Energy transfer efficiency

Definition

Energy transfer efficiency refers to the percentage of energy that is passed from one trophic level to the next in a food web or ecosystem. This concept is crucial in understanding how energy moves through marine ecosystems, highlighting that not all energy is efficiently utilized as it flows from producers to various consumer levels, resulting in energy losses primarily through metabolic processes and heat.

5 Must Know Facts For Your Next Test

1. Typically, only about 10% of the energy at one trophic level is transferred to the next level; this is known as the 10% rule.
2. Energy losses at each trophic level occur due to factors like respiration, growth, reproduction, and excretion.
3. In marine ecosystems, the efficiency of energy transfer can be influenced by factors like nutrient availability and species interactions.
4. Higher trophic levels often have lower energy availability due to the cumulative losses at each step in the food chain.
5. Energy transfer efficiency plays a significant role in determining the productivity and structure of marine food webs.

Review Questions

• How does energy transfer efficiency impact the structure of marine food webs?
  • Energy transfer efficiency affects the structure of marine food webs by limiting the number of trophic levels that can be supported. Since only about 10% of energy is passed from one level to the next, higher trophic levels receive significantly less energy. This means there are generally fewer predators than prey in a healthy ecosystem. Consequently, marine food webs are typically pyramid-shaped, with a broad base of producers and progressively fewer consumers at higher levels.
• Evaluate how primary production relates to energy transfer efficiency in marine ecosystems.
  • Primary production is crucial for establishing the baseline energy available in marine ecosystems. The efficiency with which primary producers convert sunlight into chemical energy directly influences how much energy is available for subsequent trophic levels. If primary production is high and efficient, it supports more primary consumers and subsequently higher secondary consumers. Conversely, low primary production limits overall energy availability, reducing the overall biomass supported by the ecosystem.
• Synthesize information on how energy transfer efficiency may influence bioaccumulation in marine organisms.
  • Energy transfer efficiency influences bioaccumulation because as energy moves up trophic levels, pollutants tend to concentrate in organisms. Since only a fraction of energy (around 10%) is transferred between levels, predators consume multiple prey items, leading to higher concentrations of toxins or heavy metals in their tissues. This means that even if a pollutant is present in low concentrations at the producer level, it can become significantly more concentrated in top predators due to inefficient energy transfer and accumulation through the food web.

Related terms

Trophic Level: The position an organism occupies in a food web, defined by its role in the flow of energy and nutrients, typically categorized as producers, primary consumers, secondary consumers, and so on.

Primary Production:

The process by which autotrophs, such as phytoplankton, convert sunlight into chemical energy through photosynthesis, forming the base of the marine food web.

Bioaccumulation: The accumulation of substances, such as pesticides or heavy metals, in an organism, which can increase as you move up the trophic levels due to energy transfer inefficiencies.