Veterinary antibiotics are intensively used in livestock farming to prevent and treat infections. However, they are often poorly absorbed in the animal gut and thus excreted unmetabolized. Through the use of contaminated manure as fertilizer, large amounts of antibiotics can enter the environment unintentionally and might accumulate in the soil of crop fields and adjacent natural vegetation. A number of studies have shown that a variety of antibiotics can be taken up by plants and accumulate in different plant parts with possible negative consequences, for example inhibited shoot and root growth or change of branching pattern. Plant responses are usually dose-dependent and vary with the type of antibiotic. Studies on the effects of antibiotics on higher trophic levels are rare and the majority of them use artificial diets enriched with antibiotics as experimental set-up. So far, there is no knowledge on how antibiotics transferred from manure to soil affect plant and animal communities in croplands and adjacent habitats.
This project therefore aims to study the effects of antibiotics in soil on specific traits of plants and on their interaction partners (higher trophic levels), using concentrations often found in manure-amended soils of croplands. Specifically, we will investigate the effect of different concentrations of the three most commonly sold antibiotic compound classes (sulfonamide, penicillin, tetracycline) on plants species from two functional groups (herbs, grasses) and agricultural cultivation (crop, non-crop). Here, we will investigate germination responses and plant traits such as canopy height, internode length, leaf chlorophyll content, biomass allocation, root length and element allocation. We will also test whether these antibiotics taken up by the plants affect the behaviour and reproductive success of herbivores (aphids) and pollinators (bees) in feeding and choice experiments. Our key objectives are to provide specific information on the responses to antibiotics in soil at the plant individual level, plant-trait level, plant community level and responses of higher trophic levels. This information will give us the basis to predict changes in plant and insect communities due to antibiotics at the landscape level.
Project duration: until 31.05.2017, funding by DFG