Human activities and the resulting global climate change have profound effects on ecosystems, and economic and social systems, including those dependent on the ocean. Increasing concentrations of atmospheric CO2 have led to gradual changes in the marine carbonate system. It is well known that environmental changes determine the composition and abundance of algal populations. In the present study, we evaluated the growth, photosynthesis, nutrient uptake rates, tissue C and N content, nitrate reductase activity, and nitrate transporter gene expression of Ulva prolifera, Ulva linza, and Ulva compressa exposed to 400, 1000, and 2000 ppm CO2 levels after one life cycle culture. Elevated CO2 promoted the rapid propagation of three Ulva species, which can result in the formation of a green tide. This was due to enhanced photosynthetic and respiration efficiency, reductions in energy requirements for biosynthesis and metabolism for maintaining external pH, and promotion of NO3− uptake by increased NO3− gene expression level and NO3− reductase activity.
Wang Y., Xu D., Ma J., Zhang X., Fan X., Zhang Y., Wang W., Sun K. & Ye N., in press. Elevated CO2 accelerated the bloom of three Ulva species after one life cycle culture. Journal of Applied Phycology. Article (subscription required).
