2022 Early Hearing Detection & Intervention Virtual Conference

March 13 - 15, 2022

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5/26/2021  |   8:30 AM - 10:30 AM   |  STRENGTHS AND WEAKNESSES OF USING INCUBATION METHODS TO MEASURE EGESTION IN AQUATIC VERTEBRATES   |  Virtual Platform

STRENGTHS AND WEAKNESSES OF USING INCUBATION METHODS TO MEASURE EGESTION IN AQUATIC VERTEBRATES

Ecological stoichiometry uses mass-balance to evaluate how organisms convert dietary nutrients into waste. However, most aquatic research evaluates excreted wastes without considering egested wastes, as it is difficult both to collect egesta and to accurately analyze its nutrient content. We have systematically analyzed incubation methods to determine their efficacy in measuring egestion. We fed wild-caught stickleback, incubated them in 2L of water for 24 hours at one of two temperatures (16°C or 22°C), and checked for egestion at fixed intervals. We then estimated the mean quantity of phosphorus (P) leached from feces using the hindgut contents of euthanized fish as a fecal proxy. Egestion occurrence varied. While 82% and 75% of fish egested within 24 hours of feeding at 17°C and 22°C respectively, only 38% and 6% cleared their guts, making mass-balance analysis impossible. Furthermore, feces leached a mean of 41% (sd: 26.3) of its P during 2, 4, and 16 hour fecal incubations. These results imply that short incubations underestimate both quantity and nutrient content of egesta in aquatic animals. Therefore, researchers should incorporate other methods, such as foregut-hindgut analyses, with their incubation experiments to accurately evaluate egestion.

  • Nutrient cycling
  • Stoichiometry
  • Vertebrates

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Presenters/Authors

Emily May (), University of Victoria, emilymay@uvic.ca;


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Rana El-Sabaawi (), University of Victoria, rana@uvic.ca;


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