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SFS Annual Meeting

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A TEST OF ALGAL PRIMING EFFECTS DURING TYPHA LATIFOLIA DECOMPOSITION UNDER CONTRASTING DISSOLVED NUTRIENT LEVELS

The algal priming effect describes the stimulatory influence of labile carbon additions (e.g. exudates) on the microbial decomposition and mineralization of refractory organic matter. In aquatic ecosystems, the availability of dissolved nutrients could affect algal priming of microbial decomposition and mineralization of detritus. We incubated Typha latifolia leaf litter in greenhouse aquatic mesocosms under contrasting light/dark and low/high dissolved nutrient availability. Litter was collected to measure mass loss and litter-associated algal, fungal, and bacterial biomass and growth rates. Litter-associated algal production rates responded positively to increased light (P<0.001) and nutrients (P<0.05) additively. There were no significant effects of light or nutrient treatments on litter decomposition rates, although decomposition rates were consistently higher in dark treatments. While fungal biomass also did not respond to light or nutrient treatments, fungal growth rates were strongly stimulated by light (P<0.001). These findings suggest algae stimulate fungal growth short-term but may elicit weaker effects on long-term fungal biomass accrual or litter decomposition. Our findings carry important implications for our understanding of carbon cycling in aquatic ecosystems and suggest increased nutrient concentrations may not always affect the strength of algal priming during litter decomposition.

Tori Hebert (Primary Presenter/Author), University of Southern Mississippi, tori.hebert@usm.edu;


Halvor Halvorson (Co-Presenter/Co-Author), University of Southern Mississippi, halvor.halvorson@usm.edu;


Cody Pope (Co-Presenter/Co-Author), University of Southern Mississippi, Cody.pope@usm.edu;


Robert Findlay (Co-Presenter/Co-Author), University of Alabama, rfindlay@ua.edu;


Steven Francoeur (Co-Presenter/Co-Author), Eastern Michigan University, sfrancoeu@emich.edu;


Kevin Kuehn (Co-Presenter/Co-Author), The University of Southern Mississippi, kevin.kuehn@usm.edu;