Seawater carbonate chemistry and growth and enzyme activities of Nitzschia closterium


In this study, Nitzschia closterium was incubated in seawater at different pH values (8.10, 7.71, and 7.45) and using different nitrogen forms (NO3–N and NH4–N) in the laboratory. The results showed that the growth of N. closterium was inhibited by ocean acidification, with individuals under lower pH levels showing lower growth rates and lower nitrogen uptake rates for both nitrogen forms. The Vmax/Ks ratio decreased with decreasing pH, indicating the inhibition of nitrogen uptake, whereas the ratios for NH4–N cultures were higher than those for NO3–N cultures, implying the highly competitive position of NH4–N. Acidification might induce reactive oxygen species based on the result that the maximum enzyme activities of SuperOxide Dismutase (SOD) and CATalase (CAT) increased under lower pH levels. The SOD and CAT activities for the NO3–N cultures were higher than those for NH4–N cultures at the low pH level, indicating that acidification might cause more oxidative stress for NO3–N cultures than for NH4–N cultures. Thus, ocean acidification might have a more detrimental effect on the growth of N. closterium under NO3–N conditions than NH4–N conditions, with a lower ratio (γ) of the maximum growth rate to the maximum nutrient uptake rate, and a drop in nitrate reductase activity under lower pH levels.

In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Gattuso et al, 2019) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI). The date of carbonate chemistry calculation by seacarb is 2020-05-6.

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Metadata Access
Creator Li, Keqiang; Li, Min; He, Yunfeng; Gu, Xingyan; Pang, Kai; Ma, Yunpeng
Publisher PANGAEA
Contributor Yang, Yan
Publication Year 2020
Rights Creative Commons Attribution 4.0 International;
OpenAccess true
Resource Type Dataset
Format text/tab-separated-values
Size 3075 data points
Discipline Earth System Research