一类新的赤潮藻源——微塑料附生赤潮藻

A new source of harmful algae:epimicroplastic microalgae

全球海洋中持续增长的微塑料(microplastics,MPs)为微藻提供了新的栖息生境和传播载体,附生在MPs表面的微藻被称为微塑料附生微藻(epimicroplastic microalgae,EMP-MA)。有关EMP-MA的研究可以追溯到1971年,但直到2022年才正式提出EMP-MA的概念,并且由于MPs污染加剧,EMP-MA也逐渐受到了关注。硅藻、甲藻、蓝藻、绿藻等藻类均会在MPs表面附生,其中硅藻是最丰富和最多样的类群,常见的附生硅藻有曲壳藻属(Achnantes)、双眉藻属(Amphora)、卵形藻属(Cocconeis)、舟形藻属(Navicula)和菱形藻属(Nitzschia)等。值得注意的是,在EMP-MA群落中还发现了多种赤潮藻类,如卵形蛎甲藻(近似种)(Ostreopsis cf.ovata)、太平洋亚历山大藻(Alexandrium pacificum)、具刺膝沟藻(Gonyaulax spinifera)、东海原甲藻(Prorocentrum donghaiense)和尖刺伪菱形藻(Pseudo-nitzschia pungens)等。这些赤潮藻类可能随着MPs一起在风、海流等外力的驱动下向四处扩散,从而为赤潮的发生提供种源,增加赤潮的暴发和扩散风险,并且随着MPs污染加剧和全球气候变化,这种风险可能会随之增加。然而,目前尚未有直接证据证明MPs表面附生的赤潮藻类确实引发了赤潮或造成了赤潮扩散。为此,我们应当持续关注MPs附生赤潮藻类的时空动态并积极建立MPs附生赤潮藻类扩散风险评估体系,对其引发赤潮的可能性或诱发赤潮的关键环境因子开展深入研究,以期完善赤潮暴发和扩散机制,为海洋防灾减灾工作提供理论依据。

Microplastics(MPs)with a growing trend in the global ocean provide new habitat and dispersal vectors for microalgae,those microalgae attached to MPs are referred to as Epimicroplastic microalgae(EMP-MA).Research on EMP-MA can be traced back to 1971,but the concept of EMP-MA was not formally proposed until 2022 and is gradually gaining attention due to increasing pollution from MPs.Algae such as diatoms,dinoflagellates,cyanobacteria and green algae can attach to MPs,where diatoms are the most abundant and diverse taxa with common diatoms including Achnantes,Amphora,Cocconeis,Navicula,Nitzschia,etc.It is worth noting that in the EMP-MA community it presences some harmful algae such as Ostreopsis cf.ovata,Alexandrium pacificum,Gonyaulax spinifera,Prorocentrum donghaiense,Pseudo-nitzschia pungens,etc.They may be transferred to other regions with MPs driven by wind and currents,providing seeds and increasing the risk of outbreaks and spread of HABs.And this risk is likely to increase with growing pollution from MPs and changing global climate.However,no study reported that those harmful algae attached to MPs have caused harmful algal blooms(HABs)or dispersal of HABs.Therefore,we should continue to pay attention to the spatial and temporal dynamics of harmful algae attached to MPs,actively establish a risk assessment system and carry out in-depth research on the possibility of HABs or the key environmental factors causing HABs,so as to exploit the mechanism of HABs outbreaks and dispersal,and to provide a theoretical basis for the work of marine disaster prevention and mitigation.