Changes in nutrient stoichiometry, elemental homeostasis and growth rate of aquatic litter-associated fungi in response to inorganic nutrient supply

Aquatic fungi mediate important energy and nutrient transfers in freshwater ecosystems, a role potentially altered by widespread eutrophication. We studied the effects of dissolved nitrogen (N) and phosphorus (P) concentrations and ratios on fungal stoichiometry, elemental homeostasis, nutrient upta...

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Bibliographic Details
Published in:The ISME Journal 2017-12, Vol.11 (12), p.2729-2739
Main Authors: Gulis, Vladislav, Kuehn, Kevin A, Schoettle, Louie N, Leach, Desiree, Benstead, Jonathan P, Rosemond, Amy D
Format: Article
Language:English
Subjects:
Aquatic ecosystems
Aquatic fungi
Biomass
Carbon - metabolism
Ecological monitoring
Ecosystem
Environmental changes
Eutrophication
Food chains
Food webs
Fresh Water - chemistry
Fresh Water - microbiology
Freshwater ecosystems
Fungi
Fungi - growth & development
Fungi - metabolism
Growth rate
Homeostasis
Leaf litter
Microcosms
Nitrogen
Nitrogen - metabolism
Nutrient concentrations
Nutrient flow
Nutrient uptake
Nutrients
Original
Phosphorus
Phosphorus - metabolism
Plant Leaves - chemistry
Plant Leaves - microbiology
Radioactive tracers
Stoichiometry
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Summary:Aquatic fungi mediate important energy and nutrient transfers in freshwater ecosystems, a role potentially altered by widespread eutrophication. We studied the effects of dissolved nitrogen (N) and phosphorus (P) concentrations and ratios on fungal stoichiometry, elemental homeostasis, nutrient uptake and growth rate in two experiments that used (1) liquid media and a relatively recalcitrant carbon (C) source and (2) fungi grown on leaf litter in microcosms. Two monospecific fungal cultures and a multi-species assemblage were assessed in each experiment. Combining a radioactive tracer to estimate fungal production (C accrual) with N and P uptake measurements provided an ecologically relevant estimate of mean fungal C:N:P of 107:9:1 in litter-associated fungi, similar to the 92:9:1 obtained from liquid cultures. Aquatic fungi were found to be relatively homeostatic with respect to their C:N ratio (~11:1), but non-homeostatic with respect to C:P and N:P. Dissolved N greatly affected fungal growth rate and production, with little effect on C:nutrient stoichiometry. Conversely, dissolved P did not affect fungal growth and production but controlled biomass C:P and N:P, probably via luxury P uptake and storage. The ability of fungi to immobilize and store excess P may alter nutrient flow through aquatic food webs and affect ecosystem functioning.
ISSN:1751-7362
1751-7370
DOI:10.1038/ismej.2017.123