Microcystin-LR in Brazilian aquaculture production systems

The growth of aquaculture production systems, mostly the sport-fishing kind, coupled with a lack of control, brings about concerns on the quality of water and food produced. The current paper determines which factors may trigger the growth of cyanobacteria, with subsequent concentrations of microcystins in collected water samples, at the surface and in the water column, from 10 aquaculture systems, during the dry and rainy seasons. The above is undertaken by measurements of biotic (counting of Chlorophyceae, cyanobacteria, and microcystin-LR [MC-LR]) and abiotic (total nitrogen and total phosphorus) factors. Because the water from the 10 aquaculture production systems had MC-LR concentrations that were highly correlated with Microcystis aeruginosa (M. aeruginosa) biomass, most MC-LR microcystins were produced by this species. The MC-LR concentrations and M. aeruginosa counting were positively correlated with nitrogen-to-phosphorus ratios and suggest that parameters may affect not only the M. aeruginosa biomass, but also MC-LR concentrations.