ECOMARE-Laboratory for Innovation and Sustainability of Marine Biological Resources, CESAM-Centre for Environmental and Marine Studies, Department of Biology, University of Aveiro, Estrada do Porto de Pesca Costeira, 3830-565 Gafanha da Nazaré, Portugal; UCIBIO-Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal; University of Quebec in Rimouski (UQAR), Department of Biology, Chemistry and Geography, 300 Allée des Ursulines, Rimouski, QC G5L 3A1, Canada.
ECOMARE-Laboratory for Innovation and Sustainability of Marine Biological Resources, CESAM-Centre for Environmental and Marine Studies, Department of Biology, University of Aveiro, Estrada do Porto de Pesca Costeira, 3830-565 Gafanha da Nazaré, Portugal.
Sci Total Environ. 2021 Nov 15;795:148634. doi: 10.1016/j.scitotenv.2021.148634. Epub 2021 Jun 24.
Estuarine systems are critical transition zones influenced by sea, land and freshwater. An array of human activities impacts these areas leading to multiple-stressor interactions. Temperature and salinity are among the most relevant drivers in estuaries, shaping species growth, reproduction and distribution. However, few studies provide an overview of cellular rewiring processes under multiple-stressor environments. Here, we tested how salinity could shape the response of ragworms Hediste diversicolor, an important bioindicator and commercial species, to elevated temperature. We exposed polychaetes to three temperatures for a month, simulating control, ocean warming and heatwave conditions (24, 27 and 30 °C, respectively) combined with two salinities (20 and 30). We quantified whole-organism performance (wet weight gain and survival), along with cellular stress response (CSR) and energy reserves of worms after 14 and 28 days of exposure. Significant three-way interactions between temperature, salinity and exposure time show the non-linearity of molecular responses. Worms at a salinity of 20 were more sensitive to warming than worms exposed to a salinity of 30. The combination of high temperature and low salinity can act synergistically to induce oxidative stress and macromolecular damage in worm tissues. This finding was supported by an induction of the CSR, with a concomitant decrease of energy reserves, pointing towards a metabolic compensation strategy. However, under a higher salinity (30), the need for a CSR upon thermal challenge was reduced and energy content increased with temperature, which suggests that environmental conditions were within the optimum range. Heatwaves striking low-salinity areas of estuaries can therefore negatively impact the cellular physiology of H. diversicolor, with greater metabolic costs. However, extreme stress levels were not reached as worms incremented wet weight and survival was high under all conditions tested. Our findings are important for the optimization of ragworm aquaculture and adaptive conservation strategies of estuarine systems.
河口系统是受海洋、陆地和淡水影响的关键过渡区。一系列人类活动影响这些地区，导致多种胁迫因素相互作用。温度和盐度是河口最重要的驱动因素之一，影响着物种的生长、繁殖和分布。然而，很少有研究概述在多胁迫环境下细胞重布线的过程。在这里，我们测试了盐度如何塑造沙蚕 Hediste diversicolor 的反应，沙蚕是一种重要的生物指标和商业物种，对升高的温度。我们将多毛类动物暴露在三个月的三个温度下，模拟对照、海洋变暖（分别为 24、27 和 30°C）和热浪条件，同时结合两种盐度（20 和 30）。我们在暴露 14 天和 28 天后量化了整个生物体的性能（湿重增加和存活率），以及细胞应激反应（CSR）和蠕虫的能量储备。温度、盐度和暴露时间之间的显著三向相互作用表明了分子反应的非线性。在盐度为 20 的情况下，蠕虫对变暖的敏感性比暴露在盐度为 30 的情况下更高。高温和低盐度的组合会协同作用，在蠕虫组织中诱导氧化应激和大分子损伤。这一发现得到了 CSR 的诱导的支持，同时能量储备减少，表明存在代谢补偿策略。然而，在较高盐度（30）下，对热挑战的 CSR 需求减少，随着温度的升高能量含量增加，这表明环境条件在最佳范围内。因此，河口低盐度地区的热浪可能会对 H. diversicolor 的细胞生理学产生负面影响，代谢成本更高。然而，在所有测试条件下，蠕虫增加了湿重，存活率很高，因此没有达到极端应激水平。我们的研究结果对沙蚕水产养殖的优化和河口系统的适应性保护策略很重要。
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