contaminants. (Scanes and Roach 1999; Robinson et
al. 2005). In Vietnam, Saccostrea glomerata that widely
distributes in littoral areas along the coast are found
commonly attached on rocks, boulders, and underwater
structures. The rock oyster is also consumed as
seafood by local people, but there is a lack of
information related to heavy metals in the oysters in
northern Vietnam. Knowledge about heavy metal
concentrations in native species is very important for
understanding the water quality, public health, and
risk from human consumption. Therefore, the objective
of the study is to investigate heavy metal
contamination in the rock oyster at different sampling
sites and seasonal variation along Haiphong-
Quangning coastal waters.