An adapted dilution method was used to estimate viral lysis and microzooplankton grazing simultaneously. Parallel dilution experiments were performed with 30 kDa ultrafiltrate (virus and grazer-free diluent) and 0.2 \u00b5m filtered seawater (grazer-free, but virus-containing diluent). Specific viral lysis rates were calculated from the difference in P. globosa growth rates between the 2 dilution series after 24 h incubation under natural conditions. The validity of this method was tested using a culture of P. globosa infected with a known P. globosa virus (PgV).Protocol derived from:\u00a0 Baudoux, A., Noordeloos, A., Veldhuis, M., & Brussaard, C. (2006). Virally induced mortality of Phaeocystis globosa during two spring blooms in temperate coastal waters. Aquat. Microb. Ecol. Aquatic Microbial Ecology,44(3), 207-217.