Biodiversity Conservation Center, Environmental Research Institute, Av. Miguel Estéfano 3687, 04301-902, São Paulo, Brazil.
Department of Botany, Institute of Biosciences, University of São Paulo, Rua do Matão 277, 05508-090, São Paulo, Brazil.
Mar Environ Res. 2022 May;177:105620. doi: 10.1016/j.marenvres.2022.105620. Epub 2022 Apr 14.
Marine heatwaves (MHWs) frequency and intensity are increasing around the globe, affecting marine ecosystems' structure and functioning. Understanding how key marine species respond to these short-term extreme events is urgent for predicting damage to coastal ecosystems. Hypnea pseudomusciformis presents distribution in different floristic provinces on the Brazilian coast: tropical, transition and warm-temperate. Here, we evaluate the effects of simulated heatwaves on H. pseudomusciformis populations by measuring the changes in algal growth, pigment content, and photosynthesis. Based on data for the last four decades, we characterized the MHW patterns for each of the three collection sites. Perturbation levels were identified as average intensity heatwave (Δ +2 °C), maximum intensity heatwave (Δ +4 °C) and extreme intensity heatwave (Δ +6 °C), with an average duration of seven days. Based on growth rate data, corroborated with measurements of photosynthesis fluorescence and pigment contents. H. pseudomusciformis populations exhibit distinct tolerance and physiological responses to MHWs. The tropical and transition specimens were affected by Δ + 4 °C and Δ + 6 °C MHW scenarios, while the warm-temperate specimens was the only one to recover in all the MHW scenarios tested. These data are worrisome under a global warming scenario and an increase in MHWs, indicating that tropical and transition specimens of H. pseudomusciformis may be at risk of local extinction. This knowledge will be fundamental in driving any future management intervention or policy change for the conservation of marine ecosystems.
海洋热浪 (MHWs) 的频率和强度在全球范围内不断增加，影响着海洋生态系统的结构和功能。了解关键海洋物种如何应对这些短期极端事件，对于预测沿海生态系统的破坏至关重要。水云（Hypnea pseudomusciformis）在巴西海岸的不同植物区系省份都有分布：热带、过渡和暖温带。在这里，我们通过测量藻类生长、色素含量和光合作用的变化来评估模拟热浪对水云种群的影响。根据过去四十年的数据，我们对每个三个采集点的 MHW 模式进行了特征描述。扰动水平被确定为平均强度热浪（Δ +2°C）、最大强度热浪（Δ +4°C）和极端强度热浪（Δ +6°C），平均持续时间为七天。基于生长率数据，结合光合作用荧光和色素含量的测量。水云种群对 MHWs 表现出明显的耐受和生理反应。热带和过渡标本受到 Δ + 4°C 和 Δ + 6°C MHW 情景的影响，而暖温带标本是所有测试的 MHW 情景中唯一恢复的标本。在全球变暖情景和 MHWs 增加的情况下，这些数据令人担忧，表明水云的热带和过渡标本可能有局部灭绝的风险。这些知识对于推动任何未来的管理干预或保护海洋生态系统的政策变化将是至关重要的。
