González-Olalla Juan Manuel, Medina-Sánchez Juan Manuel, Carrillo Presentación
University Institute of Water Research, University of Granada, C/Ramón y Cajal, 4, 18071, Granada, Spain.
Department of Ecology, Faculty of Sciences, University of Granada, Campus Fuentenueva s/n, 18071, Granada, Spain.
Microb Ecol. 2022 Apr;83(3):555-567. doi: 10.1007/s00248-021-01787-8. Epub 2021 Jun 18.
The Metabolic Theory of Ecology (MTE) predicts that the temperature increases exert a common effect on organisms stimulating metabolic rates, this being stronger for a heterotrophic than for an autotrophic metabolism. However, no available studies within the MTE framework have focused on organisms' response under fluctuation at high temperature interacting with factors such as nutrient availability, or how this interaction could affect the coexistence between mixotrophic and strict autotrophic phytoplankton. Hence, we assess how the phytoplankton metabolism and species composition are affected under scenarios of high temperature and fluctuation at high temperature, and how nutrients alter the direction and magnitude of such impact. For that, we use a mixed culture composed of two phytoplankton species: a strict autotrophic species and a mixotrophic species. Our results indicate that, in agreement with the MTE, only fluctuation at high temperature treatment registered a greater activation energy (E) value for respiration than for primary production and stimulated mixotrophic over strict autotrophic species abundance compared to control treatment. Remarkably, fluctuation at high temperature had a strong negative impact on the total abundance of the mixed-culture. The interaction between nutrient enrichment and fluctuation at high temperature increased abundance of the strict autotrophic species and overall species abundance, and led to Ea values that were higher in primary production than in respiration. Changes in community composition, enhanced by nutrient enrichment, could be behind this response, which can have implications in ecosystem functioning in a changing world.
生态代谢理论（MTE）预测，温度升高会对生物体产生共同影响，刺激代谢率，这种影响对于异养代谢而言强于自养代谢。然而，在MTE框架内，尚无研究关注高温波动与营养有效性等因素相互作用下生物体的反应，或者这种相互作用如何影响混合营养型和严格自养型浮游植物之间的共存。因此，我们评估了高温和高温波动情况下浮游植物代谢和物种组成如何受到影响，以及营养物质如何改变这种影响的方向和程度。为此，我们使用了由两种浮游植物组成的混合培养物：一种是严格自养型物种，另一种是混合营养型物种。我们的结果表明，与MTE一致，只有高温波动处理下呼吸作用的活化能（E）值高于初级生产，并且与对照处理相比，刺激了混合营养型物种相对于严格自养型物种的丰度。值得注意的是，高温波动对混合培养物的总丰度有强烈的负面影响。营养富集与高温波动之间的相互作用增加了严格自养型物种的丰度和总体物种丰度，并导致初级生产中的Ea值高于呼吸作用。营养富集增强的群落组成变化可能是这种反应的背后原因，这可能对不断变化的世界中的生态系统功能产生影响。
