How are terrestrial ecosystems different from aquatic ecosystems?

In the study of biology, terrestrial and aquatic ecosystems are distinguished primarily by their physical environments and the factors that influence their vegetation and biological communities.1

Key Differences

• Environmental Drivers: Terrestrial ecosystems—such as forests, grasslands, and deserts—are primarily influenced by precipitation and temperature. In contrast, aquatic ecosystems (including marine and freshwater environments) are influenced most significantly by light availability and nutrient concentrations.21
• Physical Medium: Organisms transitioning from terrestrial to aquatic environments must adapt to a medium of significantly greater density and viscosity, which also typically contains less oxygen than air.3
• Biological Composition: While both systems share fundamental trophic levels—producers, consumers, and decomposers—the specific organisms differ. Terrestrial ecosystems are defined by major vegetational types, whereas aquatic ecosystems rely heavily on algae and other aquatic plants as primary producers.412
• Evolutionary Origins: Notably, no major group of organisms evolved originally in inland aquatic environments; these ecosystems were colonized over time by species originating from either the sea or land.3

Would you like to learn more about the specific adaptations organisms use to survive in these different environments?