Svalbard archipelago is experiencing the effects of climate changes (i.e., glaciers’ thickness reduction and glacier front retreat), but how ice melting affects water biogeochemistry is still unknown. Microbial communities often act as environmental sentinels, modulating their distribution and activity in response to environmental variability. To assess microbial response to climate warming, within the ARctic: present Climatic change and pAst extreme events (ARCA) project, a survey was carried out along a transect in Konsfjorden from off-shore stations towards the Kronebreen glacier. Total bacterial abundance and the fraction of actively respiring cells (labelled by cyanotetrazolium chloride, CTC), cultivable heterotrophic bacterial abundance, and extracellular enzymatic activities (leucine aminopeptidase (LAP), beta-glucosidase (GLU), and alkaline phosphatase (AP)) were measured. In addition, water temperature, salinity, dissolved oxygen, turbidity, total suspended matter (TSM), particulate and chromophoric dissolved organic matter (CDOM), chlorophyll-a (Chl-a), and inorganic compounds were determined, in order to evaluate whether variations in microbial abundance and metabolism were related with changes in environmental variables. Colder waters at surface (3.5–5 m) depths and increased turbidity, TSM, and inorganic compounds found at some hydrological stations close to the glacier were signals of ice melting. CDOM absorption slope values (275–295 nm) varied from 0.0077 to 0.0109 nm⁻¹, and total bacterial cell count and cultivable heterotrophic bacterial abundance were in the order of 10⁶ cells/mL and 10³ colony forming units/mL, respectively. Enzymatic rates <1.78, 1.25, and 0.25 nmol/L/h were recorded for AP, LAP, and GLU, respectively. Inorganic compounds, TSM, and turbidity correlated inversely with temperature; AP was significantly related with CDOM absorption spectra and heterotrophic bacteria (r = 0.59, 0.71, p < 0.05); and LAP with Chl-a, Particulate Organic Carbon (POC) and Particulate Organic Nitrogen (PON) (0.97, 0.780, 0.734, p < 0.01), suggesting that fresh material from ice melting stimulated the metabolism of the cultivable fraction.

中文翻译：

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微生物丰度和酶活性模式：对沿Kongsfjorden（斯瓦尔巴群岛）的样带变化的环境特征的响应

斯瓦尔巴群岛正在经历气候变化的影响（即冰川的厚度减少和冰川前部撤退），但是冰融化如何影响水的生物地球化学仍然未知。微生物群落通常充当环境哨兵，响应环境变化来调节其分布和活动。为了评估微生物对气候变暖的反应，在“北极：目前的气候变化和极端事件”（ARCA）项目中，沿着Konsfjorden的一个样带进行了调查，该样带从近海站到Kronebreen冰川。总细菌丰度和活跃呼吸细胞的比例（用氰基四唑氯化物（CTC）标记），可培养的异养细菌丰度和细胞外酶活性（亮氨酸氨肽酶（LAP），β-葡萄糖苷酶（GLU），和碱性磷酸酶（AP））。此外，水温，盐度，溶解氧，浊度，总悬浮物（TSM），颗粒和发色性溶解有机物（CDOM），叶绿素a（Chl- a），并确定了无机化合物，以评估微生物丰度和代谢的变化是否与环境变量的变化有关。在接近冰川的一些水文站发现的表层（3.5–5 m）深度较冷的水以及浊度，TSM和无机化合物增加是冰融化的信号。CDOM吸收斜率值（275–295 nm）在0.0077至0.0109 nm ^{-1之间变化}，总细菌细胞数和可培养的异养细菌丰度约为10 ^6个细胞/ mL和10 ^3个集落形成单位/ mL。分别记录了AP，LAP和GLU的酶促速率<1.78、1.25和0.25 nmol / L / h。无机化合物，TSM和浊度与温度成反比。AP与CDOM吸收光谱和异养细菌显着相关（r = 0.59，0.71，p <0.05）；LAP和Chl- a，微粒有机碳（POC）和微粒有机氮（PON）（0.97，0.780，0.734，p <0.01），表明来自冰融化的新鲜物质刺激了可培养部分的代谢。