Energy Transfer through Ecosystems

Energy Transfer through Ecosystems

Overall Concept

  • Energy flows through an ecosystem in one direction.
  • The energy originates from the sun and is taken in through photosynthesis.
  • Photosynthesis is the process in which green plants and some other organisms use sunlight to synthesize foods with the aid of chlorophyll pigments.
  • The energy is then passed on through various trophic levels (different levels of a food chain).
  • Each organism in an ecosystem fits into multiple food chains and is part of a complex food web.
  • Energy is lost in each transfer between trophic levels. This can be due to respiration, movement, egestion, or death and decay (non-consumption).

Photosynthesis and Primary Producers

  • Green plants (also known as autotrophs or primary producers) capture the sun’s energy and convert it into chemical energy in the form of glucose.
  • This process is called photosynthesis and involves converting carbon dioxide (CO2) and water (H2O) into glucose (C6H12O6) and oxygen (O2).
  • 6CO2 + 6H2O + light energy –> C6H12O6 + 6O2

Herbivores and Primary Consumers

  • Organisms that consume plants are called herbivores or primary consumers.
  • They obtain energy by eating plants and converting the plant matter into a form they can use.
  • These organisms include rabbits, cows, and sheep.

Secondary and Tertiary Consumers

  • Carnivores (secondary and tertiary consumers) obtain energy by consuming primary consumers.
  • This includes organisms such as wolves, lions, and eagles.
  • They convert the consumed matter into a form they can use.
  • Omnivores, organisms that eat both plants and animals, can be primary, secondary, or tertiary consumers.

Energy Loss in Trophic Levels

  • As energy moves up the food chain, much of it is lost at each level.
  • Approximately 90% of energy is lost with each transfer, only about 10% of energy is passed to the next trophic level.
  • Much of the lost energy is used for metabolic processes in the organisms, such as growth, reproduction, and movement.
  • Other means of energy loss include faeces, urine, and heat loss due to cellular respiration.

Efficiency of Energy Transfer

  • The efficiency of energy transfer between trophic levels can be calculated using the following equation: Energy transfer efficiency = (Energy available after the transfer / Energy available before the transfer) * 100%.
  • The calculation shows that, on average, only about 10% of the energy is transferred from one trophic level to the next level.

The 10% Rule and Pyramid of Energy

  • Due to the limited energy transfer, the structure of an ecosystem is often presented as a pyramid.
  • This is known as a pyramid of energy where each level represents the amount of energy present at each trophic level.
  • The size of each level depends on the energy available to it, supporting the “10% Rule”. It is represented broader at the base (plant level) and becomes narrower towards the top (higher consumers).

Decomposers and Detritus Feeders

  • Detritus feeders and decomposers play a crucial role in the ecosystem. They obtain energy by breaking down dead organic material.
  • Decomposers, such as fungi and bacteria, break down complex organic compounds into simpler substances.
  • Detritus feeders, such as earthworms and woodlice, consume dead plant and animal material, which they return to the soil as nutrients.

Importance of Ecosystem Energy Flow

  • The flow of energy within an ecosystem is essential for the survival and functioning of that system.
  • It determines the abundance and diversity of organisms in an ecosystem.
  • Understanding this energy flow is key to managing natural resources, conserving biodiversity, and addressing issues such as climate change.