The first trophic level is the autotrophic level of a food chain or ecosystem, which is occupied by plants, algae, cyanobacteria, and chemosynthetic organisms; and dominated by primary production processes like photosynthesis.
Freshwater food chain comprises of producers like; coccolithophores, primary consumers like copoepods, secondary consumers like dragonfly nymphs, tertiary consumers like largemouth bass, and quaternary consumers like bald eagle.