Mixtures of metals and polynuclear aromatic hydrocarbons elicit complex, nonadditive toxicological interactions in meiobenthic copepods

Abstract

Abstract-The acute toxicity of metal-polynuclear aromatic hydrocarbon (PAH) mixtures (i.e., Cd, Hg, Pb, fluoranthene, and phenanthrene) associated with sediments was assessed in two benthic copepods. Schizopera knabeni was exposed to sediment amended with single contaminants and mixtures. Adult S. knabeni were highly tolerant of single-contaminant exposures to phenanthrene, Cd, Hg, and Pb as well as a mixture of Cd, Hg, and Pb. Binary experiments revealed that although phenanthrene was synergistic with Cd and Hg, the phenanthrene-Cd synergism was much stronger (2.8 times more lethal than predicted). When a mixture of Cd, Hg, and Pb was combined with phenanthrene, a synergistic response was observed, eliciting 1.5 times greater lethality than predicted. A Cd-phenanthrene synergism in S. knabeni was also observed in aqueous exposures, suggesting that the interaction was related to a pharmacological insult rather than a sediment-related exposure effect. An antagonism between Cd, Hg, and Pb was indicated, and this antagonism may have moderated the Cd-phenanthrene synergism in mixtures containing Cd, Hg, Pb, and phenanthrene. Experiments with Amphiascoides atopus revealed that phenanthrene and fluoranthene were each synergistic with Cd in aqueous exposures. Our studies suggest that interactive toxicity among metal-PAH mixtures may be common among benthic copepods and that strong synergistic effects observed in binary mixtures may be moderated in more diverse contaminant mixtures. However, the strength of the observed synergisms raises concerns that established sediment quality criteria may not be protective for organisms jointly exposed to PAH and metals, especially Cd-PAH mixtures.

Assessment of individual and combined toxicities of three heavy metals (Cu, Cd and Hg) by usingTigriopus fulvus

“…On the other hand, Vellinger et al [40] observed an antagonist 'between-metals' interaction on Gammarus pulex exposed to binary mixtures of cadmium and arsenate. An antagonist effect between Cd, Hg, and Pb was also reported by Fleeger et al [41] on benthic copepods Schizopera knabeni.…”

Effects-based spatial assessment of contaminated estuarine sediments from Bear Creek, Baltimore Harbor, MD, USA

“…In regions such as this, where site remediation is a priority and redevelopment is a likely future scenario, a thorough understanding of the spatial extent of contaminant-induced toxicity is necessary to guide management decisions. Absent an individual causative agent or clear understanding of multi-contaminant interactions, delineation of impacted regions based solely on chemical data is inadequate (Chapman 2002; Fleeger et al 2007; Kwok et al 2014; Pourabadehei and Mulligan 2016). The first objective of the present study was to demonstrate the usefulness of toxicity testing as a tool for delineating contaminant effects, particularly the unconventional use of toxicity tests on subsurface sediments from cores.…”

Dietary Carotenoids Regulate Astaxanthin Content of Copepods and Modulate Their Susceptibility to UV Light and Copper Toxicity

“…A. atopus is also more sensitive to cadmium (LC 50 96 h, 4.13 ± 0.75 μMol Cd; [63]) than to copper (LC 50 96 h, 4.42–6.23 μMol Cu), although the lower limit of the LC 50 of Cu overlaps with that of Cd. The lower sensitivity to copper relative to cadmium is the reverse to that observed for Tigriopus japonicus [64] and for Tisbe holothuriae [65].…”