Effects of Phenanthrene- and Metal-Contaminated Sediment on the Feeding Activity of the Harpacticoid Copepod, Schizopera knabeni

Abstract

The effects of sediments contaminated with sublethal concentrations of phenanthrene (PAH) and metals (Cd, Hg, Pb) were evaluated in relation to their influence on the feeding activity of a harpacticoid copepod, Schizopera knabeni. A metal mixture (at the ratio of 5Pb:3Cd:2Hg) and Cd alone reduced grazing rates of S. knabeni feeding on (14)C-labeled microalgae. Cadmium alone and Cd combined with phenanthrene significantly decreased grazing rates of S. knabeni at Cd concentrations above 49 mg kg(-1) dry sediment. No grazing was observed in 98, 106, or 157 mg kg(-1) dry sediment Cd alone or in sediment contaminated with phenanthrene (98 mg kg(-1) dry sediment) combined with Cd at these concentrations. Phenanthrene alone also caused a significant decrease (55%) in S. knabeni grazing rates. Feeding ceased above 344 mg kg(-1) dry sediment of the metal mixture alone and combined with phenanthrene. Results were consistent with an independent effect on feeding when Cd and phenanthrene were combined. When other metals were added (Pb and Hg) to the mixture, results were consistent with an additive influence on feeding rate. Because the underlying mechanisms of toxicity for metals and PAH are probably different, our observations suggest that reductions in grazing probably did not directly contribute to the lethal effects of phenanthrene or metals. The absence of interactive effects on feeding suggests that metal-PAH interactive effects on lethality have a different underlying mechanism and that reductions in grazing probably did not directly contribute to the lethality effects of phenanthrene or metals in S. knabeni.

Effects of Cadmium and Phenanthrene Mixtures on Aquatic Fungi and Microbially Mediated Leaf Litter Decomposition

“…For instance, the exposure to a mixture of the two toxins resulted in antagonistic effects on the feeding rate of the oligochaete Ilyodrilus templetoni (Gust and Fleeger 2006). In another study, Cd combined with phenanthrene decreased the grazing rates of the copepod Schizopera knabeni but no interactive effects on feeding were found (Silva et al 2009). In soils, the addition of heavy metals and PAHs, including Cd and phenanthrene, led to a greater biocidal effect on microbes when toxins were amended together than alone (Maliszewska-Kordybach and Smreczak 2003;Shen et al 2005).…”

Organic Contaminant Mixture Significantly Changes Microbenthic Community Structure and Increases the Expression of PAH Degradation Genes

“…Due to their hydrophobic nature, PAHs and PCBs are bioaccumulative (ECHA, 2017). They are often associated with higher mortality, lower reproduction (Lotufo, 1998) and feeding rates (Silva et al, 2009) of benthic populations and have been shown to interfere with oxygen and nutrient dynamics (Carman and Todaro, 1996;Fleeger et al, 2003;Quero et al, 2015). Acute exposure to high concentrations of PAHs can change the composition and ecological functions of benthic communities.…”

Contaminated Aquatic Sediments

“…The bacterial consortium comprising Pseudomonas pseudoalcaligenes and Erythrobacter citreus degraded approximately three-quarters of both aliphatic and polycyclic aromatic hydrocarbons. DaSilva et al (2009) aimed to optimize the bioremediation of crude oilindicated 85% and 100% of biodegradation of n-alkanes between C15 and C30 during 30 and 60 days, respectively.Wang et al (2009a) investigated the bioremediation of nitrobenzene-containing sediments by Pseudomonas putida. They found that the removal rate of nitrobenzene from the sediment using bioaugmentation was much faster than with biostimulation and natural attenuation Shin et al (2009).…”