Recently, the occurrence of harmful algae blooms from the Chattonella group has been increasing and expanding in the southern and western seas of Korea. We investigated the relationship between growth kinetics and nutrients in the harmful algae Chattonella marina and Chattonella ovata of the South Sea, Korea. As a result; high concentrations of ammonium ($30;{mu}M$ and above) was not effective to the growth of C. ovata, while C. marina displayed good growth at concentration of $100;{mu}M$. The half-saturation constant ($K_s$) of C. marina for ammonium ($2.51;{mu}M$), nitrate ($5.36;{mu}M$) and phosphate ($0.75;{mu}M$) was higher than C. ovata (1.85, 4.01, and $0.61;{mu}M$, respectively). This indicates that C. ovata can achieve higher cell densities than C. marina under lower nutrient conditions. These $K_s$ values were comparatively higher than those of diatoms and other flagellates previously reported. Therefore, our results indicate that the growth of C. marina and C. ovata is less adapted to lower nutrient environments than other competition species, such as Skeletonema costatum and Cochlodinium polykrikoides.