Alexandrium catenella, the main species associated with harmful algal blooms, has progressively increased its distribution through one of the most extensive and highly variable fjord systems in the world. In order to understand this successful expansion, we evaluated the effects of different salinities, light intensity, temperatures, nitrogen (N) forms and nitrogen/phosphate (N:P) ratio levels on the growth performance, using clones isolated from different locations across its wide geographic distribution. Results showed that the growth responses were plastic and, in some cases, different reaction norms among clones were observed. Despite plasticity, the optimal growth of A. catenella (i.e. highest growth rate and highest maximal cells density) was reached within a narrow thermal range (12–15°C), while salinity (20–30 PSU) and light intensity (20–120 μmol m⁻² s⁻¹) ranges were wider. These results are partially consistent with the highest cell densities recorded in the field. Furthermore, optimal growth was reached using reduced forms of nitrogen (i.e. urea and NH₄⁺) and in unbalanced N:P ratios (18:1 and 30:1). These characteristics likely allow A. catenella to grow in highly variable environmental conditions and might partly explain the recent expansion of this species.

中文翻译：

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智利峡湾亚历山大藻在不同环境驱动下的生长性能：可塑性对高度可变环境的反应

亚历山大藻（Alexandre catenella）是与有害藻华有关的主要物种，已通过世界上最广泛，变化最大的峡湾系统之一逐渐增加了其分布。为了了解这种成功的扩展，我们使用了从其不同位置分离的克隆，评估了不同盐度，光强度，温度，氮（N）形态和氮/磷酸盐（N：P）比水平对生长性能的影响。地理分布广泛。结果表明，生长反应是可塑性的，并且在某些情况下，观察到克隆之间的反应标准不同。尽管具有可塑性，但链霉菌的最佳生长（即最高的生长速率和最高的最大细胞密度）在狭窄的温度范围（12–15°C）内达到，而盐度（20–30 PSU）和光强度（20–120μmolm ^-2  s ^-1）范围内更宽。这些结果与现场记录的最高细胞密度部分一致。此外，使用减少形式的氮（即尿素和NH ₄ ⁺）以及不平衡的N：P比（18：1和30：1）可以达到最佳生长。这些特征可能允许链状土壤杆菌在高度变化的环境条件下生长，并可能部分解释该物种最近的扩展。