Influence of urbanization on organic matter processing and nutrient immobilization in wadeable streams (southeastern USA)

Document Type

Article

Publication Date

12-1-2025

School

Biological, Environmental, and Earth Sciences

Abstract

Organic matter (OM) processing is a fundamental ecosystem function in freshwater streams that fuels community productivity and supports the provisioning of ecosystem services. Land conversion can disrupt the rates and quantity of OM processing by altering the physical, chemical, and biological conditions of stream ecosystems. In urban streams, understanding of mechanistic drivers and patterns of OM processing has been confounded because of the influences of numerous anthropogenic stressors operating at varying spatial scales, as well as inconsistencies in the substrate materials traditionally used to quantify rates of OM processing. Therefore, consistent and standardized assays are needed to better quantify rates of OM processing in urban streams and to inform our management of these systems for ecosystem and human health. In a study conducted in the greater Atlanta (Georgia, USA) metropolitan region, we deployed a standardized cotton-strip assay at 18 sites to investigate the influence of environmental drivers on OM processing in urban streams. Our findings suggest a correlation between higher rates of OM processing, expressed as the loss of cotton-strip tensile strength, and streams with higher impervious surface cover in their subwatersheds. Additionally, elevated rates of tensile-strength loss were associated with higher fungal glucosamine concentrations and higher P-immobilization rates. Notably, fungal glucosamine concentrations on the cotton strips were strongly correlated with impervious surface cover in the subwatershed. This study contributes to the expanding field of urban stream ecology, providing valuable insights into the effects of urbanization on ecosystem function. It also underscores the utility of cotton strips in disentangling the mechanistic drivers of OM processing in urban streams.

Publication Title

Freshwater Science

Volume

44

Issue

4

First Page

568

Last Page

583

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