BayCEER Workshop 2016

Impact of Impatiens glandulifera on a local freshwater community: A mesocosm study

O 3.3 in Water and the environment: From biosphere to geosphere

13.10.2016, 11:45-12:00, H36, NW III

Invasive alien species (IAS) are a major threat to native plants and animals in Europe. These species are introduced intentionally or unintentionally by humans and have the potential to spread over large areas. Successful invasions can lead to a decline of many local species and as a result to a loss of biodiversity in the affected area. The annual weed plant Impatiens glandulifera Royle (Himalayan balsam) is already spreading in 27 European countries, where it occurs mainly in riparian zones and often forms large monocultures. Its invasive success is amongst others due to the release of allelopathic substances such as 2-methoxy-1,4- naphthoquinone (2-MNQ). This substance, which has been shown to have a negative impact on germination and growth of competitors, is washed out by rainfall and can therefore be expected to enter adjacent waterbodies via surface runoff. So far, it is not known if the allelopathic compounds of I. glandulifera may also affect aquatic ecosystems. In this study we conducted a mesocosm experiment to investigate the effects of I. glandulifera on a simplified aquatic ecosystem. We show that exposure to I. glandulifera does not affect primary production (i.e. chlorophyll a concentration) by the green alga Acutodesmus obliquus, but leads to a significantly reduced population size of the water flea Daphnia magna. Therefore, our results indicate that I. glandulifera does not only affect the invaded terrestrial ecosystems, but potentially also neighbouring aquatic ecosystems. Given the widespread invasion of I. glandulifera along European freshwaters, there is an urgent need to further assess its effects on this important habitat. 

Keywords: plant invasion 2-methoxy-1,4- naphthoquinone aquatic ecosystems Cladocera

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