Dissolved phosphorus uptake in subtropical and temperate streams of Argentina

Abstract

An abrupt CO 2 -mediated decrease in pH affects growth rates, cellular features and the interspecific interaction of Scenedesmus (Acutodesmus) obliquus and Cryptomonas pyrenoidiferaThe technologies of anthropogenic CO 2 mitigation, such as carbon capture and sequestration, may pose an environmental threat to aquatic systems. In a scenario of CO 2 leakage from a carbon capture and sequestration process, very low-pH values might be reached and could remain over time. The main objective of this study was to detect how an abrupt lowering of pH would affect the microalgae Scenedesmus (Acutodesmus) obliquus and Cryptomonas pyrenoidifera at physiological, morphological and population levels, and also see how these effects could lead to ecological consequences. Monospecific and mixed culture experiments were run according to this purpose over 14 days and at a pH of 6.5, controlled by CO 2 injection. An increased CO 2 concentration significantly enhanced the growth rate of both species and especially affected the cell size of C. pyrenoidifera in the monoculture. The total biovolume of C. pyrenoidifera was higher than the total biovolume of S. obliquus in the control treatment, although neither of the two species were dominant in the culture experiments. Granularity responded in different ways for the species studied, being statistically different within subjects in monospecific and mixed culture experiments. Only chlorophyll and granularity have been significantly correlated in the low pH of C. pyrenoidifera monoculture. Due to its ecological relevance, the decreased colony formation ability of S. obliquus under a high CO 2 concentration is highlighted.