Abstract:
Contaminants like trace metals and polyaromatic hydrocarbons can be carried by stormwater road runoff from impervious surfaces into receiving waters, potentially compromising ecosystem health. The microbial communities dispersed by stormwater include populations that are carried into green infrastructure designed to mitigate the effects of stormwater. In engineered bioswales, microbial communities may have an effect on the contaminant filtering functions of these swales, but this depends on the ability of microbes to survive dispersal and tolerate contaminants. Microbial communities sampled from stormwater and associated bioswales during a heavy precipitation event contained different assemblages. The evidence suggests that fungal communities and bacterial communities are assembled via different mechanisms, with deterministic processes being more important for fungi, and stochastic processes being more important for bacteria.
Bacteria selectively cultured from contaminant-amended stormwater media included isolates with variable growth and motility characteristics. Preliminary research indicates that interactions with metals can produce specific responses in growth motility-related behaviors for some isolates. This research is intended to develop methods to identify contaminant-sensitive indicator taxa for stormwater road-runoff monitoring, and the network of bioswales in Eugene, Oregon is a promising system to study for this purpose.