Effects of mine tailings on early life stages of Atlantic cod

In Norway, mine tailings waste can be deposited by coastal sumbarine dispersal. Mine tailings slurry include fine particles <10 um with elevated levels of metals (e.g. copper, iron) from residual mineral ore. Prolonged suspension of small particles in the water column may bring them into contact with locally spawned pelatic fish eggs, including Atlantic cod, Gadus morhua. Newly fertilesed cod embryos were exposed to suspended mine tailings particles up to 3.2 mg/L in flow-through aquaria for a total of 21 days. Significantly more particles adhered to the surface of the chorion from the high treatment after 11 days exposure, and dissolved Cu concentrations increased in the water (up to 0.36 +/1 0.06 ug/L). There was no adverse effect on embryo mortality, at an 8% elevation in larval mortality. There were no differences with treatment on timing of hatching, embryo and larvae morphometrics, abnormalities, or cardiac activity. There was a treatment-dependent up-regulation of stress marker genes (hspa8, cyp1c1) but no indication of metal-induced activation of metallothionien (mt gene transcription). Transcription markers for DNA and histone methyltransferases did show treatment-related up-regulation, indicative of altered methylation in larvae when developmental methylation patterns are determined, indicating some level of chronic toxicity that may have longer term effects.

Authors:

Reinardy HC, Pedersen KB, Nahrgang J, Frantzen M

Environmental Toxicology and Chemistry
03, 22, 2019
Pages:
DOI: 10.1002/etc.4415