Increasing contamination of marine ecosystems by metals such as mercury, cadmium, chromium and nickel is a global environmental concern, because elevated concentrations of metals can pose hazards to marine organisms, and humans who may consume contaminated seafood. Setting water quality criteria (WQC) for metals (i.e., environmental safety limits) is an essential step for assessing and regulating risk levels in the marine environment, and hence offering protection to marine organisms and ecosystem integrity.