title: Effects of multiple but low pesticide loads on aquatic fungal communities colonizing leaf litter.
abstract: In the first tier risk assessment (RA) of pesticides, risk for aquatic communities is estimated by using results from standard laboratory tests with algae, daphnids and fish for single pesticides such as herbicides, fungicides, and insecticides. However, fungi as key organisms for nutrient cycling in ecosystems as well as multiple pesticide applications are not considered in the RA. In this study, the effects of multiple low pesticide pulses using regulatory acceptable concentrations (RACs) on the dynamics of non-target aquatic fungi were investigated in a study using pond mesocosm. For that, fungi colonizing black alder (Alnus glutinosa) leaves were exposed to multiple, low pulses of 11 different pesticides over a period of 60days using a real farmer's pesticide application protocol for apple cropping. Four pond mesocosms served as treatments and 4 as controls. The composition of fungal communities colonizing the litter material was analyzed using a molecular fingerprinting approach based on the terminal Restriction Fragment Length Polymorphism (t-RFLP) of the fungal Internal Transcribed Spacer (ITS) region of the ribonucleic acid (RNA) gene(s). Our data indicated a clear fluctuation of fungal communities based on the degree of leaf litter degradation. However significant effects of the applied spraying sequence were not observed. Consequently also degradation rates of the litter material were not affected by the treatments. Our results indicate that the nutrient rich environment of the leaf litter material gave fungal communities the possibility to express genes that induce tolerance against the applied pesticides. Thus our data may not be transferred to other fresh water habitats with lower nutrient availability.
authors: Research Unit Environmental Genomics, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany. Electronic address: Anne.talk@hotmail.de.
authors: Anne
authors: A
authors: Talk
authors: Research Unit Environmental Genomics, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany.
authors: Susanne
authors: S
authors: Kublik
authors: Research Unit Environmental Genomics, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany.
authors: Marie
authors: M
authors: Uksa
authors: Research Unit Environmental Genomics, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany.
authors: Marion
authors: M
authors: Engel
authors: Umweltbundesamt, Dernburgstr. 7, 14057, Berlin, Germany.
authors: Rüdiger
authors: R
authors: Berghahn
authors: Research Unit Environmental Genomics, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany.
authors: Gerhard
authors: G
authors: Welzl
authors: Research Unit Environmental Genomics, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany. Electronic address: schloter@helmholtz-muenchen.de.
authors: Michael
authors: M
authors: Schloter
authors: Umweltbundesamt, Schichauweg 58, 12307, Berlin, Germany.
authors: Silvia
authors: S
authors: Mohr
mesh_terms: D055669:Ecological and Environmental Phenomena; D004784:Environmental Monitoring; D005658:Fungi / Q000187:drug effects* / Q000502:physiology; D005659:Fungicides, Industrial / Q000032:analysis / Q000633:toxicity; D006540:Herbicides / Q000032:analysis / Q000633:toxicity; D007306:Insecticides / Q000032:analysis / Q000633:toxicity; D010575:Pesticides / Q000032:analysis / Q000633:toxicity*; D018515:Plant Leaves; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity*
chemical_list: D005659:Fungicides, Industrial; D006540:Herbicides; D007306:Insecticides; D010575:Pesticides; D014874:Water Pollutants, Chemical
keywords: Fungal community structure; Leaf litter degradation; Mixture toxicity; Pesticides; Regulatory acceptable concentration