Determining the footprint of sewage discharges in a coastal lagoon in South-Western Europe

Biomarker Responses of the Clam Ruditapes decussatus Exposed to a Complex Mixture of Environmental Stressors under the Influence of an Urban Wastewater‐Treatment Plant

“…These locations were chosen based on the dilution effect of the UWWTP effluent with seawater from the lagoon along the increasing distance and the similar salinity between ST#0 (reference) and ST#3. Furthermore, at sites ST#1 and ST#2 an evident impact of the effluents on the water quality in terms of salinity, nutrients, dissolved oxygen, and chlorophyll a was previously reported (Cravo et al 2015).…”

“…Ria Formosa is a coastal lagoon approximately 55 km long, with a maximum width of 6 km, located in the central zone of the south of Portugal, occupying approximately 100 km 2 ( Figure 1) This ecosystem is highly productive and important from the ecological point of view, representing the major national center for R. decussatus clam production. On the other hand, this is a vulnerable system, where the water quality is threatened by anthropogenic pressures, particularly from tourism, markedly enhanced in the summer months, and increased volume of effluent discharged from the UWWTP (Cravo et al 2015).…”

Anthropogenic, Direct Pressures on Coastal Wetlands

“…There are three main towns in the catchment: Faro, the district capital (∼64,500); Olhão (∼45,000); and Tavira (∼26,000), as well as several smaller urban areas (population data from 2011 Census, Instituto Nacional de Estatistica 2 ). The influx of visitors in the summer increases the population, in some cases severalfold, overwhelming infrastructure designed for the resident population, such as Urban Waste-Water Treatment facilities (Newton et al, 2013;Cravo et al, 2015;Veríssimo et al, 2019).…”

“…Overfishing, shellfish harvesting, illegal harvesting of sea-cucumbers (Holothuria arguinensis) and the attempted introduction of non-indigenous species (Manila clam, Ruditapes philippinarum; Japanese prawn, Penaeus japonicus; Pacific oyster, Crassostrea gigas) are further pressures on the ecosystem. The use of fertilizers in the agricultural zone and golf-courses around the Ria Formosa, manure from animalrearing, and inadequate sewage treatment are all pressures that can lead to eutrophication (Newton et al, 2003) and microbial contamination (Cravo et al, 2015). Several studies have documented contamination and pollution of the Ria Formosa by metals and organic chemicals (Bebianno, 1997;Mudge and Duce, 2005;Bebianno et al, 2019;Moreira da Silva et al, 2019), despite the low industrial development around the wetland.…”

“…The decline of ecosystem services has impacts on human welfare (Bebianno et al, 2019). Continued microbial contamination from sewage (Cravo et al, 2015) as well as algal toxins from HAB (Lage et al, 2014) and other public health issues (Bebianno et al, 2019) are related to the degradation of the wetland. The declining incomes of shellfish harvesters and artisanal fishers eventually make these culturally unique lifestyles unsustainable and fishers seek other sources of income and ultimately employment.…”