Range expansion of tropical pyrosomes in the northeast Pacific Ocean
Range expansion of tropical pyrosomes in the northeast Pacific Ocean
复制标题
东北太平洋热带火体虫的范围扩大
DOI：
10.1002/ecy.2429
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发表时间：
2018
期刊：
影响因子：
4.8
通讯作者：
Galloway, Aaron W. E.
中科院分区：
文献类型：
--
作者：
Sutherland, Kelly R.;Sorensen, Hilarie L.;Blondheim, Olivia N.;Brodeur, Richard D.;Galloway, Aaron W. E.
Ecology，99（10），2018，pp. 2397-2399© 2018被美国生态学会认为是热带至亚热带的分布（货车索斯特1981），以前曾在大西洋东南部（Drits et al. 1992）和地中海西北部（Andersen and Sardou 1994）报道过水华。在门多西诺角以南的加州海岸，火体虫相对常见;例如，在南极丰度的时间序列中，1951年至2002年，在加州南部海岸的年度采样期间，大约有一半的时间报告了大西洋火体虫（Lavaniegos和Ohman，2003年），在其已知的纬度范围内。2014年，科学家、渔民和海滩游客首次报告说，在加州、俄勒冈州和华盛顿北部北方附近的沿海沃茨出现了P. atlanticum。在2015年和2016年再次出现了火体虫。到2017年夏天，它们沿着整个西海岸以前所未有的数量出现，到达阿拉斯加西部海湾，但在俄勒冈州附近显示出它们的最高丰度（Brodeur et al. 2018）堵塞渔网并扰乱海洋活动，如商业和体育渔业（Kaety Jacobson，个人交流）。在2017年夏天美国太平洋西北海岸的两次研究巡航中，菌落长4-26厘米，密度高达3个菌落/m3。垂直视频摄像机配置文件和相应的环境数据（温度，盐度和荧光）表明，层的pyrosomes分布在60米深，在表面混合层的基础。这些观测是在2017年5月从加州的博德加湾（北纬38度）到俄勒冈州的米尔斯角（北纬45.5度）以及2017年8月从俄勒冈州的纽波特到加拿大不列颠哥伦比亚省的温哥华岛北端（北纬44度-北纬49度）的生态系统调查巡航期间进行的。这种高密度的热带pyrosomes在温带东北太平洋的外观提出了有趣的研究问题的物理海洋学特征，导致其向北扩张，并允许其人口持续多年的环境驱动因素。从2014年开始，北太平洋形成了一个异常温暖和稳定的水团，称为“暖团”，持续了几年，然后被2016年向北发展的强烈厄尔尼诺现象所取代（Di Lorenzo和Mantua 2016），这可能有助于这种热带物种在正常范围以北的生存。此外，陆上流动可能使它们比正常情况下更接近海岸，导致2014年至2018年期间有许多关于搁浅的火体的报告（图1c）。在2018年2月的一次巡航中，我们再次在俄勒冈州纽波特（44.40 N）的沿着三个观测站（距离海岸10、25和45 km）观察到大量的火体，温度范围从10到10.8 C（图1a、B;视频S1）。与夏季巡航观测结果相似，录像显示，表层沃茨中没有火体，但在约40米深的表层混合层底部附近的一层中聚集。
Ecology, 99 (10), 2018, pp. 2397–2399© 2018 by the Ecological Society of America have been considered tropical to subtropical in their distribution (Van Soest 1981) with blooms previously reported in the southeast Atlantic (Drits et al. 1992) and the northwest Mediterranean (Andersen and Sardou 1994). Pyrosomes are relatively common off of the California coast south of Cape Mendocino; for example, in a time series of planktonic abundance, P. atlanticum was reported about half the time during annual sampling off the coast of southern California from 1951 to 2002 (Lavaniegos and Ohman 2003), within its known latitudinal range. In 2014, scientists, fishermen, and beachgoers first started reporting the appearance of P. atlanticum in coastal waters near northern California, Oregon, and Washington north of their previously reported range. The pyrosomes appeared again in 2015 and 2016. By the summer of 2017, they appeared in unprecedented numbers along the entire west coast, reaching the Western Gulf of Alaska, but showed some of their highest abundances off Oregon (Brodeur et al. 2018) clogging nets and disrupting marine activities such as commercial and sport fisheries (Kaety Jacobson, personal communication). During two research cruises off the Pacific Northwest coast, USA in the summer of 2017, colonies were 4–26 cm long and occurred in densities up to 3 colonies/m3. Vertical video camera profiles and corresponding environmental data (temperature, salinity, and fluorescence) indicated that layers of pyrosomes were distributed at~ 60 m depth, at the base of the surface mixed layer. These observations were made during ecosystem survey cruises in May 2017 from Bodega Bay, California (38 N) to Cape Meares, Oregon (45.5 N), and August 2017 from Newport, Oregon, to the north end of Vancouver Island, British Columbia, Canada (44 N–49 N). The appearance of such high densities of tropical pyrosomes in the temperate northeast Pacific presents interesting research questions about the physical oceanographic features that led to their northerly expansion, and the environmental drivers that have allowed their populations to persist for multiple years. Beginning in 2014, an unusually warm and stable water mass termed the “warm blob” formed in the North Pacific and lasted several years, and then was replaced by the northward progression of a strong El Nino in 2016 (Di Lorenzo and Mantua 2016), which may have facilitated the survival of this tropical species well north of their normal range. Furthermore, onshore flow may have pushed them closer to the shore than normal, leading to numerous reports of beached pyrosomes from 2014 to 2018 (Fig. 1c). During a February 2018 cruise, we again observed pyrosomes in large numbers during day and night at three stations (10, 25, and 45 km off shore) along the Newport, Oregon Hydrographic line (44.40 N), where temperatures ranged from 10 to 10.8 C (Fig. 1a, b; Video S1). Similar to the summer cruise observations, video footage showed that pyrosomes were absent in surface waters but aggregated in a layer near the base of the surface mixed layer at~ 40 m depth.