The estuarine diatom Thalassiosira pseudonana was studied under both summer and winter water conditions, also by the immediate response by the setup of a Pulse experiment. The study consisted in the responses of the microalgae to Copper enrichment varying from 0 to 20 µg Cu/l, in relation to physiological responses. For the Growth experiments, it was found different responses of the algae to increasing Copper, in all the analyses carried out. During winter conditions, T. pseudonana is capable in having a similar biomass throughout the whole set-up, and not compromise with the Nitrogen pool during the production of detoxifying peptides (GSH and Phytochelatins). For the summer conditions, Nitrogen limitation played an important role in the capacity of growth and detoxification of the medium, in high Copper enrichments. The relation between Carbon and Nitrogen had rather high values, mainly due to the high synthesis of Carbohydrates. For the Pulse experiments, the important aspect was that even under Nitrogen limitation, T. pseudonana, was capable in producing detoxifying peptides that were not found in the Growth experiments under the same Copper enrichments. As final conclusion of this work, the diatom Thalassiosira pseudonana, has a better capacity in detoxifying the medium when subjected to a sudden load of Copper, than when continuously grown under Copper enrich medium. |
