1. The barnacles secrete a cement-like substance that anchors them to rocks in the a. Intertidal Zone
b. Mangrove Forests
C. Pond Area
d. Tropical forests

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.