AbstractsChemistry

This thesis is based on 35 natural Emiliania huxleyi DNA samples and corresponding water samples from the North Atlantic Ocean, on a stretch between Bermuda and the Azores. Water samples were analysed for concentrations of the seven most dominant ionic species in seawater; Cl-, Na+, SO42-, Mg2+, Ca2+, K+ and HCO3-, which are also the ions that contribute the most to the salinity of solution. Distinction was made between practical salinity and absolute salinity, values were obtained for both, compared and the importance of differences discussed. pH, temperature and chlorofyll content were also measured. Methods used were atomic absorption spectroscopy, ion chromatography, titration, pH electrode, Sea-Bird Electronics CTD and ion selective electrodes. E. huxleyi strain CCMP371 was cultured at 20 °C, 16/8 - light/dark cycle with L1 medium of salinity 25 ‰. E. huxleyi cell numbers were obtained for 13 natural samples using qPCR. Qualitative exploration of data showed no obvious connections between cell numbers and specific ion concentrations, although indications of some connection between pH and cell numbers were observed. Ion selective electrodes were not suitable for measuring ion concentrations in seawater due to ion specificity issues. It was concluded that the chosen ionic species probably does not alone determine the presence of E. huxleyi, many other factors have importance, which could not be included in this project. Futher research would have to include all factors or experiments be conducted under controlled laboratory conditions.