USING ACOUSTIC MONITORING TO UNDERSTAND SOURCES OF TURBIDITY IN STREAM

Turbidity is an important measure in drinking water quality. However, there is difficulty ascertaining sources of turbidity due to the resources needed to monitor streams and finding sources of turbidity can be puzzling when there are diel cycles within a stream despite no changes in water level. Six Mile Creek, located in Mclean County, Illinois, is a small agricultural stream in the Evergreen Lake watershed that exhibits diel turbidity cycle changes of 10 NTUs. We hypothesize that turbidity is being caused by increased bioactivity in the stream at night. To understand the potential for bioactivity to influence diel turbidity cycles we deployed a hydrophone in Six Mile Creek to record frequency over time. We then analyzed the recorded acoustics in R using the packages Seewave, TunerR, and Soundecology, to obtain acoustic indices and compared the day and night cycle indices against each other. We also chose to record at different dates including those for moon cycles changes of new and full moons. When analyzing the acoustic complexity, we can see a small increase in the average from day cycles (from times 12:45 to 18:45) to night cycles (from times 21:55 to 02:55) of 7.512. In the acoustic diversity index, we see a difference of over 100% from day to night cycles (an increase from 0.342094 to 1.06686). Preliminary results show that there is a difference between day and night cycles for acoustic indices that were measured and show an increase in the amount of biodiversity at night. This supports the hypothesis that diel turbidity increases are caused by increased bioactivity at night in the stream.