The urgency to find efficient indices and indicators to prevent further deterioration of coastal areas is one of the hot topics in today's scientific publication. However, a detailed knowledge of community responses to anthropogenic impacts is essential to sustain those indices. The studies on the response of benthic community to sewage pollution on intertidal rocky shores are generally based on visual census and do not take into account the tidal levels. In order to fulfil this gap in this study: (i) the sampling was performed by destructive sampling, with all individuals identified to the species level; (ii) the sampling was done at all levels of the intertidal (sublittoral fringe, eulittoral, and littoral fringe). Sewage pollution changed the environmental variables and the abundance of macroinvertebrates, being Mytilus galloprovincialis, Melarhaphe neritoides, and Chthamalus montagui the species most responsible for the dissimilarities observed. Effects were different on the three intertidal zones: community structure changed in the sublittoral fringe; suspensionfeeders abundances and species richness increased in the eulittoral; no differences were detected in the littoral fringe. Moreover, the results confirm that the presence of sewage discharges tended to benefit suspension feeders, and that the sensitive species were replaced by opportunistic ones.

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SuMMarY: The discharges of sewage effluent treatment plants has a major impact on coastal communities. in our study area (western coast of Portugal) Melarhaphe neritoides (l. 1758) is the dominant high-shore gastropod. Two populations of M. neritoides were studied in order to understand the impact of sewage discharges on intertidal communities: one population in an impacted area and the other in a similar but unimpacted area (reference site). environmental data and abundance, biomass, population structure and annual growth production of M. neritoides were estimated in the two areas. The results showed that M. neritoides density is higher in the impacted area as a result of massive settlement. The sewage discharge increases the nutrient concentrations in the water, which causes more microalgae to grow on the rocky surfaces. This higher availability of food may promote recruitment. however, we found high mortality in the juveniles in the impacted area, which affected density values on the upper shore levels (where we found the adults) of both areas. Moreover, the adults were bigger in the unimpacted area, which suggests that individuals grow more or live longer in this area.Keywords: Melarhaphe neritoides, abundance, biomass, secondary production, sewage, nutrient enrichment, rocky shore. reSuMen: Efecto de la descarga de aguas residuales sobre la dinámica poblacional de Melarhaphe neritoides (Gastropoda: Littorinidae). -las descargas de aguas residuales de depuradoras son uno de los mayores impactos sobre las comunidades costeras. en nuestra área de estudio (costa oeste de Portugal) Melarhaphe neritoides (l. 1758) es el gasterópodo dominante en la zona supralitoral. Para entender el impacto que estos vertidos tienen sobre las comunidades intermareales, estudiamos dos poblaciones de M. neritoides: una en un área contaminada y otra en una zona similar, pero no impactada (zona de referencia). en ambas áreas se registraron datos medioambientales, datos de abundancia y biomasa de M. neritoides y se estimó la estructura de las poblaciones y la producción anual. los resultados muestran una mayor densidad de M. neritoides en la zona contaminada, como resultado de una colonización masiva. las descargas de aguas residuales aumentan la concentración de nutrientes en el agua, provocando un mayor crecimiento de microalgas en la superficie de las rocas, lo que facilita la colonización. Sin embargo, verificamos una elevada mortalidad de juveniles en la zona contaminada que aproximó los valores de la densidad de las poblaciones en las zonas más altas del litoral (donde encontramos los adultos) en ambas zonas. además, los adultos eran de mayor tamaño en las áreas no contaminadas, lo que sugiere que en esta zona los individuos tienen un mayor crecimiento o viven durante más tiempo.

