Department of Biology & Center for Environmental and Marine Studies (CESAM), University of Aveiro, 3810-193, Aveiro, Portugal.
Department of Veterinary Sciences, University of Pisa, San Piero a Grado, Pisa, 56122, Italy.
Aquat Toxicol. 2018 Sep;202:163-172. doi: 10.1016/j.aquatox.2018.07.006. Epub 2018 Jul 10.
Intertidal species are frequently exposed to environmental changes associated with multiple stressors, which they must either avoid or tolerate by developing physiological and biochemical strategies. Some of the natural environmental changes are related with the tidal cycle which forces organisms to tolerate the differences between an aquatic and an aerial environment. Furthermore, in these environments, organisms are also subjected to pollutants from anthropogenic sources. The present study evaluated the impacts in Mytilus galloprovincialis exposed to multi-walled carbon nanotubes (0.01 mg/L MWCNTs) when continuously submersed or exposed to tides (5 h of low tide, 7 h of high tide) for 14 days. Our results demonstrated that mussels were physiologically and biochemically affected by MWCNTs, especially when exposed to tides. In fact, when only exposed to the carbon nanoparticles or only exposed to tides, the stress induced was not enough to activate mussels' antioxidant defenses which resulted in oxidative damage. However, when mussels were exposed to the combination of tides and MWCNTs increased metabolism was observed, associated with a possible higher production of reactive oxygen species (ROS), leading to a significant increase in the activities of antioxidant enzymes (superoxide dismutase, SOD and glutathione peroxide, GPx) and oxidized glutathione content (GSSG), preventing the occurrence of cellular damage, expressed as no lipid peroxidation (LPO) or protein carbonylation (PC). Therefore, organisms seemed to be able to tolerate MWCNTs and air exposure during tidal regime; however, the combination of both stressors induced higher oxidative stress. These findings indicate that the increasing presence of carbon nanoparticles in marine ecosystems can induce higher toxic impacts in intertidal organisms compared to organisms continuously submerged. Also, our results may indicate that air exposure can act as a cofounding factor on the assessment of different stressors in organisms living in coastal systems.
潮间带物种经常暴露于与多种胁迫相关的环境变化中，它们必须通过发展生理和生化策略来避免或耐受这些变化。一些自然环境变化与潮汐周期有关，这迫使生物耐受水生和空气生境之间的差异。此外，在这些环境中，生物还会受到人为来源污染物的影响。本研究评估了多壁碳纳米管（0.01 mg/L MWCNTs）对连续浸没或潮间带暴露（5 小时低潮，7 小时高潮）14 天的贻贝（Mytilus galloprovincialis）的影响。我们的结果表明，MWCNTs 对贻贝的生理和生化产生了影响，尤其是在暴露于潮汐时。事实上，当仅暴露于碳纳米颗粒或仅暴露于潮汐时，所诱导的应激不足以激活贻贝的抗氧化防御系统，从而导致氧化损伤。然而，当贻贝暴露于潮汐和 MWCNTs 的组合时，观察到代谢增加，可能与活性氧（ROS）的更高产生有关，导致抗氧化酶（超氧化物歧化酶、SOD 和谷胱甘肽过氧化物酶、GPx）和氧化型谷胱甘肽含量（GSSG）的活性显著增加，从而防止细胞损伤的发生，表现为无脂质过氧化（LPO）或蛋白质羰基化（PC）。因此，生物似乎能够耐受 MWCNTs 和潮汐期间的空气暴露；然而，这两种胁迫因素的组合会导致更高的氧化应激。这些发现表明，与连续浸没的生物相比，海洋生态系统中碳纳米颗粒的增加会导致潮间带生物产生更高的毒性影响。此外，我们的结果可能表明，空气暴露可以作为评估沿海系统中生物的不同胁迫因素的混杂因素。
