Secondary salinization threatens fresh waters worldwide leading to deleterious ecological and economic consequences. The goal of the present study was to assess the potential response of catabolic functions (respiration rate, activities of acid phosphatase and β-glucosidase) of stream biofilms to salinization. Biofilm assemblages from five streams were incubated under controlled conditions in microcosms in spring water under four different treatments: no salt addition (0) and adding 0.25, 1, and 4 g NaCl l −1 . Respiration rate at 0.25 g NaCl l −1 was higher than that at 1 and 4 g l −1 , the latter concentration presenting the lowest value. Acid phosphatase activity was highest in the treatment without salt addition. The activity of β-glucosidase was highest in the non-salted treatment and at 1 g NaCl l −1 . Results reveal salinization as an important threat for catabolism-related functions of stream biofilms, which can compromise nutrient cycling in small shaded streams and consequently the ecosystem services that they provide.

中文翻译：

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盐渍化对河流生物膜功能的影响

次生盐渍化威胁着全世界的淡水，导致有害的生态和经济后果。本研究的目的是评估河流生物膜的分解代谢功能（呼吸速率、酸性磷酸酶和 β-葡萄糖苷酶的活性）对盐渍化的潜在反应。来自五个溪流的生物膜组合在四种不同处理下在泉水中的微观世界中的受控条件下温育：不添加盐 (0) 和添加 0.25、1 和 4 g NaCl l -1 。0.25 g NaCl l -1 的呼吸速率高于1 和4 gl -1 的呼吸速率，后者浓度最低。酸性磷酸酶活性在不加盐的处理中最高。β-葡萄糖苷酶的活性在无盐处理和1g NaCl l -1 时最高。