Effects of herbivore grazing on the physiognomy of the coralline alga Spongites yendoi and on associated competitive interactions
Effects of herbivore grazing on the physiognomy of the coralline alga Spongites yendoi and on associated competitive interactions
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DOI：
10.2989/ajms.2008.30.3.11.645
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发表时间：
2008-12-01
影响因子：
1.2
通讯作者：
Keats, D. W.
中科院分区：
文献类型：
--
作者：
Maneveldt, G. W.;Keats, D. W.
领土园艺帽贝Scutellastra cochlear发生沿着南部和南部西海岸的南非，而其主要食物之一，结壳珊瑚海绵yendoi，延伸到更远的北部沿着西海岸。通过对帽贝摄食频率地理变异的综合分析和对帽贝的操纵实验，研究了帽贝与其食物的相互作用。珊瑚包括大多数（C。85%），而来自帽贝花园的肉质藻类包括C。百分之七放牧造成的珊瑚叶状体薄而光滑，在没有草食动物，或低放牧频率下，地壳变得厚，高度突起。放牧削弱了珊瑚的干扰（过度生长）竞争能力，也降低了其繁殖力。尽管这两个明显的负面影响，密切的草食性珊瑚之间的关系，S。cochlear和S. yendoi显示出兼性互利共生的特征。由S。cochlear降低了珊瑚叶状体的厚度，从而增加了其侧缘延伸率。较薄的珊瑚虫生长速度比较厚的珊瑚虫快五倍。横向生长的增加导致较薄的珊瑚在南部和西南海岸非常丰富，占据了下海岸带底层的79%。S.与较厚的珊瑚相比，yendoi也较少被钻孔生物挖洞，而且附着力更强。由S。因此，耳蜗具有更快的横向生长（即，在开发竞争中的成功）和更强的附着的优点。帽贝花园里的珊瑚藻和肉质藻的有机物含量同样高。这表明，珊瑚和肉质藻类每咬一口的粗食物价值是相当的。这项研究表明，强烈相互作用的物种之间的不完全重叠分布沿着一个广泛的地理梯度不仅是陆地生态系统的一个重要特征，而且也是海洋生态系统的一个重要特征。
The territorial gardening limpet Scutellastra cochlear occurs along the south and southern west coasts of South Africa, whereas one of its primary food items, the encrusting coralline alga Spongites yendoi, extends much farther north along the West Coast. A combined analysis of geographic variation in limpet grazing frequency and a limpet-manipulation experiment was used to study the interaction between the limpet and its coralline food. The coralline comprised most (c. 85%) of the limpet's diet whereas fleshy algae from the limpet's garden comprised c. 7%. Grazing caused the thallus of the coralline to be thin and smooth; in the absence of herbivory, or under low grazing frequencies, the crust became thick and highly protuberant. Grazing weakened the coralline's interference (overgrowth) competitive ability and also reduced its fecundity. In spite of these two apparently negative impacts, the intimate herbivore coralline association between S. cochlear and S. yendoi showed characteristics of a facultative mutualism. Grazing by S. cochlear reduces the coralline's thallus thickness and consequently increased its lateral margin extension rate. Thinner forms of the coralline grew five times faster than thicker forms. An increased lateral growth results in the thinner form of the coralline being very abundant on the south and southern west coasts, occupying as much as 79% of the substratum in the lower eulittoral zone. Thinner forms of S. yendoi were also less burrowed by boring organisms and more strongly attached than thicker forms of the coralline. Grazing by S. cochlear has thus conferred the advantages of faster lateral growth (i.e. success at exploitation competition) and stronger attachment. The coralline and fleshy algae from the limpet's garden were equally high in organic content on a volume basis. This suggests that the crude food value per bite in the coralline and fleshy algae is comparable. This study has shown that incompletely overlapping distributions between strongly interacting species along a broad geographical gradient is not just a significant feature of the ecology of terrestrial, but also of marine ecosystems.