Original paper

Viability of Microcystis colonies is not damaged by silver carp (Hypophthalmichthys molitrix) digestion

Gavel, Alan; Maršálek, Blahoslav; Adámek, Zdeněk

Abstract

Ingestion of cyanobacterial biomass by silver carp is frequently considered as one of the biological methods for the water bloom formation control. We measured the photosynthetic activity of Microcystis (maximal quantum yield of photosystem II determined by PAM fluorimeter FluorCam 700) before and after the gut passage of silver carp. Viability of digested Microcystis was nearly identical with control and no serious damage in metabolic activity was observed. Moreover microscopic observation of Microcystis colonies after digestion proved that larger colonies (more than 1000 cells) were disintegrated to smaller colonies up to 50-100 cells/colony. These smaller colonies were viable and actively growing. Seven days after excretion by silver carp the photosynthetic activity of Microcystis was comparable or slightly higher than the control population. Our results provide an experimental evidence that Microcystis is not damaged by silver carp digestion. That is probably one of the reasons why silver carp is not efficient in Microcystis bloom removal.

Keywords

microcystis coloniesphotosynthetic activitychlorophyll fluorescencesilver carpgut passage