ABSTRACT: The abundances of bacteria, flagellates and ciliates were investigated over 13 mo in an unpolluted first-order stream. Four habitats on different substrates were integrated in our study: sediment, as well as the surfaces of dead wood, macrophytes, and leaf litter. Organismal biomass and secondary production in the habitats were calculated and the relative contribution to overall secondary production was estimated. We expected highest organismal densities on leaf litter in autumn and in the other 3 habitats in spring/summer. We assumed bacteria to be most abundant and ciliates to represent the highest biomass and dominate secondary production. Moreover, we hypothesized that dead wood and leaf litter would account for the largest share of total secondary production of all 4 habitats. In the stream’s sediment, protozoan abundance showed a trend towards a seasonal pattern. Annual mean abundance, biomass and secondary production by all organismal groups were highest on dead wood. Ciliates made up the highest percentage of total annual biomass in sediment and on dead wood and leaf litter, whereas on macrophytes, bacteria had the highest percentage of total annual biomass. In all habitats, ciliates had the highest share of secondary production. Total organismal secondary production during the sampled year was 660.6 µg C cm^-2, of which 71% was contributed by organisms on dead wood. The contribution of dead wood to the annual mean habitat cover ratio at the sampling site was only 9%, but it still made up 34% of total unicellular secondary production. Our study clearly showed that the unicellular secondary production on dead wood in streams has thus far been highly underestimated.

中文翻译：

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底栖生物在一级底栖生物在不同底物上的单细胞生物及其对次级生产的贡献

摘要：在未经污染的一级流中，在超过13 mo的时间内调查了细菌，鞭毛和纤毛的丰度。在我们的研究中整合了在不同基质上的四个栖息地：沉积物，以及枯木，大型植物和枯枝落叶的表面。计算了生境中的生物量和次级生产，并估算了其对总体次级生产的相对贡献。我们预计秋季和春季/夏季其他三个栖息地的凋落物的最高生物密度。我们认为细菌是最丰富的，纤毛代表最高的生物量，并主导着次级生产。此外，我们假设死木和枯枝落叶将在所有4个生境中占次生总产量的最大份额。在溪流的沉积物中 原生动物的丰度显示出向季节性模式发展的趋势。在枯木上，所有生物类别的年平均丰度，生物量和次要产量最高。纤毛虫在沉积物，枯木和枯枝落叶中的年度生物量总量中所占比例最高，而在大型植物上，细菌的生物量则占年度生物量中所占比例最高。在所有生境中，纤毛虫的次生产量所占比例最高。采样年中的总有机次级产量为660.6 µg C cm 在所有生境中，纤毛虫的次生产量所占比例最高。采样年中的总有机次级产量为660.6 µg C cm 在所有生境中，纤毛虫的次生产量所占比例最高。采样年中的总有机次级产量为660.6 µg C cm^-2，其中71％由枯木上的生物贡献。在采样地点，枯木对年平均栖息地覆盖率的贡献仅为9％，但仍占单细胞二次生产总量的34％。我们的研究清楚地表明，迄今为止，流中枯木的单细胞二次生产被大大低估了。