Chlorophyll-normalized isoprene production in laboratory cultures of marine microalgae and implications for global models

• Published in: Limnology and oceanography Vol. 58; no. 4; pp. 1301 - 1311
• Main Authors: Exton, D. A., Suggett, D. J., McGenity, T. J., Steinke, M.
• Format: Journal Article
• Language: English
• Published: Waco, TX John Wiley and Sons, Inc 01.07.2013; American Society of Limnology and Oceanography
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; General aspects; Sea water ecosystems; Synecology; Marine environment; Chlorophyll; Laboratory study; Aquatic environment; Models; Laboratory; Culture
• ISSN: 0024-3590; 1939-5590
• DOI: 10.4319/lo.2013.58.4.1301

We used laboratory cultures of marine microalgae to investigate the effects of growth conditions and their taxonomic position on the production of isoprene, a gas that has major effects on atmospheric chemistry and provides stress tolerance to many primary producers. Isoprene was quantified from 21 microalgal strains sampled during exponential growth, using purge-and-trap pre-concentration and gas chromatography with flame-ionization detection. Isoprene production rates varied by two orders of magnitude between strains (0.03–1.34 μmol [g chlorophyll a]−1 h−1), and were positively correlated with temperature (r² = 0.52, p < 0.001, n = 59). Three distinct sea surface temperature (SST)–dependent relationships were found between isoprene and chlorophyll a (μmol [g chlorophyll a]−1 h−1), an improvement in resolution over the single relationship used in previous models: for three polar strains grown at −1°C (slope = 0.03, R² = 0.76, p < 0.05, n = 9), nine strains grown at 16°C (slope = 0.24, R² = 0.43, p < 0.05, n = 27 with Dunaliella tertiolecta excluded), and eight strains grown at 26°C (slope = 0.39, R² = 0.15, p < 0.05, n = 24). We then used a simple model that applied the SST-dependent nature of isoprene production to three representative bioregions for the growth temperatures used in this study. This approach yielded an estimate of global marine isoprene production that was 51% higher than previous attempts using an SST-independent single relationship. Taking into account the effect of temperature therefore potentially allows more precise modeling of marine isoprene production, and suggests that increasing the SST-based resolution of data beyond the three groups used here could further improve future modeling simulations.