ENERGY and ECOLOGY: Ecological Pyramids

Productivity of Ecosystems Energy is the currency of ecosystem Most energy is reflected back into space or is absorbed by atmosphere Only about 1% of sun light that reaches producers is captured by photosynthesis Producers convert sun (radiant) E into chemical E that is stored in organic compounds (glucose) This energy captured by producers enables producers to make billions of kg of organic matter (BIOMASS) each year

Primary Productivity Rate at which producers in an ecosystem build biomass Set the energy budget for ecosystem Determines maximum amt of E available to all higher trophic levels in ecosystem We look at “net productivity” Total amt of organic material produced minus the amount used by the producers themselves

Three Types of Pyramids Represent Trophic Levels in Ecology Pyramids of Energy Pyramids of Biomass Pyramids of Numbers

Pyramid of Energy Aka food pyramid Energy flow thru trophic levels Primary producers covert 1% of energy from sun Only 10% of energy from one trophic level is passes onto the next The other 90% is used by the organism to carry out its life processes or it is lost to the environment So much energy required to maintain an organism Limited to 3 or 4 steps Cannot be inverted Emphasizes E LOSS b/t trophic levels

Energy Pyramid

Pyramid of Biomass Total dry weight of living tissue at each trophic level kg of living tissue/ area Usually follows traditional narrowing form of pyramid May be inverted Ex. Aquatic ecosystems Zooplankton consume phytoplankton very fast that their biomass actually ends up being larger

Biomass Pyramid

Ecological Pyramids of Biomass The total dry weight of organisms (standing crop) in a particular trophic level is referenced as biomass. Most pyramids follow the typical pattern of narrowing at each level, however in some aquatic ecosystems, the pyramid may be inverted. In the example, phytoplankton grow and reproduce so rapidly that they can support a large population of zooplankton even though at any one time, the biomass of phytoplankton is smaller than that of the zooplankton. References Campbell, N. E., & Reece, J. B. (2002). Biology (6th ed.). San Francisco: Benjamin Cummings. Holligan, P. M., Harris,R. P., Newell, R. C., Harbour, D. C., Head, R.N., Linley, E. A. S., Lucas, M. I., Tranter, P. R. G., & Weekly, C. M. (1984). Vertical distribution and partitioning of organic carbon in mixed, frontal, and stratified waters of the English Channel. Marine Ecology Progress Series, 14, 111-127. Raven, P. H., & Johnson, G. B. (2002). Biology (6th ed.). McGraw-Hill. Image Reference Young, M. (2004). Ecology Biomass Pyramid. Baylor College of Medicine, Center For Educational Outreach.

Inverted Biomass Pyramid

Pyramid of Numbers Show the number of organisms at each trophic level in ecosystem Producers at the bottom, higher trophic levels above Not always a perfect pyramid Exception is when small organisms eat larger one (insects eating a tree)

Pyramid of Numbers vs. Biomass Bluebird Bluebird

Ladybirds Arthropods

Arthropods feed on tiny algae. Sardines feed on tiny arthropods Arthropods feed on tiny algae. Sardines feed on tiny arthropods. Dolphins feed on sardines. Antelope feed on grass. Lions feed on antelope. Fleas live on lions and suck their blood. Greenflies feed on rose bush. Ladybirds feed on greenflies. Swallows feed on ladybirds. Zebras feed on long grass. Ticks suck the blood of zebras. Birds sit on the zebras’ backs and eat the ticks.