1. Impervious Surface Category
Urbanization Alters Fatty Acid Concentrations of Stream Food Webs Within the Narragansett Bay Watershed
Sarah B. Whorley1,4, Nathan J. Smucker2, Anne Kuhn3, & John D. Wehr1
1Louis Calder Center, Fordham University, Armonk, NY 10504; 2Environmental Protection Agency, Water Supply and Water Resources Division, Cincinnati, OH 45220; 3Environmental Protection Agency, Atlantic Ecology Division, Narragansett, RI 02882; 4Natural Sciences Department, Daemen College, Amherst, NY 14226
Introduction
Urbanization degrades stream ecosystem quality
Algae produce many key essential fatty acid compounds, consumed by invertebrates
Organism diversity & health often adversely affected by urbanization
How does urbanization affect stream food web quality and relationships?
Conclusions
Increased nutrients in urban runoff may benefit some invertebrates by increasing periphyton EFAs
Invertebrate relationships differed by trophic level
Higher trophic levels EFA composition less varied
Low invertebrate taxonomic diversity
Investigate relationship to Stable Isotopes
Compare EFA to Algal & Invertebrate IBIs
Impervious Surface Category
FFG
Order or Family
<5%
5-10%
10-15%
>15%
Collecters
Chimara (Philopotamidae) 1
Hydropsychidae 4
Shredders
Limnephilidae  2 8
Tipulidae 3 6
Omnivores
Amphipods (Gammaridea)
Cambaridae
Isopods (Asellota)
Rhyacophilidae
Predators
Aeshnidae 11 5
Calopterygidae
Corydalidae 12 9
Gomphidae
Libellulidae
Perloidea
Few differences among EFA and % Impervious surface
Algal trends driven by ↑ Sw3
Invertebrate FFGs have different trends: Collectors ↑, Shredders ↓, Omnivores & Predators stable
All FFG: ALA, EPA, DHA, ARA significantly ↑ w/ %Impervious surface
Methods
GIS Analysis
For 78 stream sites: % Impervious surface, developed, forested, wetland
Stream Chemistry
SRP, NO3-, NH4+, Cl-
DOC, TN, TP
Impervious Surface
Algal Collection
6 cobbles
Invertebrate Collection
10 min kick net, 50 m
Common taxa from FFGs
-Collector, Shredder, Omnivore,
Predator
EFA Analysis
Chloroform extraction
≥18C: Total, Sw3, Sw6, Sother
w3: ALA, EPA, DHA
w6: LIN, ARA
Acknowledgements
We would like to thank Carlos Cruz-Quinones and Jonathan Serbst for assistance with sampling and laboratory processing, Colleen Elonen and Terri Jicha for chemistry analyses, and Mike Charpentier for generating GIS data. Funding was provided by the EPA.
PCA: Algal & FFG essential fatty acid profiles are distinct
Algae & Shredders most similar at lower % Impervious surface
Algae & Collectors most similar at high % Impervious surface
Predators & Omnivores have distinct patterns
GIS characteristics do not explain EFA concentrations
Regressions: % Impervious, developed, forested, wetland – n/s
Further Reading
Cashman, MJ; et al Freshwater Biology 58:
Smucker, NJ; Detenbeck, NE Restoration Ecology 6:
Smucker, NJ; et al Environmental Management 57:
Walsh, CJ; Webb, JA Freshwater Science 35: