남세균 제어를 위한 동물플랑크톤(Daphinia magna)과 패류(Unio douglasiae)의 단독 및 혼합적용

Abstract

Single - and combined effects of a domestic freshwater bivalve Unio douglasiae (7.6~ 8.6 cm in shell length) and zooplankton Daphnia magna (1~ 2 mm in body size) were examined to understand whether they inhibit the growth of harmful cyanobacterial bloom (i.e. Microcystis aeruginosa) in a eutrophic lake. The experiments were triplicated with twelve glass aquaria (40 L in volume); three aquaria without mussel and zooplankton, served as a control, three zooplankton aquaria (Z, density=40 indiv. L-1), three mussel aquaria (M, density=0.5 indiv. L-1), and three mussel plus zooplankton aquarium (ZM, density=40 indiv.Z L-1 plus 0.5 indiv.M/L), respectively. Algal growth inhibition (%) calculated as a difference in the concentration of chlorophyll-a (Chl-a) before and after treatment. Chl-a in all aquaria decreased with the time, while a greatest algal inhibition was seen in the ZM aquaria. After 24 hrs of incubation, Chl-a concentration at the mid-depth (ca. 15 cm) in ZM aquaria reduced by 90.8% of the control, while 63.2% and 79.8% in Z and M aquaria, respectively. Interestingly, during the same period, the surface Chl-a was diminished by 51.9% and 65.4% relative to the control in Z and ZM aquaria, while 27.4% of initial concentration decreased in M aquarium, respectively. These results suggest that 1) this domestic freshwater filter-feeding bivalve plays a significant role in the control of cyanobacterial bloom (M. aeruginosa), and 2) the combination with zooplankton and