Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden.
FEMS Microbiol Ecol. 2013 Aug;85(2):338-47. doi: 10.1111/1574-6941.12123. Epub 2013 Apr 18.
The coastal zone is the most productive area of the marine environment and the area that is most exposed to environmental drivers associated with human pressures in a watershed. In dark bottle incubation experiments, we investigated the short-term interactive effects of changes in salinity, temperature and riverine dissolved organic matter (rDOM) on microbial respiration, growth and abundance in an estuarine community. An interaction effect was found for bacterial growth, where the assimilation of rDOM increased at higher salinities. A 3 °C rise in the temperature had a positive effect on microbial respiration. A higher concentration of DOM consistently enhanced respiration and bacterial abundance, while an increase in temperature reduced bacterial abundance. The latter result was most likely caused by a positive interaction effect of temperature, salinity and rDOM on the abundance of bacterivorous flagellates. Elevated temperature and precipitation, causing increased discharges of rDOM and an associated lowered salinity, will therefore primarily promote bacterial respiration, growth and bacterivore abundance. Our results suggest a positive net outcome for microbial activity under the projected climate change, driven by different, partially interacting environmental factors. Thus, hypoxia in coastal zones may increase due to enhanced respiration caused by higher temperatures and rDOM discharge acting synergistically.
沿海区域是海洋环境中生产力最高的区域，也是最容易受到与流域人类压力相关的环境驱动因素影响的区域。在暗瓶培养实验中，我们研究了盐度、温度和河流溶解有机物质（rDOM）变化对河口群落中微生物呼吸、生长和丰度的短期交互影响。我们发现细菌生长存在交互作用，rDOM 的同化作用在较高盐度下增加。温度升高 3°C 对微生物呼吸有积极影响。较高浓度的 DOM 始终增强呼吸和细菌丰度，而温度升高则降低细菌丰度。后一种结果很可能是由于温度、盐度和 rDOM 对噬菌鞭毛虫丰度的正交互作用造成的。因此，高温和降水导致 rDOM 排放量增加和盐度降低，这将主要促进细菌呼吸、生长和噬菌生物的丰度。我们的研究结果表明，在预期的气候变化下，由于不同的、部分相互作用的环境因素，微生物活动将呈现出积极的净结果。因此，由于温度升高和 rDOM 排放协同作用导致的呼吸作用增强，沿海地区可能会出现更多的缺氧现象。
