A high-throughput method to quantify feeding rates in aquatic organisms: A case study with Daphnia

Authors

Jessica L. Hite, Virginia Commonwealth University & University of Nebraska- LincolnFollow
Alaina C. Pfenning-Butterworth, University of Nebraska-Lincoln
Rachel E. Vetter, University of Nebraska-Lincoln
Clayton E. Cressler, University of Nebraska-LincolnFollow

ORCID IDs

Jessica L. Hite https://orcid.org/0000-0003-4955-0794

Date of this Version

2020

Citation

Hite JL, Pfenning-Butterworth AC, Vetter RE, Cressler CE. A high-throughput method to quantify feeding rates in aquatic organisms: A case study with Daphnia. Ecol Evol. 2020;10:6239–6245. https://doi.org/10.1002/ ece3.6352

Comments

Copyright 2020 by the Authors. This is an open access article under the terms of the Creative Commons Attribution License

Abstract

1. Food ingestion is one of the most basic features of all organisms. However, obtaining precise—and high-throughput—estimates of feeding rates remains challenging, particularly for small, aquatic herbivores such as zooplankton, snails, and tadpoles. These animals typically consume low volumes of food that are time-consuming to accurately measure.

2. We extend a standard high-throughput fluorometry technique, which uses a microplate reader and 96-well plates, as a practical tool for studies in ecology, evolution, and disease biology. We outline technical and methodological details to optimize quantification of individual feeding rates, improve accuracy, and minimize sampling error.

3. This high-throughput assay offers several advantages over previous methods, including i) substantially reduced time allotments per sample to facilitate larger, more efficient experiments; ii) technical replicates; and iii) conversion of in vivo measurements to units (mL^-1 hr^-1 ind^-1) which enables broad-scale comparisons across an array of taxa and studies.

4. To evaluate the accuracy and feasibility of our approach, we use the zooplankton, Daphnia dentifera, as a case study. Our results indicate that this procedure accurately quantifies feeding rates and highlights differences among seven genotypes.

5. The method detailed here has broad applicability to a diverse array of aquatic taxa, their resources, environmental contaminants (e.g., plastics), and infectious agents. We discuss simple extensions to quantify epidemiologically relevant traits, such as pathogen exposure and transmission rates, for infectious agents with oral or trophic transmission.