Re: Why do barnacles slow feeding in copper sulphate solution?

I could not find any exact experimental explanation for your results.  
However, it is generally accepted that ingestion of heavy metals in high  
concentrations (such as in your experiment) cause all sorts of 
physiological problems in various filter feeders.  For example, copper can 
cause endocrine problems in several filter feeders.  I would imagine that 
dealing with a toxic substance could easily cause an organism to slow its 
feeding and rely more on stored nutrients until less toxic materials can be 
filtered.  

Good luck in finding more answers with this.