Final Activity Report Summary - EXTALGAE (Biological consequences of global climate change. The effects of salinity and temperature in extremophilic algae)
The overall goal of this project was to investigate the physiological and chemical adjustments incurred by photosynthetic algae to parameters affected by global climate change, namely changes in salinity, temperature and light. Furthermore, we wanted to contribute to European scientific research by filling an important gap in climate modelling systems by examining and potentially enabling the prediction of production and release of volatile organic sulphur compounds (VOSC). These processes work in parallel to counteract global warming by fixing carbon while the production of VOSCs counteract global warming through enhanced cloud albedo. As a study organism we chose an extremophilic alga isolated from the water column in a permanently ice-covered Antarctic lake, since it could be expected that relatively small disturbances in the climate environment would result in large physiological responses. One very important objectives of this investigation was also to study the synergistic effects of changes in salinity, light and temperature.
The results that were achieved so far showed several very interesting outcomes. Among the most important ones was the fact that low temperature tolerance was strongly linked to the salinity in the surrounding environment of the algae during their growth, which implied that the less salty waters that we expected to find in e.g. the Atlantic ocean in the future, due to melting of the ice caps of Greenland and Antarctica, would result, in combination with the modelled increase in water temperatures, in an amplified effect on algal growth rates.
Furthermore, maximal photosynthetic capacity was enhanced at lower salinities at both low and high temperatures. However, rates of photosynthesis were higher at higher temperatures. As expected from this, respiration was reduced in both high and low temperatures with lowered salinity, while apparent quantum yields showed little change, indicating that the reduced need to adjust the osmotic balance at lower salinities resulted in a higher net photosynthetic rate, implying a potentially a faster growth rate. Indeed, we could observe the fastest growth rates for this extremophilic organism at low salinity. The obtained results should further studied and potentially incorporated in future models of climate change.
The results that were achieved so far showed several very interesting outcomes. Among the most important ones was the fact that low temperature tolerance was strongly linked to the salinity in the surrounding environment of the algae during their growth, which implied that the less salty waters that we expected to find in e.g. the Atlantic ocean in the future, due to melting of the ice caps of Greenland and Antarctica, would result, in combination with the modelled increase in water temperatures, in an amplified effect on algal growth rates.
Furthermore, maximal photosynthetic capacity was enhanced at lower salinities at both low and high temperatures. However, rates of photosynthesis were higher at higher temperatures. As expected from this, respiration was reduced in both high and low temperatures with lowered salinity, while apparent quantum yields showed little change, indicating that the reduced need to adjust the osmotic balance at lower salinities resulted in a higher net photosynthetic rate, implying a potentially a faster growth rate. Indeed, we could observe the fastest growth rates for this extremophilic organism at low salinity. The obtained results should further studied and potentially incorporated in future models of climate change.