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首页> 外文期刊>Marine ecology progress series >Geographic variation in the trophic ecology of an avian rocky shore predator, the African black oystercatcher, along the southern African coastline
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Geographic variation in the trophic ecology of an avian rocky shore predator, the African black oystercatcher, along the southern African coastline

机译：南部非洲海岸线沿岸岩石食肉动物非洲黑蛎black的营养生态地理分布

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摘要

The reflection of baseline isotopic signals along marine food chains up to higher trophic levels has been widely used in the study of oceanic top predators but rarely for intertidal predators. We investigated variation in the δ~(13)C and δ~(15)N ratios of a sedentary, rocky shore predator, the African black oystercatcher Haematopus moquini, over ～2000 km of the southern African coastline, which is characterized by strong biogeographic patterns in primary productivity and intertidal communities. Blood and feathers from breeding adults and chicks and muscle tissues from primary prey items (mussels and limpets) were sampled between southern Namibia and the southeast coast of South Africa. ~(15)N enrichment was observed between the southeast and west coasts in oystercatcher tissues and their prey, mirroring an isotope shift between the oligotrophic Agulhas Current on the east coast and the eutrophic Benguela upwelling system on the west coast. Oystercatcher blood showed δ~(13)C values that varied between those of the carbon-depleted mussels and the carbon-enriched limpets along the coastline, which reflected changes in the proportion of grazers and filter feeders in the oystercatcher diet across the sampling range. The geographic shift in diet, dominated by mussels on the west coast and composed of mixed proportions of mussels and limpets on the southeast coasts, strongly reflected regionally high abundances of the invasive Mediterranean mussel Mytilus galloprovincialis. Finally, isotope signatures of blood and feathers displayed a strong correlation throughout the study area, indicating seasonal stability in environmental conditions and feeding habits of the adults. There were, however, local discrepancies on the south coast that indicated movement of adults occurred outside the breeding season possibly in response to a lower abundance of food in this region. Overall, the results indicate that the influence of regional oceanic conditions on the base of the food web can penetrate to the predator level, but that local effects can be incorporated within this pattern.
机译：基线同位素信号沿着海洋食物链直至最高营养水平的反射已被广泛用于研究海洋顶级捕食者，但很少用于潮间带捕食者。我们调查了南部非洲海岸线约2,000公里以上的久坐，岩岸捕食者非洲黑牡蛎捕虾纲（Haematopus moquini）的δ〜（13）C和δ〜（15）N比的变化。初级生产力和潮间带社区的模式。在纳米比亚南部和南非东南海岸之间采样了来自成年成年的血液和羽毛以及来自主要猎物（贻贝和帽贝）的雏鸡和肌肉组织。在东南和西海岸的牡蛎捕捞组织及其猎物之间观察到〜（15）N富集，反映出东海岸的贫营养性Agulhas Current与西海岸的富营养化的Benguela上升流系统之间的同位素变化。牡蛎血液的δ〜（13）C值在沿海岸线的贫碳贻贝和富碳贝类之间变化，这反映了整个采样范围内牡蛎饮食中放牧者和滤食者的比例变化。饮食的地理变化以西海岸的贻贝为主，东南沿海的贻贝和贝类混合比例构成，这强烈反映了入侵地中海贻贝Mytilus galloprovincialis的区域丰富性。最后，血液和羽毛的同位素特征在整个研究区域内显示出很强的相关性，表明环境条件和成年人的进食习惯具有季节性稳定性。但是，南海岸存在局部差异，这表明成年牛的繁殖发生在繁殖季节之外，这可能是因为该地区食物不足的缘故。总体而言，结果表明，区域性海洋条件对食物网基础的影响可以渗透到捕食者的水平，但是局部影响可以纳入这种模式。

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