2023 Early Hearing Detection & Intervention Conference

March 5-7, 2023 • Cincinnati, OH

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5/23/2019  |   11:00 AM - 11:15 AM   |  AN IN SITU TEST SUPPORTS STRONG NEGATIVE ALGAL PRIMING OF LEAF DECOMPOSITION IN A LENTIC ECOSYSTEM   |  254 B

AN IN SITU TEST SUPPORTS STRONG NEGATIVE ALGAL PRIMING OF LEAF DECOMPOSITION IN A LENTIC ECOSYSTEM

During plant litter decomposition, periphytic algae can stimulate decomposer microbes and enhance decomposition through positive priming effects (PEs). Despite this potential importance of algae, the direction and magnitude of algal PEs in aquatic settings remain poorly tested, with only a limited number of studies that have shown mixed results. We tested algal PEs during decomposition of cattail litter (Typha domingensis) in a lake littoral zone using floating experimental mesocosms under extended light versus dark conditions. Light increased algal biomass and rates of algal production (P<0.001), which in turn stimulated fungal growth rates (P<0.001). Despite increases in algal-stimulated fungal growth, light significantly reduced fungal biomass (P<0.001), carbon-acquiring degradative enzymes ?-glucosidase, ?-xylosidase, and phenol oxidase (P<0.001), and litter mass loss rates (P<0.001). These findings of negative PEs support prior investigations conducted in a lotic ecosystem, where periphytic algae decoupled fungal activity from litter decomposition, likely by providing labile carbon invested in growth versus recalcitrant litter degradation. If common, such microbial interactions have important implications for our understanding of litter decay processes within aquatic ecosystems as well as flow of energy and nutrients to upper trophic levels.

• Decomposition
• Periphyton
• Organic Matter