Metal and oxygen uptake in the green mussel Perna viridis under different metabolic conditions

Abstract

Coupled respirometric and radiotracer techniques were applied to simultaneously measure the rates of oxygen and metal uptake in the green mussel Perna viridis. This was performed under different metabolic conditions by varying the ambient oxygen partial pressure (P(O2)), temperature, air exposure, and body size. When the mussels were tested under different hypoxic and anoxic conditions, Cd and Zn uptake decreased with decreasing P(O2), accompanied by a decrease in the ventilation activity of mussels. Significant reduction in metal uptake was observed at a P(O2) level of 3 kPa. Under anoxic conditions, the uptake of Cd and Zn was 1.6 to 2.7 times and 2.8 times, respectively, lower than those measured under normoxia. In contrast, both the absorption efficiencies of Cd and Zn and the oxygen extraction efficiency increased significantly with decreasing P(O2). There were significant correlations between the rates of Cd/Zn and O2 uptake by the mussels when quantified under various P(O2) levels. The uptake of Cd and Zn was temperature dependent and increased with temperature over a range of 15 to 30 degrees C. Significant correlations between the rates of Cd/Zn and O2 uptake were also found in the temperature experiments. With reimmersion of mussels after aerial exposure, the mussels experienced an apparent O2 debt. Metal uptake also increased within the first 15 min followed by gradual recovery to the control levels. Similarly, the quantified uptake rates of Zn were significantly correlated with the O2 uptake in experiments with different sizes of mussels. These results strongly suggest that Cd and Zn uptake are coupled with oxygen uptake in the mussels; thus, physiological processes need to be considered in studying metal accumulation.

Effects of temperature on scope for growth and accumulation of Cd, Co, Cu and Pb by the marine bivalve Mytilus edulis

“…However, Blackmore and Wang (2003) observed low uptake among mussels with high filtration rates, though those results may have been influenced by other factors. Respiration rate also has the potential to affect metal content of mussels, Wang et al (2005) found uptake of Cd and Zn to decrease with decrease in respiration rate. In this study, none of the SFG parameters could be directly correlated with observed metal uptake or accumulation among the temperature treatments.…”

“…In both studies temperature exposures were coupled with different salinity treatments, therefore it is not clear whether salinity or interaction between the two factors may have influenced the results. Some recent studies have reported uptake that is dependent and increases with increase in temperature (Wang et al, 2005). Baines et al (2005) also found a positive relationship between assimilation efficiency of dietary metals with temperature.…”

Interactive effects of metal pollution and temperature on metabolism in aquatic ectotherms: implications of global climate change

“…For example, the proportion of time spent actively ventilating increased with increasing temperatures and Cd exposure in eastern oysters Crassostrea virginica; at 20°C oysters spent about 30% of time actively ventilating, whereas at 28°C oysters exposed to Cd spent > 70% of time ventilating (Lannig et al 2006). Cd and Zn uptake rates were closely correlated with the rate of oxygen consumption (M · O 2 ) and ventilation rates in green mussels Perna viridis over a wide range of environmental temperatures and O 2 partial pressures (Wang et al 2005). Other studies in bivalves also demonstrate that ventilatory activity may be a rate-limiting step in metal uptake in these organisms (Massabuau & Tran 2003).…”

Climate change and seafood safety: Human health implications

“…Temperature-related increases in the uptake, bioaccumulation and toxicity of metals have been reported for several marine organisms, including crustaceans, echinoderms and molluscs (Hutchins, Teyssii, Boisson, Fowler, & Fisher, 1996;Sullivan, 1977;Wang, Chuang, & Wang, 2005) (see Table 1). However, different species respond differently to such stresses.…”