Anurse is teaching a class to parents about keeping medications and household cleaning supplies out of the reach of toddlers. the nurse explains that this is necessary because toddlers:

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.