Decay processes in woody debris influence the taxonomic and functional composition of littoral macroinvertebrates

Abstract

We examined the effects of woody debris decay state on the densities, taxonomic and functional composition, and diversity of macroinvertebrates in littoral zones of undeveloped lakes. Our study revealed that the interacting effects of increasing roughness and softness of the wood, as well as changes in the quality of food resources with progressing decomposition of woody debris, exerted the strongest impacts on macroinvertebrate communities. Structurally complex, decomposed wood supported higher densities and species richness of macroinvertebrates than undecayed wood. We also found several taxa that were typical for decayed wood, including macroinvertebrates considered as xylophages. Decaying wood underpinned greater functional richness than undecayed wood, with high densities of collector–gatherers and shredders that could benefit from organic matter originating from decomposing wooden tissue, as well as predators attracted by numerous potential prey inhabiting this complex habitat. As decaying wood enhanced abundant and diverse macroinvertebrate communities, which in turn could subsidize upper trophic levels, it provides a valuable habitat in littoral zones, particularly in lakes with already sparse macrophyte cover.

Quantitative Flow‐Ecology Relationships Using Distributed Lag Nonlinear Models: Large Floods in the Murray River Could Have Delayed Effects on Aquatic Macroinvertebrates Lasting More Than Three Decades

“…These authors noted that their models explained only about one third of the variance in macroinvertebrate metrics, concluding that food resources and substrate cover were not the only drivers of community composition. In the future, it might be worth considering the structural complexity of the woody debris as well because there is evidence that the decay state of the woody debris is an important determinant of the density and species richness of macroinvertebrates (Czarnecka & Miler, 2018). Clearly, there is a need for further research to verify whether a response measured with ASSs (a passive method) is proportional to both the amount and structural complexity (decay state) of woody debris at the reach scale.…”