Planktonic foraminiferal assemblages reflect warming during two recent mid-latitude marine heatwaves
Planktonic foraminiferal assemblages reflect warming during two recent mid-latitude marine heatwaves
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DOI：
10.3389/fmars.2023.1155761
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发表时间：
2023-03
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影响因子：
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通讯作者：
M. K. Lane;J. Fehrenbacher;J. Fisher;M. Fewings;B. Crump;C. Risien;Grace M. L. Meyer;Faith Schell
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作者：
M. K. Lane;J. Fehrenbacher;J. Fisher;M. Fewings;B. Crump;C. Risien;Grace M. L. Meyer;Faith Schell
在未来的气候情景下，目前极端的海洋温度和海洋热浪（MHW）的资格预测增加的频率和强度，但鲜为人知的是，这些事件对最常见的古代理之一，南极有孔虫的影响。浮游有孔虫是全球普遍存在的有壳海洋原生生物。它们的丰度和地球化学随海洋条件而变化，化石标本通常用于重建古代海洋条件。浮游有孔虫组合是众所周知的全球变化与海面温度，初级生产力，和其他水文条件，但尚未在中纬度MHWs的背景下进行研究。在本研究中，对2010-2019年纽波特水道沿着的浮游有孔虫群落组成和丰度进行了量化，纽波特水道是北方加州洋流（NCC）44.6°N的长期监测样带。在每年秋季（8月至10月）巡航期间，从离岸46至370公里的存档浮游生物拖丝中获得样本。在这段时间内，有两个MHW影响了该地区：第一个在2014-2016年，第二个在2019年，持续时间较短。在2014-2016年MHW期间，暖水亚热带和热带有孔虫物种比该地区常见的典型极地，亚极地和过渡物种更普遍。在2016年年底第一波MHW消散后，冷水物种再次丰富。在2019年的第二次，持续时间较短的MHW期间，该组合由温水组合组成，但不包括热带物种。有孔虫组合的变化与温度和盐度的变化在上100米，并没有与离岸或上升流的距离。这些结果表明，化石有孔虫组合从深海沉积物芯可以提供洞察过去MHWs的规模和频率。
Under future climate scenarios, ocean temperatures that are presently extreme and qualify as marine heatwaves (MHW) are forecasted to increase in frequency and intensity, but little is known about the impact of these events on one of the most common paleoproxies, planktonic foraminifera. Planktonic foraminifera are globally ubiquitous, shelled marine protists. Their abundances and geochemistry vary with ocean conditions and fossil specimens are commonly used to reconstruct ancient ocean conditions. Planktonic foraminiferal assemblages are known to vary globally with sea surface temperature, primary productivity, and other hydrographic conditions, but have not been studied in the context of mid-latitude MHWs. For this study, the community composition and abundance of planktonic foraminifera were quantified for 2010-2019 along the Newport Hydrographic Line, a long-term monitoring transect at 44.6°N in the Northern California Current (NCC). Samples were obtained from archived plankton tows spanning 46 to 370 km offshore during annual autumn (August – October) cruises. Two MHWs impacted the region during this timeframe: the first during 2014-2016 and a second, shorter duration MHW in 2019. During the 2014-2016 MHW, warm water subtropical and tropical foraminifera species were more prevalent than the typical polar, subpolar, and transitional species common to this region. Cold water species were abundant again after the first MHW dissipated in late 2016. During the second, shorter-duration MHW in 2019, the assemblage consisted of a warm water assemblage but did not include tropical species. The foraminiferal assemblage variability correlated with changes in temperature and salinity in the upper 100 meters and was not correlated with distance offshore or upwelling. These results suggest that fossil foraminiferal assemblages from deep sea sediment cores may provide insight into the magnitude and frequency of past MHWs.