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This study focused on comparing the lethal and sublethal toxicity of water-accommodated fractions (WAF) and chemically enhanced WAF (CEWAF) of crude oil to zebrafish (Danio rerio) on early life stages (ELS). Results showed that the addition of GM-2 dispersant caused an increase in the levels of total petroleum hydrocarbons (TPHs) and total priority polycyclic aromatic hydrocarbons (ΣPAHs). Based on ΣPAHs, the LC estimates for WAF and CEWAF were 4.88 µg L and 1.19 µg L, respectively, indicating that CEWAF was approximately four times more toxic. CEWAF exposure caused markedly lower hatching rates and higher malformation frequencies than WAF. Meanwhile, the general morphology score (GMS) values in CEWAF were about fourfold lower than that in WAF, indicating that CEWAF exposure induced more significant developmental delay. The results suggested that chemical dispersant enhanced the toxicity of crude oil to zebrafish on ELS and its application could increase the exposure of fishes to crude oil.

The purpose of this study was to explore and compare the sex-specific differences in the toxic effects of water-accommodated fractions of 380# heavy fuel oil (HFO WAF) on the sea urchin Strongylocentrotus intermedius. Sea urchins were acutely exposed to HFO WAF at different nominal concentrations (0%, 10% and 20%) for seven days. The results showed that females had a higher polycyclic aromatic hydrocarbons (PAHs) bioaccumulation in gonad tissues and that both the total antioxidant capacity (TAC) and lipid peroxidation (LPO) levels in the gonad tissues of females were much higher than those of males. The PAHs bioaccumulation in gametes indicated that parents’ exposure could lead to a transfer of PAHs to their offspring, and eggs had higher TAC and LPO than sperms. After maternal and paternal exposure to HFO WAF, the frequency of morphological abnormalities of the offspring was increased when compared to the control. Overall, these results indicated that maternal exposure to HFO WAF could cause more significantly toxic effects on sea urchins than paternal exposure could, which could lead to more significantly negative effects on their offspring.

Currently, oil spill pollution is one of the major environmental concerns for sea cucumber (Apostichopus japonicus) aquaculture. During oil spills, spraying chemical dispersants is generally considered an efficient oil spill response. However, the impact of chemical dispersant deployment during oil spills on sea cucumbers is still less known. In this study, we treated sea cucumbers with physically and chemically (by GM-2 chemical dispersant) dispersed Oman crude oil for 24 h. For antioxidant defense capacities, our results showed that physically dispersed crude oil caused a significant elevation on superoxide dismutase (SOD) and catalase (CAT) activities, and glutathione (GSH) content, while chemically dispersed crude oil caused a significant decrease in SOD activity and GSH content with no apparent change in CAT activity. As for non-specific immune responses, our results indicated that physically dispersed crude oil up-regulated acid phosphatase (ACP) and lysozyme (LZM) activities but had no obvious impact on alkaline phosphatase (ALP) activity. Differently, chemically dispersed crude oil down-regulated ACP and LZM activities while up-regulating ALP activity. Based on the integrated biomarker response analysis, the overall impact of chemically dispersed crude oil on antioxidant defense capacities and non-specific immune responses of sea cucumbers was more severe than physically dispersed crude oil.

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