Aquatic ecology and Biodiversity

Unit 2- Ecosystem ecology

2.2.3. Thermodynamics
The first law of thermodynamics
It states that “energy can neither be created nor destroyed, but it can simply change in form”. The light energy of the sun is converted into electrical energy in the chlorophyll. The electrical energy is converted into chemical energy during photosynthesis. The chemical energy is transformed in to heat energy during metabolism. The heat energy is transformed into mechanical energy for doing work. Energy can neither created nor destroyed i.e. the energy of ecosystem is constant and thus it obeys the first law of thermo dynamics.

The second law of thermodynamics
It states that “during energy transfer, large part of energy is degraded into heat and dissipates”. When energy is transferred from producers to herbivores about 90% of energy is lost as heat. The change of energy from one form to another the free energy diminishes and thus it obeys the second law of thermo dynamics

Flow of energy between phyto and zooplankton.
Ecological efficiency Et = Pt

Pt-1

Et will be equal to the amount of herbivore (Pt) divided primary productivity(Pt-1 ) in marine ecosystem ie. 20% plants to herbivores and 15-10% at higher tropic levels.