Effects of seawater acidification on the growth rates of the diatom Thalassiosira (Conticribra) weissflogii under different nutrient, light, and UV radiation regimes

Effects of ocean acidification (OA) on marine organisms are suggested to be altered by other environmental drivers, such as low nutrient, increased light, and UVR exposures; however, little has been documented on this aspect. Thalassiosira (Conticribra) weissflogii, a marine diatom, was used to examine the OA effects under multiple stressors on its growth. The specific growth rate was inhibited by low nutrient (LN), though it increased with increased sunlight regardless of the nutrient supplies. Presence of UVR reduced the maximal growth rate (mu (max)) in low CO2 (LC) conditions (both LN and HN) and inhibited the apparent growth light use efficiency (alpha) in the cells acclimated to LN under both low (LC) and high (HC) CO2 conditions. The HC-grown cells grew faster under HN and low light levels. Conclusively, presence of UVR with high solar radiation, LN and OA acted synergistically to reduce the diatom growth, though, in contrast UVR and OA enhanced the growth under HN.