Ecosystem Organization

Marine environment is divided by distance from land, depth and the type of organisms living there.

Food chains, the linkage between food webs, are fairly easy to determine when animals are specialists. In this three step chain, whales are the top predator existing ultimately on krill (which exist on phytoplankton). Each step in the chain is known as a trophic level. How many trophic levels are present here?

Multiple food chains at multiple trophic levels result in a food web. As you can observe, many interactions are possible. Energy can be transferred from one level to the other in amazing ways.

Here is another way of looking at it. Killer whales are the top predators. Each part of the trophic level could be viewed as a “factory” for converting one thing to another! How many “factories” does it take to convert diatoms into killer whale??

Trophic Pyramids: Heat conversion In a trophic pyramid plants and animals all are assigned a caloric value. As we travel “up” the trophic pyramid, heat is lost. By the time we reach the uppermost level many calories have been used, and much heat produced to make a pound of blue or right whale.

How much is being produced? By measuring the rates of p-synth. Ecologists are often able to determine how much carbon is fixed by plants (gross primary productivity) This is yet another method to measure system productivity and its efficiency. Units: gC/m2/day

Earth’s Primary Production Ocean Production: Red = high, blue = low Land Production: Green = high, yellow = low

Carbon Cycle

Nitrogen Cycle

Phosphorus Cycle