Why are phytoplankton important? Sharon Sample 03.13.01 These small plants are the beginning of the food chain for most of the planet. As phytoplankton grow and multiply, small fish and other animals eat them as food. Larger animals then eat these smaller ones. The ocean fishing industry often finds good fishing spots by looking at ocean color images to locate areas rich in phytoplankton.    Phytoplankton, as revealed by ocean color, frequently show scientists where ocean currents provide nutrients for plant growth.    ln addition, the plants show where pollutants poison the ocean and prevent plant growth, and where subtle changes in the climate-warmer or colder more saline or less saline-affect phytoplankton growth. Since phytoplankton depend upon specific conditions for growth, they frequently become the first indicator of a change in their environment.  National Atmospherica and Space Administration (NASA)  Earth Science Enterprise  kids.earth.nasa.gov ©2001 The Aurora Collection, Inc. All Rights Reserved. Site Development by: Interactive Multimedia. Inc.