Microcystis aeruginosa complex (MAC) encompasses noxious colonial bloom forming cyanobacteria. MAC representatives bloom in eutrophic freshwater and brackish ecosystems with stagnant water, were temperature and salinity are the main variables modulating their distribution, biomass and toxicity. Cell abundance and biovolume of MAC colonies define regulatory standards for public health. These variables depend upon colony size that in turn changes with environmental conditions. Here, we conducted two series of experiments to evaluate the response of MAC colonies morphological traits (length, volume, mucilage and number of cells) to temperature and salinity. In two series of experiments in the laboratory, we exposed natural MAC communities to three different temperatures (10, 21 and 30 °C) and four salinity levels (0, 5, 10 and 25 ppt) typically found in estuaries. We found that average colony length, volume and mucilage thickness did not change with temperature, but the cell-free space inside the colonies was smaller at the highest evaluated temperature (30 °C). Salinity fostered an increase in colony length, volume and mucilage thickness, while cell-free space diminished, resulting in higher cell density. The number of cells per colony was significantly related to colony size (length and volume) and both, temperature and salinity, affected the parameters of the relationships. Based on present results we propose statistical models to predict cell number per colony based on length and volume and accounting for the effect of salinity and temperature on these traits. This is applicable to ecological studies and to the monitoring of estuarine aquatic environments, by means of a fast and more accurate estimation of cell numbers to define MAC toxic populations early warning systems. A protocol is suggested for its application while the analysis of the interaction of temperature and salinity, as well as the variability in natural environments are objectives for future researches.

铜绿微囊藻复合体（MAC）包含形成蓝藻的有害菌落。MAC代表在富营养化的淡水和微咸的生态系统中停滞不前，其中水和盐分是调节其分布，生物量和毒性的主要变量。MAC菌落的细胞丰度和生物量确定了公共卫生的监管标准。这些变量取决于菌落大小，而菌落大小又随环境条件而变化。在这里，我们进行了两个系列的实验，以评估MAC菌落的形态特征（长度，体积，黏液和细胞数）对温度和盐度的响应。在实验室的两个系列实验中，我们将天然MAC群落暴露在河口中通常遇到的三个不同温度（10、21和30°C）和四个盐度水平（0、5、10和25 ppt）下。我们发现平均菌落长度，体积和粘液厚度不会随温度变化，但在最高评估温度（30°C）下，菌落内部的无细胞空间较小。盐度促进菌落长度，体积和粘液厚度的增加，而无细胞空间减少，从而导致更高的细胞密度。每个菌落的细胞数与菌落大小（长度和体积）显着相关，温度和盐度均影响到相关参数。根据目前的结果，我们提出统计模型，根据长度和体积预测每个菌落的细胞数量，并说明盐度和温度对这些性状的影响。这适用于生态研究和河口水生环境的监测，通过快速，更准确地估计细​​胞数量来定义MAC毒性种群预警系统。建议使用该协议，而温度和盐度相互作用以及自然环境中的可变性分析则是未来研究的目标。