Did you consider ammonium? A possible confounding factor in evaluating the toxicity of marine sediments

Bioassays are a crucial tool for assessing environmental quality, but they face inherent variability due to unexplored confounding factors in marine ecosystems. Ammonium (NH₄⁺) is a vital form of nitrogen in aquatic environments, but it is also a significant focus due to its toxic effects, particularly on marine invertebrates. This study examines the impact of ammonium toxicity on Paracentrotus lividus embryo-development bioassays, which are widely used to evaluate the environmental quality of dredged sediment. The aim is to establish threshold values (EC₀₁, EC₀₅, EC₂₀, and EC₅₀ values) for the correct application of the P. lividus bioassay. The research reveals that ammonium has a significant impact on larval development (EC₅₀ for NH₄⁺ equivalent to 0.81 mg/L). The results emphasize the ecological implications of elevated NH₄⁺ levels in dredged material and highlight the need for precise assessments in environmental management. This study provides essential data for refining guidelines and understanding the complex interactions of this compound in marine ecosystems, ensuring accurate evaluations of environmental quality.