Abstract：
Microplastics (MPs) are a heterogeneous class of pollutants fouling aquatic environments and they are hazardous to aquatic organisms. This study investigated the size-dependent effects of polystyrene microspheres (PSMPs) on the swimming ability, metabolism, and oxidative stress of juvenile grass carp (Ctenopharyngodon idella). Test fish were exposed to four sizes of PSMPs (0.07, 0.5, 5, and 20-μm), and swimming ability was tested after different exposure times (2, 7, and 15 days). To measure the effect on swimming ability, critical swimming speed (Ucrit) was determined, and to assess metabolic effects, oxygen consumption (MO2), routine metabolic rate (RMR), maximum oxygen consumption (MMR), and excess post-exercise oxygen consumption (EPOC) were determined. To assess the effects on oxidative stress, the activities of two antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT) were determined in the liver and gills of test fish. After exposure to 20 μm PSMPs, there was a significant drop in Ucrit compared to the control group (P<0.05), with decreases of 22 % on Day 2 and Day 7, and 21 % on Day 15. The RMR and MMR increased significantly (P<0.05), the RMR by 23.9 % on Day 2 and the MMR by 17.2 % on Day 2 and on Day 15, 44.7 % and 20.0 % respectively. The EPOC decreased with exposure time, by 31 % (0.07-μm), 45 %-(0.5-μm), 49 % (5-μm), and 57 % (20-μm) after 15 days. Exposure to the larger PSMPs increased CAT and SOD activity more than the smaller PSMPs and the increases began with SOD activity in the gills. The larger PSMPs were consistently more harmful to juvenile grass carp than the smaller PSMPs. Our results clearly show that PSMPs have detrimental effects on juvenile grass carp and provide additional scientific evidence that environmental monitoring and regulation of microplastic pollution is necessary.
摘要：
微塑料（MP）是污染水生环境的一类异质污染物，对水生生物有害。这项研究调查了聚苯乙烯微球（PSMPs）对游泳能力的尺寸依赖性影响，新陈代谢，和幼鱼（Ctenopharyngodonidella）的氧化应激。测试鱼暴露于四种大小的PSMPs（0.07、0.5、5和20μm），在不同的暴露时间（2、7和15天）后测试游泳能力。为了测量对游泳能力的影响，确定了临界游泳速度(Ucrit)，并评估代谢作用，耗氧量(MO2),常规代谢率（RMR），最大耗氧量(MMR),并确定了运动后过量耗氧量（EPOC）。为了评估对氧化应激的影响，两种抗氧化酶的活性，在测试鱼的肝脏和g中测定了超氧化物歧化酶（SOD）和过氧化氢酶（CAT）。暴露于20μmPSMP后，Ucrit与对照组相比有显著下降(P<0.05),在第2天和第7天下降22%，在第15天下降21%。RMR和MMR显著增加(P<0.05),第2天的RMR为23.9%，第2天和第15天的MMR为17.2%，分别为44.7%和20.0%。EPOC随暴露时间的增加而降低,31%(0.07-μm)，45%-(0.5-μm),49%(5-μm),15天后为57%(20μm)。与较小的PSMPs相比，暴露于较大的PSMPs的CAT和SOD活性增加更多，并且增加始于the中的SOD活性。较大的PSMP对幼鱼的危害始终大于较小的PSMP。我们的结果清楚地表明，PSMPs对幼鱼有有害影响，并提供了额外的科学证据，表明有必要对环境进行监测和调节微塑料污染。
