Correa Sandra Bibiana, Winemiller Kirk
Program of Ecology and Evolutionary Biology, Department of Wildlife and Fisheries Sciences, Texas A&M University, 2258 TAMU, College Station, TX, 77843-2258, USA.
Department of Wildlife, Fisheries and Aquaculture, Mississippi State University, Box 9680, Mississippi State, MS, 39762, USA.
Oecologia. 2018 Apr;186(4):1069-1078. doi: 10.1007/s00442-018-4093-7. Epub 2018 Feb 17.
Despite low in situ primary productivity, tropical oligotrophic rivers support highly diverse fish assemblages and productive fisheries. This raises the question, what energy sources support fish production in these ecosystems? We sampled fish and food resources in the floodplain of a nearly pristine, large, oligotrophic river in western Amazonia. We combined data from stomach contents and stable isotopes to test the hypothesis that floodplain forests sustain fisheries in tropical oligotrophic rivers. Analysis of stomach contents from > 800 specimens of 12 omnivorous fish species demonstrated that during the annual flood, forest plant matter dominated diets. Yet, our isotope mixing models estimated that arthropods from the forest canopy made a greater proportional contribution to fish biomass. Most of these arthropods are entirely terrestrial and, therefore, serve as trophic links between forests and fishes. Our results suggest that forest vegetation, particularly fruits, may provide much of the energy supporting metabolism and arthropods contribute significant amounts of protein for somatic growth. Moreover, the importance of terrestrial arthropods in support of fish biomass in oligotrophic rivers depends on interactions between riparian vegetation, terrestrial arthropods and flood pulse dynamics affecting accessibility of arthropods to fishes. The apparent paradox of high fish diversity in an oligotrophic river with low primary productivity may be explained, at least partially, by dynamic terrestrial-aquatic trophic linkages. This study further emphasizes the importance of seasonally flooded forests for sustaining fisheries in the Amazon.
尽管原位初级生产力较低，但热带贫营养河流却支持着高度多样的鱼类群落和高产渔业。这就引发了一个问题：在这些生态系统中，是什么能量来源支持鱼类生产？我们对亚马逊西部一条近乎原始的大型贫营养河流泛滥平原中的鱼类和食物资源进行了采样。我们结合了胃内容物数据和稳定同位素数据，以检验泛滥平原森林维持热带贫营养河流渔业这一假设。对12种杂食性鱼类的800多个样本的胃内容物分析表明，在年度洪水期间，森林植物物质在饮食中占主导地位。然而，我们的同位素混合模型估计，树冠层的节肢动物对鱼类生物量的比例贡献更大。这些节肢动物大多完全来自陆地，因此充当了森林与鱼类之间的营养纽带。我们的研究结果表明，森林植被，尤其是果实，可能提供了支持新陈代谢的大部分能量，而节肢动物为体细胞生长贡献了大量蛋白质。此外，陆地节肢动物在支持贫营养河流鱼类生物量方面的重要性取决于河岸植被、陆地节肢动物和洪水脉冲动态之间的相互作用，这些动态影响着节肢动物对鱼类的可及性。在初级生产力较低的贫营养河流中鱼类多样性较高这一明显的矛盾现象，至少部分可以通过动态的陆地 - 水生营养联系来解释。这项研究进一步强调了季节性淹没森林对维持亚马逊地区渔业的重要性。
