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SFS Annual Meeting

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HIGH VARIATION IN NUTRIENT EXCRETION WITHIN A GUILD OF CLOSELY RELATED CADDISFLY SPECIES

Understanding the amount of variation in functional traits between closely related species within guilds is critical for understanding links between community composition and ecosystem processes. Nutrient excretion by aquatic animals can supply a considerable proportion of nutrient demand, but the functional redundancy within closely related guilds is unknown. To determine the magnitude of variation in nutrient excretion within a guild, we quantified nitrogen (N) and phosphorus (P) excretion rates of 10 larval caddisfly species that inhabit high elevation ponds. We found considerable interspecific variation in mass-specific excretion of N, P, and molar N:P ratios. We compared the success of species and trait-based models in explaining this variation, and found that traits can predict excretion as well as or better than species identity alone. A meta-analysis revealed a large range in variation among guilds of vertebrates and invertebrates, and that the variation within this caddisfly guild is comparatively high for N and intermediate for P excretion. Thus, despite similarities of species within biological groups such as guilds, using broad groupings could hinder predicting the consequences of species gains or losses due to substantial species-level variation in functional traits.

Jared Balik (Primary Presenter/Author), North Carolina State University, Rocky Mountain Biological Laboratory, jabalik2@ncsu.edu;


Brad Taylor (Co-Presenter/Co-Author), North Carolina State University Dept. of Applied Ecology; Rocky Mountain Biological Laboratory, bwtaylo3@ncsu.edu ;


Susan Washko (Co-Presenter/Co-Author), University of Arizona, swashko@email.arizona.edu;


Scott Wissinger (Co-Presenter/Co-Author), Allegheny College, swissing@allegheny.edu;