349-356The effects of different thermal regimes on growth and physiological performance of the marine microalgae Emiliania huxleyi were studied . Two morphological distinct strains, one coccoliths-bearing cells called Calcified cells and one non-motile naked cells, were allocated to four different experimental groups. The groups were submitted to constant temperature of 20 °C and three different daily fluctuation ranges of temperature: a lower range of 20±2 °C, an intermediate range of 20±4 °C and the last higher range of 20±6 °C. This investigation demonstrated that there is a correlation between degree of calcification and photosynthesis. The cells with a decreased level of calcification resulted in a down regulation of photoprotective mechanisms. The cells grew high extent for all levels of fluctuation, presenting elevated concentrations at higher temperature amplitude. Elevated temperature shifts (20±6 °C) increased photosynthetic activity on both morphotypes strains of E. huxleyi
