Delineating copper accumulation pathways for the freshwater bivalve Corbicula using stable copper isotopes

Area of Science:

• Environmental toxicology
• Aquatic invertebrate physiology
• Biogeochemistry

Background:

• Understanding metal uptake in aquatic organisms is vital for assessing bioaccumulation and ecological risks.
• Copper (Cu) exposure poses significant risks to freshwater ecosystems.

Purpose of the Study:

• To quantify copper assimilation efficiency (AE) and efflux rate constant (ke) in the freshwater bivalve Corbicula fluminea.
• To determine the relative importance of dietary versus dissolved routes for copper uptake.
• To develop a biodynamic model for predicting copper accumulation in Corbicula.

Main Methods:

• Utilized stable copper isotopes (65Cu) to trace uptake and loss pathways.
• Manipulated isotopic ratios in exposure media (water and algae) to determine physiological parameters.
• Incorporated physiological parameters into a bioaccumulation model.

Main Results:

• Copper AE from ingested algae was 38% in Corbicula fluminea.
• Efflux rate constant (ke) was approximately 0.004 per day, unaffected by uptake route.
• Corbicula accumulated twice as much copper from diet as from water at a dissolved copper concentration of 6.7 microg/L.

Conclusions:

• Dietary uptake is the predominant route for copper accumulation in Corbicula in most freshwater environments.
• The developed biodynamic model accurately represents copper accumulation processes in Corbicula.
• Results are applicable to real-world scenarios, such as the San Francisco Bay-Delta.