The secondary production of rocky shore macroinvertebrate assemblages impacted through sewage discharge was assessed, taking into account the trends of production among dominant species and feeding guilds. The present study was conducted on the Peniche peninsula (central-western Portuguese coast, temperate region), in three areas: one area near a sewage discharge and two undisturbed reference areas. Within each area, three intertidal zones were monitored ‐ littoral fringe, eulittoral and sublittoral fringe ‐ by taking seasonal samples during one year. The empirical model of Cusson and Bourget (2005) was used to evaluate secondary production. In the littoral fringe, no differences in the production values were found between impacted and reference areas. In the eulittoral, sewage discharge seemed to affect the natural competition between patellidae and barnacles by favouring suspension feeders (barnacles), presumably due to higher food resources near the sewage. In the sublittoral fringe, near the sewage discharge, an increase in the production values of tolerant species was observed to the detriment of the sensitive species, with higher production levels in the reference areas. Overall, secondary production was higher in the communities near the sewage affected areas, but this increase was mostly due to the production of tolerant species. The present study showed that the incorporation of secondary production in the biological assessment provided further insight into the health of the ecosystem, thus being an important tool for understanding differences in the functioning of the ecosystem.

A Universidade de Coimbra, com mais de 730 anos de história, possui um vasto património acumulado, material e imaterial, que reflete todos os períodos da história e investigação científica em Portugal. O valor universal deste imenso acervo, em particular das coleções biológicas e bibliotecas, convoca a Universidade de Coimbra para o esforço de o conservar, mas também de o difundir e valorizar. Na convicção do conhecimento ser de todos e para todos, revemo-nos na certeza de a Ciência Aberta ser indispensável a uma sociedade mais informada e mais consciente do Planeta que habita, contribuindo para a tornar mais humana, mais justa e mais democrática. As ilustrações aqui reproduzidas foram retiradas de várias obras à guarda da biblioteca do Departamento de Ciências da Vida da Universidade de Coimbra. Foi, assim, também nosso propósito dar a conhecer o rico e amplo acervo da Universidade de Coimbra, bem utilizando os livros para um dos seus fins: a aprendizagem e o gosto pelas ciências.

Arsenic is a widely distributed element in marine ecosystems. The main anthropogenic sources of this contaminant are domestic and industrial wastewaters, and since it can be harmful to humans even at low concentrations, it has been ranked as one of the top hazardous substances. Therefore, the analysis of arsenic is an essential task to assess the potential environmental and human health risk associated with sewage discharges. The accumulation of total arsenic on intertidal rocky shore macroalgae exposed to contaminated sewage discharges was measured in five macroalgae species (Asparagopsis armata, Codium sp., Plocamium cartilagineum, Saccorhiza polyschides and Ulva sp.). Differences in the concentrations of arsenic were examined in the seawater and in the macroalgae species. The results showed significantly higher concentrations of arsenic near the sewage discharges in all the species except S. polyschides. Although the information obtained from total arsenic determination is not enough to assess the toxicological risk in the environment, this paper gives an important contribution on contamination risks and helps in choosing potential good biomonitors.

The search for cost-effective indicators able to detect anthropogenic impacts is an essential prerequisite to plan mitigation\ud interventions, which can prevent further deterioration of coastal areas. Eulittoral assemblages are accessible for sampling,\ud and their dominant species are easy to identify and widely distributed. This study assessed the potential of eulittoral\ud assemblages to reflect environmental perturbations related to sewage discharge across different environmental and geographical\ud locations. Sampling occurred in impacted (near sewage discharge) and control areas, on both Atlantic and\ud Mediterranean shores. Multivariate analyses showed that the structure of eulittoral invertebrate assemblages differed\ud significantly between control and impacted areas for the Mediterranean, but not for the Atlantic case study. Macroalgae\ud responses to sewage discharge were found on the Mediterranean shore with a significantly higher abundance of Chlorophyta\ud near the outfall. Limpet populations of the genus Patella appear to be affected by sewage discharge. The response of limpet\ud populations differed between Atlantic and Mediterranean shores, probably due to among-species differences of ecological\ud traits. Our results suggest that the response of eulittoral assemblages and limpets to sewage discharge might be strictly\ud context-dependent, thus limiting their potential to serve as general indicators in monitoring the effects of this source of\ud human impact over large spatial scales

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