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URBANIZATION ALTERS FATTY ACID CONCENTRATIONS OF STREAM FOOD WEBS IN THE NARRAGANSETT BAY WATERSHED
Citation:
Whorley, S., N. Smucker, A. Kuhn, AND J. Wehr. URBANIZATION ALTERS FATTY ACID CONCENTRATIONS OF STREAM FOOD WEBS IN THE NARRAGANSETT BAY WATERSHED. Presented at Society for Freshwater Science, Sacramento, CA, May 21 - 26, 2016.
Impact/Purpose:
Urbanization negatively affects the biology of stream ecosystems by increasing the delivery of pollutants and by altering habitats and flow regimes. Many of these stressors act directly on stream organisms, but organisms may be further affected by changes in the nutritional quality of food resources. This study found that watershed urbanization can alter the concentrations of fatty acids in stream organisms, which is important because animals cannot independently synthesize fatty acids essential to their growth, behavior, and survival, making them reliant on the fatty acid content of their diets.
Description:
Urbanization and associated human activities negatively affect stream algal and invertebrate assemblages, likely altering food webs. Our goal was to determine if urbanization affects food web essential fatty acids (EFAs) and if EFAs could be useful ecological indicators in monitoring efforts. Streams along a gradient of urbanization in the Narragansett Bay Watershed (USA) were sampled for water chemistry, benthic algae, and invertebrates. EFA content of algae and invertebrates was categorized in several compound groups (Total, omega-3, omega-6, and Other). Algal total EFA content increased from 0.89 mg/m2 in rural streams to 1.63 mg/m2 in urbanized streams. Biologically important omega-3 compounds of algae increased 0.402 mg/m2 from rural to urban streams, but not significantly (Total: F = 1.149, P = 0.344). For invertebrate functional feeding groups, total EFA content decreased for collectors (1.08 mg/g) and omnivores (2.40 mg/g) with increasing urbanization, whereas total EFA content increased for shredders (0.69 mg/g) and predators (0.32 mg/g). These results indicate that urbanization likely affects nutritional qualities of different trophic positions in stream food webs.
