Floodplain lakes are ecosystems characterised by annual flood and dry cycles. Fish ecology is influenced by the flood pulse due to the large influx of allochthonous food resources and diversification of habitats during the flood cycle, while during the dry cycle, fishes tend to be confined in reduced habitat. The aim of this study was to evaluate the seasonal variation in trophic niche width and overlap of four species—Mylossoma duriventre, Prochilodus nigricans, Cichla.pleiozona and Serrasalmus rhombeus—in an Amazonian floodplain lake. Stable isotope analyses were used to estimate trophic niche width and overlap during the flood and dry seasons. We hypothesised broader niche width for all species during the flood cycle and a higher degree of overlap between the two piscivorous fishes during the dry cycle. Isotopic niche width was 72% broader for P. nigricans, 61% for S. rhombeus and 54% for C. pleiozona during the dry cycle, which did not support our hypothesis. Core niche width overlaps were not observed between piscivorous species in either flood or dry cycle. The results indicate that seasonal variation in isotopic niche width is specific to feeding habit. Understanding how fish trophic ecology responds to changes in the hydrological regime during the seasons is crucial for sustainable fishery management in a region where many people rely heavily on fish for nutritional and economic purposes.

中文翻译：

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亚马逊河漫滩湖中的鱼类同位素生态位是否会随着水文状况发生变化？

泛滥平原湖泊是具有年度洪水和干旱循环特征的生态系统。由于洪水周期期间外来食物资源的大量涌入和栖息地的多样化，鱼类生态受到洪水脉冲的影响，而在旱季期间，鱼类往往被限制在减少的栖息地中。本研究的目的是评估四个物种 — Mylossoma duriventre、Prochilodus nigricans、Cichla.pleiozona和Serrasalmus rhombeus的营养生态位宽度和重叠的季节性变化——在亚马逊河漫滩湖中。稳定同位素分析用于估计洪水和旱季期间的营养生态位宽度和重叠。我们假设在洪水周期期间所有物种的生态位宽度更宽，而在干旱周期期间两种食鱼鱼类之间的重叠程度更高。P. nigricans的同位素生态位宽度宽 72% ， S. rhombeus 宽61% ， C. pleiozona宽54%在干循环期间，这不支持我们的假设。在洪水或干循环中，食鱼物种之间没有观察到核心生态位宽度重叠。结果表明，同位素生态位宽度的季节性变化是特定于摄食习惯的。了解鱼类营养生态如何响应季节期间水文状况的变化对于许多人严重依赖鱼类获得营养和经济目的的地区的可持续渔业管理至关重要。