EARLY HEARING DETECTION AND INTERVENTION VIRTUAL CONFERENCE
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6/05/2017 | 3:30 PM - 3:45 PM | NITROGEN AND PHOSPHORUS HAVE DIFFERENT EFFECTS AT THE TOP AND BOTTOM OF STREAM FOOD WEBS | 306B

NITROGEN AND PHOSPHORUS HAVE DIFFERENT EFFECTS AT THE TOP AND BOTTOM OF STREAM FOOD WEBS

Causal relationships between excess nutrients and ecological responses that include diverse components of stream ecosystems are needed to effectively address nutrient pollution. Characterizing ecosystem-level nutrient limitation requires identifying the relative control of specific nutrient stressors (nitrogen [N] and/or phosphorus [P]) among ecosystem compartments. We used laboratory, mesocosm, and whole-stream studies to determine the response of organisms and processes to gradients in N vs P concentrations. From microorganisms to vertebrate predators, we detected differential trophic-level responses to streamwater N compared to P. We found greater responses to N than to P by fungi (2.2-15x, production) and algae (6-15x, chl-a; 3.3x, biomass) at the base of the food web, but greater responses to P than to N of macroinvertebrates (1.1-2.5x, production) and salamanders (1.1-1.6x, growth) at the top of the food web. Litter decomposition rates, which integrate microbial and macroinvertebrate processing, were limited more equally by both N and P. Our results show the complex nature of nutrient limitation among organisms across multiple trophic levels that need to be considered in establishing effective nutrient criteria to protect and restore aquatic ecosystems.

C25 Food Webs
C36 Water Resource Management
C01 Algae & C24 Eutrophication

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Presenters/Authors

Amy D. Rosemond (), University of Georgia, rosemond@uga.edu;