Implications of water hardness in ecotoxicological assessments for water quality regulatory purposes: a case study with the aquatic snail Biomphalaria glabrata (Say, 1818)

Abstract

Water hardness is a property depending on the presence of alkaline earth metals, mainly calcium and magnesium. Among the strategies for water quality monitoring, ecotoxicological assays are performed to minimize impacts and classify water bodies. For these laboratory evaluations parameters are previously defined in the guidelines, including water hardness for both cultivation and testing medium. The present work was performed to evaluate the effects of different levels of water hardness on the survival and reproduction of the freshwater snail Biomphalaria glabrata and discuss the influence of natural water hardness on the results of ecotoxicological tests with these environmental samples. Comparing the groups it was possible to observe that those maintained in waters with least hardness had lower reproductive success, while the groups maintained in highest hardness showed better reproduction. These data show that waters with low hardness make the reproduction of the snail B. glabrata unfeasible, and this reveal a problem for ecotoxicity assays using natural water samples.Keywords: ecotoxicology, biological assays, standard methods, guidelines, environmental factors.Implicações da dureza da água nas avaliações ecotoxicológicas com propósitos reguladores de qualidade da água: um estudo de caso com o caramujo aquático Biomphalaria glabrata ResumoA dureza da água é uma propriedade dependente da presença de metais alcalino terrosos, principalmente cálcio e magnésio. Entre as estratégias para monitorar a qualidade da água ensaios ecotoxicológicos são realizados para minimizar impactos e classificar os corpos hídricos. Para essas avaliações em laboratório, parâmetros são previamente definidos nos protocolos, incluindo a dureza da água para cultivo e para a água de diluição. O presente trabalho foi realizado para avaliar os efeitos de diferentes níveis de dureza da água sobre a sobrevivência e a reprodução do caramujo de água doce Biomphalaria glabrata e discutir a influência da dureza de águas naturais nos resultados dos testes ecotoxicológicos com estas amostras ambientais. Comparando os grupos foi possível observar que aqueles mantidos em águas com menor dureza tiveram pior sucesso reprodutivo, enquanto os mantidos nas águas com maiores durezas tiveram melhor reprodução. Esses dados mostram que águas com baixas durezas tornam a reprodução do caramujo B. glabrata inviável, e esse fato revela-se como um problema para os ensaios ecotoxicológicos utilizando amostras de água naturais.Palavras-chave: ecotoxicologia, ensaios biológicos, métodos padrão, protocolos, fatores ambientais.

Impacts of the Urbanization Process on Water Quality of Brazilian Savanna Rivers: The Case of Preto River in Formosa, Goiás State, Brazil

“…Water hardness is mainly related to the content of Ca 2+ and Mg 2+ , a fact that was observed in this work, since the increase in the level of these elements was accompanied by an increase in hardness, shown in Figure 4 A [ 9 ]. The low hardness at P1 (source) is probably related to the low content of calcium and magnesium in the soils of the Cerrado region, as also observed by other studies [ 5 , 17 ]. The concentrations of magnesium in Cerrado natural surface waters are generally around or lower than 1 mg/L [ 3 ].…”

Selection of variables in the definition of a water quality index for the Brazilian Federal District

“…A common feature observed in the three monitored water bodies is the low values detected in their springs for the hardness, and it is natural for these waters to always have low hardness (Aquino et al, 2009;Muniz et al, 2011;Oliveira-Filho et al, 2014); thus, it is believed that when this parameter changes, resulting in higher values, it signals the point at which anthropic interference occurs.…”

“…Água vol. 14 n. 4, e2385 -Taubaté 2019 regional conditions, with wide climatic and geomorphological variation, possessing seven biomes, three ecotones and 79 ecoregions (Arruda et al, 2008), exemplifies how necessary it is to know the characteristics of water (Oliveira-Filho et al, 2014). This is because the impacts of any activity on water bodies can only be measured if there is prior knowledge of the natural conditions of the resource.…”

Challenging the Metallothionein (MT) Gene of Biomphalaria glabrata: Unexpected Response Patterns Due to Cadmium Exposure and Temperature Stress

“…This feature enables aquatic lung snails to remain under water over extended periods of time. The adaptive transition from marine to freshwater conditions may have evolved through a number of preadaptations in marine ancestors [ 20 ], confronting freshwater neocolonizers with the necessity to readjust their mechanisms for energy acquisition and osmotic regulation [ 21 , 22 , 23 , 24 ]. This may also have implications on their mechanisms for metal uptake and regulation [ 25 , 26 ].…”