iES Landau, Institute for Environmental Sciences, University of Koblenz-Landau, Fortstraße 7, D-76829, Landau, Germany.
iES Landau, Institute for Environmental Sciences, University of Koblenz-Landau, Fortstraße 7, D-76829, Landau, Germany; Eußerthal Ecosystem Research Station, University of Koblenz-Landau, Birkenthalstraße 13, D-76857, Eußerthal, Germany.
Environ Pollut. 2021 Sep 15;285:117234. doi: 10.1016/j.envpol.2021.117234. Epub 2021 Apr 24.
Aquatic hyphomycetes (AHs), a group of saprotrophic fungi adapted to submerged leaf litter, play key functional roles in stream ecosystems as decomposers and food source for higher trophic levels. Fungicides, controlling fungal pathogens, target evolutionary conserved molecular processes in fungi and contaminate streams via their use in agricultural and urban landscapes. Thus fungicides pose a risk to AHs and the functions they provide. To investigate the impacts of fungicide exposure on the composition and functioning of AH communities, we exposed four AH species in monocultures and mixed cultures to increasing fungicide concentrations (0, 5, 50, 500, and 2500 μg/L). We assessed the biomass of each species via quantitative real-time PCR. Moreover, leaf decomposition was investigated. In monocultures, none of the species was affected at environmentally relevant fungicide levels (5 and 50 μg/L). The two most tolerant species were able to colonize and decompose leaves even at very high fungicide levels (≥500 μg/L), although less efficiently. In mixed cultures, changes in leaf decomposition reflected the response pattern of the species most tolerant in monocultures. Accordingly, the decomposition process may be safeguarded by tolerant species in combination with functional redundancy. In all fungicide treatments, however, sensitive species were displaced and interactions between fungi changed from complementarity to competition. As AH community composition determines leaves' nutritional quality for consumers, the data suggest that fungicide exposures rather induce bottom-up effects in food webs than impairments in leaf decomposition.
水生真菌（AHs）是一组适应水下落叶的腐生真菌，作为分解者和更高营养级的食物来源，在溪流生态系统中发挥着关键的功能作用。杀菌剂通过控制真菌病原体，针对真菌中进化保守的分子过程，通过在农业和城市景观中的使用而污染溪流。因此，杀菌剂对 AHs 和它们提供的功能构成了威胁。为了研究杀菌剂暴露对 AH 群落组成和功能的影响，我们将四种 AH 物种在纯培养物和混合培养物中暴露于不断增加的杀菌剂浓度（0、5、50、500 和 2500μg/L）下。我们通过定量实时 PCR 评估了每种物种的生物量。此外，还研究了叶片分解。在纯培养物中，在环境相关的杀菌剂水平（5 和 50μg/L）下，没有一种物种受到影响。两种最具耐受性的物种即使在非常高的杀菌剂水平（≥500μg/L）下也能够定殖和分解叶片，尽管效率较低。在混合培养物中，叶片分解的变化反映了在纯培养物中最耐受物种的响应模式。因此，分解过程可能通过具有功能冗余的耐受物种来保护。然而，在所有杀菌剂处理中，敏感物种都被取代，真菌之间的相互作用从互补变为竞争。由于 AH 群落组成决定了叶片对消费者的营养质量，这些数据表明，杀菌剂暴露更可能在食物网中引起自上而下的效应，而不是对叶片分解造成损害。
