Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, Hawai'i, USA.
Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, Kāne'ohe, Hawai'i, USA.
Environ Microbiol. 2024 Jul;26(8):e16689. doi: 10.1111/1462-2920.16689.
In oligotrophic oceans, the smallest eukaryotic phytoplankton are both significant primary producers and predators of abundant bacteria such as Prochlorococcus. However, the drivers and consequences of community dynamics among these diverse protists are not well understood. Here, we investigated how trophic strategies along the autotrophy-mixotrophy spectrum vary in importance over time and across depths at Station ALOHA in the North Pacific Subtropical Gyre. We combined picoeukaryote community composition from a 28-month time-series with traits of diverse phytoplankton isolates from the same location, to examine trophic strategies across 13 operational taxonomic units and 8 taxonomic classes. We found that autotrophs and slower-grazing mixotrophs tended to prevail deeper in the photic zone, while the most voracious mixotrophs were relatively abundant near the surface. Within the mixed layer, there was greater phagotrophy when conditions were most stratified and when Chl a concentrations were lowest, although the greatest temporal variation in trophic strategy occurred at intermediate depths (45-100 m). Dynamics at this site are consistent with previously described spatial patterns of trophic strategies. The success of relatively phagotrophic phytoplankton at shallower depths in the most stratified waters suggests that phagotrophy is a competitive strategy for acquiring nutrients when energy from light is plentiful.
在贫营养的海洋中，最小的真核浮游植物既是重要的初级生产者，也是丰富细菌（如聚球藻）的捕食者。然而，这些不同的原生生物群落动态的驱动因素和后果还不是很清楚。在这里，我们研究了在北太平洋亚热带环流的 ALOHA 站，沿着自养-混合营养光谱的营养策略在时间和深度上的重要性如何变化。我们将 28 个月的时间序列中的微微型真核生物群落组成与同一地点的不同浮游植物分离物的特征相结合，以检查 13 个操作分类单位和 8 个分类类群的营养策略。我们发现，自养生物和生长缓慢的混合营养生物往往在光区深处占优势，而最贪婪的混合营养生物在表面附近相对丰富。在混合层中，当条件分层最严重和 Chl a 浓度最低时，吞噬作用更大，尽管在中间深度（45-100 m）发生了最大的营养策略时间变化。该地点的动态与先前描述的营养策略的空间模式一致。在最分层的水域中，相对吞噬性浮游植物在较浅深度的成功表明，吞噬作用是一种在光能量丰富时获取营养的竞争策略。
