Pringault Olivier auteur aut IRD Buffan-Dubau E auteur aut IRD De Wit R auteur aut IRD text journalArticle eng Short-term temperature effects on oxygen turn-over in artificial cold-adapted microbial mats were experimentally studied using microsensor techniques. The artificial mats were cultured in benthic gradient chambers under opposing oxygen and sulphide gradients, and community metabolism was analysed after 8 mo of incubation at 5°C. Microbial mat samples from Lake Fryxell (Antarctica) were used as inocula. Both net and gross O2 productivity were maximal at 10°C, whereas gross O2 production was completely inhibited at 15°C. Thus, the microbial community exhibited a psychrophilic response. Nevertheless, the inhibition of oxygenic photosynthesis at 15°C might result from indirect effects of accumulation of H2S in the photic zone, which might induce the inhibition of photosystem II activity. The dynamics of the dark and light net metabolism of O2 were estimated from transient oxygen profiles. They were strongly affected by the temperature changes, exhibiting temperature characteristics well above those calculated from the steady-state approaches. This indicates that indirect effects of temperature probably occurred, i.e. (1) migration of microorganisms locally resulting in higher biomass, (2) an increase of the oxygen requirements for the oxidation of reduced compounds such as H2S, or both. The results show that the metabolic rates of the different functional groups in these artificial microbial mats were fine-tuned to the prevailing temperature. This resulted in a close coupling of oxygen and sulphur cycles as has been previously found for mesophilic hypersaline mats. specialized ANTARCTIQUE 032 084 021 26 127-138 2001 0948-3055 https://www.documentation.ird.fr/hor/fdi:010091836 10.3354/ame026127 0948-3055 [F B010091836] https://www.documentation.ird.fr/hor/fdi:010091836 IRD - Base Horizon / Pleins textes 2024-10-17 2024-10-17 fdi:010091836 fre