Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche, Villefranche-sur-Mer, France; DECOD, L'Institut Agro, IFREMER, INRAE, 44000 Nantes, France.
Institute of Marine Sciences (ICM-CSIC), Barcelona, Spain.
Sci Total Environ. 2024 Oct 15;947:174726. doi: 10.1016/j.scitotenv.2024.174726. Epub 2024 Jul 11.
Fast environmental changes and high coastal human pressures and impacts threaten the Mediterranean Sea. Over the last decade, recurrent blooms of the harmful dinoflagellate Ostreopsis cf. ovata have been recorded in many Mediterranean beaches. These microalgae produce toxins that affect marine organisms and human health. Understanding the environmental conditions that influence the appearance and magnitude of O. cf. ovata blooms, as well as how climate change will modify its future distribution and dynamics, is crucial for predicting and managing their effects. This study investigates whether the spatio-temporal distribution of this microalga and the frequency of its blooms could be altered in future climate change scenarios in the Mediterranean Western basin. For the first time, an ecological habitat model (EHM) is forced by physico-chemical climate change simulations at high-resolution, under the strong greenhouse gas emission trajectory (RCP8.5). It allows to characterize how O. cf. ovata may respond to projected conditions and how its distribution could shift over a wide spatial scale, in this plausible future. Before being applied to the EHM, future climate simulations are further refined by using a statistical adaptation method (Cumulative Distribution Function transform) to improve the predictions robustness. Temperature (optimum 23-26 °C), high salinity (>38 psu) and high inorganic nutrient concentrations (nitrate >0.25 mmol N·m and phosphate >0.035 mmol P·m) drive O. cf. ovata abundances. High spatial disparities in future abundances are observed. Namely, O. cf. ovata abundances could increase on the Mediterranean coasts of France, Spain and the Adriatic Sea while a decrease is expected in the Tyrrhenian Sea. The bloom period could be extended, starting earlier and continuing later in the year. From a methodological point of view, this study highlights best practices of EHMs in the context of climate change to identify sensitive areas for current and future harmful algal blooms.
快速的环境变化和高海岸人类压力和影响威胁着地中海。在过去的十年中，许多地中海海滩都记录到了有害双鞭甲藻 cf. ovata 的频繁爆发。这些微藻产生的毒素会影响海洋生物和人类健康。了解影响 O. cf. ovata 爆发出现和规模的环境条件，以及气候变化将如何改变其未来分布和动态，对于预测和管理其影响至关重要。本研究调查了这种微藻的时空分布及其爆发的频率是否会在未来地中海西部盆地的气候变化情景中发生变化。这是首次在高分辨率下，根据强烈的温室气体排放轨迹（RCP8.5），由物理化学气候变化模拟驱动生态生境模型（EHM）。它可以描述 O. cf. ovata 可能如何应对预测条件，以及在这个可能的未来，其分布可能在广泛的空间尺度上发生怎样的变化。在将未来气候模拟应用于 EHM 之前，进一步使用统计适应方法（累积分布函数变换）对其进行细化，以提高预测的稳健性。温度（最佳 23-26°C）、高盐度（>38 psu）和高无机营养浓度（硝酸盐>0.25 mmol N·m 和磷酸盐>0.035 mmol P·m）驱动 O. cf. ovata 的丰度。未来丰度存在显著的空间差异。即，O. cf. ovata 的丰度可能会在法国、西班牙和亚得里亚海的地中海沿岸增加，而在第勒尼安海预计会减少。爆发期可能会延长，开始得更早，持续到一年中的晚些时候。从方法论的角度来看，本研究强调了 EHM 在气候变化背景下的最佳实践，以确定当前和未来有害藻华的敏感区域。
