Microcystin production in Rivularia colonies of calcareous streams from Mediterranean Spanish basins
Aboal, Marina; Puig, MªAngeles
The communities of Rivularia in Mediterranean Spanish calcareous streams were surveyed during a year in an attempt to understand the factors promoting or inhibiting their production of microcystins in nature. The hydrological variables seemed to be more important than chemical factors in controlling the synthesis. No relation was found with nitrate or orthophosphate but there was a clear positive correlation of total intracellular microcystin contents and of dominant microcystins with total phosphorus, while the dissolved microcystins were inversely correlated with it. The concentration of microcystins dissolved in water remained most of the time below the legal limits (except in summer), but, due to the carcinogenic character of the toxins in low concentrations and in a scenario of global warming probably leading to an increase of these communities, greater control is recommended especially in areas where water treatment is inadequate.