Freshwater Salinization Impacts the Interspecific Competition between Microcystis and Scenedesmus

Abstract

Freshwater salinization is a growing environmental issue caused by various anthropic or natural factors that lead to changes in water chemistry and physical conditions, affecting the survival and diversity of phytoplankton. In this study, we tested the physiological, morphological and interspecific competition of the freshwater cyanobacterium Microcystis aeruginosa and the green algae Scenedesmus obliquus to salinity stress. Results demonstrated that increasing salinity had a significant negative effect on the growth of M. aeruginosa and S. obliquus. M. aeruginosa showed a decline in growth rate with increasing salinity, while S. obliquus showed a lower growth rate under salinity stress but with no significant difference between the two salinity groups. In cocultures, S. obliquus outcompeted M. aeruginosa, and the displacement was accelerated with increasing salinity. The photosynthetic performance of both algae was affected by salinity, the presence of competitors, and the cultivation time. S. obliquus showed morphological variations under salinity stress and the presence of a competitor. The study suggests that salinity stress and competition can have a significant impact on the growth and performance of algae species. The findings of our study suggest that the salinization of freshwater can impact the interspecific interactions among phytoplankton, which play a crucial role in the functioning of freshwater ecosystems.

Nejayote and Food Waste Leachate as a Medium for Scenedesmus acutus and Haematococcus pluvialis Production: A Mixture Experimental Design

“…Twenty days were used for monitoring the development of both microalgae. The trend of the development curve (Figure 2a) was consistent with the findings of other studies that stabilization occurred around day 15 [21]; nonetheless, our study's findings show that, in the case of S. acutus, stabilization started after day 16. Furthermore, the growth kinetics of our sample matched those of the S. acutus growing in the central region of BG-11, as reported previously [22,23].…”