Study of phytoplankton in Maltese coastal waters using in-situ and remote sensing techniques

Abstract

The impact of various physiochemical parameters on the growth of phytoplankton in Maltese coastal waters was investigated in a number of sites in the north of Malta; Gozo channel, Mellieha Bay and St. Paul's Bay and in the south of Malta, Marsaxlokk Bay. Concentrations of chlorophyll a were used as an indicator phytoplankton growth. ln-situ analysis of temperature, pH, conductivity, dissolved oxygen, Secchi depth, phosphates and chlorophyll a was carried out. This was compared with satellite analysis of chlorophyll a, Secchi depth and phosphates. The results showed that there was a significant difference in the level of chlorophyll a between the sites in the north and south with Marsaxlokk having approximately three times more chlorophyll a than the bays in the north. There were also significant differences in the temperature and level of dissolved oxygen and conductivity between the two localities. Pearson's correlation analysis showed a strong correlation between chlorophyll a concentrations, temperature, dissolved oxygen and conductivity in the north and chlorophyll a concentration, temperature and dissolved oxygen in the south. The water in Marsaxlokk was found to be homogenous. There were differences in the degree of importance of the various parameters based on rank analysis between different sited in the north, suggesting that the morphology of the bays and the degree of water movement in and out of the bay may be influence water quality and the growth of phytoplankton. There was a correlation between LANDSAT 8 band analysis and in-situ analysis of chlorophyll a, Secchi depth and phosphate concentration, suggesting that LANDSAT 8 may be used to identify areas rich in chlorophyll a and the physiochemical conditions needed for phytoplankton growth.