有害甲藻Stoeckeria algicida在辽东湾的时空分布

Stoeckeria algicida为甲藻纲胸甲球藻科,有侵噬鱼类细胞杀鱼的能力,可导致鱼类成群死亡,同时也会杀死其他海洋微藻。由于该藻个体微小、形态学鉴定困难,研究较为迟缓,我国海域几乎没有该藻的研究报道。近几年,高通量测序技术的发展极大地推动了微型/微微型浮游植物的鉴定研究,为了解我国辽东湾海域是否存在Stoeckeria algicida及其分布情况,以18S rD NA V4区作为目标基因,结合高通量测序技术,专门设计了微型/微微型浮游植物鉴定引物对V4(F/R),随后对辽东湾2014年四季海水中微型和微微型浮游植物多样性进行了检测。结果发现,Stoeckeria algicida除了春季未检出外,其他季节均有检出,温度是影响该藻繁殖的主要因素。虽然Stoeckeria algicida在整个环境样品中优势度不太明显,但其夏季密度较高(最高达2.753×10~3个/L),高值区主要分布在辽东湾东西两岸,致灾风险较高,应引起有关方面足够重视。Stoeckeria algicida在我国海域首次报道,其危害后果严峻,必须加强监测监管。

Distribution of the toxic dinoflagellate Stoeckeria algicida in Liaodong Bay

The toxic dinoflagellate, Stoeckeria algicida, belongs to the family Thoracosphaeraceae. It invades fish cells, causing high fish mortality, and also kills other marine microalgae.. algicida was first found in Masan Bay, Korea, in 2004. The morphology and ecology of S. algicida have been reported, and it has been identified as an invasive microalgae. Its vegetative and biflagellate cells are oval, and measure 7.3-15.9 mm (mean 11.6) and 2.7-12.2 mm (mean 7.3), respectively. Based on morphological and genealogical analyses, a previous study suggested that it could be a new species in a new genus. Grazing coefficients of up to 0.142 min^-1 have been reported for S. algicida on Heterosigma akashiwo, suggesting that S. algicida grazing can have a considerable impact on H. akashiwo populations. Morphological identification of S. algicida is difficult because of its small size, which has delayed research progress. Therefore, research on S. algicida in the China Sea has been limited. Recently, the development of high-throughput next generation sequencing (NGS) technology has increased nano- and picophytoplankton research output. To identify S. algicida and its distribution in Liaodong Bay, we used the 18S rDNA V4 region as the target gene to design the primer V4(F/R), and employed NGS technology to investigate nano- and picophytoplankton diversity in Liaodong Bay. The results revealed that S. algicida was present in Liaodong Bay in every season except spring. Temperature was a significant factor in S. algicida reproduction. S. algicida was not dominant in the phytoplankton community, but its density was higher in summer (2.753×10³ cells/L). S. algicida density was high on the east and west coasts of Liaodong Bay, where the risk of disastrous ecological impacts is higher. In the study, S. algicida was found and reported in Liaodong Bay, China, S. algicida could be classified as a newly naturalized species based on its distribution in Liaodong Bay. Although there are no records of red tides caused by S. algicida, measures should be taken to prevent such an occurrence, rather than mitigating the effects should a red tide occur. Furthermore, monitoring and management of toxic microalgae in aquacultural areas should be increased and a red tide early warning system should be established to avoid disasters in fisheries ecosystems.