trophic

Examples of trophic in the following topics:

• Transferring of Energy between Trophic Levels

  • Large amounts of energy are lost from the ecosystem between one trophic level and the next level as energy flows from the primary producers through the various trophic levels of consumers and decomposers.
  • The measurement of energy transfer efficiency between two successive trophic levels is termed the trophic level transfer efficiency (TLTE) and is defined by the formula:
  • $TLTE=\frac { production\quad at\quad present\quad trophic\quad level }{ production\quad at\quad previous\quad trophic\quad level } x100$
  • Thus, NPE measures how efficiently each trophic level uses and incorporates the energy from its food into biomass to fuel the next trophic level.
  • Notice how some lines point to more than one trophic level.

• Biological Magnification

  • When toxic substances are introduced into the environment, organisms at the highest trophic levels suffer the most damage.
  • In some aquatic ecosystems, organisms from each trophic level consumed many organisms of the lower level, which caused DDT to increase in birds (apex consumers) that ate fish.
  • This chart shows the PCB concentrations found at the various trophic levels in the Saginaw Bay ecosystem of Lake Huron.
  • Numbers on the x-axis reflect enrichment with heavy isotopes of nitrogen (15N), which is a marker for increasing trophic levels.
  • Notice that the fish in the higher trophic levels accumulate more PCBs than those in lower trophic levels.

• Food Chains and Food Webs

  • Energy and nutrients move up trophic levels in the following order:
  • Therefore, after a limited number of trophic energy transfers, the amount of energy remaining in the food chain cannot support a higher trophic level.
  • These are the trophic levels of a food chain in Lake Ontario.
  • The relative energy in trophic levels in a Silver Springs, Florida, ecosystem is shown.
  • Each trophic level has less energy available and supports fewer organisms at the next level.

• Ecological Pyramids

  • Ecological pyramids can also be called trophic pyramids or energy pyramids.
  • Even in smaller numbers, primary producers in forests are still capable of supporting other trophic levels.
  • This pyramid measures the amount of energy converted into living tissue at the different trophic levels.
  • Pyramid ecosystem modeling can also be used to show energy flow through the trophic levels.
  • Ecological pyramids depict the (a) biomass, (b) number of organisms, and (c) energy in each trophic level.

• Productivity within Trophic Levels

  • Productivity within an ecosystem can be defined as the percentage of energy entering the ecosystem incorporated into biomass in a particular trophic level.
  • Biomass is the total mass in a unit area (at the time of measurement) of living or previously-living organisms within a trophic level.
  • Ecosystems have characteristic amounts of biomass at each trophic level.
  • The net productivity is then available to the primary consumers at the next trophic level.
  • Notice that the energy decreases with each increase in trophic level.

• Planktonic Food Webs

  • However, determining the trophic level of some plankton is not straightforward.
  • As these organisms form the base of the marine food web, this variability in phytoplankton growth influences higher trophic levels.

• Organization of Ecosystems

  • All life forms in an ecosystem can be broadly grouped into one of two categories (called trophic levels):
  • In general, trophic levels are used to describe the way in which a particular organism within an ecosystem gets its food.

• Planktonic Communities

  • Plankton are primarily divided into broad functional (or trophic level) groups: Phytoplankton , Zooplankton, and Bacterioplankton.
  • However, determining the trophic level of some plankton is not straightforward.
  • As these organisms form the base of the marine food web, this variability in phytoplankton growth influences higher trophic levels.

• Chemoautotrophs and Chemoheterotrophs

• Hydrothermal Vent Microbial Ecosystems

  • The chemosynthetic bacteria grow into a thick mat, covering the hydrothermal vent, and this is the first trophic level of the ecosystem.