Alexandrium catenella produces paralytic shellfish toxins that affect marine fisheries and aquaculture as well as ecosystem and human health worldwide. This harmful algal species is extremely sensitive to environmental conditions and potentially to future climate change. Using a generalized additive mixed model (GAMM) we studied the potential effects of changing salinity and temperatures on A. catenella bloom (≥1000 cells L–1) occurrence along Canada’s East Coast throughout the 21st century. Our GAMM was applied to two high greenhouse gas emissions scenarios (RCP 8.5) and one mitigation scenario (RCP 4.5). Under present-day conditions, our model successfully predicted A. catenella’s spatio-temporal distribution in Eastern Canada. Under future conditions, all scenarios predict increases in bloom frequency and spatial extent as well as changes in bloom seasonality. Under one RCP 8.5 scenario, A. catenella bloom occurrences increased at up to 3.5 days per decade throughout the 21st century, with amplified year-to-year variability. Blooms expanded into the Gulf of St. Lawrence and onto the Scotian Shelf. These conditions could trigger unprecedented bloom events in the future throughout our study region. In all climate scenarios, the bloom season intensified earlier (May–June) and ended later (October). In some areas of the Gulf of St. Lawrence, the thermal habitat of A. catenella was exceeded, thereby locally reducing bloom risk during the summer months. We conclude that an increase in A. catenella’s environmental bloom window could further threaten marine fauna including endangered species as well as fisheries and aquaculture industries on Canada’s East Coast. Similar impacts could be felt in other coastal regions of the globe where warming and freshening of waters are intensifying.

中文翻译：

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预测气候变化对加拿大东海岸有毒甲藻亚历山大藻发生的影响

链状亚历山大藻产生麻痹性贝类毒素，影响全球海洋渔业和水产养殖以及生态系统和人类健康。这种有害的藻类对环境条件和未来的气候变化极其敏感。我们使用广义加性混合模型 (GAMM) 研究了盐度和温度变化对整个 21 世纪加拿大东海岸的链状藻华（≥1000 个细胞 L-1）发生的潜在影响。我们的 GAMM 应用于两种高温室气体排放情景 (RCP 8.5) 和一种缓解情景 (RCP 4.5)。在当前条件下，我们的模型成功预测了链状链球菌在加拿大东部的时空分布。在未来的条件下，所有情景都预测开花频率和空间范围的增加以及开花季节性的变化。在一个 RCP 8.5 情景下，在整个 21 世纪，链状链球菌水华发生率以每 10 年 3.5 天的速度增加，逐年变异性扩大。布鲁姆斯扩展到圣劳伦斯湾和苏格兰大陆架。这些条件可能会在我们的研究区域内引发未来前所未有的爆发事件。在所有气候情景中，开花季节较早（5 月至 6 月）加剧，较晚（10 月）结束。在圣劳伦斯湾的某些地区，A. catenella 的热栖息地超出了范围，从而在夏季月份局部降低了水华风险。我们得出结论，A 的增加。链球菌的环境爆发窗口可能进一步威胁海洋动物群，包括加拿大东海岸的濒危物种以及渔业和水产养殖业。全球其他沿海地区可能会感受到类似的影响，这些地区的水域变暖和变淡水正在加剧。