Faculty Mentor

Dr. Cynthia Tant


College of Arts and Sciences


Department of Biology



Download Poster (419 KB)


Availability of nutrients, particularly nitrogen (N) and phosphorus (P), is a key driver of microbial growth and metabolism in freshwater ecosystems. Microbial biofilms composed of both autotrophs and heterotrophs play crucial roles in freshwater food webs. These stream communities may be limited by N, P, or both N and P. This project examined nutrient limitation of biofilm communities in two small, freshwater streams in the Catawba river basin within the Catawba Nation in South Carolina. Stream conditions were monitored and nutrient concentrations for ambient ammonium and phosphate were monitored. We quantified nutrient limitation, community respiration, gross primary production, and ash-free dry mass of biofilms on two substrate types, selecting for autotrophs or heterotrophs, using nutrient diffusing substrates (NDS). NDS allow for slow, constant nutrient amendments for autotrophic and heterotrophic communities without affecting the rest of the ecosystem. Ambient nutrient concentrations in both streams were relatively low. Nevertheless, for all parameters except community respiration in one stream, microbial biofilms did not appear to be nutrient limited. In one stream, community respiration on substrates selecting for heterotrophs suggested those communities may be nutrient limited. Understanding how nutrients impact microorganism growth and metabolism in these streams is important for managing these resources and managing anthropogenic inputs in the surrounding watershed.

Publication Date





This project was supported by SC INBRE grants from the National Institute of General Medical Sciences (8 P20 GM103499) of the National Institutes of Health.

Nutrient limitation in freshwater streams in the South Carolina Piedmont

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Biology Commons



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