A Framework for Trait Inclusion in Fourth Corner Models: Application to Zooplankton Communities in Ontario Lakes

Characterizing zooplankton communities through functional traits offers a powerful complement to taxonomic approaches, yet no standardized framework guides the inclusion in ecological models. We develop and demonstrate a generalizable framework to evaluate trait inclusion in fourth corner RLQ models, using data from 45 lakes across Ontario, Canada. Taxonomic abundance, functional traits, and environmental variables were integrated to test how environmental and anthropogenic factors structure zooplankton communities. Bayesian regression provided quantitative support for including traits, after which RLQ and fourth corner analyses were applied. While ecoregion did not differ based on environmental variables alone, RLQ identified distinct community gradients along axes of nutrient productivity and lake depth. Fishing pressure was associated with shifts in feeding strategy rather than body size, with filter-feeders associated with low pressure lakes and raptorial feeders with high pressure lakes. Rotifers, often excluded from such analyses, comprised a substantial proportion of observed communities highlighting the importance of their inclusion. We recommend broader adoption of trait-based approaches across zooplankton and other taxa, as they reveal community patterns not captured by environmental gradients and taxonomy alone. 

Presentation Preference: Standard Oral (12 Minutes)

Primary Presenter: Sarah Rijkenberg, Ontario Tech University (sarah.rijkenberg@ontariotechu.net)

Authors:

Sarah Rijkenberg, Ontario Tech University  (sarah.rijkenberg@ontariotechu.net)

Tyler Harrow-Lyle, Toronto Region Conservation Authority and Ontario Tech University  (harrowlyle.tyler@gmail.com)

Andrea Kirkwood, Ontario Tech University  (andrea.kirkwood@ontariotechu.ca)