Can algicide (the thiazolidinedione derivative TD49) truly contribute to the restoration of microbial communities?

Abstract

To mitigate HABs, numerous studies have been conducted to develop an effective algicide, but few studies have elucidated the effect of algicides on marine environmental health. In this study, thiazolidinedione derivative 49 (TD49), which has been developed as an algicide for the dinoflagellate Heterocapsa circularisquama, was used, and we investigated changes in phytoplankton biomass (abundance, chlorophyll a, and carbon biomass) and biodiversity (diversity, evenness, and richness) following the application of TD49. To gain deeper understanding, a large-scale mesocosm (1,300 L) experiment containing control and treatment with four different concentrations (0.2, 0.4, 0.6 and 1 &micro M) was conducted for 10 days. Based on a previous study, TD49 shows algicidal activity against H. circularisquama depending on its concentration. The phytoplankton biomass in the TD49 treatmentswas generally lower than that in the control due to the algicidal effectof TD49 on H. circularisquama. The biodiversity indices (e.g.,the Shannon-Weaver index) in the treatmentswere consistently higher than thosein the control before depletion of nitrite+nitrate. Interestingly, the 0.6 &micro M TD49 treatmenthad higher biodiversity indices than the high-concentration treatment (1 &micro M), which appeared to show a better algicidal effect. These findings suggest that mitigation of H.circularisquama blooms with TD49 treatment may enhance phytos been developed as an algicide for the dinoflagellate Heterocapsa circularisquama, was used, and we investigated changes in phytoplankton biomass (abundance, chlorophyll a, and carbon biomass) and biodiversity (diversity, evenness, and richness) following the application of TD49. To gain deeper understanding, a large-scale mesocosm (1,300 L) experiment containing control and treatment with four different concentrations (0.2, 0.4, 0.6 and 1 &micro M) was conducted for 10 days. Based on a previous study, TD49 shows algicidal activity against H. circularisquama depending on its concentration. The phytoplankton biomass in the TD49 treatmentswas generally lower than that in the control due to the algicidal effectof TD49 on H. circularisquama. The biodiversity indices (e.g.,the Shannon-Weaver index) in the treatmentswere consistently higher than thosein the control before depletion of nitrite+nitrate. Interestingly, the 0.6 &micro M TD49 treatmenthad higher biodiversity indices than the high-concentration treatment (1 &micro M), which appeared to show a better algicidal effect. These findings suggest that mitigation of H.circularisquama blooms with TD49 treatment may enhance phyto