Bacteria, Phytoplankton, and Water Quality

Abstract

This chapter will consider the importance of aquatic organisms as agents controlling water quality. Organisms having the greatest influence on water quality are the microscopic algae, called phytoplankton, and bacteria. Phytoplankton produce large amounts of organic matter through photosynthesis and release large quantities of oxygen into water during this process. Bacteria decompose organic matter and cause many transformations of chemical compounds. The respiration of bacteria and the respiration and photosynthesis of phytoplankton have a pronounced effect on pH and concentrations of carbon dioxide and dissolved oxygen in water. Certain bacteria and other microscopic organisms are pathogenic, and some species of algae can impart bad tastes and odors to water. Therefore, aquatic organisms play a central role in water quality.