Marques Ana, Piló David, Araújo Olinda, Pereira Fábio, Guilherme Sofia, Carvalho Susana, Santos Maria Ana, Pacheco Mário, Pereira Patrícia
CESAM - Center for Environmental and Marine Studies and Department of Biology, University of Aveiro, Campus Universitário de Santiago, 3810-193, Aveiro, Portugal.
IPMA - The Portuguese Sea and Atmosphere Institute, Avenida 5 de Outubro, 8700-305, Olhão, Portugal.
Ecotoxicology. 2016 May;25(4):664-76. doi: 10.1007/s10646-016-1625-y. Epub 2016 Feb 24.
The chronic exposure of benthic organisms to metals in sediments can lead to the development of tolerance mechanisms, thus diminishing their responsiveness. This study aims to evaluate the accumulation profiles of V, Cr, Co, Ni, As, Cd, Pb and Hg and antioxidant system responses of two benthic organisms (Cerastoderma edule, Bivalvia; Nephtys hombergii, Polychaeta). This approach will provide clarifications about the ability of each species to signalise metal contamination. Organisms of both species were collected at the Tagus estuary, in two sites with distinct contamination degrees (ALC, slightly contaminated; BAR, highly contaminated). Accordingly, C. edule accumulated higher concentrations of As, Pb and Hg at BAR compared to ALC. However, antioxidant responses of C. edule were almost unaltered at BAR and no peroxidative damage occurred, suggesting adjustment mechanisms to the presence of metals. In contrast, N. hombergii showed a minor propensity to metal accumulation, only signalising spatial differences for As and Pb and accumulating lower concentrations of metals than C. edule. The differences in metal accumulation observed between species might be due to their distinctive foraging behaviour and/or the ability of N. hombergii to minimise the metal uptake. Despite that, the accumulation of As and Pb was on the basis of the polychaete antioxidant defences inhibition at BAR, including CAT, SOD, GR and GPx. The integrated biomarker response index (IBRv2) confirmed that N. hombergii was more affected by metal exposure than C. edule. In the light of current findings, in field-based studies, the information of C. edule as a bioindicator should be complemented by that provided by another benthic species, since tolerance mechanisms to metals can hinder a correct diagnosis of sediment contamination and of the system's health. Overall, the present study contributed to improve the lack of fundamental knowledge of two widespread and common estuarine species, providing insights of the metal accumulation profiles under a scenario of chronic contamination. Finally, this work provided useful information that can be applied in the interpretation of future environmental monitoring studies.
底栖生物长期接触沉积物中的金属会导致耐受机制的形成，从而降低它们的反应能力。本研究旨在评估两种底栖生物（双壳纲的紫贻贝；多毛纲的霍氏海蛹）对钒、铬、钴、镍、砷、镉、铅和汞的积累情况以及抗氧化系统的反应。这种方法将阐明每个物种对金属污染发出信号的能力。两个物种的生物均在塔霍河口的两个污染程度不同的地点采集（ALC，轻度污染；BAR，高度污染）。因此，与ALC相比，紫贻贝在BAR积累了更高浓度的砷、铅和汞。然而，紫贻贝在BAR的抗氧化反应几乎没有变化，也没有发生过氧化损伤，这表明其对金属的存在具有调节机制。相比之下，霍氏海蛹对金属积累的倾向较小，仅显示出砷和铅的空间差异，且积累的金属浓度低于紫贻贝。物种间观察到的金属积累差异可能是由于它们独特的觅食行为和/或霍氏海蛹将金属吸收降至最低的能力。尽管如此，在BAR，砷和铅的积累是基于多毛纲动物抗氧化防御（包括过氧化氢酶、超氧化物歧化酶、谷胱甘肽还原酶和谷胱甘肽过氧化物酶）的抑制。综合生物标志物反应指数（IBRv2）证实，霍氏海蛹比紫贻贝更容易受到金属暴露的影响。根据目前的研究结果，在基于实地的研究中，紫贻贝作为生物指示物的信息应由另一种底栖物种提供的信息加以补充，因为对金属的耐受机制可能会妨碍对沉积物污染和系统健康状况的正确诊断。总体而言，本研究有助于改善对两种广泛分布且常见的河口物种基础知识的缺乏，提供了在长期污染情况下金属积累情况的见解。最后，这项工作提供了可应用于未来环境监测研究解释的有用信息。
