trace additives are only useful when you have the means to test for it.
It can become an act of futility or a pre-curser to concentration toxity levels curving with a step climb.
anyway.
copper> they pull you up for speeding & unless you've got boobs, they pin you for it! haha,

ok
copper> your crustations require trace amounts of
copper consistantly for proper blood/oxygen circulation within their bodies. pretty much anything thats carbon based uses
copper on some level as a catalyst to metabolism & growth. You'd be supprissed actually at how much is taken up by various species from both fresh & salt based levels, & more so from land based sources. proberbly the biggest user of
copper in any given situation would be bactera, Once again, building blocks for growth.
Even more spun out is the ability of some aquatic fourna to process usable forms of organic
copper into in-organic forms to deter or stunt the growth of a would-be aggressor. so you see,
copper has its uses, its just the animals you keep determin usage, & as others have mentioned before, modern day salts should be more than balanced in this area.