Abstract Fish may affect macrobenthic communities through trophic interactions and modification of habitat conditions. We compared the density, diversity and taxonomic composition of larval chironomids under low vs high fish impact, created by stocking semi-natural ponds with either young/small common carp Cyprinus carpio at low biomass densities or with high biomass densities of older/large common carp, supplemented by other cyprinids and predatory fish species. Over the study season, May–August, total chironomid abundance was considerably lower in ponds with high fish biomass than in low fish biomass ponds. In July–August larval densities declined significantly, irrespective of the fish status of the ponds. The composition of larval communities diverged between ponds with different fish status. Chironomus riparius and C. plumosus accounted for most of the observed dissimilarity. C. plumosus densities were not affected by the fish status of the pond, constituting on average >38 % of chironomid specimens in both types of ponds. C. riparius was abundant in ponds with low fish biomass (on average 30 %), but rare in ponds with high fish biomass (4 %). Other common taxa were Glyptotendipes pallens (15 % and 13 %, respectively) and Procladius sp. (14 % in ponds with low fish impact). Canonical correspondence analysis showed that fish biomass was more important in determining chironomid community composition than environmental variables indicative of pond eutrophication (total N, P, chlorophyll a and conductivity). Despite adverse effects on total abundance, chironomid diversity was higher under apparently stronger trophic pressure by fish. Fish may have relieved some chironomid species from invertebrate predation and competition with dominant Chironomus larvae. Other important drivers of chironomid assemblage and diversity patterns may include species-specific feeding modes and prey size selectivity of fish, the ability of chironomid larvae to attain size- and depth-refuge from small fish but not larger fish, and differential vulnerability of free-living and tube-dwelling larvae relative to ontogenetic niche shifts of fish.

中文翻译：

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在半永久性池塘鱼类较高的营养压力下，摇蚊幼虫的丰度减少但多样性增加

摘要 鱼类可能通过营养相互作用和栖息地条件的改变影响大型底栖动物群落。我们比较了在低和高鱼类影响下幼体摇蚊的密度、多样性和分类组成，通过在半天然池塘中放养低生物量密度的幼鱼/小型鲤鱼 Cyprinus carpio 或具有高生物量密度的老年/大型鲤鱼，辅以其他鲤科鱼类和掠食性鱼类。在 5 月至 8 月的研究季节，鱼类生物量高的池塘中摇蚊的总丰度远低于鱼类生物量低的池塘。无论池塘的鱼类状况如何，7 月至 8 月的幼虫密度都显着下降。幼虫群落的组成在不同鱼类状况的池塘之间存在差异。河岸摇蚊和 C. 羽毛占观察到的差异的大部分。C. plumosus 密度不受池塘鱼类状况的影响，在两种类型的池塘中平均占摇蚊样本的 38% 以上。C. riparius 在鱼类生物量低（平均 30%）的池塘中含量丰富，但在鱼类生物量高（4%）的池塘中很少见。其他常见的分类群是 Glyptotendipes pallens（分别为 15% 和 13%）和 Procladius sp。（在对鱼类影响较小的池塘中为 14%）。典型对应分析表明，鱼类生物量在确定摇蚊群落组成方面比指示池塘富营养化的环境变量（总 N、P、叶绿素 a 和电导率）更重要。尽管对总丰度有不利影响，但在鱼类明显更强的营养压力下，摇蚊的多样性更高。鱼类可能使一些摇蚊物种摆脱了无脊椎动物的捕食和与优势摇蚊幼虫的竞争。摇蚊组合和多样性模式的其他重要驱动因素可能包括特定物种的摄食模式和鱼类的猎物大小选择性、摇蚊幼虫从小鱼而不是大鱼获得大小和深度避难所的能力，以及自由环境脆弱性的不同脆弱性。与鱼类个体发育生态位变化相关的活体和管状幼虫。