Energy Transfer
Energy transfers among trophic levels: How much energy is passed from one trophic level to the next? How efficient
are such transfers?
The answer actually varies based on many factors, such as the type of organism, but there are a few key rules of
thumb that we can use to estimate how much energy is used and how much is available to the next trophic level of
the food web.
First, let's start with the autotrophs. Organisms that use photosynthesis to harness energy are only able to convert
about one percent of the total light energy that hits them into usable chemical energy. Of that energy that is
harnessed by producers through photosynthesis, about 30% is used during metabolic processes and dissipated as
heat, and about 70% becomes stored energy.
What about consumers? Consumers do not consume all of the energy stored in producers; they only consume about
one-seventh of all of the energy stored, which turns out to be about ten percent of the total energy that is
harnessed by producers through photosynthesis. They also use energy very differently than producers, and that is
largely due to the fact that consumers are usually mobile. Movement uses a lot of energy, and in addition, some
consumers, like birds and mammals, also use a lot of energy specifically to create their own heat and maintain body
temperature. However, secondary, tertiary, and quaternary consumers consume more of the stored energy
available to them. So, when all is said and done, the consumers at each trophic level, on average, pass along about
ten percent of the total energy they receive to the next trophic level that feeds upon them. Most of the other 90%
of the energy is used in various functions, such as metabolism and movement, and is ultimately dissipated as heat,
and whatever isn't used or eaten by predators is consumed by detritivores.
http://ecology2.weebly.com/energy-transfer.html
Energy Transfer
Energy transfers among trophic levels: How much energy is passed from one trophic level to the next? How efficient
are such transfers?
The answer actually varies based on many factors, such as the type of organism, but there are a few key rules of
thumb that we can use to estimate how much energy is used and how much is available to the next trophic level of
the food web.
First, let's start with the autotrophs. Organisms that use photosynthesis to harness energy are only able to convert
about one percent of the total light energy that hits them into usable chemical energy. Of that energy that is
harnessed by producers through photosynthesis, about 30% is used during metabolic processes and dissipated as
heat, and about 70% becomes stored energy.
What about consumers? Consumers do not consume all of the energy stored in producers; they only consume about
one-seventh of all of the energy stored, which turns out to be about ten percent of the total energy that is
harnessed by producers through photosynthesis. They also use energy very differently than producers, and that is
largely due to the fact that consumers are usually mobile. Movement uses a lot of energy, and in addition, some
consumers, like birds and mammals, also use a lot of energy specifically to create their own heat and maintain body
temperature. However, secondary, tertiary, and quaternary consumers consume more of the stored energy
available to them. So, when all is said and done, the consumers at each trophic level, on average, pass along about
ten percent of the total energy they receive to the next trophic level that feeds upon them. Most of the other 90%
of the energy is used in various functions, such as metabolism and movement, and is ultimately dissipated as heat,
and whatever isn't used or eaten by predators is consumed by detritivores.
http://ecology2.weebly.com/energy-transfer.html