Seawater carbonate chemistry and the toxicity of a hydrophobic organic compound on a benthic community

• Main Authors: Ferraz, Mariana Aliceda, Kiyama, Ana Carolina, Primel, Ednei Gilberto, Barbosa, Sergiane Caldas, Castro, Ítalo Braga, Choueri, R B, Gallucci, Fabiane
• Format: Dataset
• Language: English
• Published: PANGAEA 2022
• Subjects: Alkalinity; total; standard deviation; Aragonite saturation state; Benthos; Bicarbonate ion; Bottles or small containers/Aquaria (<20 L); Brackish waters; Calcite saturation state; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Calculated using seacarb after Orr et al. (2018); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Community composition and diversity; Cybutryne; Entire community; EXP; Experiment; Experiment day; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Fugacity of carbon dioxide in seawater; Genus richness; Individuals; Itaguare_river_mouth; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.947936; https://doi.org/10.1594/PANGAEA.947936

Natural pH values in coastal waters vary largely among locations, ecosystems, and time periods; still, there is an ongoing acidification trend. In this scenario, more acidic pH values can alter bioavailability of organic contaminants, to organisms. Despite this, interactive effects between pH and chemical substances are not usually considered in Ecological Risk Assessment protocols. This study investigated the effects of pH on the toxicity of a hydrophobic organic compound on a benthic community using a microcosm experiment setup to assess the response of nematode assemblages exposed to environmentally relevant concentrations of Irgarol at two natural pH conditions. Estuarine nematode assemblages were exposed to two concentrations of Irgarol at pH 7.0 and 8.0 for periods of 7 and 35 days. Lower diversity of nematode genera was observed at the highest tested Irgarol concentration (1281 ± 65 ng/g). The results showed that the effects of Irgarol contamination were independent of pH variation, indicating no influence of acidification within this range on the toxicity of Irgarol to benthic meiofauna. However, the results showed that estuarine nematode assemblages are impacted by long-term exposure to low (but naturally occurring) pHs. This indicates that estuarine organisms may be under naturally high physiological pressure and that permanent changes in the ecosystem's environmental factors, such as future coastal ocean acidification, may drive organisms closer to the edges of their tolerance windows.