Which is one of the six fundmental elements that are found in living organisms

The six fundmental elements are carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur.

poor water quality affects most estuarine organisms, including commercially important fish and shellfish. the pollutants that have the greatest impact on the health of estuaries include toxic substances like chemicals and heavy metals, nutrient pollution (or eutrophication), and pathogens such as bacteria or viruses.