Anthropogenic carbon dioxide (CO2) emissions simultaneously increase ocean temperatures and reduce ocean surface pH, a process termed ocean acidification (OA). OA is expected to negatively affect the growth and physiology of many calcified organisms, but the response of non-calcified (fleshy) organisms is less well understood. Rising temperatures and pCO2 can enhance photosynthetic rates (within tolerance limits). Therefore, warming may interact with OA to alter biological responses of macroalgae in complicated ways.
Ulva is the dominant genus in the green tide events and is considered to have efficient CO2 concentrating mechanisms (CCMs). However, little is understood regarding the impacts of ocean acidification on the CCMs of Ulva and the consequences of thalli's acclimation to ocean acidification in terms of responding to environmental factors. Here, we grew a cosmopolitan green alga, Ulva linza at ambient (LC) and elevated (HC) CO2 levels and investigated the alteration of CCMs in U. linza grown at HC and its responses to the changed seawater carbon chemistry and light intensity.
Ulva spp., an increasingly important food, are the dominant species of the large-scale green tides. In this study, both the growth and the physiological responses of the Ulva prolifera were studied after cultured in three different light and dark regimes (12:12, 14:10 and 16:8-h light/dark) in combination with current (420 $μ$atm; LC) and increased (1000 $μ$atm; HC) levels of atmospheric CO2. Grown rate of U.