The toxin‐producing dinoflagellate Alexandrium pseudogonyaulax has become increasingly abundant in northern European waters, replacing other Alexandrium species. A. pseudogonyaulax produces goniodomins and lytic substances, which can be cytotoxic toward other organisms, including fish, but we still know little about the environmental conditions influencing its growth and toxicity. Here, we investigated the impacts of different nitrogen sources and light intensities, common bottom‐up drivers of bloom formation, on the growth and toxin content of three A. pseudogonyaulax strains isolated from the Danish Limfjord. While the growth rates were significantly influenced by nitrogen source and light intensity, the intracellular toxin contents only showed strong differences between the exponential and stationary growth phases. Moreover, the photophysiological response of A. pseudogonyaulax showed little variation across varying light intensities, while light‐harvesting pigments were significantly more abundant under low light conditions. This study additionally highlights considerable physiological variability between strains, emphasizing the importance of conducting laboratory experiments with several algal strains. A high physiological plasticity toward changing abiotic parameters points to a long‐term establishment of A. pseudogonyaulax in northern European waters.

中文翻译：

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自下而上因素对有害藻华甲藻生长和毒素含量的影响

产毒甲藻假膝亚历山大藻在北欧水域变得越来越丰富，取代了其他亚历山大藻物种。假膝沟藻产生角异蛋白和溶解物质，对包括鱼类在内的其他生物体具有细胞毒性，但我们对影响其生长和毒性的环境条件仍然知之甚少。在这里，我们研究了不同氮源和光强度（水华形成的常见自下而上驱动因素）对三种植物生长和毒素含量的影响假膝沟藻从丹麦利姆峡湾分离出的菌株。虽然生长速率受氮源和光强度的显着影响，但细胞内毒素含量仅在指数生长期和稳定生长期之间表现出强烈差异。此外，光生理反应假膝沟藻在不同的光强度下表现出很小的变化，而光捕获色素在低光条件下明显更加丰富。这项研究还强调了菌株之间相当大的生理变异性，强调了用几种藻类菌株进行实验室实验的重要性。对于改变非生物参数的高生理可塑性表明长期建立假膝沟藻在北欧水域。