ABSTRACT The physiological plasticity of five cyanobacteria microbial mats from an extreme high temperature intertidal environment (SW Iceland) was analysed both daily and seasonally. Daily cycles under in situ natural conditions were monitored from June to October using pulse-amplitude modulated (PAM) fluorometry and pigment composition in order to study the photosynthetic performance of these microbial mats in relation to environmental fluctuations linked to irradiance and temperature. In vitro temperature and salinity experiments of photosynthetic responses were also conducted. A total of 10 taxa were identified, the most abundant species being Cyanobacterium sp. and Geitlerinema sp. The microbial mats showed a remarkable photosynthetic adaptation to daily and seasonal changes in temperature and solar radiation. For all microbial mats, rETRmax values decreased from June to October, while Fv/Fm remained constant in terms of absolute values. Although high irradiances during June and July affected photosynthesis through photoinhibition, recovery was observed under high temperatures (between 40–50°C), which supports the hypothesis that temperature is a determining factor in the photosynthetic performance of these cyanobacterial mats. Our results showed a significant increase in the Chla-b and phycobiliproteins content from June to October, as well as a significant decrease in total carotenoids content.

中文翻译：

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高温潮间带蓝藻微生物垫对温度和盐度的生理可塑性：日常和季节性原位光合性能

摘要每天和季节性地分析了来自极端高温潮间带环境（冰岛西南）的五种蓝藻微生物垫的生理可塑性。使用脉冲幅度调制 (PAM) 荧光测定法和色素成分监测 6 月至 10 月在原位自然条件下的每日循环，以研究这些微生物垫的光合性能与与辐照度和温度相关的环境波动的关系。还进行了光合反应的体外温度和盐度实验。共鉴定了 10 个分类群，最丰富的物种是蓝藻。和 Geitlerinema sp。微生物垫对温度和太阳辐射的日常和季节性变化表现出显着的光合适应性。对于所有微生物垫，rETRmax 值从 6 月到 10 月下降，而 Fv/Fm 的绝对值保持不变。尽管 6 月和 7 月的高辐照度通过光抑制影响了光合作用，但在高温（40-50°C 之间）下观察到了恢复，这支持了温度是这些蓝藻垫光合性能的决定性因素的假设。我们的结果显示，从 6 月到 10 月，Chla-b 和藻胆蛋白含量显着增加，总类胡萝卜素含量显着下降。这支持了温度是这些蓝藻垫光合性能的决定因素的假设。我们的结果显示，从 6 月到 10 月，Chla-b 和藻胆蛋白含量显着增加，总类胡萝卜素含量显着下降。这支持了温度是这些蓝藻垫光合性能的决定因素的假设。我们的结果显示，从 6 月到 10 月，Chla-b 和藻胆蛋白含量显着增加，总类胡萝卜素含量显着下降。