Trophic Levels & Energy Flow

Trophic Levels & Energy FlowChapter 2.3 & 2.4Nutrient Flow Through EcosystemsWe have already studied how nutrients flow through ecosystems:

Nutrient Flow Through EcosystemsNotice that nutrients are continuously recycled through ecosystems by decomposers through a process called biodegradation.Nutrient Flow Through EcosystemsEnergy Flow Through EcosystemsDefine energy:The ability to make things move, orThe ability to do work.

Law of conservation of energy:Energy can neither be created nor destroyed, it can only change from one form to another.Energy Flow Through EcosystemsWhat is the ultimate source of energy in any ecosystem?The Sun it gives off heat and light.

Energy Flow Through EcosystemsWhat is the only type of organism that can derive energy directly from solar energy?Producers they usesunlight to manufacturefood by photosynthesis.

Energy Flow Through EcosystemsFrom there, solarenergy indirectlypasses to theprimaryconsumers whichare also calledherbivores.

Energy Flow Through EcosystemsFrom there, solar energy indirectly passes to the secondary consumerswhich are also called carnivores.

Energy Flow Through EcosystemsFinally, this solar energy indirectly passes to the tertiary consumers which are also called top predators or top consumers.

Energy Flow Through EcosystemsSo how is the flow of energy different than the flow of nutrients through an ecosystem?Energy, unlike nutrients, cannot be recycled.Energy is lost to heat along each step of the pathway. Each organism changes up to 90% of energy gained to heat. (So only 10% of the energy gets passed onto the next organism!)Trophic Levels and Ecological PyramidsOrganisms can be arranged by the energy they consume in the shape of a pyramid.Trophic Levels and Ecological PyramidsEach level of this pyramid is called a trophic level and it shows the position of the organism in the energy pyramid.There is less energy as we get nearer the top of the pyramid.Trophic Levels and Ecological PyramidsThe pyramid must broad at the base and narrower at the top because energy is lost to heat by each organism as we go up the pyramid, so less energy is available at each trophic level.This limits the number of organisms at each level.There is not enough energy to support large populations at each level.Trophic Levels and Ecological PyramidsThe pyramid willnever have morethat 4 trophic levelsbecause there is notenough energy tosupport animals at ahigher trophic level.

Food ChainsDefine food chain:The pathway taken by nutrients through different trophic levels in an ecosystem. (ex. Grazing food chain.)

Food ChainsDetritus Food ChainThis is different from a regular food chain because it occurs when left overs (undigestible remains) that cannot be a part of the grazing food chains are left for the detrivores and decomposers to recycle for other consumers.