Seasonal variation in fish trophic networks in two clear-water streams in the Central Llanos region, Venezuela
Seasonal variation in fish trophic networks in two clear-water streams in the Central Llanos region, Venezuela
复制标题
委内瑞拉中部亚诺斯地区两条清水溪流鱼类营养网络的季节变化
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
K. Winemiller
中科院分区：
文献类型：
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作者：
C. Peterson;F. W. Keppeler;David E. Saenz;L. Bower;K. Winemiller
食物网不是静态的实体；消费者资源的相互作用在时间和空间上都是不同的，这使得食物网结构的描述和比较变得复杂。我们估计了委内瑞拉Llanos地区两条清水溪流（Charcote和Charcotico）的鱼类组合结构和饮食，并在每年洪水脉冲的四个时期构建了营养网络（由鱼类定义为主要消费者的子网）。随着河流条件从高水位到低水位的变化，我们假设：1)鱼类与非鱼类的比例会增加；2)膳食多样性降低；3)种间食料重叠减少；4)减少对外来食品的消费；食物网的联系也会增加。在低潮期，两条河流的鱼类与非鱼类丰度比均较高。饵料多样性随水位下降、水生生境和资源有效性降低而降低，但种间饵料重叠度不降低。与我们的假设相反，随着旱季的推进，Charcote的种间平均膳食重叠增加，尽管物种之间的膳食重叠明显低于偶然预期。我们没有发现强有力的证据支持我们关于异域资源消费和食物网连接的季节性模式的假设，这两个假设都显示了很少的季节性变化。
Food webs are not static entities; consumer resource interactions vary in both time and space, which complicates depiction and comparisons of food web structures. We estimated fish assemblage structure and diets in two clear-water streams in the Venezuelan Llanos region (Charcote and Charcotico) and constructed trophic networks (sub-webs defined by fishes as the principal consumers) during four periods of the annual flood pulse. As stream conditions changed from high-water to low-water, we hypothesized that: 1) the piscivore–non-piscivore ratio would increase; 2) dietary diversity would decrease; 3) interspecific dietary overlap would decline; 4) fewer allochthonous food items would be consumed; and 5) food-web connectance would increase. The piscivore-non-piscivore abundance ratio was higher in both streams during the low-water period. Dietary diversity declined as water levels dropped and availability of aquatic habitats and resources declined, but interspecific dietary overlap was not lower. Contrary to our hypothesis, average interspecific dietary overlap increased at Charcote as the dry season progressed, even though dietary overlap among species was significantly lower than expected by chance. We did not find strong support for our hypotheses regarding seasonal patterns of consumption of allochthonous resources and food web connectance, both of which revealed little seasonal variation.