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THE EFFECTS OF LOW-LEVEL SALT CONCENTRATIONS ON PHOTOSYNTHESIS, GROWTH, AND CARBOHYDRATE CONCENTRATIONS OF PERIPHYTON

Freshwater salinization is increasing from activities associated with human development. Although the rise of ions is reducing aquatic biodiversity, the effects of ion identity on freshwater organisms are largely unknown. Previous studies have quantified mostly lethal effects of elevated salt concentrations on periphyton photosynthetic and growth processes, while few have quantified sub-lethal responses. We quantified photoautotrophic and heterotrophic responses to low salt concentrations. Sodium chloride (NaCl), a common contaminant, could alter the photosynthetic capacity and biochemistry of periphyton to alter aquatic function. Periphyton was exposed to 4 NaCl concentrations for 27 days: ambient (~3 mg/L NaCl), low (16 mg/L NaCl), medium (32 mg/L NaCl), and high (64 mg/L NaCl) (n=10, N=40). We measured respiration, chlorophyll a, ash-free dry mass and glucose concentrations. Periphyton respiration was greater during light and dark incubations in the ambient compared to the high salt treatment. We did not observe altered growth, or biochemistry of periphyton, but observed possible changes in heterotrophic communities. Combined results suggest suppressed heterotrophic respiration with increasing salt concentrations. Relatively low-level salinization may alter microbial community structure and slow detrital processes in aquatic ecosystems.

Anastasia Mogilevski (Primary Presenter/Author), Gettysburg College, mogian01@gettysburg.edu;


Brooke Howard-Parker ( Co-Presenter/Co-Author), University of Arkansas, bbhowardparker@gmail.com;


Sally Entrekin ( Co-Presenter/Co-Author), University of Central Arkansas , sentrekin@uca.edu;