Detection of the toxic cyanobacteria by Nodularia spumigena means of a 4-keto-myxoxanthophyll-like pigment in the Baltic Sea

The pigment composition of cyanobacterial species regularly forming blooms in the Baltic Sea was investigated. A 4-keto-myxoxanthophyll-like pigment was found in 2 strains of the toxic Nodularia spumigena isolated from the SE Baltic Sea. Strains of Aphanizomenon sp. and Anabaena lemmermannii did not contain this rarely observed pigment. The 4-keto-myxoxanthophyll-like pigment was also found in samples taken during intense blooms of N. spumigena and was found to be correlated with the concentration of the algal toxin nodularin (r = 0.97). N. spumigena could be detected by the 4-keto-myxoxanthophyll-like pigment at very low abundances by HPLC, i.e. down to 0.4 mug chlorophyll a (chl a) l(-1). As it is rapid, very sensitive and objective, this method can be used for early warning of toxic blooms of cyanobacteria in the Baltic Sea. CHEMTAX software was used to estimate the contribution of cyanobacteria species as well as other algal classes present to total chl a.