Lesson 21: The Flow of Energy in Ecosystems
In this lesson, we will be looking at the flow of energy through the trophic
levels and how some energy is wasted, and we will also see how Aquatic
ecosystems are more efficient than Terrestrial ecosystems.
Only 2% of incoming solar energy is captured through photosynthesis,
yet this fuels all the life in a biome.
Not all energy is consumed from
one trophic level to the next. Some energy is wasted, and some energy goes out
through waste. More energy is required to feed carnivores that eat foods that
take longer to produce.
Warm-blooded animals in a terrestrial ecosystem require more energy and
are less efficient than cold-blooded animals in an aquatic system.
Energy flows more efficiently in aquatic systems. Since less energy is required
at each tropic level, there is more energy available for the next level. Hence,
aquatic systems may have more than 4 trophic levels. At the highest level,
larger fish consume smaller fish. Smaller fish in turn consumer zoo (animal)
plankton. Zoo plankton, in turn, consume phyto (plant) plankton.
Also,
aquatic systems have the opposite type of biomass pyramid of terrestrial
systems - the pyramid is inverted. This happens also because turnover is high
and life spans are shorter at lower tropic levels.