VIRAL ACTIVITY IN RELATION TO EMILIANIA-HUXLEYI BLOOMS - A MECHANISM OF DMSP RELEASE

The role of viral activity with respect to bloom dynamics and producti on of dissolved dimethylsulfoniopropionate (DMSP) and dimethylsulfide (DMS) was investigated in Norwegian coastal waters and in sea water me socosms during blooms of the coccolithophorid Emiliania huxleyi (Lohm. ) Hay & Mohler. In coastal waters the collapse of the E. huxleyi bloom was accompanied by a simultaneous increase in large virus-like partic les (LVLP) and there was a significant inverse relationship between ce ll-specific calcification rate and LVLP abundance. Results from the me socosm study indicate that the viral activity may either prevent or te rminate the development of E. huxleyi blooms. No significant relations hips were found between the abundance of LVLPs and the concentrations of dissolved DMSP and DMS in the field or in the mesocosms. This may b e explained by the relatively small size of the E. huxleyi blooms (max imum cell concentration of 11 x 10(6) l(-1)) and bacterial degradation of DMSP and DMS, which may have been sufficient to prevent the accumu lation of sulfur compounds released after lysis of the cells.