indirectly limits the population of P. vulgata by facilitating the growth of a red algal turf. Eighteen months after Ascophyllum removal, a mixed canopy of Fucus vesiculosus and Fucus serratus developed. This acted in a similar manner to the original canopy, providing shade for turf species, which resulted in restoration of the balance between algal turf and limpet grazing. Despite this, the red algal turf had not fully recovered 5 yr after it was originally bleached, illustrating the long-term effects of Ascophyllum canopy loss on this community. Removal of the canopy also resulted in high levels of Ascophyllum recruitment, but the slow growth rate of these juvenile plants meant that nearly 6 yr after canopy removal, an Ascophyllum canopy had still not developed. Nonetheless, we predict that Ascophyllum will eventually outcompete the established Fucus spp. canopy. Detailed examination of the distribution of Ascophyllum juveniles suggests that the low density of juveniles in the natural population is due to a lack of substratum free from both limpets and space-occupying turf, rather than a direct effect of the canopy.