High interspecific variation in nutrient excretion within a guild of closely related caddisfly species

Abstract

Abstract. 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 is an important link between animals and their environments, and aquatic invertebrate communities can supply a considerable proportion of ecosystem nutrient demand via excretion. We quantified nitrogen (N) and phosphorus (P) excretion rates of 10 species of larval caddisflies that inhabit high-elevation ponds and wetlands to determine the magnitude of variation in nutrient excretion within this guild. We found considerable interspecific variation in biomass-specific excretion of nitrogen (eightfold differences), phosphorus (sevenfold differences), and the stoichiometric N:P ratios (fivefold differences). Through a meta-analysis, we compared the variation within this guild to the variation found in other family-level species assemblages to determine the overall range in the variation of nutrient excretion that could be expected across guilds and to determine whether the variation in this caddisfly guild is comparatively extreme, average, or low. The meta-analysis revealed a large range in variation among guilds, and comparatively, the variation within this caddisfly guild is high for N excretion and intermediate for P excretion. The considerable variation within guilds revealed by our metaanalysis suggests that functional redundancy among guild members is difficult to predict. Thus, some natural or human-caused species gains or losses within biological groupings such as guilds and trophic levels could have little or no effect on ecosystem processes, whereas others could have very large effects.

Evolutionary history drives aspects of stoichiometric niche variation and functional effects within a guild

“…This lower tissue N:P resulted in higher excretion N:P. We suggest that since tissue stoichiometry, especially N:P, varies as a result of life‐history characteristics, it is a powerful tool for examining the congruence between evolutionary history and trait variation, and their consequential effects of community assembly and ecosystem function. Recent work in ES and consumer‐driven nutrient dynamics has shown a large degree of intra‐ and interspecific variation in tissue and nutrient recycling stoichiometry (El‐Sabaawi et al 2015, Balik et al 2018, Dalton et al 2018) and further research across taxa, populations, and life stages will help elucidate the patterns and processes associated with stoichiometric niche partitioning.…”

Biomass loss and change in species dominance shift stream community excretion stoichiometry during severe drought

“…Although crayfish stoichiometry may vary during base-flow conditions, we predict that nutrients controlled by crayfishes may be important to ecosystem functions, including microbial respiration and leaf decomposition in isolated pools dominated by this group (Rosemond, Pringle, Ramírex, Paul, & Meyer, 2002). Other aquatic macroinvertebrates not quantified in our study can maintain high densities during stream drying (Boulton & Lake, 1992) and their contributions to nutrient cycling may exceed that of the macroconsumers measured here Balik, Taylor, Washko, & Wissinger, 2018). Regardless, our study contributes evidence that the relative dominance of broad taxonomic groups (e.g.…”

“…For example, previous work investigating somatic stoichiometry of crayfish (Evans-White & Lamberti, 2005) indicated that they might act as P sinks in isolated pools given their relatively high excretion N:P and low N:P tissue stoichiometry. Other aquatic macroinvertebrates not quantified in our study can maintain high densities during stream drying (Boulton & Lake, 1992) and their contributions to nutrient cycling may exceed that of the macroconsumers measured here Balik, Taylor, Washko, & Wissinger, 2018). Other aquatic macroinvertebrates not quantified in our study can maintain high densities during stream drying (Boulton & Lake, 1992) and their contributions to nutrient cycling may exceed that of the macroconsumers measured here Balik, Taylor, Washko, & Wissinger, 2018).…”

Retreat but no surrender: net-spinning caddisfly (Hydropsychidae) silk has enduring effects on stream channel hydraulics

“…Hydropsychid caddisflies have alternative forms of silk structures depending on several environmental factors, including pollutants, flow velocity, and species (Petersen & Petersen, 1983;Loudon & Alstad, 1992;Balch et al, 2000;Wiggins, 2007;Albertson et al, 2014b). A growing body of literature highlights the importance of both inter-and intraspecific trait variation in modulating animal-environment realtionships (Bolnick et al, 2011;Balik et al, 2018). In our study system, this variation in form and durability of the caddisfly retreat structures could mediate how much a particular retreat influences local flow conditions since evidence does suggest that net-building design is plastic and not under strict genetic control (Plague & McArthur, 2003).…”