Effects of Dracontomelon duperreanum Leaf Litter on the Growth and Photosynthesis of Microcystis aeruginosa.

This study investigated the use of Dracontomelon duperreanum leaf litter extract (DDLLE) in inhibiting the growth and photosynthesis of the algae Microcystis aeruginosa. The goal of the study was to evaluate a potential solution for cyanobacterial bloom prevention. M. aeruginosa was exposed to extract concentrations from 0.4 to 2.0 g L-1. Chlorophyll-a (Chl-a) content and photosynthesis levels were assessed using pulse amplitude modulated fluorimetry phytoplankton analyzer. Results suggested that the extract could efficiently suppress M. aeruginosa growth. The content of Chl-a was only 19.0 µg L-1 and achieved 96.0% inhibition rate when exposed to 2.0 g L-1 on day 15. Growth rate in response to different extract concentrations were consistent with changes in the photosynthesis efficiency (alpha), maximal relative electron transport rate and maximal photochemical efficiency of photosystem II (F v /F m ). Furthermore, several kinds of volatile chemicals and their concentrations in DDLLE had been identified by GC-MS, which of them play major role to suppress the growth of M. aeruginosa should be further studied.