Interactive effects of light, CO.sub.2 and temperature on growth and resource partitioning by the mixotrophic dinoflagellate, Karlodinium veneficum

• Published in: PloS one 2021-10, Vol.16 (10), p.e0259161
• Main Authors: Coyne, Kathryn J, Salvitti, Lauren R, Mangum, Alicia M, Ozbay, Gulnihal, Main, Christopher R, Kouhanestani, Zohreh M, Warner, Mark E
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Karlodinium; Properties
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0259161

There is little information on the impacts of climate change on resource partitioning for mixotrophic phytoplankton. Here, we investigated the hypothesis that light interacts with temperature and CO.sub.2 to affect changes in growth and cellular carbon and nitrogen content of the mixotrophic dinoflagellate, Karlodinium veneficum, with increasing cellular carbon and nitrogen content under low light conditions and increased growth under high light conditions. Using a multifactorial design, the interactive effects of light, temperature and CO.sub.2 were investigated on K. veneficum at ambient temperature and CO.sub.2 levels (25°C, 375 ppm), high temperature (30°C, 375 ppm CO.sub.2 ), high CO.sub.2 (30°C, 750 ppm CO.sub.2 ), or a combination of both high temperature and CO.sub.2 (30°C, 750 ppm CO.sub.2) at low light intensities (LL: 70 [mu]mol photons m.sup.-2 s.sup.-2) and light-saturated conditions (HL: 140 [mu]mol photons m.sup.-2 s.sup.-2). Results revealed significant interactions between light and temperature for all parameters. Growth rates were not significantly different among LL treatments, but increased significantly with temperature or a combination of elevated temperature and CO.sub.2 under HL compared to ambient conditions. Particulate carbon and nitrogen content increased in response to temperature or a combination of elevated temperature and CO.sub.2 under LL conditions, but significantly decreased in HL cultures exposed to elevated temperature and/or CO.sub.2 compared to ambient conditions at HL. Significant increases in C:N ratios were observed only in the combined treatment under LL, suggesting a synergistic effect of temperature and CO.sub.2 on carbon assimilation, while increases in C:N under HL were driven only by an increase in CO.sub.2 . Results indicate light-driven variations in growth and nutrient acquisition strategies for K. veneficum that may benefit this species under anticipated climate change conditions (elevated light, temperature and pCO.sub.2) while also affecting trophic transfer efficiency during blooms of this species.