Litter breakdown is an important ecological process at the bottom of food webs in streams. Previous studies have been based only on a temporal interval of a single season, thus ignoring seasonal variation in litter input and community structure. We investigated organic matter input in a Brazilian savanna stream and the influence of its associated hyphomycetes on the invertebrate community. Organic matter input was sampled monthly and the leaves submitted to decomposition experiments. There were lower breakdown rates and higher invertebrate species richness and abundance during the dry season, which reached their maximum in July due to low stream discharge. Invertebrate composition was best explained by hyphomycetes (mainly byFlagellospora curvulaandAnguillospora filiformis). Hyphomycetes have the capacity to degrade complex compounds of litter and to rapidly absorb nutrients by growing branched filaments, thus making the leaves more favourable for consumption by invertebrates. Shredder abundance was negatively related to litter richness, indicating possible species-specific relationships. We observed a sequential process with increased leaf litter input promoting an increase in hyphomycetes biomass, which in turn favoured invertebrate density.

中文翻译：

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巴西稀树草原溪流中的垃圾输入、丝状菌和无脊椎动物的模式：退化演替过程

凋落物分解是溪流食物网底部的一个重要生态过程。以前的研究仅基于单个季节的时间间隔，因此忽略了垫料输入和群落结构的季节性变化。我们调查了巴西稀树草原溪流中的有机物输入及其相关的丝状菌对无脊椎动物群落的影响。每月对有机物质输入进行采样，并将叶子进行分解实验。在旱季，分解率较低，无脊椎动物物种丰富度和丰度较高，由于河流流量较低，在 7 月达到最大值。无脊椎动物的组成最好用丝状菌来解释（主要是弯鞭毛孢菌和丝状鳗鲡）。Hyphomycetes 具有降解复杂复合物的能力，并通过生长分枝细丝快速吸收养分，从而使叶子更适合无脊椎动物食用。碎纸机丰度与凋落物丰富度呈负相关，表明可能存在物种特异性关系。我们观察到一个连续的过程，增加的落叶输入促进了丝状菌生物量的增加，这反过来又有利于无脊椎动物的密度。