**6. Organisms as biomarker for monitoring study**

Marine aquatic organisms can accumulate metals from various sources in their surrounding environment. The possible sources of these metals include sediments and soil erosion [93, 94], air depositions of dust and aerosol [93, 95], and discharges of wastewater [93, 94]. The accumulation of metals in marine aquatic organisms can pose a long-term burden on biogeochemical cycling in the ecosphere [96]. Once the metals enter the food chain, they may accumulate to dangerous levels and be harmful to human health.

Shellfish species which are laying at the second trophic level in the aquatic ecosystem have long been known to accumulate both essential and nonessential metals. Many researchers have reported the potentiality of using mollusks, especially mussel and oyster species, as bioindicators or biomarkers for monitoring the metal contamination of the aquatic system [97, 98]. Besides being a biomarker for marine pollution studies, these mollusk species have also been used in ecotoxicology and toxicity studies. Individual biomonitors respond differently to different sources of bioavailable chemical elements, for example, in the solution, in sediments, or in foods. In order to conclude a complete picture of total metal bioavailability in a marine habitat, it is necessary, therefore, to use a correct biomonitor that can reflect the metal bioavailability in all available potential sources [99]. Such comparative use of different biomonitors should allow identification of the particular source of the contaminant elements [100] (**Figure 6**).

*Sediment and Organisms as Marker for Metal Pollution DOI: http://dx.doi.org/10.5772/intechopen.85569* 

**Figure 6.**  *Shellfish (left, green mussel; right, oyster) are commonly used as biomonitor to study the pollution status.* 

 Metal accumulation in marine aquatic organisms depended on several factors, including the environmental concentrations of metals in water and sediments; the species of organisms; and body size and age of the marine organisms. Different concentrations of metal can also be found in different organs (stomach, gill, muscle, tissue) in the same biological sample [101, 102]. However, scientists mainly focused on the general metal burden in shellfish species such as oyster and mussel and the potential major pathways for metal contaminant in the coastal environment.
