Responses of microbial communities to dosing with the algicide thiazolidinedione derivative TD49 in a mesocosm experiment

Abstract

To determine the effects of the algicide thiazolidinedione derivative 49 (TD49) on a microbial community, including the targeted harmful alga Heterocapsa circularisquama, we conducted exposure experiments (control, blank, 0.2, 0.4, 0.6, and 1.0 &micro M) with TD49 in mesocosm enclosures (1300 L). The algicidal effects on the target alga depended on the concentration of TD49. Following the addition of TD49, heterotrophic bacteria (HB) and heterotrophic nano-flagellates (HNFs) grew well in all treatments. Total ciliates remained relatively low in abundance in TD49 treatments compared to control and blank groups, whereas aloricate ciliate abundance gradually increased at the end of the experimental period, even with high TD49 concentrations. Therefore, TD49 has a positive effect on the microbial community, particularly through its growth-promoting effects on HB and HNFs. and 1.0 &micro M) with TD49 in mesocosm enclosures (1300 L). The algicidal effects on the target alga depended on the concentration of TD49. Following the addition of TD49, heterotrophic bacteria (HB) and heterotrophic nano-flagellates (HNFs) grew well in all treatments. Total ciliates remained relatively low in abundance in TD49 treatments compared to control and blank groups, whereas aloricate ciliate abundance gradually increased at the end of the experimental period, even with high TD49 concentrations. Therefore, TD49 has a positive effect on the microbial community, particularly through its growth-promoting effects on HB and HNFs.