Unravelling the effects of treated wastewater discharges on the water quality in a coastal lagoon system (Ria Formosa, South Portugal): Relevance of hydrodynamic conditions

Cravo, Alexandra; Barbosa, Ana B.; Correia, Carla; Matos, André Vicente Ruiz de; Caetano, Sandra; Lima, Maria Joao; Jacob, José

doi:10.1016/j.marpolbul.2021.113296

Cited by 21 publications

(36 citation statements)

References 130 publications

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“…According to the results, most of the Ria Formosa is in a moderate state. This is not consistent with our perception of the lagoon, which is heavily influenced by seawater, with high water renewal rates and complex hydrodynamics (Cravo et al, 2013(Cravo et al, , 2014(Cravo et al, , 2015(Cravo et al, , 2022aCravo and Jacob, 2019;Verissimo et al, 2019). As an analogy, imagine a small class (n = 15) of very able students.…”

Section: Nhcontrasting

confidence: 60%

“…Thus, long-term chemical and biological data covering wide spatial gradients, including at least those sites with distinct hydromorphological features, are needed to guarantee the health of dynamic ecosystems, especially in the context of climate change. This is extremely important given the great natural, economic and social capital of this lagoon (Cravo et al, 2022a).…”

Section: Discussionmentioning

confidence: 99%

“…Thus, it is probable that the boundary setting was inappropriate because of the lack of a strong eutrophication gradient, i.e., most of the studied sites had low chlorophyll a and nutrient concentration. The importance of mixing and complex hydrodynamics make the assessment of treated wastewater disposal in the Ria Formosa coastal lagoon particularly challenging (Cravo et al, 2022a). Further studies on site-specific water quality for the Ria Formosa should explore new approaches to redefine the boundaries between water quality categories, e.g., by plotting nutrient data against different pressure variables (Cravo et al, 2015).…”

Section: Nhmentioning

confidence: 99%

“…Thus, the nutrient condition is important not only for compliance with the WFD but also for the dynamics of phytoplankton communities in the lagoon (Brito et al, 2012a), while chlorophyll a and dissolved oxygen are important for the bivalves and other consumers. Understanding the link between hydrodynamics, water quality and the delivery of valuable ecosystem services is key to this management approach (Newton et al, 2018;Pérez-Ruzafa et al, 2019;Cravo et al, 2022a).…”

Section: Nhmentioning

confidence: 99%

“…The human pressures are increasing with population increase in the Algarve, from ∼395000 in the 2001 census to 467000 in the 2021 census (Intituto National de Estatistica portal consulted on 30/08/2022 1 ). The main threats now include erosion, storm 10.3389/fevo.2022.508218 surges and overtopping (Carrasco et al, 2021;Domingues et al, 2021); climate change (Brito et al, 2012b;Rodrigues et al, 2021); flooding and sea level rise (Lopes et al, 2022); sewage (Cravo et al, 2022a); eutrophication and hypoxia (Cravo et al, 2020); pharmacological contamination (Cravo et al, 2022b) and chemical pollution (Silva et al, 2021).…”

mentioning

confidence: 99%

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Assessing the effectiveness of management measures in the Ria Formosa coastal lagoon, Portugal

et al. 2022

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The Ria Formosa is an important transitional and coastal lagoon on the south coast of Portugal that provides valuable ecosystem services. The lagoon is a protected area under national and international conventions. There is a great potential for Blue Growth sectors, such as aquaculture and coastal tourism, but these rely on good water quality. European environmental legislation, such as the Water Framework Directive, requires member states, such as Portugal to implement management measures if a surface water body is not of good ecological status. This work addresses the effectiveness of management measures, such as wastewater treatment plant implementation and dredging, on the water quality of the Ria Formosa coastal lagoon system. This is an important social-ecological issue, since management measures can be very expensive. The ecological status of Ria Formosa was evaluated, according to the physico-chemical and biological quality elements of the Water Framework Directive. The main indicators were the physico-chemical quality elements of nutrient and oxygen condition, and the biological quality element chlorophyll a, as a proxy for phytoplankton biomass, under the Water Framework Directive. The data for these quality elements from the Ria Formosa were analyzed for consistency with the classification for the Water Framework Directive water bodies. The data after the implementation of management measures was compared with historical data to evaluate if these measures had been effective. The relation between nutrient pressures, meteorological and hydrological conditions was addressed, especially rainfall and runoff. Results showed a decrease in nutrient concentration after the management interventions, despite the increase of population and intensifying agriculture in the catchment. The Ecological Status is spatially variable with an overall moderate status, indicating the need for further management measures. There is a significant reduction in nutrient pressure on the lagoon during drought years. This indicates that climate change may alter the structure and function of the lagoon in the future.

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Section: Nhcontrasting

confidence: 60%

Section: Discussionmentioning

confidence: 99%