2023 Early Hearing Detection & Intervention Conference

March 5-7, 2023 • Cincinnati, OH

5/20/2019 | 11:45 AM - 12:00 PM | AMINO ACID STABLE ISOTOPES AND HETEROTROPHIC BIOFILMS IN RIVER FOOD WEBS | 250 DE

AMINO ACID STABLE ISOTOPES AND HETEROTROPHIC BIOFILMS IN RIVER FOOD WEBS

Patterns in essential amino acid (AAESS) d13C values from autotrophs and heterotrophs that can synthesize AAESS de novo may provide enhanced discriminatory power to trace heterotrophic biofilm-derived energy through freshwater food webs. However, no study has characterized producer patterns in AAESS d13C values in adjacent freshwater and terrestrial ecosystems. We analyzed AAESS d13C values of 14 producer taxa, including instream algae and riparian trees from the Rio Grande River and plants from the Chihuahuan Desert in New Mexico (n = 90). Using linear discriminant analysis, we characterized AAESS d13C patterns of producer taxa, yielding a successful reclassification rate of >70%. After confirming the utility of this approach, we completed a series of mesocosm experiments to study the trophic transfer of terrestrial- and heterotrophic biofilm-derived organic matter into aquatic invertebrates. Bulk tissue d13C data reveal freshwater invertebrates consumed terrestrial organic matter, including C4 grasses. Ongoing AAESS d13C analysis will allow us to examine the role of fungi and bacteria in converting terrestrial biomass into more palatable forms of energy. Our work highlights the potential for AAESS d13C analysis to reveal important biological interactions among producers, decomposers, and consumers in freshwater ecosystems.

Isotope
Aquatic-terrestrial Linkage
Food Webs

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Presenters/Authors

Alexi Besser (), University of New Mexico , acbesser@unm.edu;