Viral activity in relation to Emiliania huxleyi blooms: A mechanism of DMSP release?

The role of viral activity with respect to bloom dynamics and production of dissolved dimethylsulfoniopropionate (DMSP) and dimethylsulfide (DMS) was investigated in Norwegian coastal waters and in sea water mesocosms 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 particles (LVLP) and there was a significant inverse relationship between cell-specific calcification rate and LVLP abundance. Results from the mesocosm study indicate that the viral activity may either prevent or terminate the development of E. huxleyi blooms. No significant relationships were found between the abundance of LVLPs and the concentrations of dissolved DMSP and DMS in the field or in the mesocosms. This may be explained by the relatively small size of the E. huxleyi blooms (maximum cell concentration of 11 x 10(6) l(-1)) and bacterial degradation of DMSP and DMS, which may have been sufficient to prevent the accumulation of sulfur compounds released after lysis of the cells.