COMPARING THE EFFECTS OF SUB-LETHAL GRADIENTS OF TWO SODIUM SALTS ON AQUATIC MICROBIAL COMMUNITIES
Salinization of freshwaters is a global issue due to anthropogenic activities such as road salting, irrigation practices, resource extraction, and discharge of inadequately treated waste water. Arkansas streams have relatively low concentrations of salts currently, but are at risk due to expanding agriculture and urbanization. Few studies address the effects of sub-lethal salinization on freshwater microbes; likewise, little attention has been given to the possibly differential effects of specific salt ions on freshwater biota. We investigated the effects of two common Na salts (NaCl and NaHCO3) at sub-lethal concentrations on detrital-associated microbial communities. We predicted 1) autotrophic (algal) and heterotrophic (fungal and bacterial) microbial biomass would positively relate to salt concentrations (subsidy response), 2) respiration would decrease with increasing salinity, and 3) remaining leaf litter detritus mass would decrease with increasing salinity. In most cases, at least low to moderate salt additions yielded a subsidy response pattern for microbial biomass. Sodium bicarbonate (NaCO3) had a stimulatory effect and NaCl elicited suppression of respiration rates for microbial communities. Remaining leaf litter detritus mass was similar across treatments. Results suggest aquatic microbes respond differently to specific salt ions even at sub-lethal concentrations.
Brooke Howard-Parker (Co-Presenter/Co-Author), University of Arkansas, firstname.lastname@example.org;
Thomas Williams (Primary Presenter/Author), University of Arkansas, email@example.com;
Sally Entrekin (Co-Presenter/Co-Author), Virginia Tech, firstname.lastname@example.org;
Natalie Clay (Co-Presenter/Co-Author), Louisiana Tech University, email@example.com;
Michelle Evans-White (Co-Presenter/Co-Author), University of Arkansas, firstname.lastname@example.org;