Consumption explains intraspecific variation in nutrient recycling stoichiometry in a desert fish

Eric K. Moody, Evan W. Carson, Jessica R. Corman, Hector Espinosa-Pérez, Jorge Ramos, John Sabo, James Elser

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

Consumer-driven nutrient recycling can have substantial effects on primary production and patterns of nutrient limitation in aquatic ecosystems by altering the rates as well as the relative supplies of the key nutrients nitrogen (N) and phosphorus (P). While variation in nutrient recycling stoichiometry has been well-studied among species, the mechanisms that explain intraspecific variation in recycling N:P are not well-understood. We examined the relative importance of potential drivers of variation in nutrient recycling by the fish Gambusia marshi among aquatic habitats in the Cuatro Ciénegas basin of Coahuila, Mexico. There, G. marshi inhabits warm thermal springs with high predation pressure as well as cooler, surface runoff-fed systems with low predation pressure. We hypothesized that variation in food consumption among these habitats would drive intraspecific differences in excretion rates and N:P ratios. Stoichiometric models predicted that temperature alone should not cause substantial variation in excretion N:P, but that further reducing consumption rates should substantially increase excretion N:P. We performed temperature and diet ration manipulation experiments in the laboratory and found strong support for model predictions. We then tested these predictions in the field by measuring nutrient recycling rates and ratios as well as body stoichiometry of fish from nine sites that vary in temperature and predation pressure. Fish from warm, high-predation sites excreted nutrients at a lower N:P ratio than fish from cool, low-predation sites, consistent with the hypothesis that reduced consumption under reduced predation pressure had stronger consequences for P retention and excretion among populations than did variation in body stoichiometry. These results highlight the utility of stoichiometric models for predicting variation in consumer-driven nutrient recycling within a phenotypically variable species.

Original languageEnglish (US)
Pages (from-to)1552-1561
Number of pages10
JournalEcology
Volume99
Issue number7
DOIs
StatePublished - Jul 1 2018

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Keywords

  • Chihuahuan desert
  • desert spring
  • ecological stoichiometry
  • elemental phenotype
  • excretion
  • mosquitofish

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

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