I found
Caridina sp. LC10 (48hr)= 0.5327 to 0.0447 ppm "acid digested copper" from a completely dubious and unreliable
source...
Ignore completely.
And back to the 1970s we have
this for
Caridina sp. LC50 (48hr) = 0.281 ppm copper sulphate...
Let's do the time warp again.
Which one
hobbyist/blogger/breeder felt wasn't "dangerous"
🙄 ...Consider what a lethal concentration represents over time.
For the freshwater Whisker shrimp
Macrobrachium lamarrei (same taxonomic order as Caridina) two researchers in the 1980s
published LC25 (48hr) = 0.225 and LC25 (96hr) = 0.211 ppm copper sulphate...
Back to the future.
For the Giant river prawn
Macrobrachium rosenbergii this study in 2013 published LC50 (96 hr) = 0.35 ppm copper sulphate, with a detailed discussion of survivability.
NB, Copper(II) sulphate molecular mass 159.609 g/mol, copper Cu(I) molecular mass: 63.545 g/mol, yield of copper ions = 25.59% lower than copper sulphate? so can we reduce the values above somewhat if we assume it was dissociated?
Bioavailable copper might be
a bit different to chelated copper, and apparently: "Organic chelators, such as EDTA and dissolved organic matter, complex cupric ions to generally decrease toxicity although increased toxicity is sometimes observed".
For the freshwater Australian glass shrimp
Paratya australiensis LC-50 (96 hr) = 0.020 ppm copper(II) at 9.1 ppm calcium carbonate alkalinity, and LC-50 (96 hr) = 0.045 ppm copper(II) at 100 ppm calcium carbonate alkalinity, in a
study published in 1990.
Apparently gastropods are more tolerant to copper and can accumulate quite high concentrations without toxic effects.
Well who knew... I'll take that with a sprinkling of salt.
Gammarus are sometimes "model" organisms.
Gammarus pseudolimnaeus hatched and grew to adult stage in total copper concentrations below 0.0046 ppm according to
this publication, but we know that they are very sensitive, except possibly in Darrel's tanks. The newly hatched
Gammarus were markedly reduced when total copper concentrations were between 0.0129 and 0.0062 ppm. It
could depend upon whether they ingest it too.
The no observed adverse effect level (NOAEL) would be far nicer to know that the LC50 or LC25 (48hr).
Anybody got shrimp to sacrifice in the name of progress.
yield about 0.006ppm Cu added per week
My guess is that if EI appears to allow most
Gammarus to hatch and grow, then it would be fairly suitable nutrient dosing, but I could not access that study (above) to see the survival distribution.
My feeling is that you can go ahead with this dosing plan, but also be aware of your water source chemistry (supplier quality reports).
It was mentioned more than once in the literature that copper pipework (especially when it corrodes) and hot water cylinders increase the ionic copper concentration, so I might revise my position
here, and people could factor that in if they were super concerned. It might not matter that much if water conditioners work as advertised and remove copper anyway, but if you started breeding
Gammarus then it might matter.
