Clayton Sophie, Chrabot Jacqueline B, Echevarria Michael, Gibala-Smith Leah, Mogatas Kathryn, Bernhardt Peter, Mulholland Margaret R
National Oceanography Centre, Southampton, United Kingdom.
Department of Ocean and Earth Sciences, Old Dominion University, Norfolk, VA, United States.
Front Microbiol. 2024 Nov 13;15:1378552. doi: 10.3389/fmicb.2024.1378552. eCollection 2024.
is a mixotrophic dinoflagellate harmful algal bloom (HAB) species that blooms annually in the lower Chesapeake Bay. undertakes a diel vertical migration (DVM) which may give it a competitive advantage over purely phototrophic organisms who cannot access deeper nutrient pools and allow it to form large toxic blooms. Laboratory-based estimates of DVM rates suggest that it is one of the fastest known dinoflagellate swimmers and understanding this behavior is likely important for modeling and predicting blooms. However, to date, no field-derived estimates of DVM rates have been made in the Chesapeake Bay. In this study, we conducted four targeted field experiments to investigate the DVM of in the Lafayette River, a sub-tributary of the Chesapeake Bay. Vertical profiles of chlorophyll fluorescence collected at least every 2 h over diel periods were used to track the DVM of during blooms. The maximum observed DVM rate for was 2.5 m h, with mean DVM rates around 1.3 m h for both ascents and descents. As in studies from other regions, our results show that ascent to/descent from the surface initiates before sunrise/sunset, suggesting phototaxis is not the primary trigger of their DVM. However, unlike in other studies where was observed to modulate its DVM to avoid excessively warm temperatures (≥30°C), we do not observe active thermotaxic avoidance, despite ambient temperatures exceeding their optimal threshold.
是一种混合营养的甲藻有害藻华物种，每年在切萨皮克湾下游形成藻华。进行昼夜垂直迁移（DVM），这可能使其比无法获取更深层营养库的纯光合生物具有竞争优势，并使其能够形成大型有毒藻华。基于实验室的DVM速率估计表明，它是已知游动速度最快的甲藻之一，了解这种行为可能对藻华的建模和预测很重要。然而，迄今为止，切萨皮克湾尚未有来自实地的DVM速率估计。在本研究中，我们进行了四项有针对性的实地实验，以调查切萨皮克湾的一条支流拉斐特河中 的DVM。在昼夜期间至少每2小时收集一次叶绿素荧光的垂直剖面，用于追踪藻华期间 的DVM。观测到的 的最大DVM速率为2.5米/小时，上升和下降的平均DVM速率约为1.3米/小时。与其他地区的研究一样，我们的结果表明， 从水面上升/下降在日出/日落之前开始，这表明趋光性不是其DVM的主要触发因素。然而，与其他观察到 调节其DVM以避免过高温度（≥30°C）的研究不同，尽管环境温度超过了它们的最佳阈值，我们并未观察到主动的热趋避现象。
