Tulatz Simon, Tillmann Urban, Krock Bernd, Tebben Jan, Meunier Cédric Leo
Section Ecological Chemistry, Alfred Wegener Institut-Helmholtz Zentrum für Polar- und Meeresforschung, Bremerhaven, Germany.
Section Ecological Chemistry, Alfred Wegener Institut-Helmholtz Zentrum für Polar- und Meeresforschung, Bremerhaven, Germany.
Harmful Algae. 2025 Sep;148:102918. doi: 10.1016/j.hal.2025.102918. Epub 2025 Jun 30.
The harmful algal bloom species Alexandrium ostenfeldii has a worldwide distribution from polar to tropical habitats and from oceanic to brackish waters. Among other species of the genus Alexandrium, it is one of the causative organisms of paralytic shellfish toxins, but additionally, A. ostenfeldii has also been shown to produce another class of toxins, cyclic imines. The wide distribution of A. ostenfeldii suggests population-specific adaptations to a multitude of environmental parameters and therefore, variable responses to global change drivers, such as warming and shifts in sea surface salinity. In this study we quantified growth and toxin cell quota of two strains of A. ostenfeldii isolated from the arctic Kongsfjord and two strains from the northern European Baltic Sea at various temperature conditions, to assess the impact of global warming on locally adapted populations. Overall, growth of the arctic strains was detected at temperatures between 7.5 and 20 °C, with a maximum growth rate at 15 °C for both strains. The two strains from the Baltic Sea revealed intraspecific differences concerning their thermal tolerance. One strain showed no growth at 25 °C, while the other still had a positive growth rate at 27 °C. Furthermore, three of the strains were exposed to salinities between 10 and 40, revealing a tolerance to a broad range of salinities. Neither temperature nor salinity affected the qualitative toxin composition of any strain, but we detected novel cyclic imines in three of the four tested strains. Furthermore, different temperatures and salinities led to dynamic shifts in total toxin cell quota. Additionally, we detected novel spirolides in both arctic strains of A. ostenfeldii. These findings suggest that arctic A. ostenfeldii might significantly benefit from global warming, while populations from the Baltic Sea may not, and that the Baltic Sea might become unfavourable for western Baltic A. ostenfeldii due to climate change driven decreasing salinity in this area.
有害藻华物种奥氏亚历山大藻广泛分布于从极地到热带的栖息地，以及从海洋到咸淡水区域。在亚历山大藻属的其他物种中，它是麻痹性贝类毒素的致病生物之一，但此外，奥氏亚历山大藻还被证明会产生另一类毒素——环亚胺。奥氏亚历山大藻的广泛分布表明其种群对多种环境参数具有特定适应性，因此对全球变化驱动因素（如变暖和海表盐度变化）的反应也各不相同。在本研究中，我们对从北极孔斯峡湾分离出的两株奥氏亚历山大藻和从北欧波罗的海分离出的两株奥氏亚历山大藻在不同温度条件下的生长和毒素细胞配额进行了量化，以评估全球变暖对当地适应种群的影响。总体而言，北极菌株在7.5至20°C的温度范围内被检测到有生长，两株菌株的最大生长速率均出现在15°C。来自波罗的海的两株菌株在耐热性方面表现出种内差异。一株在25°C时不生长，而另一株在27°C时仍有正生长速率。此外，其中三株菌株暴露于10至40的盐度范围内，显示出对广泛盐度的耐受性。温度和盐度均未影响任何菌株的毒素定性组成，但我们在四个测试菌株中的三个中检测到了新型环亚胺。此外，不同的温度和盐度导致总毒素细胞配额发生动态变化。此外，我们在奥氏亚历山大藻的两株北极菌株中都检测到了新型螺旋环肽。这些发现表明，北极的奥氏亚历山大藻可能会从全球变暖中显著受益，而波罗的海的种群可能不会，并且由于气候变化导致该地区盐度下降，波罗的海西部可能会变得不利于奥氏亚历山大藻生存。
