Chapter 27
Ecosystems
![What is an Ecosystem?](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/10926.jpg)
An ecosystem is the interaction between all abiotic and biotic factors in an environment and can be classified as terrestrial or aquatic.…
![Trophic Levels](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/10927.jpg)
All organisms in an ecosystem occupy a trophic level in the food chain. The lowest level consists of primary producers, which synthesize their food…
![Production Efficiency](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/10929.jpg)
Net production efficiency (NPE) is the efficiency at which organisms assimilate energy into biomass for the next trophic level. Due to low metabolic…
![Trophic Efficiency](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/10930.jpg)
Trophic level transfer efficiency (TLTE) is a measure of the total energy transfer from one trophic level to the next. Due to extensive energy loss…
![The Water Cycle](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/10932.jpg)
The Earth’s hydrosphere includes all of the areas where the storage and movement of water occurs. Since water is the basis of all living…
![The Carbon Cycle](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/10933.jpg)
Carbon is the basis of all organic matter on Earth, and is recycled through the ecosystem in two primary processes: one in which carbon is exchanged…
![The Phosphorus Cycle](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/10935.jpg)
Unlike carbon, water, and nitrogen, phosphorus is not present in the atmosphere as a gas. Instead, most phosphorus in the ecosystem exists as…
![The Sulfur Cycle](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/10936.jpg)
Sulfur, an important element in the chemical makeup of proteins, is recycled through the atmosphere and aquatic and terrestrial environments. Found…
![Understanding Dissolved Organic Matter Biogeochemistry Through <em>In Situ</em> Nutrient Manipulations in Stream Ecosystems](https://cloudfront.jove.com/files/thumbs/54704_t.png)
Dissolved organic matter (DOM) is a highly diverse mixture of molecules providing one of the largest sources of energy and nutrients to stream…
![Removal of Exogenous Materials from the Outer Portion of Frozen Cores to Investigate the Ancient Biological Communities Harbored Inside](https://cloudfront.jove.com/files/thumbs/54091_t.png)
The cryosphere offers access to preserved organisms that persisted under past environmental conditions. In fact, these frozen materials could reflect…