Name: Heliatrice Louise Hadlich
Type: PhD thesis
Publication date: 14/12/2020
Advisor:
Name |
Role |
|---|---|
| Angelo Fraga Bernardino | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| Angelo Fraga Bernardino | Advisor * |
| Jean-Christophe Joyeux | Internal Examiner * |
| Levy de Carvalho Gomes | External Examiner * |
| Renato Rodrigues Neto | Internal Examiner * |
| Sergio Antonio Netto | External Examiner * |
Summary: Estuaries in South America commonly receive untreated effluents from nearby
metropolitan areas demanding ecosystem-based management solutions to access the different types of pollutant impacts. Despite the increased and widespread usage of benthic indices for environmental health assessment in estuarine areas some problems underlying ambiguous assessments still remain to be elucidated. The benthic indices may respond either to man-induced or natural disturbances and are likely to vary in space and time at many scales due to distinct interacting processes. Chemical markers such as sterols are used in parallel to biological indices in order to determine correspondence between sewage contamination and ecological impacts. The application of indexes that respond to organic enrichment still requires tests that adequately detect patterns of variability with a robust sample design. The main objective of this study was to assess the environmental quality of two estuaries located in the Eastern Brazil Marine Ecoregion, with different characteristics of use and conservation, based on determination of multiple organic (biopolymers and sterols) and inorganic (trace metals) indicators of contamination and use of the application of biotic indices. To this purpose, the following approaches were employed in the next two chapters: (i) a multivariate approach was used to characterize the trophic state of two estuaries (Vitória Bay and Piraquê-Açú estuarie) with different urbanization conditions, through the chemical indicators of contamination; (ii) testing the responses of AMBI, M-AMBI, BENTIX and BO2A indices, using a hierarchical sampling design in two estuaries with distinct levels of urbanization, with correlations to chemical proxies of contamination and analyzes of similarity of the responses. In the first chapter, the multiple organic biomarkers of sedimentary quality suggested that Vitória Bay is predominantly eutrophic or
hypertrophic given a high entry of untreated sewage into the estuary, while the
Piraquê-Açu estuary may be considered a pristine estuary with indication from low to moderate contamination by sewage input and the presence of eutrophic to
hypertrophic sediments, not correlated to faecal contamination. The results of the second chapter indicated good applicability of benthic indices. AMBI, M-AMBI,
BENTIX and BO2A did vary significantly at the largest spatial scale or the scale at
which pollution acts and were mostly correlated to the chemical proxies of
contamination, showing a congruence to the these markers. However, some
ambiguities or inconsistencies were found between their responses, suggesting that the AMBI and BO2A indices should be applied with caution in management
practices, as they tend to overestimate the ecological quality of the impacted
stations.
