Effects of temperature and salinity on growth of Thalassiosira pseudonana (Bacillariophyceae) isolated from ballast water

Abstract

We examined the impacts of environmental factors on the survival of ballast water-introduced planktonic organisms and specifically described the effects of temperature and salinity on growth of the centric diatom Thalassiosira pseudonana. In salinity gradient experiments for natural phytoplankton communities of the vessel Daewoo Diamond, several freshwater and marine species were successfully identified. Of these, T. pseudonana was the dominant species in all salinity conditions (2-30 psu). In combination experiments of temperature and salinity with a T. pseudonana monoculture, the organism did not grow between 5 degrees C and 10 degrees C in freshwater culture media but exhibited growth at low temperature (5 degrees C) in brackish and marine waters. Furthermore, the T. pseudonana population grew significantly with increasing of temperature (10-30 degrees C) in brackish and marine waters. Our results indicate that T. pseudonana is well adapted to euryhaline and eurythermal conditions and its viability is suitable for successful colonization into local Korean aquatic ecosystems.