2015 Volume 3 Issue 1 Pages 259-267
In our previous studies, a series of laboratory experiments were performed in order to evaluate the feasibility of applying the freshwater bivalve Sinanodonta woodiana as a Microcystis blooms removal tool. The results suggested that S. woodiana could greatly graze both the pure cultured Microcystis aeruginosa and the natural blooms of toxic Microcystis spp. in unicellular and colonial forms. Furthermore, in the subsequent long-term grazing experiment, the bivalves themselves demonstrated strong survival ability during exposure to natural eutrophic water containing microcystins (MCs) for 12 days. In order to clarify the survival mechanisms (selective feeding and detoxification mechanisms), we summarized all the conducted experiments and made a correlation analysis between the diet characters and the bivalves' physiological rates. The results showed that (1) MCs did not restrain the feeding behavior of S. woodiana; instead, the exorbitant initial food concentration could inhibit the filtration rates; (2) the absorption efficiency increased with the elevation of the toxic algae Microcystis concentration; (3) there was an obvious positive correlation between ammonia excretion rates and microcystin concentrations. Finally, combined with the phenomena in the long-term grazing experiment, the possible detoxification mechanism in this bivalve was inferred.