Relationships between physiology, tissue contaminants, and biomarker responses in Atlantic cod (Gadus morhua L.)

It is generally assumed that there should be some relationship between tissue residues of contaminants and related biomarker responses in the same individual, with a possible additional modulation through physiological processes. The main basis for such assumptions originated from experimental studies, but it has been less easy to detect and quantify any such relationships in field-collected material. The aim of the current study was to clarify whether the responses of selected biomarkers (cytochrome P-4501A [CYP1A], delta-aminolevulinic acid dehydratase [ALA-D], metallothionein [MT]) could be correlated with physiological parameters and/or contaminant levels. Atlantic cod (Gadus morhua L.) were sampled over a decade at a number of locations along the Norwegian coast. The locations included both polluted and reference areas. In addition to contaminant-related responses (biomarkers), physiological characteristics were registered for each individual and the contaminant load determined. There were clear relationships between responses in all three biomarkers and tissue contaminants, but additional factors such as age or size and liver lipid or liver somatic index also contributed in multiple-regression models. The results indicated that responses in all three biomarkers reflected relevant, contaminant-related processes in the cod even though none of them provided a simple separation between polluted and pristine locations.