Final answer:
Trophic levels in terrestrial and aquatic food chains include producers, primary consumers, secondary consumers, and tertiary consumers.
Step-by-step explanation:
Trophic levels are different feeding positions in a food chain or web. In both terrestrial and aquatic ecosystems, the trophic levels include producers, primary consumers, secondary consumers, and tertiary consumers. Producers, such as plants or green algae, occupy the first trophic level as they convert sunlight into energy through photosynthesis. Primary consumers, like herbivores, feed on producers and are found in the second trophic level. Secondary consumers, such as carnivores, eat primary consumers and occupy the third trophic level. Tertiary consumers, at the top of the food chain, eat secondary consumers and are usually apex predators.