Abstract
Widespread applications of cadmium (Cd) in various products have caused Cd contamination in marine ecosystems. Meanwhile, human activities in the ocean have also generated an increasing amount of noise in recent decades. Although anthropogenic noise and Cd contaminants could be present simultaneously in marine environments, the physiological responses of marine bivalve mollusks upon coexposure to anthropogenic noise and toxic metal contaminants, including Cd remain unclear. Therefore, the combined effects of anthropogenic noise and Cd on the physiological characteristics of the blood clam Tegillarca granosa were investigated in this study. The results showed that 10 days of coexposure to anthropogenic noise and Cd can enhance adverse impacts on metabolic processes, as indicated by the clearance rate, respiration rate, ammonium excretion rate, and O:N ratio of T. granosa. In addition, both the ATP content, ATP synthase activity and genes encoding important enzymes in ATP synthesis significantly declined after coexposures to anthropogenic noise and Cd, which have resulted from reduced feeding activity and respiration. Furthermore, the expressions of neurotransmitter-related genes (MAO, AChE, and mAChR3) were all significantly down-regulated after coexposure to anthropogenic noise and Cd, which suggests an enhanced neurotoxicity under coexposure. In conclusion, our study demonstrated that anthropogenic noise and Cd would have synergetic effects on the feeding activity, metabolism, and ATP synthesis of T. granosa, which may be due to the add-on of stress responses and neurotransmitter disturbances.
Highlights
As a byproduct of the zinc, lead and copper refinery, cadmium (Cd) has been recognized as one of the most dangerous toxic metals for many years (Järup, 2003; Kim et al, 2014)
Coexposure to Cd and anthropogenic noise aggravated the suppression of the respiration rates, which declined to approximately 26.0 and 24.0% of the control for groups coexposed to Cd and 70 or 100 dB re 1 μPa anthropogenic noise, respectively (Figure 1B)
Unlike the clearance rate and respiration rate, the ammonium excretion rates were significantly induced by exposure of the blood clams to Cd and/or anthropogenic noise (p < 0.05, Figure 1C)
Summary
As a byproduct of the zinc, lead and copper refinery, cadmium (Cd) has been recognized as one of the most dangerous toxic metals for many years (Järup, 2003; Kim et al, 2014). Noise Aggravates Cd Toxicity and enter into their cells through calcium channels (Vercauteren and Blust, 1999; Shi et al, 2018a), which would subsequently provoke a series of physiological responses, such as a decreased filtration rate, a hampered metabolism, and an altered sex ratio (Liu et al, 2014; Peng et al, 2015a; Shi et al, 2016; Wu et al, 2017). To date, only a few acoustic studies have been conducted with marine invertebrates, especially bivalve mollusks (Peng et al, 2015b). Limited studies have shown that exposure to anthropogenic noise could lead to physiological alterations such as hampered metabolism in marine invertebrates (Peng et al, 2016). An altered O:N ratio and the expression of metabolism-related genes were detected in razor clams, Sinonovacula constricta, in response to anthropogenic noise at intensities of ∼80 and ∼100 dB re 1 μPa (Peng et al, 2016)
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