College of Marine Science, University of South Florida, 140 7th Avenue South, Saint Petersburg, FL 33701, United States.
College of Marine Science, University of South Florida, 140 7th Avenue South, Saint Petersburg, FL 33701, United States.
Harmful Algae. 2016 Sep;58:59-65. doi: 10.1016/j.hal.2016.07.005. Epub 2016 Aug 25.
The toxic marine dinoflagellate, Karenia brevis (the species responsible for most of red tides or harmful algal blooms in the Gulf of Mexico), is known to be able to swim vertically to adapt to the light and nutrient environments, nearly all such observations have been made through controlled experiments using cultures. Here, using continuous 3-dimensional measurements by an ocean glider across a K. brevis bloom in the northeastern Gulf of Mexico between 1 and 8 August 2014, we show the vertical migration behavior of K. brevis. Within the bloom where K. brevis concentration is between 100,000 and 1,000,000cellsL, the stratified water shows a two-layer system with the depth of pycnocline ranging between 14-20m and salinity and temperature in the surface layer being <34.8 and >28°C, respectively. The bottom layer shows the salinity of >36 and temperature of <26°C. The low salinity is apparently due to coastal runoff, as the top layer also shows high amount of colored dissolved organic matter (CDOM). Within the top layer, chlorophyll-a fluorescence shows clear diel changes in the vertical structure, an indication of K. brevis vertical migration at a mean speed of 0.5-1mh. The upward migration appears to start at sunrise at a depth of 8-10m, while the downward migration appears to start at sunset (or when surface light approaches 0) at a depth of ∼2m. These vertical migrations are believed to be a result of the need of K. brevis cells for light and nutrients in a stable, stratified, and CDOM-rich environment.
有毒的海洋甲藻凯伦藻（该物种是墨西哥湾大部分赤潮或有害藻华的罪魁祸首），已知能够垂直游动以适应光照和营养环境，几乎所有此类观察都是通过使用培养物进行的受控实验得出的。在这里，我们使用海洋滑翔机在 2014 年 8 月 1 日至 8 日期间在墨西哥湾东北部的一次凯伦藻藻华期间进行的连续 3 维测量，展示了凯伦藻的垂直迁移行为。在浓度在 100,000 到 1,000,000cellsL 之间的藻华内，分层水呈现出两层系统，密度跃变层的深度在 14-20m 之间，表层的盐度和温度分别为 <34.8 和 >28°C。底层的盐度>36，温度<26°C。低盐度显然是由于沿海径流造成的，因为上层也显示出大量的有色溶解有机物（CDOM）。在上层中，叶绿素-a 荧光在垂直结构中显示出明显的昼夜变化，表明凯伦藻以 0.5-1mh 的平均速度进行垂直迁移。向上迁移似乎在日出时从 8-10m 的深度开始，而向下迁移似乎在日落时（或当表面光接近 0 时）从 2m 的深度开始。这些垂直迁移被认为是凯伦藻细胞在稳定、分层和富含 CDOM 的环境中对光和营养物质的需求的结果。
