Studies or surveys often use shellfish as useful indicators of bacterial contamination as well. The non-mobile bivalves are particularly helpful as they pinpoint specific areas of contamination. Shellfish, therefore, often reflect some of the most important mea sures of water quality. By analyzing the hazardous compounds in the animals' tissues, scientists can gain insight into selective aspects of local estuarine health. The Contaminants Several types of contaminants can accumulate in shellfish.
Some shellfish are more susceptible to certain contaminants than others.
While a species may easily tolerate high concentrations of one chemical, low concentrations of another can be lethal. The life stage of an individuallarva, juvenile, or adultwill also greatly affect its response to a toxic substance. In general, larvae and juveniles are more vulnerable to injury or death from exposure to these substances. Studies of the effects of toxic compounds must consider both the age and species of the specimens to fully assess the chemical's toxicity. Bacteria Shellfish collect fecal bacteria in their gut, making them good indicators of recent exposure to sewage waste.