The pulmonata snail Lymnaea is a potential biomanipulation species for use against cyanobacteria blooms

Abstract

Cyanobacteria blooms caused by eutrophication lead to serious impacts on aquatic ecosystems and human health. Biomanipulation, using aquatic animals to reduce the algal population, is one of most promising strategies for controlling cyanobacteria blooms and improving water quality. In preliminary experiments in aquaculture ponds, the stocking of the pulmonata snail Lymnaea spp. led to reduced cyanobacterial cell density in highly trophic water. In the present study, the inhibitory effects of Lymnaea spp. against the growth of natural mixed cyanobacteria or of Microcystis aeruginosa were examined. The results indicated that the growth of mixed natural cyanobacteria with an initial cell density of 4 × 105 cell/mL was remarkably inhibited by the presence of Lymnaea spp. with a density of five individuals per liter. The growths of M. aeruginosa with various initial cell densities of 1.76 × 106, 4.38 × 106, 14.25 × 106, 25.55 × 106, and 69.1 × 106 cells/mL were inhibited by introducing 15 or even fewer individuals into one liter of algal culture. Lymnaea spp. adapted and survived in the water containing M. aeruginosa with cell densities up to 69.1 × 106 cell/mL. Moreover, the reduction in cyanobacteria density by Lymnaea sp. was dependent on filter feeding and associated microorganisms. Therefore, Lymnaea spp. possess the potential to be used as a biomanipulation species.