Autotrophs or primary producers are organisms that acquire their energy from sunlight and materials from nonliving sources. Copepods are a group of small crustaceans found in nearly every freshwater and saltwater habitat. Copepods are major secondary producers in the World Ocean. They represent an important link between phytoplankton, microzooplankton and higher trophic levels such as fish. They are an important source of food for many fish species but also a significant producer of detritus. Hence, option 1 is not correct. Cyanobacteria, also called blue- green algae, are microscopic organisms found naturally in all types of water. Cyanobacteria are