Fine sediment on leaves : shredder removal of sediment does not enhance fungal colonisationReport as inadecuate




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1 ECOLAB - Laboratoire Ecologie Fonctionnelle et Environnement - ECOLAB 2 UBC - University of British Columbia

Abstract : Inorganic fine sediments are easily carried into streams and rivers from disturbed land. These sediments can affect the stream biota, including detritivorous invertebrates shredders and impair ecosystem functions, such as leaf litter decomposition. We hypothesized that fine sediment kaolin deposited on leaves would reduce or suppress fungal development, reducing decomposition rates of leaves. Moreover, we predicted that shredders would act as ecosystem engineers by perturbing sediment deposition, reducing its impact on decomposition and fungi. We used a fully crossed experimental design of sediment addition control, 400 mg L-1 and shredders none, Gammarus, Potamophylax in laboratory aquaria. Leaf mass loss, sus- pended solids, microbial respiration, fungal biomass and spore production were measured. Sediment addition had no significant effects on the leaf mass remaining nor on shredders- consumption rates. However, sediment slightly reduced fungal assemblage richness and the sporulation rate of three fungal species. The presence of shredders sub- stantially increased the resuspension of fine sediments 300%,resultinginhighersuspendedloads.However,the action of shredders did not have a significant effect on fungal biomass nor on leaf mass loss. Even if shredders did not enhance fungal colonisation, they affected the settle- ment of fine sediment, serving as allogenic engineers. Our study suggests that concentrations of fine sediment of 400 mg L-1 with short exposure times 192 h can have some effect on leaf decomposition.

Keywords : Fine sediments Litter breakdown Aquatic hyphomycetes Detritivorous invertebrates Stream disturbance





Author: Isis Sanpera-Calbet - Eric Chauvet - John S. Richardson -

Source: https://hal.archives-ouvertes.fr/



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