Mesocosm 실험을 통한 Naphthoquinone 살조물질 처리후 Stephanodiscus 대발생 소멸에 따른 미생물 군집구조 변동 연구

Abstract

Naphthoquinone (NQ) algicidal substance is an algicidal for Stephanodiscus, but studies on its influence on other microbial communities have rarely been reported. Therefore, we conducted a mesocosm experiment in order to investigate the effects of NQ algicidal substance on microbial communities through analyzing environmental factors (e.g., pH, water temperature, dissolved oxygen (DO), dissolved organic carbon (DOC) , nutrients, and chlorophyll-a (Chl-a)) and biotic factors (e.g., phytoplankton, bacteria, HNF, ciliate, and zooplankton). After it was treated with NQ algicidal substance, the concentration of Chl-a decreased from 20.4 μg L-1 to 9.5 μg L-1 after 2 days and the abundance of Stephanodiscus was significantly reduced by more than 80% after the mesocosm test, which implied that NQ algicidal substance has high algicidal effects on Stephanodiscus. During the treatment, the concentrations of phosphate, silicate, and DOC were slightly higher than those in the control due to the decomposition of the dead Stephanodiscus, while the DO and pH in the treatment were slightly lower than those in the control. The bacteria abundance had similar variations in pattern in the control and treatment, but the next generation sequencing (NGS) analysis showed that the bacterial community compositions were slightly different between the control and the treatment. The variation in the HNF showed that it changed following the bacteria abundance variation. The ciliates abundance and the dominant species Halteria grandinella decreased during the treatment. The Shannon-Wiener diversity index of the phytoplankton and zooplankton in the treatment of the mesocosm increased after 5 days and 9 days, respectively. These results showed that NQ algicidal substance could affect the microbial community composition directly or indirectly, but it appears to provide an eco-friendly approach to the control of Stephanodisucs.