It is very difficult, even for professional marine biologists, to build these energy pyramids. The water world is made up of many interconnected biomes, and some animals spend different parts of their lives in different environments. Water depth affects how much light reaches plants, and so productivity changes as the water gets deeper. In addition, aquatic life is dependent on receiving nutrients from the water. Sometimes (most often in spring and then fall) water up-welling from the deep sea brings up nutrients that the phytoplankton feed on. Phytoplankton can react in hours to changes in nutrients and light. Nutrients are quickly utilized by the tiny plants, which are then devoured by the tiny animals that make up the zooplankton.
On land, we know what to expect from a desert area or a forest: in the water, an area may be incredibly fertile for a few weeks and then a nutrient-poor desert for a couple of months. Given all these uncertainties, let us grasp the Big Ideas firmly and make guesses on the numbers.
Let's take a quick look at the light situation.
This soon to be extrememly exciting page is still under construction!