Exploring the link between biomarkers and bioindicators in Ave River – an integrative assessment

• Autor(a) principal: Tavares, Diana Carolina Moreira
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10348/11751
• topic: Ave River; ecological integrity

Due to anthropogenic activity, the environment is constantly impacted by xenobiotics, being the aquatic ecosystems the most affected, as the ultimate sink for some of these contaminants. Water Framework Directive (established in 2000), aiming to improve the European Union waterbodies to good ecological status, established several biological quality elements (BQEs), supported by hydromorphological and chemical factors, to assess the quality of the waterbodies. Environmental assessment, using BQEs, can be done through several biological levels (suborganismal, organism, population, and ecosystem). At the population level, the presence or absence of certain species (bioindicators) can be indicative of disturbance in the ecosystem. Macroinvertebrates and fish fauna are some of the biological quality elements established in the WFD to assess the ecosystem’s ecological status. At a lower biological level, biomarkers can also be evaluated to assess earlier warning signs of stress. There is an array of possible biomarkers, being one of them the histopathological changes, namely on fish gills, the first target organ to waterborne pollution. Previous studies have reported Ave River as severely impacted, due to various anthropogenic pressures along its basin. Accordingly, this study aimed to assess the BQEs framed by WFD assessment methods, using an integrated approach to improve the links between biological and ecological responses to anthropogenic impacts in the Ave River watershed. To reach this aim, 12 sampling sites were selected along Ave River, in which water quality was assessed, macroinvertebrates and fish species were identified. In 7 of these 12 sites, the fish species Luciobarbus bocagei and Pseudochondrostoma duriense were sampled, measured and the gills were excised for histopathological assessment. The results highlight that upstream sites, L6 and L7, according to the evaluated parameters, are in line with healthier ecosystems. Throughout the remaining sampling sites, the presence of several heavy metals was proved, some above the recommended levels (such as Fe and Cr). Bioindicators and biomarkers responses were highly correlated with physicochemical parameters and with heavy metals, even if within the recommended values (Mg, Co, Cu and Pb). Gill histopathology showed a correlation with more metals than either of the bioindicators under study, which can denote that the contamination by those metals may not have a visible impact on higher biological levels but should be of rising concern.