环境特征的微塑料早期暴露对海水青鳉后期生长、繁殖及子代发育的影响

Microplastics in marine environments are an emerging environmental problem of international concern. As the prevalence of microplastics in wide range of marine biota is rising rapidly in recent years, the researches on bioaccumulation and toxicity of microplastics have become increasingly concerned in the world. There is growing evidence that ingestion of microplastics can have negative impacts on organisms; however, the microplastic concentrations used in most of existing experimental studies are much higher than the levels documented in the marine environment, and many of these studies focus on the effects caused by short-term exposure of microplastics. To date, the processes and mechanisms of accumulation and elimination of microplastics in marine juvenile fishes are poorly understood. The long-term effects after ingestion of microplastics have not been identified, especially for the reproduction and generational effects. Marine medaka (Oryzias melastigma), known as a potentially appropriate marine model fish, are used as the tested organism. The main works are as follows: to determine the processes of uptake, accumulation and elimination of microplastics in marine medaka; to detect the influence of environmental characteristics (concentration, type and size) on the change of microplastics bioaccumulation in fish; to examine how environmental levels of microplastic particles affect the development, behavior, growth, and survival of marine medaka; and to discuss the later-life consequences following early-life exposure to microplastics on the growth, reproduction and offspring development of marine medaka. This study is expected to reveal the mechanisms realted to long-term effects and potential ecological risk after the ingestion of microplastics by marine fish. Hopefully, insights gained from this study could aid future studies to obtain a more comprehensive picture of the long-term effects of microplastic pollution in coastal environments and biota, and contribute to establish pertinent management approaches for this type of contaminant in vulnerable coastal environments.

海洋环境中的微塑料作为一种新兴污染物近年来受到广泛关注。随着不同营养级海洋生物体中的微塑料不断被检出，其生物富集性与毒性效应愈加受重视。但已有研究多集中于高浓度的短期影响，而微塑料在鱼类体内的蓄积、释放过程及其潜在的长期效应，尤其对生殖和世代的影响知之甚少。本项目拟选海洋模式鱼种-海水青鳉作为受试生物，以环境特征的微塑料（浓度、形状和尺寸）为研究对象，以鱼类最为敏感的早期生活阶段为出发点，综合运用光学、化学、分子生物学等技术手段，开展环境特征微塑料在海水青鳉仔鱼体内蓄积和排出过程研究，揭示微塑料在海水鱼类体内的转移机制；通过对行为、能量代谢、繁殖能力、子代发育、关键基因和蛋白的差异表达等信息，评估微塑料对鱼类早期发育毒性，以及微塑料早期暴露对鱼类后期生长、繁殖与子代发育的影响，阐明其潜在的作用机制及生态危害。为科学认识微塑料的环境行为及生态风险提供新的方法和依据。

微塑料污染是当前海洋环境问题的焦点之一，但其生态危害还存在很大争议，尤其是低含量、长时间和不同性质的微塑料长期影响还不清楚。本研究从微塑料的实际环境情况出发，选取具有代表性的环境特征微塑料，以海水青鳉鱼为受试生物，分别从微塑料在青鳉体内的动力学过程、不同粒径和浓度微塑料对青鱂生长发育、不同材质老化微塑料对青鱂繁殖与子代影响、微塑料与典型污染物（抗生素和磷酸三苯酯）的复合效应等几个方面开展了一系列研究工作。通过研究建立了海水、沉积物和生物体（浮游动物和鱼类）等不同环境介质中微塑料的定性定量检出方法，首次揭示了北极地区海洋微塑料的污染特征，并发现北冰洋可能是全球微塑料的一个重要汇；探明了聚苯乙烯（PS）微塑料颗粒在海水青鱂体内的动力学过程，评估了微塑料长期暴露对青鱂的生长、繁殖和子代发育的影响，发现粒径大小和表面修饰的官能团是影响微塑料毒性的关键因素，微塑料的存在可显著降低磺胺嘧啶（SM2）和磷酸三苯酯对青鱂的发育毒性，其原因可能与表面电荷与青鱂肠道损伤等有关，微塑料和SM2的母代共暴露引起子代雌鱼的肠道氧化应激，提示着微塑料和SM2的复合污染物可能产生有别于单独污染物暴露所产生的新跨代毒性。总体上，通过研究表明微塑料在海水鱼类体内的吸收和富集与微塑料的粒径大小、性质以及进食情况有关，其作用靶器官主要为肠道，肠道损伤以及微生物的改变与其毒性大小具有相关性，这一研究结论为后续进一步的机制研究提供了新思路与线索，并为实际环境中微塑料的生态风险评估与健康危害提供了科学依据。