Effects of mine tailings on early life stages of cod
Mineral industries produce millions of tons of mine tailings waste and in Norway the common practice is to deposit tailings waste by coastal submarine dispersal. Mine tailings slurry include fine particles <100 µm and can have elevated levels of heavy metals from residual mineral ore. Prolonged suspension of small particles in the water column may bring them into contact with locally spawned pelagic fish eggs, including commercially valuable Atlantic cod, Gadus morhua; however, very little is known about the potential impacts of submarine tailings waste disposal on sensitive early life stages of cod. In this experiment we will expose cod embryos and larvae to suspended fine particle mine tailings treatments of different concentrations and with or without addition of the commercial floculant, Magnafloc. The experimental exposure will start up to 2 hours post fertilisation and be carried through hatching and first feeding with live artemia naupliee. This application is for the period of the experiment after first feeding.
We conducted an initial trail experiment with cod embryos and larvae up to 5 days post hatching, and results indicated elevated mortality in hatched larvae, therefore the aim of this experiment will be to investigate the effects in larvae as they develop beyond first feeding. We will have three treatment levels: control, low, and high. The low concentration treatment of tailings will be guided by the level permitted to be released by Nussir AS in Repparfjorden, and the high treatment will be approximately ten times higher. Additionally, we will test the effects of addition with the commercial floculant, Magnafloc. The results will provide valuable information on the environmental impacts of submarine mine tailings dispersal on sensitive early life stages of cod, particularly in fjords such as Repparfjord that are important spawning grounds for cod and where pelagic early life stages of cod will likely come into contact with mine tailings.
We conducted an initial trail experiment with cod embryos and larvae up to 5 days post hatching, and results indicated elevated mortality in hatched larvae, therefore the aim of this experiment will be to investigate the effects in larvae as they develop beyond first feeding. We will have three treatment levels: control, low, and high. The low concentration treatment of tailings will be guided by the level permitted to be released by Nussir AS in Repparfjorden, and the high treatment will be approximately ten times higher. Additionally, we will test the effects of addition with the commercial floculant, Magnafloc. The results will provide valuable information on the environmental impacts of submarine mine tailings dispersal on sensitive early life stages of cod, particularly in fjords such as Repparfjord that are important spawning grounds for cod and where pelagic early life stages of cod will likely come into contact with mine tailings.