Cyanobacteria blooms are common in Baltic Sea and their intensity have been increased due to
anthropogenic eutrophication. In this study we investigated the cyanotoxin levels in the water samples
collected from four different locations in the Baltic Sea at three different seasons including summer 2011.
Protein phosphatase 2A (PP2A) inhibition assays, Enzyme-linked immunosorbent assays (ELISA) and liquid
chromatography-mass spectrometry (LC-MS) were employed to detect cyanotoxin variants. Microcystin-
LR equivalents (MCE) were detected in a number of the water samples collected at site A (0.4 to 0.64 μg MCE/ L) and at site B (0.24 to 0.44 μg MCE/ L). Cyanotoxin concentrations, as measured by ELISA, ranged between 0.98 -7.45 μg MCE/L in samples collected at site A and between 0.12 to 0.68 μg MCE/L, in samples collected at site B. By using LC-MS one of the molecules present in the samples from site A was determined to be nodularin (0.213 to 0.524 μg/L) whereas samples from site B did not contain this toxin nor did they contain any of the most toxic microcystin species mentioned. The data obtained show good correlation with the MC concentration changes measured in samples and these concentrations were relatively higher during warmer months. In addition we also investigated the adsorption of toxins from water into the circulation of grazing cattle and the results show no measureable liver damage resulting from cyanotoxin poisoning.