Responses of the large centric diatom Coscinodiscus sp. to interactions between warming, elevated CO2, and nitrate availability. (30th January 2018)

• Record Type: Journal Article
• Authors: Qu, Pingping; Fu, Feixue; Hutchins, David A.
• Is Part Of: Limnology and oceanography. Volume 63:Number 3(2018)
• Page Start: 1407
• Page End: 1424
• Publication Date: 2018-01-30
• Subjects: Limnology -- Periodicals; Oceanography -- Periodicals; Océanographie; Limnologie; Limnology; Oceanography; Computer network resources; Périodique électronique (Descripteur de forme); Ressource Internet (Descripteur de forme); Periodicals; 551.4805
• DOI: 10.1002/lno.10781
• Languages: English
• ISSNs: 0024-3590

Abstract

Abstract: Marine ecosystems are facing multiple anthropogenic global changes, including ocean acidification, warming, and reduced nutrient supplies. Together, these will challenge phytoplankton including large centric diatoms such as Coscinodiscus sp., a group that is important to ocean food webs and carbon export. We investigated the interactive effects of warming, elevated CO2, and nitrate availability on Coscinodiscus growth, elemental stoichiometry, and Fe and C uptake rates in a four‐treatment factorial experiment combining two CO2 levels (∼400 ppm and 800 ppm) and two temperatures (16°C and 20°C) across seven nitrate concentrations (1–100 μ mol L −1 ). Higher temperatures led to higher maximum growth rates ( μ max ), but also higher half‐saturation constants for nitrate ( K 1/2 ), while elevated CO2 increased K 1/2 only at the warmer temperature. Lower μ max / K 1/2 ratios under warming and rising CO2 indicated a higher nitrate requirement at these conditions. High temperature decreased cellular P and Si contents and consequently increased N : P and C : Si ratios, especially at ambient CO2 . Fe : C uptake ratios responded positively to lower nitrate levels, lower CO2, and warming. Significant interactions between nitrate availability and temperature or CO2 were observed for specific growth rates, chlorophyll a and Si contents, Fe : C, N : P, and Si : C, while temperature and CO2 interactions were only significant for μ max / K 1/2 and cellular P content. The mutual interactions among CO2 concentrations, temperature, and nitrate supply may all affect future growth, physiology, and carbon export by Coscinodiscus sp., however, in general warming and nitrate availability appear to be more influential than CO2 .