In this Thesis is examined the influence of salinity and presence of heavy metal cadmium in culture on the response of marine phytoplankton Dunaliella tertiolecta Butcher in terms of growth rate, physiological activity, cell shape and adhesion behavior on the electrode. Microscopic and electrochemical methods of polarography and chromoamperometry at the dropping mercury electrode were used. D.tertiolecta cell has no solid cellular cell wall in contrast to other green algae, which makes it susceptible to changes in the ecosystem and is why a model organism is often used in stress research. Adaptation of D. tertiolecta cell culture in lower salinity conditions suggests a slightly larger cell dimension, a change in spherical cell shape, a somewhat faster growth, while the adhesion properties at the broader potentials area remains preserved. Adaptation of phytoplankton to the presence of heavy metal cadmium in culture resulted in decrease of cell density with increasing cadmium concentration, cells are slightly smaller in size and show a deterioration in shape, the occurrence of surface active particles and microagregates in the culture which could be the result of the changed metabolic activity of cells due to stress. These results contribute to a better understanding of the adhesion behavior of phytoplankton cells in stress conditions in vitro and improve knowledge about survival and adaptation of phytoplankton organisms at natural interfaces in the aquatic environment under pressure.