Department of Marine Biotechnology, College of Ocean Science and Technology, Kunsan National University, Kunsan 54150, Republic of Korea.
Department of Marine Biotechnology, College of Ocean Science and Technology, Kunsan National University, Kunsan 54150, Republic of Korea.
Harmful Algae. 2017 Sep;68:105-117. doi: 10.1016/j.hal.2017.07.012. Epub 2017 Aug 11.
Cryptophytes are ubiquitous and one of the major phototrophic components in marine plankton communities. They often cause red tides in the waters of many countries. Understanding the bloom dynamics of cryptophytes is, therefore, of great importance. A critical step in this understanding is unveiling their trophic modes. Prior to this study, several freshwater cryptophyte species and marine Cryptomonas sp. and Geminifera cryophila were revealed to be mixotrophic. The trophic mode of the common marine cryptophyte species, Teleaulax amphioxeia has not been investigated yet. Thus, to explore the mixotrophic ability of T. amphioxeia by assessing the types of prey species that this species is able to feed on, the protoplasms of T. amphioxeia cells were carefully examined under an epifluorescence microscope and a transmission electron microscope after adding each of the diverse prey species. Furthermore, T. amphioxeia ingestion rates heterotrophic bacteria and the cyanobacterium Synechococcus sp. were measured as a function of prey concentration. Moreover, the feeding of natural populations of cryptophytes on natural populations of heterotrophic bacteria was assessed in Masan Bay in April 2006. This study reported for the first time, to our knowledge, that T. amphioxeia is a mixotrophic species. Among the prey organisms offered, T. amphioxeia fed only on heterotrophic bacteria and Synechococcus sp. The ingestion rates of T. amphioxeia on heterotrophic bacteria or Synechococcus sp. rapidly increased with increasing prey concentrations up to 8.6×10 cells ml, but slowly at higher prey concentrations. The maximum ingestion rates of T. amphioxeia on heterotrophic bacteria and Synechococcus sp. reached 0.7 and 0.3 cells predator h, respectively. During the field experiments, the ingestion rates and grazing coefficients of cryptophytes on natural populations of heterotrophic bacteria were 0.3-8.3 cells predatorh and 0.012-0.033d, respectively. Marine cryptophytes, including T. amphioxeia, are known to be favorite prey species for many mixotrophic and heterotrophic dinoflagellates and ciliates. Cryptophytes, therefore, likely play important roles in marine food webs and may exert a considerable potential grazing impact on the populations of marine bacteria.
隐藻是海洋浮游生物群落中普遍存在的一种主要的光合生物成分，它们经常在许多国家的水域引发赤潮。因此，了解隐藻的繁殖动态非常重要。在这一理解过程中的一个关键步骤是揭示它们的营养方式。在此之前，人们已经发现几种淡水隐藻物种和海洋Cryptomonas sp. 和 Geminifera cryophila 是混合营养的。然而，常见的海洋隐藻物种 Teleaulax amphioxeia 的营养模式尚未得到研究。因此，为了通过评估该物种能够摄食的猎物种类来探索 T. amphioxeia 的混合营养能力，在添加每种不同的猎物后，使用荧光显微镜和透射电子显微镜仔细检查了 T. amphioxeia 细胞的原生质体。此外，还测量了 T. amphioxeia 对异养细菌和蓝藻 Synechococcus sp. 的摄食率，作为猎物浓度的函数。此外，还于 2006 年 4 月在马山湾评估了海洋隐藻自然种群对异养细菌自然种群的摄食情况。本研究首次报道，T. amphioxeia 是一种混合营养物种。在所提供的猎物生物中，T. amphioxeia 仅摄食异养细菌和蓝藻 Synechococcus sp.。T. amphioxeia 对异养细菌或蓝藻 Synechococcus sp. 的摄食率随着猎物浓度的增加迅速增加到 8.6×10 个细胞 ml，然后在更高的猎物浓度下缓慢增加。T. amphioxeia 对异养细菌和蓝藻 Synechococcus sp. 的最大摄食率分别达到 0.7 和 0.3 个细胞捕食者 h。在野外实验中，海洋隐藻对自然种群异养细菌的摄食率和牧食系数分别为 0.3-8.3 个细胞捕食者 h 和 0.012-0.033 d。众所周知，海洋隐藻包括 T. amphioxeia 在内，是许多混合营养和异养鞭毛藻和纤毛虫的首选猎物物种。因此，隐藻在海洋食物网中可能发挥重要作用，并可能对海洋细菌种群产生相当大的潜在牧食影响。
