TEMPERATURE AND SALINITY EFFECTS ON GROWTH OF A NON-CHAIN-FORMING STRAIN OF GYMNODINIUM-CATENATUM (DINOPHYCEAE) ESTABLISHED FROM A CYST FROM RECENT SEDIMENTS IN THE SOUND (ORESUND), DENMARK

The athecate, marine dinoflagellate Gymnodinium catenatum Graham 1943 was cultured from a resting cyst found in sediment samples from The So und, Denmark. Gymnodinium catenatum has not previously been registered alive in Danish waters, although fossilized cysts have been found in old sediments. The description (morphology and ultrastructure) of the strain established from the cyst complied with earlier studies of G. c atenatum with the exception that chains longer than two cells were nev er seen. Fitting the growth rates of the motile stage of G. catenatum to a linear model showed a significant influence of temperature and sa linity. Maximal division rate was 0.4 div . day-1 at 20-25-degrees-C a nd 20 parts per thousand salinity. Gymnodinium catenatum ca uses paral ytic shellfish poisoning in other parts of the world, but the toxicity of the Danish strain has not been determined. Possible explanations f or the presence of G. catenatum in Danish waters are discussed.