Dissolved oxygen concentration in freshwater streams is an important regulator of ecosystem processes and indicator of stream health. Urbanization may impact dissolved oxygen concentration in streams via increased primary production or decomposition of organic matter, which can be elevated due to a higher percentage of impervious surfaces and nonpoint source pollution or in-stream production.  In addition, streams in urban areas typically exhibit greater temperatures which can further influence dissolved oxygen levels compared to minimally disturbed forest streams. In order to determine the effects of urbanization on temperature and dissolved oxygen, we used sensors to continuously record these parameters for at least 24 hours once a month over an annual period.

Results/Conclusions

Preliminary analyses show that daily means and diurnal variation in dissolved oxygen concentrations are higher at suburban sites compared to urban and ultra-urban sites. Sites in areas of less urban development exhibit higher dissolved oxygen concentrations and lower temperatures than sites closer to the urban center.  There is a significant increase in dissolved oxygen concentration as temperature decreases. This occurs diurnally as well as seasonally. Initial results point to the conclusion that urban development correlates with increased temperature and decreased concentration of dissolved oxygen, but that suburban streams show surprisingly high levels of variability in dissolved oxygen.  Urban streams may be metabolically active transformers of organic matter, and future changes in temperatures may interact with urbanization to influence the carbon cycle in streams