Risk Assessment of Heavy Metals Pollution in Fishing Ports Using an Integrated Biomarker Response Approach

Abstract

Fishing ports play an essential role in fisheries development and supply chains, as all catches are landed through fishing ports to enter the seafood market. Frequent and intensive fishing activities inevitably affect the fishing port ecosystem by discharging sewage and waste oil from sources such as fishing vessels, leaching ship paint, and operating wharves. However, fishing ports are usually located in semi-enclosed seas, leading to the accumulation of land-based pollution in port environments. Fishing ports are known potential sinks for land-sourced pollutants, such as heavy metals, phthalates, polycyclic aromatic hydrocarbons, and petroleum hydrocarbons. Currently, comprehensive research on the distribution and ecological risk of heavy metals in fishing ports is very limited. With no environmental and scientific data available for reference, it is difficult to formulate appropriate pollution control and prevention strategies for fishing ports. Environmental risk assessment in aquatic ecosystems typically uses biomarkers to detect interactions between potential hazards and biological systems. Next to knowing environmental contaminant levels in tissues and the environment, it is important to link to potentially deleterious effects at higher levels of biological organization, such as biochemistry, physiology, and overall health status. Biochemical reactions are frequently used as biomarkers in sentinel model species sampled from reference sites, for monitoring xenobiotic pollution in coastal areas. However, multiple biomarkers were too complex and could not directly reflect the toxic effects of pollutants on organisms, while the integrated biomarker response (IBR) index could overcome this and comprehensively evaluate the aquatic ecosystem health status.The primary purpose of this study was to evaluate the overall pollution level and risks in fishing ports. Samples of green mussels (Perna viridis) and surface water were collected at 12 sampling points in four fishing ports located in Guangdong and Guangxi provinces, China. Six types of heavy metals were measured in the surface water and soft tissues of P. viridis by inductively coupled plasma mass spectrometry. Moreover, biomarkers of the antioxidant defense system, such as superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), and malondialdehyde (MDA), were analyzed in the hepatopancreas of P. viridis to calculate the IBR index. The results showed that the range of concentrations of Cu, Zn, Pb, Cd, As, and Cr in seawater was 1.13–2.37, 6.67–33.43, 0.14–0.32, 0.03–0.32, 1.09–1.73, and 0.80–1.20 μg/L, respectively, while in the soft tissues of P. viridis, it was 8.31–11.93, 67.92–103.17, 0.88–3.07, 0.80–2.33, 9.61–12.70, and 2.54–4.75 mg/kg, respectively. The mean concentrations of Cu, Zn, Pb, Cd, As, and Cr in each fishing port were lower than the fourth grade of the National Seawater Quality Standard (GB 3097-1997). The concentrations of heavy metals in the surface water and soft tissues of P. viridis were generally at a low level, the comprehensive pollution indices (PI) of heavy metals in the surface water of all four fishing ports were within the natural background range, and the comprehensive pollution indices (Pin) of heavy metals in the soft tissues of P. viridis were in the no pollution category. The PI of heavy metals in the surface water was Shekou Port > Nanwan Port > Dahao Port > Yuwan Port, while the Pin of heavy metals in the soft tissues of P. viridis was Yuwan Port > Shekou Port > Nanwan Port > Dahao Port. In addition, Cu concentrations in both the surface water and soft tissues of P. viridis from Shekou Port were the highest among those from the four fishing ports. Furthermore, there was no significant difference in MDA content or SOD, CAT, and GPx enzyme activities, in the hepatopancreas of P. viridis from the four fishing ports. The IBR index of P. viridis was 4.50 in Shekou Port, 2.14 in Yuwan Port, 1.91 in Dahao Port, and 1.50 in Nanwan Port, which showed a decreasing trend from Shekou Port > Yuwan Port > Dahao Port > Nanwan Port. The highest IBR index was identified at Shekou Port, which agreed with the profiles of the comprehensive pollution index of seawater. According to the correlation analysis, the IBR index showed no significant correlation with the comprehensive pollution index of seawater and marine mussels. It was noteworthy that the IBR index displayed significant positive correlations with Cu concentrations in seawater and mussel tissues, which indicated that Cu pollution may be an important factor to consider in pollution assessments of fishing ports.Overall, this study provides the first evidence of using the IBR index to evaluate the heavy metal pollution status of fishing ports. The pollution level and potential risk of heavy metals in Shekou Port were higher than those of the other three fishing ports. The IBR index coupled with chemical analysis is useful to assess the environmental pollution status of fishing ports for pollution source control and management policy formulation.

Keywords

• fishing port
• heavy metals
• perna viridis
• biomarker
• integrated biomarker response (ibr) index